feat：移除了弹窗，服务器添加sls

packages/app-lib/src/api/cache.rs

@@ -0,0 +1,177 @@
+use crate::state::{
+    CacheBehaviour, CacheValueType, CachedEntry, ModrinthProjectId,
+    ModrinthVersionId, Organization, Project, ProjectV3, SearchResults,
+    SearchResultsV3, TeamMember, User, Version, VersionV3,
+};
+
+macro_rules! impl_cache_methods {
+    ($(($variant:ident, $type:ty)),*) => {
+        $(
+            paste::paste! {
+                #[tracing::instrument]
+                pub async fn [<get_ $variant:snake>](
+                    id: &str,
+                    cache_behaviour: Option<CacheBehaviour>,
+                ) -> crate::Result<Option<$type>>
+                {
+                    let state = crate::State::get().await?;
+                    Ok(CachedEntry::[<get_ $variant:snake _many>](&[id], cache_behaviour, &state.pool, &state.api_semaphore).await?.into_iter().next())
+                }
+
+                #[tracing::instrument]
+                pub async fn [<get_ $variant:snake _many>](
+                    ids: &[&str],
+                    cache_behaviour: Option<CacheBehaviour>,
+                ) -> crate::Result<Vec<$type>>
+                {
+                    let state = crate::State::get().await?;
+                    let entries =
+                        CachedEntry::[<get_ $variant:snake _many>](ids, None, &state.pool, &state.api_semaphore).await?;
+
+                    Ok(entries)
+                }
+            }
+        )*
+    }
+}
+
+impl_cache_methods!(
+    (ProjectV3, ProjectV3),
+    (User, User),
+    (Team, Vec<TeamMember>),
+    (Organization, Organization),
+    (SearchResults, SearchResults),
+    (SearchResultsV3, SearchResultsV3)
+);
+
+#[tracing::instrument]
+pub async fn get_project(
+    id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Option<Project>> {
+    let id = ModrinthProjectId::new(id.to_string())?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_project(
+        &id,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_project_many(
+    ids: &[&str],
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<Project>> {
+    let ids = ids
+        .iter()
+        .map(|id| ModrinthProjectId::new((*id).to_string()))
+        .collect::<crate::Result<Vec<_>>>()?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_project_many(
+        &ids,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_version(
+    id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Option<Version>> {
+    let id = ModrinthVersionId::new(id.to_string())?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_version(
+        &id,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_version_many(
+    ids: &[&str],
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<Version>> {
+    let ids = ids
+        .iter()
+        .map(|id| ModrinthVersionId::new((*id).to_string()))
+        .collect::<crate::Result<Vec<_>>>()?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_version_many(
+        &ids,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_version_v3(
+    id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Option<VersionV3>> {
+    let id = ModrinthVersionId::new(id.to_string())?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_version_v3(
+        &id,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_version_v3_many(
+    ids: &[&str],
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<VersionV3>> {
+    let ids = ids
+        .iter()
+        .map(|id| ModrinthVersionId::new((*id).to_string()))
+        .collect::<crate::Result<Vec<_>>>()?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_version_v3_many(
+        &ids,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+pub async fn purge_cache_types(
+    cache_types: &[CacheValueType],
+) -> crate::Result<()> {
+    let state = crate::State::get().await?;
+    CachedEntry::purge_cache_types(cache_types, &state.pool).await?;
+
+    Ok(())
+}
+
+/// Get versions for a project (without changelogs for fast loading).
+/// Uses the cache system with the ProjectVersions cache type.
+#[tracing::instrument]
+pub async fn get_project_versions(
+    project_id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Option<Vec<Version>>> {
+    let project_id = ModrinthProjectId::new(project_id.to_string())?;
+    let state = crate::State::get().await?;
+    CachedEntry::get_project_versions(
+        &project_id,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}

packages/app-lib/src/api/content_favorites.rs

@@ -0,0 +1,28 @@
+pub use crate::state::content_favorites::{
+    ContentFavorite, ContentFavoriteInput, ContentFavoriteProvider,
+    ContentFavoriteType,
+};
+
+#[tracing::instrument]
+pub async fn list() -> crate::Result<Vec<ContentFavorite>> {
+    let state = crate::State::get().await?;
+    crate::state::content_favorites::list(&state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn add(
+    favorite: ContentFavoriteInput,
+) -> crate::Result<ContentFavorite> {
+    let state = crate::State::get().await?;
+    crate::state::content_favorites::add(favorite, &state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn remove(
+    provider: ContentFavoriteProvider,
+    project_id: &str,
+) -> crate::Result<()> {
+    let state = crate::State::get().await?;
+    crate::state::content_favorites::remove(provider, project_id, &state.pool)
+        .await
+}

packages/app-lib/src/api/friends.rs

@@ -0,0 +1,36 @@
+use crate::state::{FriendsSocket, UserFriend};
+use ariadne::users::UserStatus;
+
+#[tracing::instrument]
+pub async fn friends() -> crate::Result<Vec<UserFriend>> {
+    let state = crate::State::get().await?;
+    let friends =
+        FriendsSocket::friends(&state.pool, &state.api_semaphore).await?;
+
+    Ok(friends)
+}
+
+pub async fn friend_statuses() -> crate::Result<Vec<UserStatus>> {
+    let state = crate::State::get().await?;
+    let statuses = state.friends_socket.friend_statuses();
+
+    Ok(statuses)
+}
+
+#[tracing::instrument]
+pub async fn add_friend(user_id: &str) -> crate::Result<()> {
+    let state = crate::State::get().await?;
+    FriendsSocket::add_friend(user_id, &state.pool, &state.api_semaphore)
+        .await?;
+
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn remove_friend(user_id: &str) -> crate::Result<()> {
+    let state = crate::State::get().await?;
+    FriendsSocket::remove_friend(user_id, &state.pool, &state.api_semaphore)
+        .await?;
+
+    Ok(())
+}

packages/app-lib/src/api/google_ip.rs

@@ -0,0 +1,831 @@
+//! Direct-connect IP selection for Google Translate.
+//!
+//! `translate-pa.googleapis.com` is pinned in memory to a probed IPv4 so the
+//! HTTPS URL, Host header, and TLS SNI stay unchanged while TCP connects to
+//! the selected IP. The system hosts file, IPv6, and TLS certificate
+//! verification are never used or modified.
+
+use std::collections::HashSet;
+use std::net::{IpAddr, SocketAddr};
+use std::sync::{Arc, LazyLock};
+use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
+
+use futures::{StreamExt, stream};
+use reqwest::Client;
+use serde::{Deserialize, Serialize};
+use sqlx::{Row, SqlitePool};
+use tokio::sync::Mutex;
+
+use crate::util::proxy::ProxyConfig;
+use crate::{ErrorKind, State};
+
+// IP list source: Ponderfly/GoogleTranslateIpCheck, MIT License.
+// https://github.com/Ponderfly/GoogleTranslateIpCheck
+const IP_LIST_URL: &str = "https://ghfast.top/https://raw.githubusercontent.com/Ponderfly/GoogleTranslateIpCheck/refs/heads/master/src/GoogleTranslateIpCheck/GoogleTranslateIpCheck/ip.txt";
+const GOOGLE_TRANSLATE_HOST: &str = "translate-pa.googleapis.com";
+const TOP_IPS: usize = 20;
+const SCAN_BATCH_SIZE: usize = 1000;
+const PROBE_CONCURRENCY: usize = 32;
+const PROBE_CONNECT_TIMEOUT: Duration = Duration::from_secs(3);
+const PROBE_TIMEOUT: Duration = Duration::from_secs(6);
+const DOWNLOAD_TIMEOUT: Duration = Duration::from_secs(20);
+const CACHE_REFRESH_AGE: Duration = Duration::from_secs(7 * 24 * 60 * 60);
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
+pub struct GoogleTranslateIp {
+    pub ip: String,
+    pub latency_ms: u64,
+}
+
+#[derive(Debug)]
+struct GoogleIpRuntime {
+    candidates: Vec<GoogleTranslateIp>,
+    current: usize,
+    client: Option<Client>,
+    pinned_ip: Option<String>,
+}
+
+impl GoogleIpRuntime {
+    fn current_ip(&self) -> Option<IpAddr> {
+        self.candidates
+            .get(self.current)
+            .and_then(|candidate| parse_ipv4(&candidate.ip))
+    }
+}
+
+struct RefreshHandle {
+    task: tokio::task::JoinHandle<()>,
+    done: tokio::sync::watch::Receiver<bool>,
+}
+
+static RUNTIME: LazyLock<Mutex<Option<GoogleIpRuntime>>> =
+    LazyLock::new(|| Mutex::new(None));
+static REFRESH_TASK: LazyLock<Mutex<Option<Arc<RefreshHandle>>>> =
+    LazyLock::new(|| Mutex::new(None));
+
+/// Returns a reqwest client pinned to the currently selected Google Translate
+/// IPv4 address.
+pub async fn google_translation_client() -> crate::Result<Client> {
+    let proxy = State::get().await?.proxy_config().await.unwrap_or_default();
+    loop {
+        let mut runtime = RUNTIME.lock().await;
+        match runtime.as_mut() {
+            Some(runtime) if runtime.current < runtime.candidates.len() => {
+                let pinned_matches = runtime
+                    .candidates
+                    .get(runtime.current)
+                    .is_some_and(|candidate| {
+                        runtime.pinned_ip.as_deref()
+                            == Some(candidate.ip.as_str())
+                    });
+                if let Some(client) = runtime.client.as_ref()
+                    && pinned_matches
+                {
+                    return Ok(client.clone());
+                }
+                let Some(ip) = runtime.current_ip() else {
+                    runtime.current += 1;
+                    runtime.client = None;
+                    runtime.pinned_ip = None;
+                    continue;
+                };
+                let client = client_for(ip, &proxy);
+                runtime.client = Some(client.clone());
+                runtime.pinned_ip = Some(ip.to_string());
+                return Ok(client);
+            }
+            Some(_) => {
+                drop(runtime);
+                let task = start_refresh().await;
+                wait_for_refresh(&task).await;
+                return refreshed_client().await;
+            }
+            None => {
+                drop(runtime);
+                return initialize().await;
+            }
+        }
+    }
+}
+
+/// Marks the current pinned IP as failed so the next call moves to a cached
+/// backup or triggers a background rescan.
+pub async fn mark_current_failed() {
+    let mut runtime = RUNTIME.lock().await;
+    if let Some(runtime) = runtime.as_mut() {
+        let failed_ip = runtime.current_ip();
+        runtime.current = runtime.current.saturating_add(1);
+        runtime.client = None;
+        runtime.pinned_ip = None;
+        tracing::warn!(
+            ip = ?failed_ip.map(|ip| ip.to_string()),
+            next_index = runtime.current,
+            pool_size = runtime.candidates.len(),
+            "Google Translate IP marked failed; switching to next cached IP"
+        );
+    }
+}
+
+/// Returns the number of cached Google Translate IPs currently available.
+pub async fn ip_pool_size() -> usize {
+    {
+        let runtime = RUNTIME.lock().await;
+        if let Some(runtime) = runtime.as_ref() {
+            return runtime.candidates.len();
+        }
+    }
+    let Ok(state) = State::get().await else {
+        tracing::warn!(
+            "Unable to resolve launcher state for Google Translate IP cache"
+        );
+        return 0;
+    };
+    let pool = &state.pool;
+    let stale = cache_is_stale(pool).await;
+    let cached = load_cache(pool).await;
+    let size = cached.len();
+    if cached.is_empty() {
+        tracing::warn!(
+            "Google Translate IP cache is missing or empty; starting background refresh"
+        );
+        let _ = start_refresh().await;
+    } else if stale {
+        tracing::info!(
+            size,
+            "Google Translate IP cache is stale; starting background refresh"
+        );
+        let _ = start_refresh().await;
+    } else {
+        tracing::info!(size, "Google Translate IP cache loaded from database");
+    }
+    size
+}
+
+async fn initialize() -> crate::Result<Client> {
+    let proxy = State::get().await?.proxy_config().await.unwrap_or_default();
+    preload().await;
+    {
+        let mut runtime = RUNTIME.lock().await;
+        if let Some(runtime) = runtime.as_mut()
+            && runtime.current < runtime.candidates.len()
+        {
+            if let Some(client) = runtime.client.as_ref() {
+                return Ok(client.clone());
+            }
+            if let Some(ip) = runtime.current_ip() {
+                let client = client_for(ip, &proxy);
+                runtime.client = Some(client.clone());
+                runtime.pinned_ip = Some(ip.to_string());
+                return Ok(client);
+            }
+        }
+    }
+    let task = start_refresh().await;
+    wait_for_refresh(&task).await;
+    refreshed_client().await
+}
+
+/// Warms the in-memory Google Translate IP pool without blocking startup.
+///
+/// Loads the cached Top 20 and verifies the first usable IP. A missing, empty,
+/// stale, or fully failed cache only starts a background refresh and returns
+/// immediately.
+pub async fn preload() {
+    let proxy = match State::get().await {
+        Ok(state) => state.proxy_config().await.ok().unwrap_or_default(),
+        Err(_) => ProxyConfig::default(),
+    };
+    {
+        let runtime = RUNTIME.lock().await;
+        if runtime
+            .as_ref()
+            .is_some_and(|runtime| runtime.current < runtime.candidates.len())
+        {
+            tracing::debug!("Google Translate IP pool already initialized");
+            return;
+        }
+    }
+
+    let Ok(state) = State::get().await else {
+        tracing::warn!(
+            "Unable to resolve launcher state during Google Translate IP preload"
+        );
+        return;
+    };
+    let pool = &state.pool;
+    let candidates = load_cache(pool).await;
+    let stale = cache_is_stale(pool).await;
+    tracing::info!(
+        cached = candidates.len(),
+        "Preloading Google Translate IP pool"
+    );
+    if candidates.is_empty() {
+        tracing::warn!(
+            "Google Translate IP cache missing or empty during preload; starting background refresh"
+        );
+        let _ = start_refresh().await;
+        return;
+    }
+    if stale {
+        tracing::info!(
+            "Google Translate IP cache stale during preload; starting background refresh"
+        );
+        let _ = start_refresh().await;
+    }
+
+    for (index, candidate) in candidates.iter().enumerate() {
+        let Some(ip) = parse_ipv4(&candidate.ip) else {
+            continue;
+        };
+        let Some(latency_ms) = probe(ip).await else {
+            tracing::debug!(ip = %ip, "Cached Google Translate IP failed preload verification");
+            continue;
+        };
+        tracing::info!(
+            ip = %ip,
+            latency_ms,
+            "Cached Google Translate IP verified during preload"
+        );
+        let client = client_for(ip, &proxy);
+        let mut runtime = RUNTIME.lock().await;
+        *runtime = Some(GoogleIpRuntime {
+            candidates,
+            current: index,
+            client: Some(client.clone()),
+            pinned_ip: Some(ip.to_string()),
+        });
+        return;
+    }
+
+    tracing::warn!(
+        "All cached Google Translate IPs failed preload verification; starting background refresh"
+    );
+    let _ = start_refresh().await;
+}
+
+async fn refreshed_client() -> crate::Result<Client> {
+    let proxy = State::get().await?.proxy_config().await.unwrap_or_default();
+    let mut runtime = RUNTIME.lock().await;
+    if let Some(runtime) = runtime.as_mut()
+        && let Some(ip) = runtime
+            .candidates
+            .first()
+            .and_then(|candidate| parse_ipv4(&candidate.ip))
+    {
+        runtime.current = 0;
+        let client = client_for(ip, &proxy);
+        runtime.client = Some(client.clone());
+        runtime.pinned_ip = Some(ip.to_string());
+        return Ok(client);
+    }
+    Err(ErrorKind::OtherError(
+        "GOOGLE_IP_UNAVAILABLE: no usable Google Translate IP found"
+            .to_string(),
+    )
+    .into())
+}
+
+fn client_for(ip: IpAddr, proxy: &ProxyConfig) -> Client {
+    tracing::info!(ip = %ip, "Pinning Google Translate requests to IP");
+    let builder = Client::builder()
+        .resolve(GOOGLE_TRANSLATE_HOST, SocketAddr::new(ip, 443))
+        .timeout(Duration::from_secs(20))
+        .user_agent(crate::launcher_user_agent());
+    proxy
+        .apply(builder)
+        .expect("google translate proxy configuration should be valid")
+        .build()
+        .expect("google translate client configuration should be valid")
+}
+
+fn parse_ipv4(value: &str) -> Option<IpAddr> {
+    value.trim().parse::<IpAddr>().ok().filter(IpAddr::is_ipv4)
+}
+
+fn parse_ip_list(content: &str) -> Vec<IpAddr> {
+    let mut seen = HashSet::new();
+    content
+        .lines()
+        .filter_map(|line| {
+            let line = line.trim();
+            if line.is_empty() || line.starts_with('#') {
+                return None;
+            }
+            let ip = line.parse::<IpAddr>().ok()?;
+            if !ip.is_ipv4() || !seen.insert(ip) {
+                return None;
+            }
+            Some(ip)
+        })
+        .collect()
+}
+
+fn rank_candidates(
+    mut candidates: Vec<GoogleTranslateIp>,
+) -> Vec<GoogleTranslateIp> {
+    let mut seen = HashSet::new();
+    candidates.retain(|candidate| {
+        parse_ipv4(&candidate.ip).is_some() && seen.insert(candidate.ip.clone())
+    });
+    candidates.sort_by_key(|candidate| candidate.latency_ms);
+    candidates.truncate(TOP_IPS);
+    candidates
+}
+
+async fn scan_batched(ips: &[IpAddr]) -> Vec<GoogleTranslateIp> {
+    let mut offset = 0;
+    while offset < ips.len() {
+        let end = (offset + SCAN_BATCH_SIZE).min(ips.len());
+        let batch = &ips[offset..end];
+        let found = current_pool_size().await;
+        tracing::info!(
+            start = offset + 1,
+            end,
+            total = ips.len(),
+            found,
+            "Probing Google Translate IP batch"
+        );
+        let mut stream = stream::iter(batch.iter().copied())
+            .map(|ip| async move { (ip, probe(ip).await) })
+            .buffer_unordered(PROBE_CONCURRENCY);
+        let mut full = false;
+        while let Some((ip, latency)) = stream.next().await {
+            let Some(latency_ms) = latency else {
+                continue;
+            };
+            let size = insert_candidate(ip, latency_ms).await;
+            tracing::info!(
+                ip = %ip,
+                latency_ms,
+                size,
+                "Google Translate IP added to pool"
+            );
+            if size >= TOP_IPS {
+                full = true;
+                break;
+            }
+        }
+        drop(stream);
+        if full || current_pool_size().await >= TOP_IPS {
+            break;
+        }
+        offset = end;
+    }
+    let candidates = current_candidates().await;
+    tracing::info!(
+        candidates = candidates.len(),
+        "Google Translate IP scan complete"
+    );
+    candidates
+}
+
+async fn insert_candidate(ip: IpAddr, latency_ms: u64) -> usize {
+    let mut runtime = RUNTIME.lock().await;
+    let runtime = runtime.get_or_insert_with(|| GoogleIpRuntime {
+        candidates: Vec::new(),
+        current: 0,
+        client: None,
+        pinned_ip: None,
+    });
+    let candidate = GoogleTranslateIp {
+        ip: ip.to_string(),
+        latency_ms,
+    };
+    if runtime
+        .candidates
+        .iter()
+        .any(|existing| existing.ip == candidate.ip)
+    {
+        return runtime.candidates.len();
+    }
+    let index = runtime
+        .candidates
+        .binary_search_by(|existing| {
+            existing.latency_ms.cmp(&candidate.latency_ms)
+        })
+        .unwrap_or_else(|index| index);
+    runtime.candidates.insert(index, candidate);
+    let became_best = index == 0;
+    runtime.candidates.truncate(TOP_IPS);
+    if became_best {
+        runtime.current = 0;
+        runtime.client = None;
+        runtime.pinned_ip = None;
+    }
+    runtime.candidates.len()
+}
+
+async fn current_pool_size() -> usize {
+    RUNTIME
+        .lock()
+        .await
+        .as_ref()
+        .map_or(0, |runtime| runtime.candidates.len())
+}
+
+async fn current_candidates() -> Vec<GoogleTranslateIp> {
+    RUNTIME
+        .lock()
+        .await
+        .as_ref()
+        .map(|runtime| runtime.candidates.clone())
+        .unwrap_or_default()
+}
+
+#[cfg(test)]
+async fn scan_batched_with<F, Fut>(
+    ips: &[IpAddr],
+    mut probe: F,
+) -> Vec<GoogleTranslateIp>
+where
+    F: FnMut(IpAddr) -> Fut,
+    Fut: std::future::Future<Output = Option<u64>>,
+{
+    let mut candidates = Vec::new();
+    let mut offset = 0;
+    while offset < ips.len() && candidates.len() < TOP_IPS {
+        let end = (offset + SCAN_BATCH_SIZE).min(ips.len());
+        let batch = &ips[offset..end];
+        tracing::info!(
+            start = offset + 1,
+            end,
+            total = ips.len(),
+            found = candidates.len(),
+            "Probing Google Translate IP batch"
+        );
+        let probed = stream::iter(batch.iter().copied())
+            .map(|ip| {
+                let future = probe(ip);
+                async move { (ip, future.await) }
+            })
+            .buffer_unordered(PROBE_CONCURRENCY)
+            .collect::<Vec<_>>()
+            .await;
+        candidates.extend(probed.into_iter().filter_map(|(ip, latency)| {
+            latency.map(|latency_ms| GoogleTranslateIp {
+                ip: ip.to_string(),
+                latency_ms,
+            })
+        }));
+        candidates = rank_candidates(candidates);
+        offset = end;
+    }
+    tracing::info!(
+        candidates = candidates.len(),
+        "Google Translate IP scan complete"
+    );
+    candidates
+}
+
+async fn probe(ip: IpAddr) -> Option<u64> {
+    let proxy = match State::get().await {
+        Ok(state) => state.proxy_config().await.ok().unwrap_or_default(),
+        Err(_) => ProxyConfig::default(),
+    };
+    let builder = Client::builder()
+        .resolve(GOOGLE_TRANSLATE_HOST, SocketAddr::new(ip, 443))
+        .connect_timeout(PROBE_CONNECT_TIMEOUT)
+        .timeout(PROBE_TIMEOUT)
+        .user_agent(crate::launcher_user_agent());
+    let client = match proxy.apply(builder) {
+        Ok(builder) => builder.build().ok()?,
+        Err(_) => {
+            tracing::warn!(
+                "Failed to apply proxy config for probe, using direct"
+            );
+            Client::builder()
+                .resolve(GOOGLE_TRANSLATE_HOST, SocketAddr::new(ip, 443))
+                .connect_timeout(PROBE_CONNECT_TIMEOUT)
+                .timeout(PROBE_TIMEOUT)
+                .user_agent(crate::launcher_user_agent())
+                .no_proxy()
+                .build()
+                .ok()?
+        }
+    };
+    let started = Instant::now();
+    let response = client
+        .get(format!("https://{GOOGLE_TRANSLATE_HOST}/"))
+        .send()
+        .await;
+    let Ok(response) = response else {
+        tracing::debug!(ip = %ip, "Google Translate IP probe failed");
+        return None;
+    };
+    drop(response);
+    let latency_ms = started.elapsed().as_millis() as u64;
+    tracing::debug!(ip = %ip, latency_ms, "Google Translate IP probe succeeded");
+    Some(latency_ms)
+}
+
+async fn download_ip_list() -> crate::Result<Vec<IpAddr>> {
+    let proxy = State::get().await?.proxy_config().await.unwrap_or_default();
+    tracing::info!(url = IP_LIST_URL, "Downloading Google Translate IP list");
+    let builder = Client::builder()
+        .timeout(DOWNLOAD_TIMEOUT)
+        .user_agent(crate::launcher_user_agent());
+    let client = match proxy.apply(builder) {
+        Ok(builder) => builder.build()?,
+        Err(e) => {
+            tracing::warn!(%e, "Failed to apply proxy config for IP list download, using direct");
+            Client::builder()
+                .timeout(DOWNLOAD_TIMEOUT)
+                .user_agent(crate::launcher_user_agent())
+                .no_proxy()
+                .build()?
+        }
+    };
+    let response = client.get(IP_LIST_URL).send().await?;
+    if !response.status().is_success() {
+        tracing::warn!(
+            status = %response.status(),
+            "Google Translate IP list download failed"
+        );
+        return Err(ErrorKind::OtherError(format!(
+            "GOOGLE_IP_LIST_FAILED: Ponderfly IP list returned HTTP {}",
+            response.status()
+        ))
+        .into());
+    }
+    let text = response.text().await?;
+    let ips = parse_ip_list(&text);
+    tracing::info!(
+        bytes = text.len(),
+        ips = ips.len(),
+        "Google Translate IP list downloaded"
+    );
+    if ips.is_empty() {
+        return Err(ErrorKind::OtherError(
+            "GOOGLE_IP_LIST_FAILED: Ponderfly IP list contained no IPv4 addresses"
+                .to_string(),
+        )
+        .into());
+    }
+    Ok(ips)
+}
+
+async fn refresh_in_background() {
+    tracing::info!("Starting background Google Translate IP refresh");
+    let result: crate::Result<()> = async {
+        let ips = download_ip_list().await?;
+        let candidates = scan_batched(&ips).await;
+        if candidates.is_empty() {
+            return Err(ErrorKind::OtherError(
+                "GOOGLE_IP_UNAVAILABLE: no usable Google Translate IP found"
+                    .to_string(),
+            )
+            .into());
+        }
+
+        let state = State::get().await?;
+        if let Err(error) = save_cache(&state.pool, &candidates).await {
+            tracing::warn!(%error, "Unable to persist Google Translate IP cache");
+        }
+        Ok(())
+    }
+    .await;
+
+    if let Err(error) = result {
+        tracing::warn!(%error, "Background Google Translate IP refresh failed");
+    } else {
+        tracing::info!("Google Translate IP cache refreshed");
+    }
+}
+
+async fn start_refresh() -> Arc<RefreshHandle> {
+    let mut guard = REFRESH_TASK.lock().await;
+    if let Some(handle) = guard.as_ref()
+        && !handle.task.is_finished()
+    {
+        return handle.clone();
+    }
+    let (done_tx, done_rx) = tokio::sync::watch::channel(false);
+    let task = tokio::spawn(async move {
+        refresh_in_background().await;
+        let _ = done_tx.send(true);
+    });
+    let handle = Arc::new(RefreshHandle {
+        task,
+        done: done_rx,
+    });
+    *guard = Some(handle.clone());
+    handle
+}
+
+async fn wait_for_refresh(handle: &RefreshHandle) {
+    if handle.task.is_finished() {
+        return;
+    }
+    let mut done = handle.done.clone();
+    let _ = done.wait_for(|done| *done).await;
+}
+
+async fn load_cache(pool: &SqlitePool) -> Vec<GoogleTranslateIp> {
+    let rows = match sqlx::query(
+        "SELECT ip, latency_ms FROM google_translate_ip_cache \
+         ORDER BY latency_ms ASC, ip ASC LIMIT ?",
+    )
+    .bind(TOP_IPS as i32)
+    .fetch_all(pool)
+    .await
+    {
+        Ok(rows) => rows,
+        Err(error) => {
+            tracing::warn!(
+                %error,
+                "Unable to read Google Translate IP cache from database; treating it as empty"
+            );
+            return Vec::new();
+        }
+    };
+    let candidates = rows
+        .into_iter()
+        .filter_map(|row| {
+            let ip: String = row.try_get("ip").ok()?;
+            let latency_ms: i64 = row.try_get("latency_ms").ok()?;
+            Some(GoogleTranslateIp {
+                ip,
+                latency_ms: latency_ms.max(0) as u64,
+            })
+        })
+        .collect();
+    rank_candidates(candidates)
+}
+
+async fn save_cache(
+    pool: &SqlitePool,
+    candidates: &[GoogleTranslateIp],
+) -> crate::Result<()> {
+    let created_at = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|duration| duration.as_secs() as i64)
+        .unwrap_or(0);
+    let mut transaction = pool.begin().await?;
+    sqlx::query("DELETE FROM google_translate_ip_cache")
+        .execute(&mut *transaction)
+        .await?;
+    for candidate in candidates {
+        sqlx::query(
+            "INSERT INTO google_translate_ip_cache (ip, latency_ms, created_at) \
+             VALUES (?, ?, ?)",
+        )
+        .bind(&candidate.ip)
+        .bind(candidate.latency_ms as i64)
+        .bind(created_at)
+        .execute(&mut *transaction)
+        .await?;
+    }
+    transaction.commit().await?;
+    tracing::info!(
+        count = candidates.len(),
+        "Google Translate IP cache saved to database"
+    );
+    Ok(())
+}
+
+async fn cache_is_stale(pool: &SqlitePool) -> bool {
+    let Ok(created_at) = sqlx::query_scalar::<_, Option<i64>>(
+        "SELECT MAX(created_at) FROM google_translate_ip_cache",
+    )
+    .fetch_one(pool)
+    .await
+    else {
+        return true;
+    };
+    let Some(created_at) = created_at else {
+        return true;
+    };
+    let now = SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map(|duration| duration.as_secs() as i64)
+        .unwrap_or(0);
+    now.saturating_sub(created_at) >= CACHE_REFRESH_AGE.as_secs() as i64
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_only_unique_ipv4_addresses() {
+        let content = "# comment\n\n1.2.3.4\r\n2001:db8::1\n1.2.3.4\n8.8.8.8\n";
+        assert_eq!(
+            parse_ip_list(content),
+            vec![
+                "1.2.3.4".parse::<IpAddr>().unwrap(),
+                "8.8.8.8".parse::<IpAddr>().unwrap(),
+            ]
+        );
+    }
+
+    #[test]
+    fn ranks_and_truncates_candidates() {
+        let candidates = (0..25)
+            .map(|index| GoogleTranslateIp {
+                ip: format!("10.0.{}.1", index),
+                latency_ms: 1000 - index,
+            })
+            .collect();
+        let ranked = rank_candidates(candidates);
+        assert_eq!(ranked.len(), TOP_IPS);
+        assert_eq!(ranked.first().unwrap().latency_ms, 976);
+        assert!(
+            ranked
+                .windows(2)
+                .all(|window| window[0].latency_ms <= window[1].latency_ms)
+        );
+    }
+
+    #[tokio::test]
+    async fn stops_scanning_after_first_batch_reaches_top() {
+        use std::sync::atomic::{AtomicUsize, Ordering};
+
+        let ips = (0..2500)
+            .map(|index| {
+                format!("10.{}.{}.1", index / 256, index % 256)
+                    .parse::<IpAddr>()
+                    .unwrap()
+            })
+            .collect::<Vec<_>>();
+        let probed = Arc::new(AtomicUsize::new(0));
+        let probe_count = probed.clone();
+        let candidates = scan_batched_with(&ips, move |_ip| {
+            let probe_count = probe_count.clone();
+            async move {
+                probe_count.fetch_add(1, Ordering::Relaxed);
+                Some(10)
+            }
+        })
+        .await;
+
+        assert_eq!(candidates.len(), TOP_IPS);
+        assert_eq!(probed.load(Ordering::Relaxed), SCAN_BATCH_SIZE);
+    }
+
+    #[tokio::test]
+    async fn continues_to_next_batch_when_first_is_insufficient() {
+        use std::sync::atomic::{AtomicUsize, Ordering};
+
+        let ips = (0..2000)
+            .map(|index| {
+                let prefix = if index < SCAN_BATCH_SIZE { 10 } else { 11 };
+                let octet = index % SCAN_BATCH_SIZE;
+                format!("{prefix}.{}.{}.1", octet / 256, octet % 256,)
+                    .parse::<IpAddr>()
+                    .unwrap()
+            })
+            .collect::<Vec<_>>();
+        let probed = Arc::new(AtomicUsize::new(0));
+        let probe_count = probed.clone();
+        let candidates = scan_batched_with(&ips, move |ip| {
+            let probe_count = probe_count.clone();
+            async move {
+                probe_count.fetch_add(1, Ordering::Relaxed);
+                let IpAddr::V4(ipv4) = ip else {
+                    return None;
+                };
+                if ipv4.octets()[0] == 11 {
+                    Some(5)
+                } else {
+                    None
+                }
+            }
+        })
+        .await;
+
+        assert_eq!(probed.load(Ordering::Relaxed), 2000);
+        assert_eq!(candidates.len(), TOP_IPS);
+    }
+
+    #[tokio::test]
+    async fn cache_round_trip() {
+        use sqlx::sqlite::SqlitePoolOptions;
+
+        let pool = SqlitePoolOptions::new()
+            .connect("sqlite::memory:")
+            .await
+            .unwrap();
+        sqlx::query(
+            "CREATE TABLE google_translate_ip_cache (
+                ip TEXT NOT NULL PRIMARY KEY,
+                latency_ms INTEGER NOT NULL,
+                created_at INTEGER NOT NULL
+            )",
+        )
+        .execute(&pool)
+        .await
+        .unwrap();
+        let candidates = vec![
+            GoogleTranslateIp {
+                ip: "1.1.1.1".to_string(),
+                latency_ms: 10,
+            },
+            GoogleTranslateIp {
+                ip: "8.8.8.8".to_string(),
+                latency_ms: 20,
+            },
+        ];
+        save_cache(&pool, &candidates).await.unwrap();
+        assert_eq!(load_cache(&pool).await, candidates);
+    }
+}

packages/app-lib/src/api/handler.rs

@@ -0,0 +1,138 @@
+use std::path::PathBuf;
+
+use crate::{
+    event::{
+        CommandPayload,
+        emit::{emit_command, emit_warning},
+    },
+    util::io,
+};
+use url::form_urlencoded;
+use urlencoding::decode;
+
+/// Handles external functions (such as through URL deep linkage)
+/// Link is extracted value (link) in somewhat URL format, such as
+/// subdomain1/subdomain2
+/// (Does not include axolotl://)
+pub async fn handle_url(sublink: &str) -> crate::Result<CommandPayload> {
+    // /seed-map?{query}   -    Opens the Lab seed map with a shared state
+    if let Some(rest) = sublink.strip_prefix("seed-map")
+        && (rest.is_empty() || rest.starts_with('?') || rest.starts_with('/'))
+    {
+        let query = rest.trim_start_matches('/').trim_start_matches('?');
+        return Ok(CommandPayload::OpenSeedMap {
+            query: query.to_string(),
+        });
+    }
+    Ok(match sublink.split_once('/') {
+        // /mod/{id}   -    Installs a mod of mod id
+        Some(("mod", id)) => CommandPayload::InstallMod { id: id.to_string() },
+        // /version/{id}   -    Installs a specific version of id
+        Some(("version", id)) => {
+            CommandPayload::InstallVersion { id: id.to_string() }
+        }
+        // /modpack/{id}   -    Installs a modpack of modpack id
+        Some(("modpack", id)) => {
+            CommandPayload::InstallModpack { id: id.to_string() }
+        }
+        // /server/{id}   -    Opens a server project page and triggers play flow
+        Some(("server", id)) => {
+            CommandPayload::InstallServer { id: id.to_string() }
+        }
+        // /launch/instance/{id}   -    Launches an instance
+        Some(("launch", rest)) if rest.starts_with("instance/") => {
+            let raw = rest.trim_start_matches("instance/");
+            let (raw, query) = raw.split_once('?').unwrap_or((raw, ""));
+            let mut server = None;
+            let mut singleplayer_world = None;
+
+            for (key, value) in form_urlencoded::parse(query.as_bytes()) {
+                match &*key {
+                    "server" => server = Some(value.into_owned()),
+                    "singleplayer_world" => {
+                        singleplayer_world = Some(value.into_owned());
+                    }
+                    _ => {}
+                }
+            }
+
+            if server.is_some() && singleplayer_world.is_some() {
+                emit_warning(
+                    "Invalid command, cannot launch both a server and a singleplayer world",
+                )
+                .await?;
+                return Err(crate::ErrorKind::InputError(
+                    "Cannot launch both a server and a singleplayer world"
+                        .to_string(),
+                )
+                .into());
+            }
+
+            match decode(raw) {
+                Ok(decoded) => CommandPayload::LaunchInstance {
+                    id: decoded.to_string(),
+                    server,
+                    singleplayer_world,
+                },
+                Err(e) => {
+                    emit_warning(&format!(
+                        "Invalid UTF-8 in instance path: {e}"
+                    ))
+                    .await?;
+                    return Err(crate::ErrorKind::InputError(format!(
+                        "Invalid UTF-8 in instance path: {e}"
+                    ))
+                    .into());
+                }
+            }
+        }
+        _ => {
+            emit_warning(&format!(
+                "Invalid command, unrecognized path: {sublink}"
+            ))
+            .await?;
+            return Err(crate::ErrorKind::InputError(format!(
+                "Invalid command, unrecognized path: {sublink}"
+            ))
+            .into());
+        }
+    })
+}
+
+pub async fn parse_command(
+    command_string: &str,
+) -> crate::Result<CommandPayload> {
+    tracing::debug!("Parsing command: {}", &command_string);
+
+    // axolotl://some-command
+    // This occurs when following a web redirect link
+    if let Some(sublink) = command_string.strip_prefix("axolotl://") {
+        Ok(handle_url(sublink).await?)
+    } else {
+        // We assume anything else is a filepath to a modpack file; zip
+        // archives are format-sniffed by the pack installer.
+        let path = PathBuf::from(command_string);
+        let path = io::canonicalize(path)?;
+        if let Some(ext) = path.extension()
+            && (ext == "mrpack" || ext == "zip")
+        {
+            return Ok(CommandPayload::RunMRPack { path });
+        }
+        emit_warning(&format!(
+            "Invalid command, unrecognized filetype: {}",
+            path.display()
+        ))
+        .await?;
+        Err(crate::ErrorKind::InputError(format!(
+            "Invalid command, unrecognized filetype: {}",
+            path.display()
+        ))
+        .into())
+    }
+}
+
+pub async fn parse_and_emit_command(command_string: &str) -> crate::Result<()> {
+    let command = parse_command(command_string).await?;
+    emit_command(command).await?;
+    Ok(())
+}

packages/app-lib/src/api/instance.rs

@@ -0,0 +1,81 @@
+//! Theseus instance management interface
+
+mod content;
+mod core_components;
+mod export_mrpack;
+mod get;
+mod home;
+mod install;
+mod lifecycle;
+mod mcarchive;
+mod paths;
+mod planet_minecraft;
+mod projects;
+mod run;
+mod upgrade;
+
+pub use self::content::{
+    apply_content_update_plan, get_content_items, get_content_items_by_paths,
+    get_content_snapshot, get_dependencies_as_content_items,
+    get_install_candidates, get_installed_project_ids,
+    get_linked_modpack_content, get_linked_modpack_info, get_projects,
+    list_content_sets, plan_content_updates, refresh_content,
+    sync_content_files,
+};
+pub(crate) use self::core_components::assemble_for_launch;
+pub use self::core_components::{
+    McArchiveCoreInstallResult, add_core_jar_mod, import_mcarchive_modloader,
+    install_mcarchive_modloader, list_core_components, move_core_component,
+    preview_core_jar, remove_core_component, replace_core_jar,
+    restore_core_component, set_core_component_enabled,
+};
+pub use self::export_mrpack::{
+    create_mrpack_json, export_mrpack, get_pack_export_candidates,
+};
+pub use self::get::{get, get_many, list};
+pub use self::home::{
+    get_daily_playtime, get_daily_playtime_details, set_pinned,
+};
+pub use self::install::get_optimal_jre_key;
+pub(crate) use self::lifecycle::create;
+pub use self::lifecycle::{
+    cache_icon, create_with_direct_link, edit, edit_icon, remove,
+    sync_direct_links,
+};
+pub use self::mcarchive::{
+    McArchiveContentInstallRequest, McArchiveContentInstallResult,
+    import_mcarchive_content, install_mcarchive_content,
+};
+pub use self::paths::{get_full_path, get_mod_full_path};
+pub use self::planet_minecraft::{
+    PlanetMinecraftContentInstallRequest, PlanetMinecraftContentInstallResult,
+    import_planet_minecraft_content, install_planet_minecraft_content,
+};
+pub(crate) use self::projects::emit_content_changed;
+pub use self::projects::{
+    ContentToggleResult, InstallProjectWithDependenciesRequest,
+    add_project_from_path, add_project_from_version, import_world_save,
+    install_datapack_bytes_to_world, install_datapack_to_world,
+    install_project_with_dependencies, preview_project_with_dependencies,
+    preview_project_with_dependencies_for_target, queue_curseforge_content,
+    queue_curseforge_world, queue_project_with_dependencies,
+    remove_content_entry, remove_project, repair_managed_modrinth,
+    restore_pack_member_default, rollback_project,
+    switch_content_entry_version, switch_project_version_with_dependencies,
+    toggle_content_entries, toggle_content_entry, toggle_disable_project,
+    update_all_projects, update_content_entry, update_managed_modrinth_version,
+    update_project,
+};
+pub use self::run::{
+    GcLaunchIntent, GcLaunchReport, QuickPlayType, kill, run,
+    run_with_extra_launch_args, run_with_extra_launch_args_with_gc,
+    try_update_playtime_by_instance_id,
+};
+pub use self::upgrade::{
+    dismiss_instance_post_upgrade_notice, execute_instance_upgrade,
+    get_instance_post_upgrade_notice, get_instance_upgrade_plan,
+    plan_instance_upgrade, reset_instance_upgrade_resolution,
+    resolve_custom_instance_upgrade_solution, select_instance_upgrade_solution,
+    update_instance_upgrade_resolution, update_instance_upgrade_resolutions,
+};
+pub use crate::state::{DailyPlaytime, DailyPlaytimeEntry};

packages/app-lib/src/api/instance/content.rs

@@ -0,0 +1,530 @@
+use crate::state::{
+    CacheBehaviour, ContentFile, ContentItem, ContentItemUpdate,
+    ContentOwnershipKind, ContentProvider, ContentSet, ContentUpdatePlan,
+    ContentUpdatePlanAction, ContentUpdateResolution,
+    ContentUpdateResolutionChoice, ContentUpdateScope, Dependency,
+    InstanceContentSnapshot, InstanceInstallCandidate, InstanceInstallTarget,
+    LinkedModpackInfo, ProjectType, State,
+};
+use dashmap::DashMap;
+use std::sync::LazyLock;
+
+static CONTENT_UPDATE_PLANS: LazyLock<DashMap<String, ContentUpdatePlan>> =
+    LazyLock::new(DashMap::new);
+
+#[tracing::instrument]
+pub async fn sync_content_files(
+    instance_id: &str,
+) -> crate::Result<Vec<crate::state::instances::InstanceFile>> {
+    let state = State::get().await?;
+    crate::state::sync_content_files(instance_id, &state).await
+}
+
+#[tracing::instrument]
+pub async fn list_content_sets(
+    instance_id: &str,
+) -> crate::Result<Vec<ContentSet>> {
+    let state = State::get().await?;
+    crate::state::list_content_sets(instance_id, &state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn get_projects(
+    instance_id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<DashMap<String, ContentFile>> {
+    let state = State::get().await?;
+    crate::state::get_content_projects(
+        instance_id,
+        None,
+        cache_behaviour,
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_installed_project_ids(
+    instance_id: &str,
+) -> crate::Result<Vec<String>> {
+    let state = State::get().await?;
+    crate::state::get_installed_project_ids_for_instance(
+        instance_id,
+        None,
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_install_candidates(
+    project_id: &str,
+    project_type: ProjectType,
+    targets: Vec<InstanceInstallTarget>,
+) -> crate::Result<Vec<InstanceInstallCandidate>> {
+    let state = State::get().await?;
+    crate::state::get_instance_install_candidates(
+        project_id,
+        project_type,
+        &targets,
+        &state.pool,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_content_items(
+    instance_id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<ContentItem>> {
+    let state = State::get().await?;
+    crate::state::list_content(instance_id, None, cache_behaviour, &state).await
+}
+
+#[tracing::instrument]
+pub async fn get_content_items_by_paths(
+    instance_id: &str,
+    paths: Vec<String>,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<ContentItem>> {
+    let state = State::get().await?;
+    crate::state::list_content_by_paths(
+        instance_id,
+        &paths,
+        cache_behaviour,
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_content_snapshot(
+    instance_id: &str,
+) -> crate::Result<InstanceContentSnapshot> {
+    let state = State::get().await?;
+    crate::state::get_content_snapshot(instance_id, false, &state).await
+}
+
+#[tracing::instrument]
+pub async fn refresh_content(
+    instance_id: &str,
+) -> crate::Result<InstanceContentSnapshot> {
+    let state = State::get().await?;
+    require_installed_instance(instance_id, &state).await?;
+    crate::state::get_content_snapshot(instance_id, true, &state).await
+}
+
+#[tracing::instrument]
+pub async fn plan_content_updates(
+    instance_id: &str,
+    scope: ContentUpdateScope,
+    target: Option<&str>,
+) -> crate::Result<ContentUpdatePlan> {
+    let state = State::get().await?;
+    let snapshot =
+        crate::state::get_content_snapshot(instance_id, true, &state).await?;
+    let mut actions = Vec::new();
+
+    match scope {
+        ContentUpdateScope::UserAdded | ContentUpdateScope::Item => {
+            if scope == ContentUpdateScope::Item && target.is_none() {
+                return Err(crate::ErrorKind::InputError(
+                    "An item update plan requires a stable content ID"
+                        .to_string(),
+                )
+                .into());
+            }
+            for item in &snapshot.items {
+                let content_id = item
+                    .entry_id
+                    .as_deref()
+                    .or(item.member_id.as_deref())
+                    .or(item.file_id.as_deref());
+                let selected =
+                    update_scope_selects_item(scope, target, item, content_id);
+                if !selected {
+                    continue;
+                }
+                let Some(content) = item.content.as_ref() else {
+                    continue;
+                };
+                let Some(update) = content.update.as_ref() else {
+                    continue;
+                };
+                let Some(content_id) = content_id else {
+                    continue;
+                };
+                actions.push(update_action(
+                    content_id.to_string(),
+                    Some(item.expected_relative_path.clone()),
+                    item.ownership_kind,
+                    update,
+                ));
+            }
+        }
+        ContentUpdateScope::Pack => {
+            let pack = snapshot.pack.as_ref().ok_or_else(|| {
+                crate::ErrorKind::InputError(
+                    "This instance is not linked to a managed pack".to_string(),
+                )
+            })?;
+            if !pack.reconciled {
+                return Err(crate::ErrorKind::InputError(
+					"Pack membership is not calibrated yet; refresh while online before updating the pack"
+						.to_string(),
+				)
+				.into());
+            }
+            if let Some(target_release_id) = target {
+                let provider = pack.provider.ok_or_else(|| {
+                    crate::ErrorKind::InputError(
+                        "This pack has no managed provider".to_string(),
+                    )
+                })?;
+                actions.push(ContentUpdatePlanAction {
+                    content_id: "pack".to_string(),
+                    relative_path: None,
+                    ownership_kind: ContentOwnershipKind::PackManaged,
+                    provider,
+                    current_release_id: pack.version_id.clone(),
+                    target_release_id: target_release_id.to_string(),
+                });
+            } else if let Some(update) = pack
+                .metadata
+                .as_ref()
+                .and_then(|metadata| metadata.update.as_ref())
+            {
+                actions.push(update_action(
+                    "pack".to_string(),
+                    None,
+                    ContentOwnershipKind::PackManaged,
+                    update,
+                ));
+            }
+        }
+    }
+
+    let plan = ContentUpdatePlan {
+        id: format!("content-update-plan:{}", uuid::Uuid::new_v4()),
+        instance_id: instance_id.to_string(),
+        revision: snapshot.revision,
+        scope,
+        actions,
+        warnings: snapshot
+            .warnings
+            .into_iter()
+            .map(|warning| warning.message)
+            .collect(),
+    };
+    CONTENT_UPDATE_PLANS.insert(plan.id.clone(), plan.clone());
+    Ok(plan)
+}
+
+#[tracing::instrument]
+pub async fn apply_content_update_plan(
+    plan_id: &str,
+    resolutions: Vec<ContentUpdateResolution>,
+) -> crate::Result<InstanceContentSnapshot> {
+    let plan = CONTENT_UPDATE_PLANS
+        .get(plan_id)
+        .map(|entry| entry.clone())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "The content update plan has expired".to_string(),
+            )
+        })?;
+    let state = State::get().await?;
+    let current_revision = crate::state::instances::adapters::sqlite::content_rows::get_applied_content_set(
+		&plan.instance_id,
+		&state.pool,
+	)
+	.await?
+	.ok_or_else(|| {
+		crate::ErrorKind::InputError(
+			"Instance has no applied content set".to_string(),
+		)
+	})?
+	.revision;
+    if let Err(error) =
+        ensure_update_plan_revision(plan.revision, current_revision)
+    {
+        CONTENT_UPDATE_PLANS.remove(plan_id);
+        return Err(error);
+    }
+
+    for resolution in resolutions {
+        if resolution.choice
+            == ContentUpdateResolutionChoice::RestorePackDefault
+        {
+            super::projects::restore_pack_member_default(
+                &plan.instance_id,
+                &resolution.content_id,
+            )
+            .await?;
+        }
+    }
+
+    if plan.scope == ContentUpdateScope::Pack {
+        if let Some(action) = plan.actions.first() {
+            match action.provider {
+                ContentProvider::Modrinth => {
+                    super::projects::update_managed_modrinth_version(
+                        &plan.instance_id,
+                        &action.target_release_id,
+                    )
+                    .await?;
+                }
+                ContentProvider::CurseForge => {
+                    let file_id = action
+                        .target_release_id
+                        .parse::<u32>()
+                        .map_err(|_| {
+                            crate::ErrorKind::InputError(
+                                "The planned CurseForge file ID is invalid"
+                                    .to_string(),
+                            )
+                        })?;
+                    crate::install::runner::update_managed_curseforge_modpack(
+                        plan.instance_id.clone(),
+                        file_id,
+                    )
+                    .await?;
+                }
+                ContentProvider::McArchive => {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCArchive does not support automatic pack updates"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                ContentProvider::Local => {}
+            }
+        }
+    } else {
+        for action in &plan.actions {
+            super::projects::switch_content_entry_version(
+                &plan.instance_id,
+                &action.content_id,
+                &action.target_release_id,
+            )
+            .await?;
+        }
+    }
+
+    CONTENT_UPDATE_PLANS.remove(plan_id);
+    crate::state::get_content_snapshot(&plan.instance_id, false, &state).await
+}
+
+fn update_action(
+    content_id: String,
+    relative_path: Option<String>,
+    ownership_kind: ContentOwnershipKind,
+    update: &ContentItemUpdate,
+) -> ContentUpdatePlanAction {
+    match update {
+        ContentItemUpdate::Modrinth {
+            current_version_id,
+            target_version_id,
+            ..
+        } => ContentUpdatePlanAction {
+            content_id,
+            relative_path,
+            ownership_kind,
+            provider: ContentProvider::Modrinth,
+            current_release_id: Some(current_version_id.to_string()),
+            target_release_id: target_version_id.to_string(),
+        },
+        ContentItemUpdate::CurseForge {
+            current_file_id,
+            target_file_id,
+            ..
+        } => ContentUpdatePlanAction {
+            content_id,
+            relative_path,
+            ownership_kind,
+            provider: ContentProvider::CurseForge,
+            current_release_id: Some(current_file_id.get().to_string()),
+            target_release_id: target_file_id.get().to_string(),
+        },
+    }
+}
+
+fn update_scope_selects_item(
+    scope: ContentUpdateScope,
+    target: Option<&str>,
+    item: &crate::state::InstanceContentSnapshotItem,
+    content_id: Option<&str>,
+) -> bool {
+    match scope {
+        ContentUpdateScope::UserAdded => {
+            item.ownership_kind == ContentOwnershipKind::UserAdded
+        }
+        ContentUpdateScope::Item => content_id == target,
+        ContentUpdateScope::Pack => false,
+    }
+}
+
+fn ensure_update_plan_revision(
+    planned_revision: u64,
+    current_revision: u64,
+) -> crate::Result<()> {
+    if planned_revision == current_revision {
+        return Ok(());
+    }
+    Err(crate::ErrorKind::InputError(format!(
+        "The content update plan is stale (planned revision {planned_revision}, current revision {current_revision})"
+    ))
+    .into())
+}
+
+#[tracing::instrument]
+pub async fn get_linked_modpack_content(
+    instance_id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<ContentItem>> {
+    let state = State::get().await?;
+    crate::state::list_linked_modpack_content(
+        instance_id,
+        None,
+        cache_behaviour,
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_dependencies_as_content_items(
+    dependencies: Vec<Dependency>,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Vec<ContentItem>> {
+    let state = State::get().await?;
+    crate::state::dependencies_to_content_items(
+        &dependencies,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn get_linked_modpack_info(
+    instance_id: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Option<LinkedModpackInfo>> {
+    let state = State::get().await?;
+    require_installed_instance(instance_id, &state).await?;
+    crate::state::get_linked_modpack_info(
+        instance_id,
+        None,
+        cache_behaviour,
+        &state,
+    )
+    .await
+}
+
+async fn require_installed_instance(
+    instance_id: &str,
+    state: &State,
+) -> crate::Result<()> {
+    let metadata = crate::state::instances::commands::get_instance_metadata(
+        instance_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::UnmanagedInstanceError(instance_id.to_string())
+    })?;
+    let stage = metadata.instance.install_stage;
+    if stage != crate::state::InstanceInstallStage::Installed {
+        return Err(crate::ErrorKind::InstanceNotReady {
+            instance_id: instance_id.to_string(),
+            stage: stage.as_str().to_string(),
+        }
+        .into());
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::state::instances::{
+        ContentItemCapabilities, InstanceContentSnapshotItem,
+        PackMemberMaterializationState, PackMemberOverrideKind,
+    };
+
+    fn snapshot_item(
+        ownership_kind: ContentOwnershipKind,
+        entry_id: Option<&str>,
+        member_id: Option<&str>,
+        file_id: Option<&str>,
+    ) -> InstanceContentSnapshotItem {
+        InstanceContentSnapshotItem {
+            file_id: file_id.map(str::to_string),
+            entry_id: entry_id.map(str::to_string),
+            member_id: member_id.map(str::to_string),
+            ownership_kind,
+            materialization_state: PackMemberMaterializationState::Present,
+            override_kind: PackMemberOverrideKind::None,
+            expected_relative_path: "mods/test.jar".to_string(),
+            required: true,
+            project_type: ProjectType::Mod,
+            provider: None,
+            provider_project_id: None,
+            provider_release_id: None,
+            content: None,
+            capabilities: ContentItemCapabilities::default(),
+            dependency: None,
+        }
+    }
+
+    #[test]
+    fn user_added_update_scope_excludes_pack_and_discovered_content() {
+        let user_added = snapshot_item(
+            ContentOwnershipKind::UserAdded,
+            Some("user-entry"),
+            None,
+            Some("user-file"),
+        );
+        let pack_managed = snapshot_item(
+            ContentOwnershipKind::PackManaged,
+            Some("pack-entry"),
+            Some("pack-member"),
+            Some("pack-file"),
+        );
+        let discovered = snapshot_item(
+            ContentOwnershipKind::LocalDiscovered,
+            None,
+            None,
+            Some("discovered-file"),
+        );
+
+        assert!(update_scope_selects_item(
+            ContentUpdateScope::UserAdded,
+            None,
+            &user_added,
+            user_added.entry_id.as_deref(),
+        ));
+        assert!(!update_scope_selects_item(
+            ContentUpdateScope::UserAdded,
+            None,
+            &pack_managed,
+            pack_managed.entry_id.as_deref(),
+        ));
+        assert!(!update_scope_selects_item(
+            ContentUpdateScope::UserAdded,
+            None,
+            &discovered,
+            discovered.file_id.as_deref(),
+        ));
+    }
+
+    #[test]
+    fn update_plan_revision_rejects_stale_plans() {
+        assert!(ensure_update_plan_revision(7, 7).is_ok());
+        let error = ensure_update_plan_revision(7, 8).unwrap_err();
+        assert!(error.to_string().contains("planned revision 7"));
+        assert!(error.to_string().contains("current revision 8"));
+    }
+}

packages/app-lib/src/api/instance/export_mrpack.rs

@@ -0,0 +1,722 @@
+use super::content::get_projects;
+use super::get::get;
+use super::paths::get_full_path;
+use crate::api::content_search::original_content_relative_path;
+use crate::event::LoadingBarType;
+use crate::event::emit::{emit_loading, init_loading};
+use crate::pack::install_from::{
+    EnvType, PackDependency, PackFile, PackFileHash, PackFormat,
+};
+use crate::state::{
+    CacheBehaviour, CachedEntry, ContentProviderRef, InstanceMetadata,
+    ModLoader, ModrinthVersionId, SideType, State,
+};
+use crate::util::io::{self, IOError};
+use async_zip::tokio::write::ZipFileWriter;
+use async_zip::{Compression, DeflateOption, ZipEntryBuilder};
+use futures::io::AsyncWriteExt;
+use path_util::SafeRelativeUtf8UnixPathBuf;
+use std::collections::{HashMap, HashSet};
+use std::path::PathBuf;
+use tokio::fs::File;
+use tokio::io::AsyncReadExt;
+
+const METADATA_PROGRESS_WEIGHT: f64 = 15.0;
+const WRITE_PROGRESS_WEIGHT: f64 = 80.0;
+/// Minimum bar movement (in progress points) before another loading event is
+/// emitted, so small packs do not spam the UI with per-chunk updates.
+const PROGRESS_EMIT_THRESHOLD: f64 = 0.1;
+/// Hard floor on how many copy chunks may pass between loading events, so very
+/// large files still move the bar while they are being packed.
+const PROGRESS_EMIT_CHUNKS: u32 = 64;
+/// Deflate is only applied to compressible text/config files; a low level
+/// keeps packing fast while still shrinking those files.
+const DEFLATE_OPTION: DeflateOption = DeflateOption::Other(1);
+const COPY_BUFFER_SIZE: usize = 256 * 1024;
+
+#[tracing::instrument(skip_all)]
+pub async fn export_mrpack(
+    instance_id: &str,
+    export_path: PathBuf,
+    included_export_candidates: Vec<String>,
+    version_id: Option<String>,
+    description: Option<String>,
+    _name: Option<String>,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let _permit: tokio::sync::SemaphorePermit =
+        state.io_semaphore.0.acquire().await?;
+    let metadata = get(instance_id).await?.ok_or_else(|| {
+        crate::ErrorKind::OtherError(format!(
+            "Tried to export a nonexistent instance {instance_id}!"
+        ))
+    })?;
+    // Directly associated instances own no files: everything lives in the
+    // linked launcher's `.minecraft`, so there is nothing exportable here.
+    if metadata.instance.is_direct_linked() {
+        return Err(crate::ErrorKind::InputError(format!(
+            "\"{}\" is directly associated with an external launcher; its \
+             files are managed by that launcher and cannot be exported",
+            metadata.instance.name
+        ))
+        .into());
+    }
+    let included_export_candidates = included_export_candidates
+        .into_iter()
+        .map(|candidate| candidate.replace('\\', "/"))
+        .filter(|x| {
+            if let Some(f) = PathBuf::from(x).file_name()
+                && f.to_string_lossy().starts_with(".DS_Store")
+            {
+                return false;
+            }
+            true
+        })
+        .collect::<Vec<_>>();
+
+    let instance_base_path = get_full_path(instance_id).await?;
+    let mut file = File::create(&export_path)
+        .await
+        .map_err(|e| IOError::with_path(e, &export_path))?;
+    let mut writer = ZipFileWriter::with_tokio(&mut file);
+    let version_id = version_id.unwrap_or("1.0.0".to_string());
+    let loading_bar = init_loading(
+        LoadingBarType::ZipExtract {
+            instance_id: metadata.instance.id.clone(),
+            instance_name: metadata.instance.name.clone(),
+        },
+        100.0,
+        "Exporting instance to .mrpack",
+    )
+    .await?;
+
+    let (mut progress, mut packfile) = {
+        let mut metadata_progress = 0.0;
+        let mut on_metadata_progress = |target: f64| {
+            let target = METADATA_PROGRESS_WEIGHT * target.clamp(0.0, 1.0);
+            let delta = target - metadata_progress;
+            metadata_progress = target;
+            let _ = emit_loading(
+                &loading_bar,
+                delta,
+                Some("Preparing modpack metadata"),
+            );
+        };
+        let packfile = create_mrpack_json_inner(
+            &metadata,
+            version_id,
+            description,
+            &mut on_metadata_progress,
+        )
+        .await?;
+        drop(on_metadata_progress);
+        (metadata_progress, packfile)
+    };
+    packfile.files.retain(|f| {
+        is_export_candidate_included(
+            f.path.as_str(),
+            &included_export_candidates,
+        )
+    });
+    strip_localized_pack_file_paths(&mut packfile.files);
+
+    let mut path_list = Vec::new();
+    add_all_recursive_folder_paths(&instance_base_path, &mut path_list).await?;
+    let disk_paths = path_list
+        .iter()
+        .filter(|path| path.is_file())
+        .filter_map(|path| {
+            pack_get_relative_path(&instance_base_path, path)
+                .ok()
+                .map(|relative_path| relative_path.as_str().to_string())
+        })
+        .collect::<HashSet<_>>();
+    let mut write_list: Vec<(PathBuf, String)> = Vec::new();
+    let mut write_total_bytes: u64 = 0;
+    for path in &path_list {
+        let Ok(relative_path) =
+            pack_get_relative_path(&instance_base_path, path)
+        else {
+            continue;
+        };
+        let exported_path =
+            original_content_relative_path(relative_path.as_str());
+        let Ok(metadata) = path.metadata() else {
+            continue;
+        };
+        if !metadata.is_file()
+            || packfile
+                .files
+                .iter()
+                .any(|f| f.path.as_str() == exported_path)
+            || !is_export_candidate_included(
+                relative_path.as_str(),
+                &included_export_candidates,
+            )
+        {
+            continue;
+        }
+        write_total_bytes += metadata.len();
+        write_list.push((path.clone(), relative_path.as_str().to_string()));
+    }
+    let mut written_override_paths = HashSet::new();
+    let mut buffer = vec![0u8; COPY_BUFFER_SIZE];
+    let mut bytes_written = 0u64;
+    let mut write_progress = 0.0_f64;
+    for (path, relative_path) in write_list {
+        let exported_path =
+            original_content_relative_path(relative_path.as_str());
+        let entry_path = if exported_path != relative_path.as_str()
+            && !disk_paths.contains(&exported_path)
+            && written_override_paths.insert(exported_path.clone())
+        {
+            exported_path
+        } else {
+            relative_path.as_str().to_string()
+        };
+        let compression = if is_already_compressed(&entry_path) {
+            Compression::Stored
+        } else {
+            Compression::Deflate
+        };
+        let builder = ZipEntryBuilder::new(
+            format!("overrides/{entry_path}").into(),
+            compression,
+        )
+        .deflate_option(DEFLATE_OPTION);
+        let mut file = File::open(&path)
+            .await
+            .map_err(|e| IOError::with_path(e, &path))?;
+        let mut entry = writer.write_entry_stream(builder).await?;
+        let mut chunks_since_emit = 0u32;
+        loop {
+            let read = file
+                .read(&mut buffer)
+                .await
+                .map_err(|e| IOError::with_path(e, &path))?;
+            if read == 0 {
+                break;
+            }
+            entry
+                .write_all(&buffer[..read])
+                .await
+                .map_err(|e| IOError::with_path(e, &path))?;
+            bytes_written += read as u64;
+            chunks_since_emit += 1;
+            let target = WRITE_PROGRESS_WEIGHT
+                * (bytes_written as f64 / write_total_bytes.max(1) as f64)
+                    .min(1.0);
+            let delta = target - write_progress;
+            if delta >= PROGRESS_EMIT_THRESHOLD
+                || chunks_since_emit >= PROGRESS_EMIT_CHUNKS
+            {
+                write_progress = target;
+                progress += delta;
+                let _ = emit_loading(
+                    &loading_bar,
+                    delta,
+                    Some(relative_path.as_str()),
+                );
+                chunks_since_emit = 0;
+            }
+        }
+        entry.close().await?;
+        let target = WRITE_PROGRESS_WEIGHT
+            * (bytes_written as f64 / write_total_bytes.max(1) as f64).min(1.0);
+        let delta = target - write_progress;
+        if delta > 0.0 {
+            write_progress = target;
+            progress += delta;
+            let _ =
+                emit_loading(&loading_bar, delta, Some(relative_path.as_str()));
+        }
+    }
+
+    let data = serde_json::to_vec_pretty(&packfile)?;
+    let builder = ZipEntryBuilder::new(
+        "modrinth.index.json".to_string().into(),
+        Compression::Deflate,
+    );
+    writer.write_entry_whole(builder, &data).await?;
+    writer.close().await?;
+
+    let _ =
+        emit_loading(&loading_bar, 100.0 - progress, Some("Finalizing export"));
+
+    Ok(())
+}
+
+/// Files in these formats are already compressed, so re-compressing them
+/// with Deflate wastes CPU for little size gain; store them as-is instead.
+fn is_already_compressed(path: &str) -> bool {
+    let Some(extension) = path.rsplit('.').next() else {
+        return false;
+    };
+    matches!(
+        extension.to_ascii_lowercase().as_str(),
+        "7z" | "aac"
+            | "apk"
+            | "avif"
+            | "bz2"
+            | "flac"
+            | "gif"
+            | "gz"
+            | "heic"
+            | "jar"
+            | "jpeg"
+            | "jpg"
+            | "lz4"
+            | "lzma"
+            | "m4a"
+            | "mkv"
+            | "mov"
+            | "mp3"
+            | "mp4"
+            | "ogg"
+            | "oga"
+            | "opus"
+            | "png"
+            | "rar"
+            | "webm"
+            | "webp"
+            | "woff"
+            | "woff2"
+            | "xz"
+            | "zip"
+            | "zst"
+    )
+}
+
+fn is_export_candidate_included(
+    path: &str,
+    included_export_candidates: &[String],
+) -> bool {
+    included_export_candidates.iter().any(|candidate| {
+        path == candidate
+            || path
+                .strip_prefix(candidate)
+                .is_some_and(|suffix| suffix.starts_with('/'))
+    })
+}
+
+/// Rewrites `[中文名]`-prefixed install paths back to their original names so
+/// exported packs stay free of localized file names. Entries whose stripped
+/// path would collide with another entry keep their on-disk name.
+fn strip_localized_pack_file_paths(files: &mut [PackFile]) {
+    let mut used = files
+        .iter()
+        .map(|file| file.path.as_str().to_string())
+        .collect::<HashSet<_>>();
+    for file in files {
+        let stripped = original_content_relative_path(file.path.as_str());
+        if stripped == file.path.as_str() || used.contains(&stripped) {
+            continue;
+        }
+        let Ok(path) = SafeRelativeUtf8UnixPathBuf::try_from(stripped.clone())
+        else {
+            continue;
+        };
+        used.insert(stripped);
+        file.path = path;
+    }
+}
+
+#[tracing::instrument]
+pub async fn get_pack_export_candidates(
+    instance_id: &str,
+) -> crate::Result<Vec<SafeRelativeUtf8UnixPathBuf>> {
+    let mut path_list = Vec::new();
+    let instance_base_dir = get_full_path(instance_id).await?;
+    let mut read_dir = io::read_dir(&instance_base_dir).await?;
+    while let Some(entry) = read_dir
+        .next_entry()
+        .await
+        .map_err(|e| IOError::with_path(e, &instance_base_dir))?
+    {
+        let path = entry.path();
+        if path.is_dir() {
+            let mut read_dir = io::read_dir(&path).await?;
+            while let Some(entry) = read_dir
+                .next_entry()
+                .await
+                .map_err(|e| IOError::with_path(e, &instance_base_dir))?
+            {
+                path_list.push(pack_get_relative_path(
+                    &instance_base_dir,
+                    &entry.path(),
+                )?);
+            }
+        } else {
+            path_list.push(pack_get_relative_path(&instance_base_dir, &path)?);
+        }
+    }
+    Ok(path_list)
+}
+
+fn pack_get_relative_path(
+    instance_path: &PathBuf,
+    path: &PathBuf,
+) -> crate::Result<SafeRelativeUtf8UnixPathBuf> {
+    Ok(SafeRelativeUtf8UnixPathBuf::try_from(
+        path.strip_prefix(instance_path)
+            .map_err(|_| {
+                crate::ErrorKind::FSError(format!(
+                    "Path {path:?} does not correspond to an instance"
+                ))
+            })?
+            .components()
+            .map(|c| c.as_os_str().to_string_lossy())
+            .collect::<Vec<_>>()
+            .join("/"),
+    )?)
+}
+
+/// The `.mrpack` specification stores archive paths as Unix-style relative
+/// paths, even when the source instance is on Windows.
+fn mrpack_relative_path(
+    relative_path: &str,
+) -> crate::Result<SafeRelativeUtf8UnixPathBuf> {
+    Ok(SafeRelativeUtf8UnixPathBuf::try_from(
+        relative_path.replace('\\', "/"),
+    )?)
+}
+
+#[tracing::instrument(skip_all)]
+pub async fn create_mrpack_json(
+    metadata: &InstanceMetadata,
+    version_id: String,
+    description: Option<String>,
+) -> crate::Result<PackFormat> {
+    create_mrpack_json_inner(metadata, version_id, description, &mut |_| {})
+        .await
+}
+
+#[tracing::instrument(skip_all)]
+async fn create_mrpack_json_inner(
+    metadata: &InstanceMetadata,
+    version_id: String,
+    description: Option<String>,
+    on_progress: &mut impl FnMut(f64),
+) -> crate::Result<PackFormat> {
+    let mut dependencies = HashMap::new();
+    match (
+        metadata.applied_content_set.loader,
+        metadata.applied_content_set.loader_version.clone(),
+    ) {
+        (ModLoader::Forge, Some(v)) => {
+            dependencies.insert(PackDependency::Forge, v)
+        }
+        (ModLoader::NeoForge, Some(v)) => {
+            dependencies.insert(PackDependency::NeoForge, v)
+        }
+        (ModLoader::Fabric, Some(v)) => {
+            dependencies.insert(PackDependency::FabricLoader, v)
+        }
+        (ModLoader::Quilt, Some(v)) => {
+            dependencies.insert(PackDependency::QuiltLoader, v)
+        }
+		(ModLoader::Babric, _) => {
+			return Err(crate::ErrorKind::OtherError(
+				"Babric instances cannot be exported to mrpack, as the format has no Babric dependency type".to_string(),
+			).into())
+		}
+        (ModLoader::Vanilla, _) => None,
+        (ModLoader::OptiFine, _) => {
+            return Err(crate::ErrorKind::OtherError(
+                "OptiFine instances cannot be exported to mrpack, as the format has no OptiFine dependency type".to_string(),
+            )
+            .into());
+        }
+        _ => {
+            return Err(crate::ErrorKind::OtherError(
+                "Loader version mismatch".to_string(),
+            )
+            .into());
+        }
+    };
+    dependencies.insert(
+        PackDependency::Minecraft,
+        metadata.applied_content_set.game_version.clone(),
+    );
+
+    let state = State::get().await?;
+    let projects = get_projects(
+        &metadata.instance.id,
+        Some(CacheBehaviour::MustRevalidate),
+    )
+    .await?
+    .into_iter()
+    .collect::<Vec<_>>();
+    on_progress(0.2);
+    let instance_path = get_full_path(&metadata.instance.id).await?;
+    let mut modrinth_version_ids = projects
+        .iter()
+        .flat_map(|(_, file)| file.provider_refs.iter())
+        .filter_map(|reference| match reference {
+            ContentProviderRef::Modrinth {
+                version_id: Some(version_id),
+                ..
+            } => Some(version_id.to_string()),
+            _ => None,
+        })
+        .collect::<HashSet<_>>();
+    for file in projects.iter().map(|(_, file)| file) {
+        if let Some(metadata) = &file.modrinth {
+            modrinth_version_ids.insert(metadata.version_id.to_string());
+        }
+    }
+    let modrinth_version_id_refs = modrinth_version_ids
+        .iter()
+        .map(|id| ModrinthVersionId::new(id.clone()))
+        .collect::<crate::Result<Vec<_>>>()?;
+    let versions = CachedEntry::get_version_many(
+        &modrinth_version_id_refs,
+        None,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?;
+    on_progress(0.4);
+    let versions_by_id = versions
+        .into_iter()
+        .map(|version| (version.id.clone(), version))
+        .collect::<HashMap<_, _>>();
+    let mut files = Vec::new();
+    let mut remote_paths = HashSet::new();
+    let project_total = projects.len();
+    for (index, (path, content_file)) in projects.into_iter().enumerate() {
+        on_progress(
+            0.4 + 0.6 * ((index + 1) as f64 / project_total.max(1) as f64),
+        );
+        let disk_path = instance_path.join(path.as_str());
+        let Ok((disk_size, local_sha1)) =
+            crate::util::fetch::sha1_file_async(&disk_path).await
+        else {
+            continue;
+        };
+        let Some(file_size) = u32::try_from(disk_size).ok() else {
+            continue;
+        };
+        let mut remote: Option<(HashMap<PackFileHash, String>, String)> = None;
+        for reference in &content_file.provider_refs {
+            match reference {
+                ContentProviderRef::Modrinth {
+                    version_id: Some(version_id),
+                    ..
+                } => {
+                    let Some(version) = versions_by_id.get(version_id.as_str())
+                    else {
+                        continue;
+                    };
+                    if let Some(version_file) =
+                        version.files.iter().find(|file| {
+                            file.size == file_size
+                                && file.hashes.get("sha1").is_some_and(|hash| {
+                                    hash.eq_ignore_ascii_case(&local_sha1)
+                                })
+                                && !file.url.trim().is_empty()
+                        })
+                    {
+                        remote = Some((
+                            version_file
+                                .hashes
+                                .clone()
+                                .into_iter()
+                                .map(|(kind, hash)| {
+                                    (PackFileHash::from(kind), hash)
+                                })
+                                .collect(),
+                            version_file.url.clone(),
+                        ));
+                        break;
+                    }
+                }
+                ContentProviderRef::CurseForge {
+                    project_id,
+                    file_id: Some(file_id),
+                } => {
+                    let Ok(file) = crate::api::curseforge::get_file(
+                        project_id.get(),
+                        file_id.get(),
+                    )
+                    .await
+                    else {
+                        continue;
+                    };
+                    let allowed =
+                        crate::api::curseforge::get_project(project_id.get())
+                            .await
+                            .ok()
+                            .and_then(|project| project.allow_mod_distribution)
+                            .unwrap_or(true);
+                    if !allowed {
+                        continue;
+                    }
+                    let hash = file
+                        .hashes
+                        .iter()
+                        .find(|hash| hash.algo == 1)
+                        .map(|hash| hash.value.as_str());
+                    if file.file_length == u64::from(file_size)
+                        && hash.is_some_and(|hash| {
+                            hash.eq_ignore_ascii_case(&local_sha1)
+                        })
+                        && file
+                            .download_url
+                            .as_deref()
+                            .is_some_and(|url| !url.trim().is_empty())
+                    {
+                        let mut hashes = HashMap::new();
+                        if let Some(hash) = hash {
+                            hashes.insert(PackFileHash::Sha1, hash.to_string());
+                        }
+                        remote = Some((
+                            hashes,
+                            file.download_url.unwrap_or_default(),
+                        ));
+                        break;
+                    }
+                }
+                _ => {}
+            }
+        }
+        let Some((hashes, download)) = remote else {
+            continue;
+        };
+        let relative_path = path.as_str().replace('\\', "/");
+        let Ok(path) = mrpack_relative_path(&original_content_relative_path(
+            &relative_path,
+        )) else {
+            continue;
+        };
+        if !remote_paths.insert(path.as_str().to_string()) {
+            continue;
+        }
+        let mut env = HashMap::new();
+        env.insert(EnvType::Client, SideType::Required);
+        env.insert(EnvType::Server, SideType::Required);
+        files.push(PackFile {
+            path,
+            hashes,
+            env: Some(env),
+            downloads: vec![download],
+            file_size,
+        });
+    }
+    on_progress(1.0);
+
+    Ok(PackFormat {
+        game: "minecraft".to_string(),
+        format_version: 1,
+        version_id,
+        name: metadata.instance.name.clone(),
+        summary: description,
+        files,
+        dependencies,
+    })
+}
+
+#[async_recursion::async_recursion]
+async fn add_all_recursive_folder_paths(
+    folder: &PathBuf,
+    output: &mut Vec<PathBuf>,
+) -> crate::Result<()> {
+    let mut read_dir = io::read_dir(folder).await?;
+    while let Some(entry) = read_dir
+        .next_entry()
+        .await
+        .map_err(|e| IOError::with_path(e, folder))?
+    {
+        let path = entry.path();
+        if path.is_dir() {
+            add_all_recursive_folder_paths(&path, output).await?;
+        } else {
+            output.push(path);
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::state::{CreateDirectLinkInstance, State};
+    use std::sync::Arc;
+    use tempfile::TempDir;
+
+    #[test]
+    fn mrpack_paths_normalize_windows_separators() {
+        let path =
+            super::mrpack_relative_path(r"config\subdir\options.txt").unwrap();
+
+        assert_eq!(path.as_str(), "config/subdir/options.txt");
+    }
+
+    /// The launcher state is a process-wide singleton; initialize it once and
+    /// reuse it so `State::get()` resolves inside these APIs. The state root
+    /// is intentionally leaked (`.keep()`) because the shared state outlives
+    /// this function.
+    async fn global_state() -> Arc<State> {
+        if !State::initialized() {
+            let root = TempDir::new().unwrap().keep();
+            let _ =
+                State::init_for_test(root.to_string_lossy().to_string()).await;
+        }
+        State::get().await.unwrap()
+    }
+
+    #[tokio::test]
+    async fn direct_link_instances_cannot_be_exported() {
+        let state = global_state().await;
+        let minecraft = TempDir::new().unwrap();
+        let version_dir = minecraft.path().join("versions/export-demo");
+        std::fs::create_dir_all(&version_dir).unwrap();
+        std::fs::write(
+            version_dir.join("export-demo.json"),
+            serde_json::to_vec_pretty(&serde_json::json!({
+                "id": "export-demo",
+                "inheritsFrom": "1.20.1",
+                "mainClass": "net.minecraft.client.main.Main"
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let instance = crate::state::create_direct_link_instance(
+            CreateDirectLinkInstance {
+                name: None,
+                launcher_type:
+                    crate::api::pack::import::ImportLauncherType::Generic,
+                base_path: minecraft.path().to_path_buf(),
+                instance_folder: "versions/export-demo".to_string(),
+                instance_path: None,
+                game_dir_mode: None,
+            },
+            &state,
+        )
+        .await
+        .unwrap();
+
+        let export_target = minecraft.path().join("out.mrpack");
+        let error = super::export_mrpack(
+            &instance.id,
+            export_target,
+            Vec::new(),
+            None,
+            None,
+            None,
+        )
+        .await
+        .unwrap_err();
+
+        let message = error.to_string();
+        assert!(
+            message.contains("directly associated"),
+            "expected a friendly rejection, got: {message}"
+        );
+        assert!(
+            !minecraft.path().join("out.mrpack").exists(),
+            "no archive may be written"
+        );
+    }
+}

packages/app-lib/src/api/instance/get.rs

@@ -0,0 +1,21 @@
+use crate::state::{InstanceMetadata, State};
+
+#[tracing::instrument]
+pub async fn get(instance_id: &str) -> crate::Result<Option<InstanceMetadata>> {
+    let state = State::get().await?;
+    crate::state::get_instance(instance_id, &state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn get_many(
+    instance_ids: &[&str],
+) -> crate::Result<Vec<InstanceMetadata>> {
+    let state = State::get().await?;
+    crate::state::get_instances_metadata(instance_ids, &state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn list() -> crate::Result<Vec<InstanceMetadata>> {
+    let state = State::get().await?;
+    crate::state::list_instances(&state.pool).await
+}

packages/app-lib/src/api/instance/home.rs

@@ -0,0 +1,53 @@
+use crate::event::InstancePayloadType;
+use crate::event::emit::emit_instance;
+use crate::state::{
+    DailyPlaytime, DailyPlaytimeEntry, InstanceMetadata, State,
+};
+
+pub async fn set_pinned(
+    instance_id: &str,
+    pinned: bool,
+) -> crate::Result<InstanceMetadata> {
+    let state = State::get().await?;
+    crate::state::instances::commands::set_instance_pinned(
+        instance_id,
+        pinned,
+        &state.pool,
+    )
+    .await?;
+
+    let instance = crate::state::get_instance(instance_id, &state.pool)
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError("Unknown instance".to_string())
+                .as_error()
+        })?;
+
+    emit_instance(&instance.instance.id, InstancePayloadType::Edited).await?;
+
+    Ok(instance)
+}
+
+pub async fn get_daily_playtime(
+    start_date: chrono::NaiveDate,
+    end_date: chrono::NaiveDate,
+) -> crate::Result<Vec<DailyPlaytime>> {
+    let state = State::get().await?;
+    crate::state::instances::commands::get_daily_playtime(
+        start_date,
+        end_date,
+        &state.pool,
+    )
+    .await
+}
+
+pub async fn get_daily_playtime_details(
+    date: chrono::NaiveDate,
+) -> crate::Result<Vec<DailyPlaytimeEntry>> {
+    let state = State::get().await?;
+    crate::state::instances::commands::get_daily_playtime_details(
+        date,
+        &state.pool,
+    )
+    .await
+}

packages/app-lib/src/api/instance/install.rs

@@ -0,0 +1,48 @@
+use crate::state::{JavaVersion, State};
+
+pub async fn get_optimal_jre_key(
+    instance_id: &str,
+) -> crate::Result<Option<JavaVersion>> {
+    let state = State::get().await?;
+    let context =
+        crate::state::instances::commands::get_instance_launch_context(
+            instance_id,
+            &state.pool,
+        )
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::OtherError(format!(
+                "Tried to resolve a nonexistent instance {instance_id}!"
+            ))
+        })?;
+    let (minecraft, version_index) =
+        crate::launcher::resolve_minecraft_manifest(
+            &context.applied_content_set.game_version,
+            &state,
+        )
+        .await?;
+    let version = &minecraft.versions[version_index];
+    let loader_version = crate::launcher::get_loader_version_from_profile(
+        &context.applied_content_set.game_version,
+        context.applied_content_set.loader,
+        context.applied_content_set.loader_version.as_deref(),
+    )
+    .await?;
+    let version_info = crate::launcher::download::download_version_info(
+        &state,
+        version,
+        context.applied_content_set.loader,
+        loader_version.as_ref(),
+        None,
+        None,
+        None,
+    )
+    .await?;
+
+    let major_version = version_info
+        .java_version
+        .as_ref()
+        .map_or(8, |java| java.major_version);
+
+    crate::api::jre::find_java_for_version(major_version).await
+}

packages/app-lib/src/api/instance/lifecycle.rs

@@ -0,0 +1,189 @@
+use crate::event::InstancePayloadType;
+use crate::event::emit::emit_instance;
+use crate::state::instances::adapters::sqlite::instance_rows;
+use crate::state::{
+    CreateDirectLinkInstance, CreateInstance, EditInstance, InstanceLink,
+    InstanceMetadata, ModLoader, State,
+};
+use crate::util::{fetch::write_cached_icon, io};
+use std::path::Path;
+use std::path::PathBuf;
+
+#[tracing::instrument]
+#[allow(clippy::too_many_arguments)]
+pub(crate) async fn create(
+    name: String,
+    game_version: String,
+    modloader: ModLoader,
+    loader_version: Option<String>,
+    icon_path: Option<String>,
+    link: InstanceLink,
+    symlink_target: Option<String>,
+    game_dir_override: Option<String>,
+) -> crate::Result<InstanceMetadata> {
+    let state = State::get().await?;
+    let instance = crate::state::create_instance(
+        CreateInstance {
+            name,
+            path: None,
+            game_version,
+            loader: modloader,
+            loader_version,
+            icon_path,
+            link,
+            symlink_target,
+            game_dir_override,
+        },
+        &state,
+    )
+    .await?;
+
+    let result = async {
+        emit_instance(&instance.id, InstancePayloadType::Created).await?;
+
+        crate::state::get_instance(&instance.id, &state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(
+                    "Created instance could not be loaded".to_string(),
+                )
+                .into()
+            })
+    }
+    .await;
+
+    if result.is_err() {
+        let _ = crate::state::remove_instance(&instance.id, &state).await;
+    }
+
+    result
+}
+
+/// Creates a "directly associated" instance that launches an externally
+/// managed (HMCL/PCL) local version in place: nothing is copied, symlinked,
+/// or reinstalled, and the game directory points at the linked `.minecraft`.
+#[tracing::instrument]
+pub async fn create_with_direct_link(
+    input: CreateDirectLinkInstance,
+) -> crate::Result<InstanceMetadata> {
+    let state = State::get().await?;
+    let instance =
+        crate::state::create_direct_link_instance(input, &state).await?;
+
+    let result = async {
+        emit_instance(&instance.id, InstancePayloadType::Created).await?;
+
+        crate::state::get_instance(&instance.id, &state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(
+                    "Created instance could not be loaded".to_string(),
+                )
+                .into()
+            })
+    }
+    .await;
+
+    if result.is_err() {
+        let _ = crate::state::remove_instance(&instance.id, &state).await;
+    }
+
+    result
+}
+
+/// Reconcile configured external Minecraft roots with direct-link records.
+pub async fn sync_direct_links(
+    roots: Vec<crate::state::ExternalMinecraftRoot>,
+) -> crate::Result<crate::state::DirectLinkSyncReport> {
+    let state = State::get().await?;
+    crate::state::sync_direct_link_instances(roots, &state).await
+}
+
+pub async fn edit(
+    instance_id: &str,
+    patch: EditInstance,
+) -> crate::Result<InstanceMetadata> {
+    let state = State::get().await?;
+    crate::state::edit_instance(instance_id, patch, &state.pool).await?;
+
+    let instance = crate::state::get_instance(instance_id, &state.pool)
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError("Unknown instance".to_string())
+                .as_error()
+        })?;
+
+    emit_instance(&instance.instance.id, InstancePayloadType::Edited).await?;
+
+    Ok(instance)
+}
+
+pub async fn cache_icon(
+    icon_name: &str,
+    bytes: Vec<u8>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    let path = write_cached_icon(
+        icon_name,
+        &state.directories.caches_dir(),
+        bytes::Bytes::from(bytes),
+        &state.io_semaphore,
+    )
+    .await?;
+
+    Ok(path.to_string_lossy().to_string())
+}
+
+pub async fn edit_icon(
+    instance_id: &str,
+    icon_path: Option<&Path>,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let instance =
+        instance_rows::get_instance_display_info(instance_id, &state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError("Unknown instance".to_string())
+            })?;
+    let icon_path = if let Some(icon) = icon_path {
+        let bytes = io::read(icon).await?;
+        let file = crate::util::fetch::write_cached_icon(
+            &icon.to_string_lossy(),
+            &state.directories.caches_dir(),
+            bytes::Bytes::from(bytes),
+            &state.io_semaphore,
+        )
+        .await?;
+        Some(file.to_string_lossy().to_string())
+    } else {
+        None
+    };
+
+    crate::state::edit_instance(
+        instance_id,
+        EditInstance {
+            icon_path: Some(icon_path),
+            ..EditInstance::default()
+        },
+        &state.pool,
+    )
+    .await?;
+    emit_instance(&instance.id, InstancePayloadType::Edited).await?;
+
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn remove(instance_id: &str) -> crate::Result<()> {
+    let state = State::get().await?;
+    let instance =
+        instance_rows::get_instance_display_info(instance_id, &state.pool)
+            .await?;
+    crate::state::remove_instance(instance_id, &state).await?;
+
+    if let Some(instance) = instance {
+        emit_instance(&instance.id, InstancePayloadType::Removed).await?;
+    }
+
+    Ok(())
+}

packages/app-lib/src/api/instance/mcarchive.rs

@@ -0,0 +1,247 @@
+use crate::state::instances::commands::add_project_bytes_from_provider;
+use crate::state::{
+    ContentProviderRef, ContentSourceKind, McArchiveFileId, McArchiveProjectId,
+    McArchiveVersionId, ProjectType, State,
+};
+use bytes::Bytes;
+use sha2::{Digest, Sha256};
+use std::io::Read;
+use std::path::{Path, PathBuf};
+
+#[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct McArchiveContentInstallRequest {
+    pub project_id: String,
+    pub project_slug: String,
+    pub version_id: String,
+    pub file_id: String,
+    pub project_type: ProjectType,
+}
+
+#[derive(Clone, Debug, serde::Serialize)]
+#[serde(tag = "state", rename_all = "snake_case")]
+pub enum McArchiveContentInstallResult {
+    Installed {
+        relative_path: String,
+    },
+    ManualDownload {
+        file_name: String,
+        page_url: Option<String>,
+        expected_sha256: Option<String>,
+    },
+}
+
+#[tracing::instrument(skip(request))]
+pub async fn install_mcarchive_content(
+    instance_id: &str,
+    request: McArchiveContentInstallRequest,
+) -> crate::Result<McArchiveContentInstallResult> {
+    let (project, version, file) = resolve_requested_file(&request).await?;
+    if file.needs_manual_download() {
+        return Ok(manual_download_result(&project, &file));
+    }
+
+    let bytes = crate::api::mcarchive::download_file(&file).await?;
+    let relative_path = record_verified_file(
+        instance_id,
+        &request,
+        project,
+        version,
+        file,
+        bytes.into(),
+    )
+    .await?;
+    Ok(McArchiveContentInstallResult::Installed { relative_path })
+}
+
+#[tracing::instrument(skip(request, source_path))]
+pub async fn import_mcarchive_content(
+    instance_id: &str,
+    request: McArchiveContentInstallRequest,
+    source_path: PathBuf,
+) -> crate::Result<McArchiveContentInstallResult> {
+    let (project, version, file) = resolve_requested_file(&request).await?;
+    let expected_sha256 = file
+        .sha256
+        .as_deref()
+        .filter(|hash| !hash.trim().is_empty());
+    let Some(expected_sha256) = expected_sha256 else {
+        return Ok(manual_download_result(&project, &file));
+    };
+    let metadata = tokio::fs::metadata(&source_path).await?;
+    if !metadata.is_file() {
+        return Err(crate::ErrorKind::InputError(
+            "The selected MCArchive import must be a regular file".to_string(),
+        )
+        .into());
+    }
+    let source_path = crate::util::io::canonicalize(&source_path)?;
+    let actual_sha256 = sha256_file(&source_path).await?;
+    if !actual_sha256.eq_ignore_ascii_case(expected_sha256) {
+        return Err(crate::ErrorKind::InputError(format!(
+            "The selected file does not match MCArchive SHA-256 for {}",
+            file.name
+        ))
+        .into());
+    }
+    let bytes = tokio::fs::read(&source_path).await?;
+    let relative_path = record_verified_file(
+        instance_id,
+        &request,
+        project,
+        version,
+        file,
+        Bytes::from(bytes),
+    )
+    .await?;
+    Ok(McArchiveContentInstallResult::Installed { relative_path })
+}
+
+async fn resolve_requested_file(
+    request: &McArchiveContentInstallRequest,
+) -> crate::Result<(
+    crate::mcarchive::McArchiveMod,
+    crate::mcarchive::McArchiveModVersion,
+    crate::mcarchive::McArchiveFile,
+)> {
+    if request.project_slug.trim().is_empty()
+        || request.project_id.trim().is_empty()
+        || request.version_id.trim().is_empty()
+        || request.file_id.trim().is_empty()
+    {
+        return Err(crate::ErrorKind::InputError(
+            "MCArchive project, version, and file identifiers are required"
+                .to_string(),
+        )
+        .into());
+    }
+    let project =
+        crate::api::mcarchive::get_mod_by_slug(&request.project_slug).await?;
+    if project.uuid != request.project_id {
+        return Err(crate::ErrorKind::InputError(
+            "The selected MCArchive project no longer matches its identifier"
+                .to_string(),
+        )
+        .into());
+    }
+    let version = project
+        .mod_versions
+        .iter()
+        .find(|version| version.uuid == request.version_id)
+        .cloned()
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "The selected MCArchive version is no longer available"
+                    .to_string(),
+            )
+        })?;
+    let file = version
+        .files
+        .iter()
+        .find(|file| file.uuid == request.file_id)
+        .cloned()
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "The selected MCArchive file is no longer available"
+                    .to_string(),
+            )
+        })?;
+    Ok((project, version, file))
+}
+
+async fn record_verified_file(
+    instance_id: &str,
+    request: &McArchiveContentInstallRequest,
+    project: crate::mcarchive::McArchiveMod,
+    version: crate::mcarchive::McArchiveModVersion,
+    file: crate::mcarchive::McArchiveFile,
+    bytes: Bytes,
+) -> crate::Result<String> {
+    let provider_ref = ContentProviderRef::McArchive {
+        project_id: McArchiveProjectId::new(project.uuid)?,
+        version_id: Some(McArchiveVersionId::new(version.uuid)?),
+        file_id: Some(McArchiveFileId::new(file.uuid)?),
+    };
+    let state = State::get().await?;
+    let relative_path = add_project_bytes_from_provider(
+        instance_id,
+        &file.name,
+        bytes,
+        None,
+        request.project_type,
+        ContentSourceKind::McArchive,
+        &provider_ref,
+        &state,
+    )
+    .await?;
+    super::emit_content_changed(instance_id).await?;
+    Ok(relative_path)
+}
+
+fn manual_download_result(
+    project: &crate::mcarchive::McArchiveMod,
+    file: &crate::mcarchive::McArchiveFile,
+) -> McArchiveContentInstallResult {
+    McArchiveContentInstallResult::ManualDownload {
+        file_name: file.name.clone(),
+        page_url: file
+            .manual_download_url()
+            .map(ToString::to_string)
+            .or_else(|| project.page_url.clone()),
+        expected_sha256: file.sha256.clone(),
+    }
+}
+
+async fn sha256_file(path: &Path) -> crate::Result<String> {
+    let path = path.to_path_buf();
+    tokio::task::spawn_blocking(move || {
+        let mut file = std::fs::File::open(&path).map_err(|error| {
+            crate::util::io::IOError::with_path(error, &path)
+        })?;
+        let mut hasher = Sha256::new();
+        let mut buffer = [0_u8; 262_144];
+        loop {
+            let read = file.read(&mut buffer)?;
+            if read == 0 {
+                break;
+            }
+            hasher.update(&buffer[..read]);
+        }
+        Ok(format!("{:x}", hasher.finalize()))
+    })
+    .await?
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn manual_route_preserves_the_provider_download_page() {
+        let project = crate::mcarchive::McArchiveMod {
+            uuid: "project".to_string(),
+            slug: "project".to_string(),
+            name: "Project".to_string(),
+            summary: None,
+            description: None,
+            page_url: Some("https://mcarchive.net/mod/project".to_string()),
+            mod_versions: Vec::new(),
+        };
+        let file = crate::mcarchive::McArchiveFile {
+            uuid: "file".to_string(),
+            name: "project.jar".to_string(),
+            sha256: None,
+            archive_url: None,
+            direct_url: None,
+            redirect_url: None,
+            page_url: None,
+        };
+        assert!(matches!(
+            manual_download_result(&project, &file),
+            McArchiveContentInstallResult::ManualDownload {
+                page_url: Some(page_url),
+                ..
+            } if page_url == "https://mcarchive.net/mod/project"
+        ));
+    }
+}

packages/app-lib/src/api/instance/paths.rs

@@ -0,0 +1,224 @@
+use crate::launcher::instance_runtime::InstanceRuntimeAdapter;
+use crate::state::State;
+use crate::util::io;
+use std::path::PathBuf;
+
+#[tracing::instrument]
+pub async fn get_full_path(instance_id: &str) -> crate::Result<PathBuf> {
+    let state = State::get().await?;
+    let instance = crate::state::get_instance(instance_id, &state.pool)
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError("Unknown instance".to_string())
+        })?;
+
+    // Directly associated instances never have a profile directory under
+    // `profiles`; interactive APIs (open folder, worlds, servers, ...) must
+    // operate on the linked `.minecraft` instead.
+    let adapter = InstanceRuntimeAdapter::for_instance(
+        &instance.instance,
+        &state.directories,
+    )?;
+    Ok(io::canonicalize(adapter.game_dir())?)
+
+    // `instance_game_dir` honours a per-instance `game_dir_override` before
+    // falling back to the profile directory.
+}
+
+#[tracing::instrument]
+pub async fn get_mod_full_path(
+    instance_id: &str,
+    project_path: &str,
+) -> crate::Result<PathBuf> {
+    Ok(get_full_path(instance_id).await?.join(project_path))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::state::CreateDirectLinkInstance;
+    use std::path::Path;
+    use std::sync::Arc;
+    use tempfile::TempDir;
+
+    /// The launcher state is a process-wide singleton; initialize it once and
+    /// reuse it so `State::get()` resolves inside these APIs. The state root
+    /// is intentionally leaked (`.keep()`) because the shared state outlives
+    /// this function.
+    async fn global_state() -> Arc<State> {
+        if !State::initialized() {
+            let root = TempDir::new().unwrap().keep();
+            let _ =
+                State::init_for_test(root.to_string_lossy().to_string()).await;
+        }
+        State::get().await.unwrap()
+    }
+
+    async fn create_direct_link_fixture(
+        label: &str,
+    ) -> (TempDir, crate::state::InstanceMetadata) {
+        let state = global_state().await;
+        let minecraft = TempDir::new().unwrap();
+        let version_dir = minecraft.path().join("versions").join(label);
+        std::fs::create_dir_all(&version_dir).unwrap();
+        std::fs::write(
+            version_dir.join(format!("{label}.json")),
+            serde_json::to_vec_pretty(&serde_json::json!({
+                "id": label,
+                "inheritsFrom": "1.20.1",
+                "mainClass": "net.minecraft.client.main.Main"
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let instance = crate::state::create_direct_link_instance(
+            CreateDirectLinkInstance {
+                name: None,
+                launcher_type:
+                    crate::api::pack::import::ImportLauncherType::Generic,
+                base_path: minecraft.path().to_path_buf(),
+                instance_folder: format!("versions/{label}"),
+                instance_path: None,
+                game_dir_mode: None,
+            },
+            &state,
+        )
+        .await
+        .unwrap();
+        let metadata = crate::state::get_instance(&instance.id, &state.pool)
+            .await
+            .unwrap()
+            .expect("metadata for created fixture");
+        (minecraft, metadata)
+    }
+
+    #[tokio::test]
+    async fn direct_link_instance_resolves_to_isolated_version_directory() {
+        let state = global_state().await;
+        let (_minecraft, metadata) =
+            create_direct_link_fixture("paths-demo").await;
+
+        let resolved = get_full_path(&metadata.instance.id).await.unwrap();
+
+        assert!(resolved.ends_with(Path::new("versions").join("paths-demo")));
+        assert!(
+            !state
+                .directories
+                .instances_dir()
+                .join(&metadata.instance.path)
+                .exists(),
+            "no profile directory may be created for a direct-link instance"
+        );
+    }
+
+    #[tokio::test]
+    async fn shared_direct_link_instance_resolves_to_minecraft_root() {
+        let state = global_state().await;
+        let minecraft = TempDir::new().unwrap();
+        let version_name = "paths-shared";
+        let version_dir = minecraft.path().join("versions").join(version_name);
+        std::fs::create_dir_all(&version_dir).unwrap();
+        std::fs::write(
+            version_dir.join(format!("{version_name}.json")),
+            serde_json::to_vec_pretty(&serde_json::json!({
+                "id": version_name,
+                "inheritsFrom": "1.20.1",
+                "mainClass": "net.minecraft.client.main.Main"
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let instance = crate::state::create_direct_link_instance(
+            CreateDirectLinkInstance {
+                name: None,
+                launcher_type:
+                    crate::api::pack::import::ImportLauncherType::Generic,
+                base_path: minecraft.path().to_path_buf(),
+                instance_folder: Path::new("versions")
+                    .join(version_name)
+                    .to_string_lossy()
+                    .to_string(),
+                instance_path: None,
+                game_dir_mode: Some(
+                    crate::launcher::ExternalGameDirMode::Shared,
+                ),
+            },
+            &state,
+        )
+        .await
+        .unwrap();
+
+        let resolved = get_full_path(&instance.id).await.unwrap();
+
+        assert_eq!(resolved, io::canonicalize(minecraft.path()).unwrap());
+    }
+
+    #[tokio::test]
+    async fn direct_link_file_browser_lists_linked_content() {
+        let _state = global_state().await;
+        let (minecraft, metadata) =
+            create_direct_link_fixture("paths-browse").await;
+
+        // The file browser lists directories relative to the resolved root.
+        let version_dir =
+            minecraft.path().join("versions").join("paths-browse");
+        std::fs::create_dir_all(version_dir.join("mods")).unwrap();
+        std::fs::write(
+            version_dir.join("mods").join("browse-fixture.jar"),
+            b"browse fixture",
+        )
+        .unwrap();
+
+        let root = get_full_path(&metadata.instance.id).await.unwrap();
+        let listed = root.join("mods").read_dir().unwrap();
+        let names = listed
+            .filter_map(Result::ok)
+            .map(|entry| entry.file_name().to_string_lossy().into_owned())
+            .collect::<Vec<_>>();
+
+        assert_eq!(
+            names,
+            vec!["browse-fixture.jar".to_string()],
+            "the browser root must expose the linked installation's content"
+        );
+    }
+
+    #[tokio::test]
+    async fn ordinary_instance_still_resolves_to_its_profile_directory() {
+        let state = global_state().await;
+        let metadata = crate::api::instance::create(
+            format!("paths-normal {}", uuid::Uuid::new_v4()),
+            "1.20.1".to_string(),
+            crate::state::ModLoader::Vanilla,
+            None,
+            None,
+            crate::state::InstanceLink::Unmanaged,
+            None,
+            None,
+        )
+        .await
+        .unwrap();
+
+        std::fs::create_dir_all(
+            state
+                .directories
+                .instances_dir()
+                .join(&metadata.instance.path),
+        )
+        .unwrap();
+
+        let resolved = get_full_path(&metadata.instance.id).await.unwrap();
+        assert_eq!(
+            resolved,
+            io::canonicalize(
+                state
+                    .directories
+                    .instances_dir()
+                    .join(&metadata.instance.path)
+            )
+            .unwrap()
+        );
+    }
+}

packages/app-lib/src/api/instance/planet_minecraft.rs

@@ -0,0 +1,134 @@
+use crate::api::planet_minecraft::PlanetMinecraftInstallRoute;
+use crate::state::instances::commands::add_project_bytes;
+use crate::state::{ContentSourceKind, ProjectType, State};
+use bytes::Bytes;
+use std::path::PathBuf;
+
+#[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PlanetMinecraftContentInstallRequest {
+    pub project_id: String,
+    pub version_id: String,
+    pub project_type: ProjectType,
+}
+
+#[derive(Clone, Debug, serde::Serialize)]
+#[serde(tag = "state", rename_all = "snake_case")]
+pub enum PlanetMinecraftContentInstallResult {
+    Installed {
+        relative_path: String,
+    },
+    ManualDownload {
+        page_url: String,
+        file_name: Option<String>,
+    },
+}
+
+pub async fn install_planet_minecraft_content(
+    instance_id: &str,
+    request: PlanetMinecraftContentInstallRequest,
+) -> crate::Result<PlanetMinecraftContentInstallResult> {
+    let project =
+        crate::api::planet_minecraft::get_project(&request.project_id).await?;
+    let version = project
+        .versions
+        .iter()
+        .find(|version| version.id == request.version_id)
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "The selected Planet Minecraft release is no longer available"
+                    .to_string(),
+            )
+        })?;
+    match version.download.install_route() {
+        PlanetMinecraftInstallRoute::Manual {
+            page_url,
+            file_name,
+        } => Ok(PlanetMinecraftContentInstallResult::ManualDownload {
+            page_url,
+            file_name,
+        }),
+        PlanetMinecraftInstallRoute::Automatic {
+            direct_url,
+            sha256,
+            file_name,
+        } => {
+            let bytes = crate::api::planet_minecraft::download_verified_file(
+                &direct_url,
+                &sha256,
+            )
+            .await?;
+            let name =
+                file_name.unwrap_or_else(|| format!("{}.jar", version.name));
+            let state = State::get().await?;
+            let relative_path = add_project_bytes(
+                instance_id,
+                &name,
+                Bytes::from(bytes),
+                None,
+                Some(request.project_type),
+                ContentSourceKind::Local,
+                &state,
+            )
+            .await?;
+            super::emit_content_changed(instance_id).await?;
+            Ok(
+                PlanetMinecraftContentInstallResult::Installed {
+                    relative_path,
+                },
+            )
+        }
+    }
+}
+
+pub async fn import_planet_minecraft_content(
+    instance_id: &str,
+    request: PlanetMinecraftContentInstallRequest,
+    source_path: PathBuf,
+) -> crate::Result<PlanetMinecraftContentInstallResult> {
+    let project =
+        crate::api::planet_minecraft::get_project(&request.project_id).await?;
+    let version = project
+        .versions
+        .iter()
+        .find(|version| version.id == request.version_id)
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "The selected Planet Minecraft release is no longer available"
+                    .to_string(),
+            )
+        })?;
+    let PlanetMinecraftInstallRoute::Manual {
+        file_name,
+        page_url: _,
+    } = version.download.install_route()
+    else {
+        return Err(crate::ErrorKind::InputError(
+				"This Planet Minecraft release has a verified direct download; use automatic installation"
+					.to_string(),
+			)
+			.into());
+    };
+    let metadata = tokio::fs::metadata(&source_path).await?;
+    if !metadata.is_file() {
+        return Err(crate::ErrorKind::InputError(
+            "The selected Planet Minecraft import must be a regular file"
+                .to_string(),
+        )
+        .into());
+    }
+    let bytes = tokio::fs::read(&source_path).await?;
+    let state = State::get().await?;
+    let relative_path = add_project_bytes(
+        instance_id,
+        file_name.as_deref().unwrap_or("planet-minecraft.jar"),
+        Bytes::from(bytes),
+        None,
+        Some(request.project_type),
+        ContentSourceKind::Local,
+        &state,
+    )
+    .await?;
+    super::emit_content_changed(instance_id).await?;
+    Ok(PlanetMinecraftContentInstallResult::Installed { relative_path })
+}

packages/app-lib/src/api/instance/projects.rs

@@ -0,0 +1,995 @@
+use crate::event::emit::{emit_instance, emit_loading, init_loading};
+use crate::event::{InstancePayloadType, LoadingBarType};
+use crate::state::instances::adapters::sqlite::{content_rows, instance_rows};
+use crate::state::instances::{
+    ContentOwnershipKind, PackMemberMaterializationState,
+    PackMemberOverrideKind,
+};
+use crate::state::{ContentProvider, ContentSourceKind, ProjectType, State};
+use crate::util::fetch;
+use modrinth_content_management::{
+    ContentType, ResolutionPreferences, ResolveContentPlan,
+};
+use std::collections::HashMap;
+use std::path::Path;
+
+#[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
+pub struct InstallProjectWithDependenciesRequest {
+    pub project_id: String,
+    pub version_id: Option<String>,
+    pub content_type: ContentType,
+    #[serde(default)]
+    pub selected: ResolutionPreferences,
+    #[serde(default)]
+    pub excluded_project_ids: Vec<String>,
+    #[serde(default)]
+    pub force_project_ids: Vec<String>,
+}
+
+#[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ContentToggleResult {
+    pub content_id: String,
+    pub path: String,
+    pub enabled: bool,
+}
+
+#[tracing::instrument]
+pub async fn update_all_projects(
+    instance_id: &str,
+) -> crate::Result<HashMap<String, String>> {
+    let state = State::get().await?;
+    let instance = get_instance_display_info(instance_id, &state).await?;
+    let loading_bar = init_loading(
+        LoadingBarType::InstanceUpdate {
+            instance_id: instance.id.clone(),
+            instance_name: instance.name.clone(),
+        },
+        100.0,
+        "Updating instance",
+    )
+    .await?;
+    let map = crate::state::instances::commands::update_all_projects(
+        instance_id,
+        &state,
+    )
+    .await?;
+    emit_loading(&loading_bar, 100.0, Some("Updated instance"))?;
+    emit_content_changed(&instance.id).await?;
+
+    Ok(map)
+}
+
+#[tracing::instrument]
+pub async fn update_project(
+    instance_id: &str,
+    project_path: &str,
+    skip_send_event: Option<bool>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    let path = crate::state::instances::commands::update_project(
+        instance_id,
+        project_path,
+        &state,
+    )
+    .await?;
+
+    if !skip_send_event.unwrap_or(false) {
+        emit_content_changed(instance_id).await?;
+    }
+
+    Ok(path)
+}
+
+#[tracing::instrument]
+pub async fn add_project_from_version(
+    instance_id: &str,
+    version_id: &str,
+    reason: fetch::DownloadReason,
+    dependent_on_version_id: Option<String>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    let project_path =
+        crate::state::instances::commands::add_project_from_version(
+            instance_id,
+            version_id,
+            reason,
+            dependent_on_version_id,
+            crate::state::ContentSourceKind::Local,
+            crate::state::instances::ContentOwnershipKind::UserAdded,
+            &state,
+        )
+        .await?;
+    emit_content_changed(instance_id).await?;
+
+    Ok(project_path)
+}
+
+#[tracing::instrument]
+pub async fn install_project_with_dependencies(
+    instance_id: &str,
+    request: InstallProjectWithDependenciesRequest,
+) -> crate::Result<ResolveContentPlan> {
+    let state = State::get().await?;
+    let metadata = super::get::get(instance_id).await?.ok_or_else(|| {
+        crate::ErrorKind::InputError("Unknown instance".to_string())
+    })?;
+    let plan = crate::state::instances::commands::resolve_install_plan(
+        instance_id,
+        crate::state::instances::commands::InstanceInstallProjectRequest {
+            project_id: request.project_id,
+            version_id: request.version_id,
+            content_type: request.content_type,
+            selected: request.selected,
+            excluded_project_ids: request.excluded_project_ids,
+            force_project_ids: request.force_project_ids,
+        },
+        &state,
+    )
+    .await?;
+
+    let instance_id = metadata.instance.id;
+    let project_ids = plan_project_ids(&plan);
+    let install_plan = plan.clone();
+    tokio::spawn(async move {
+        match crate::state::instances::commands::install_resolved_content_plan(
+            &instance_id,
+            &install_plan,
+            &state,
+        )
+        .await
+        {
+            Ok(_paths) => {
+                if let Err(error) = emit_instance(
+                    &instance_id,
+                    InstancePayloadType::ContentInstallFinished {
+                        project_ids: project_ids.clone(),
+                        dependency_project_ids: plan_project_ids(&install_plan)
+                            .into_iter()
+                            .skip(1)
+                            .collect(),
+                    },
+                )
+                .await
+                {
+                    tracing::error!(
+                        "Failed to emit content install finished event: {error}"
+                    );
+                }
+                if let Err(error) = emit_content_changed(&instance_id).await {
+                    tracing::error!(
+                        "Failed to emit instance edited event after content install: {error}"
+                    );
+                }
+            }
+            Err(error) => {
+                if let Err(emit_error) = emit_instance(
+                    &instance_id,
+                    InstancePayloadType::ContentInstallFailed {
+                        project_ids,
+                        message: error.to_string(),
+                    },
+                )
+                .await
+                {
+                    tracing::error!(
+                        "Failed to emit content install failed event: {emit_error}"
+                    );
+                }
+            }
+        }
+    });
+
+    Ok(plan)
+}
+
+#[tracing::instrument]
+pub async fn preview_project_with_dependencies(
+    instance_id: &str,
+    request: InstallProjectWithDependenciesRequest,
+) -> crate::Result<ResolveContentPlan> {
+    let state = State::get().await?;
+    super::get::get(instance_id).await?.ok_or_else(|| {
+        crate::ErrorKind::InputError("Unknown instance".to_string())
+    })?;
+    crate::state::instances::commands::resolve_install_plan(
+        instance_id,
+        crate::state::instances::commands::InstanceInstallProjectRequest {
+            project_id: request.project_id,
+            version_id: request.version_id,
+            content_type: request.content_type,
+            selected: request.selected,
+            excluded_project_ids: request.excluded_project_ids,
+            force_project_ids: request.force_project_ids,
+        },
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn preview_project_with_dependencies_for_target(
+    request: InstallProjectWithDependenciesRequest,
+    game_version: String,
+    loader: crate::state::ModLoader,
+) -> crate::Result<ResolveContentPlan> {
+    let state = State::get().await?;
+    crate::state::instances::commands::resolve_install_plan_for_target(
+        crate::state::instances::commands::InstanceInstallProjectRequest {
+            project_id: request.project_id,
+            version_id: request.version_id,
+            content_type: request.content_type,
+            selected: request.selected,
+            excluded_project_ids: request.excluded_project_ids,
+            force_project_ids: request.force_project_ids,
+        },
+        game_version,
+        loader,
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn queue_project_with_dependencies(
+    instance_id: &str,
+    request: InstallProjectWithDependenciesRequest,
+    display_title: String,
+    display_icon: Option<String>,
+) -> crate::Result<crate::install::InstallJobSnapshot> {
+    crate::install::install_content(
+        instance_id.to_string(),
+        request.project_id,
+        request.version_id,
+        request.content_type,
+        request.selected,
+        request.excluded_project_ids,
+        display_title,
+        display_icon,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn queue_curseforge_content(
+    request: crate::api::curseforge::CurseForgeInstallRequest,
+    display_title: String,
+    display_icon: Option<String>,
+) -> crate::Result<crate::install::InstallJobSnapshot> {
+    crate::install::install_curseforge_content(
+        request,
+        display_title,
+        display_icon,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn queue_curseforge_world(
+    request: crate::api::curseforge::CurseForgeWorldInstallRequest,
+    display_title: String,
+    display_icon: Option<String>,
+) -> crate::Result<crate::install::InstallJobSnapshot> {
+    crate::install::install_curseforge_world(
+        request,
+        display_title,
+        display_icon,
+    )
+    .await
+}
+
+fn plan_project_ids(plan: &ResolveContentPlan) -> Vec<String> {
+    let mut project_ids = Vec::with_capacity(plan.dependencies.len() + 1);
+    project_ids.push(plan.primary.project_id.clone());
+    project_ids.extend(
+        plan.dependencies
+            .iter()
+            .map(|dependency| dependency.project_id.clone()),
+    );
+    project_ids
+}
+
+#[tracing::instrument]
+pub async fn switch_project_version_with_dependencies(
+    instance_id: &str,
+    project_path: &str,
+    version_id: &str,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    let metadata = super::get::get(instance_id).await?.ok_or_else(|| {
+        crate::ErrorKind::InputError("Unknown instance".to_string())
+    })?;
+    let path =
+        crate::state::instances::commands::switch_project_version_with_dependencies(
+            instance_id,
+            project_path,
+            version_id,
+            &state,
+        )
+        .await?;
+    emit_content_changed(&metadata.instance.id).await?;
+
+    Ok(path)
+}
+
+#[tracing::instrument]
+pub async fn add_project_from_path(
+    instance_id: &str,
+    path: &Path,
+    project_type: Option<ProjectType>,
+    inner_base: Option<&str>,
+) -> crate::Result<String> {
+    if let Some(relative_path) =
+        crate::api::curseforge::import_pending_manual_download_from_path(
+            instance_id,
+            path,
+        )
+        .await?
+    {
+        emit_content_changed(instance_id).await?;
+        return Ok(relative_path);
+    }
+
+    let state = State::get().await?;
+    let result = crate::state::instances::commands::add_project_from_path(
+        instance_id,
+        path,
+        project_type,
+        inner_base,
+        &state,
+    )
+    .await;
+
+    if result.is_ok() {
+        emit_instance(instance_id, InstancePayloadType::Synced).await?;
+    }
+
+    result
+}
+
+#[tracing::instrument]
+pub async fn import_world_save(
+    instance_id: &str,
+    source_path: &Path,
+    inner_base: Option<&str>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    crate::state::instances::commands::import_world_save(
+        &state,
+        instance_id,
+        source_path,
+        inner_base,
+    )
+    .await
+}
+
+pub async fn install_datapack_to_world(
+    instance_id: &str,
+    world_path: &str,
+    source_path: &Path,
+    inner_base: Option<&str>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    crate::state::instances::commands::install_datapack_to_world(
+        instance_id,
+        world_path,
+        source_path,
+        inner_base,
+        &state,
+    )
+    .await
+}
+
+pub async fn install_datapack_bytes_to_world(
+    instance_id: &str,
+    world_path: &str,
+    file_name: &str,
+    bytes: Vec<u8>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    crate::state::instances::commands::install_datapack_bytes_to_world(
+        instance_id,
+        world_path,
+        file_name,
+        &bytes,
+        &state,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn toggle_disable_project(
+    instance_id: &str,
+    project: &str,
+    desired_enabled: Option<bool>,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    let res = crate::state::instances::commands::toggle_disable_project(
+        instance_id,
+        project,
+        desired_enabled,
+        &state,
+    )
+    .await?;
+    emit_content_changed(instance_id).await?;
+
+    Ok(res)
+}
+
+#[tracing::instrument]
+pub async fn rollback_project(
+    instance_id: &str,
+    project_path: &str,
+) -> crate::Result<String> {
+    let state = State::get().await?;
+    let res = crate::state::instances::commands::rollback_project(
+        instance_id,
+        project_path,
+        &state,
+    )
+    .await?;
+    emit_content_changed(instance_id).await?;
+
+    Ok(res)
+}
+
+#[tracing::instrument]
+pub async fn remove_project(
+    instance_id: &str,
+    project: &str,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    crate::state::instances::commands::remove_project(
+        instance_id,
+        project,
+        &state,
+    )
+    .await?;
+    emit_content_changed(instance_id).await?;
+
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn toggle_content_entry(
+    instance_id: &str,
+    content_id: &str,
+    desired_enabled: Option<bool>,
+) -> crate::Result<String> {
+    let mut results = toggle_content_entries(
+        instance_id,
+        vec![content_id.to_string()],
+        desired_enabled,
+    )
+    .await?;
+    results.pop().map(|result| result.path).ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected content no longer exists".to_string(),
+        )
+        .into()
+    })
+}
+
+#[tracing::instrument]
+pub async fn toggle_content_entries(
+    instance_id: &str,
+    content_ids: Vec<String>,
+    desired_enabled: Option<bool>,
+) -> crate::Result<Vec<ContentToggleResult>> {
+    let state = State::get().await?;
+    let results = crate::state::instances::commands::toggle_content_entries(
+        instance_id,
+        &content_ids,
+        desired_enabled,
+        &state,
+    )
+    .await?
+    .into_iter()
+    .map(|result| ContentToggleResult {
+        content_id: result.content_id,
+        path: result.path,
+        enabled: result.enabled,
+    })
+    .collect::<Vec<_>>();
+    if !results.is_empty() {
+        emit_content_changed(instance_id).await?;
+    }
+    Ok(results)
+}
+
+#[tracing::instrument]
+pub async fn remove_content_entry(
+    instance_id: &str,
+    content_id: &str,
+) -> crate::Result<()> {
+    let target = content_mutation_target(instance_id, content_id).await?;
+    let path = target.relative_path.ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected content is not present on disk".to_string(),
+        )
+    })?;
+    remove_project(instance_id, &path).await
+}
+
+#[tracing::instrument]
+pub async fn update_content_entry(
+    instance_id: &str,
+    content_id: &str,
+) -> crate::Result<String> {
+    let target = content_mutation_target(instance_id, content_id).await?;
+    let path = target.relative_path.ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected content is not present on disk".to_string(),
+        )
+    })?;
+    match target.provider {
+        Some(ContentProvider::CurseForge) => {
+            let result = crate::api::curseforge::update_installed_file(
+                instance_id,
+                &path,
+            )
+            .await?;
+            let updated_path = result
+                .installed
+                .iter()
+                .find(|file| !file.dependency)
+                .map_or(path, |file| file.relative_path.clone());
+            emit_content_changed(instance_id).await?;
+            Ok(updated_path)
+        }
+        Some(ContentProvider::McArchive) => Err(crate::ErrorKind::InputError(
+            "MCArchive content updates require selecting a file manually"
+                .to_string(),
+        )
+        .into()),
+        _ => update_project(instance_id, &path, None).await,
+    }
+}
+
+#[tracing::instrument]
+pub async fn switch_content_entry_version(
+    instance_id: &str,
+    content_id: &str,
+    version_id: &str,
+) -> crate::Result<String> {
+    let target = content_mutation_target(instance_id, content_id).await?;
+    let path = target.relative_path.ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected content is not present on disk".to_string(),
+        )
+    })?;
+    match target.provider {
+        Some(ContentProvider::CurseForge) => {
+            let file_id = version_id.parse::<u32>().map_err(|_| {
+                crate::ErrorKind::InputError(
+                    "The selected CurseForge file ID is invalid".to_string(),
+                )
+            })?;
+            let result = crate::api::curseforge::switch_installed_file_version(
+                instance_id,
+                &path,
+                file_id,
+            )
+            .await?;
+            let updated_path = result
+                .installed
+                .iter()
+                .find(|file| !file.dependency)
+                .map_or(path, |file| file.relative_path.clone());
+            emit_content_changed(instance_id).await?;
+            Ok(updated_path)
+        }
+		Some(ContentProvider::McArchive) => Err(crate::ErrorKind::InputError(
+			"MCArchive content version changes require selecting a file manually"
+				.to_string(),
+		)
+		.into()),
+        _ => {
+            switch_project_version_with_dependencies(
+                instance_id,
+                &path,
+                version_id,
+            )
+            .await
+        }
+    }
+}
+
+#[tracing::instrument]
+pub async fn restore_pack_member_default(
+    instance_id: &str,
+    member_id: &str,
+) -> crate::Result<Option<String>> {
+    let state = State::get().await?;
+    let target = content_rows::get_content_mutation_target(
+        instance_id,
+        member_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected pack member no longer exists".to_string(),
+        )
+    })?;
+    if target.member_id.as_deref() != Some(member_id) {
+        return Err(crate::ErrorKind::InputError(
+            "Restore requires a pack member ID".to_string(),
+        )
+        .into());
+    }
+
+    let member = content_rows::get_pack_members(
+        &content_rows::get_applied_content_set(instance_id, &state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(
+                    "Instance has no applied content set".to_string(),
+                )
+            })?
+            .id,
+        &state.pool,
+    )
+    .await?
+    .into_iter()
+    .find(|member| member.id == member_id)
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected pack member no longer exists".to_string(),
+        )
+    })?;
+
+    if member.override_kind == PackMemberOverrideKind::None
+        && member.materialization_state
+            == PackMemberMaterializationState::Present
+    {
+        return Ok(target.relative_path);
+    }
+    if member.override_kind == PackMemberOverrideKind::Disabled
+        && let Some(path) = target.relative_path
+    {
+        return toggle_disable_project(instance_id, &path, Some(true))
+            .await
+            .map(Some);
+    }
+
+    let project_id =
+        member.provider_project_id.as_deref().ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "This pack member has no provider project to restore from"
+                    .to_string(),
+            )
+        })?;
+    let release_id =
+        member.provider_release_id.as_deref().ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "This pack member has no original version to restore"
+                    .to_string(),
+            )
+        })?;
+    let old_path = target.relative_path;
+    let (restored_path, pending_manual) = match member.provider {
+        Some(ContentProvider::Modrinth) => (
+            Some(
+                crate::state::instances::commands::add_project_from_version(
+                    instance_id,
+                    release_id,
+                    fetch::DownloadReason::Update,
+                    None,
+                    ContentSourceKind::ModrinthModpack,
+                    ContentOwnershipKind::PackManaged,
+                    &state,
+                )
+                .await?,
+            ),
+            false,
+        ),
+        Some(ContentProvider::CurseForge) => {
+            let content_set =
+                content_rows::get_applied_content_set(instance_id, &state.pool)
+                    .await?
+                    .ok_or_else(|| {
+                        crate::ErrorKind::InputError(
+                            "Instance has no applied content set".to_string(),
+                        )
+                    })?;
+            let result = crate::api::curseforge::install_file(
+				crate::api::curseforge::CurseForgeInstallRequest {
+					instance_id: instance_id.to_string(),
+					project_id: project_id.parse().map_err(|_| {
+						crate::ErrorKind::InputError(
+							"Stored CurseForge project ID is invalid".to_string(),
+						)
+					})?,
+					file_id: release_id.parse().map_err(|_| {
+						crate::ErrorKind::InputError(
+							"Stored CurseForge file ID is invalid".to_string(),
+						)
+					})?,
+					project_type: member.project_type.get_name().to_string(),
+					ownership_kind: ContentOwnershipKind::PackManaged,
+					manual_operation_kind: crate::state::instances::ManualDownloadOperationKind::ContentUpdate,
+					game_version: Some(content_set.game_version),
+					mod_loader_type: curseforge_loader_type(content_set.loader),
+					world_name: None,
+					install_dependencies: false,
+					excluded_dependency_project_ids: Vec::new(),
+					force_dependency_project_ids: Vec::new(),
+					dependency_plan_id: None,
+				},
+			)
+			.await?;
+            let pending_manual = !result.manual_downloads.is_empty();
+            let failure_reason = result
+                .failed_downloads
+                .first()
+                .map(|failure| failure.reason.clone());
+            let restored_path = result
+                .installed
+                .into_iter()
+                .find(|file| !file.dependency)
+                .map(|file| file.relative_path);
+            if restored_path.is_none() && !pending_manual {
+                return Err(crate::ErrorKind::OtherError(
+                    failure_reason.unwrap_or_else(|| {
+                        "CurseForge did not return the restored file"
+                            .to_string()
+                    }),
+                )
+                .into());
+            }
+            (restored_path, pending_manual)
+        }
+        Some(ContentProvider::Local) => {
+            return Err(crate::ErrorKind::InputError(
+                "This pack member has no managed provider".to_string(),
+            )
+            .into());
+        }
+        Some(ContentProvider::McArchive) => {
+            return Err(crate::ErrorKind::InputError(
+                "MCArchive pack members must be restored from an imported file"
+                    .to_string(),
+            )
+            .into());
+        }
+        None => {
+            return Err(crate::ErrorKind::InputError(
+                "This pack member has no managed provider".to_string(),
+            )
+            .into());
+        }
+    };
+
+    if let (Some(old_path), Some(new_path)) =
+        (old_path.as_deref(), restored_path.as_deref())
+        && old_path != new_path
+        && crate::state::instances::commands::archive_project_file(
+            instance_id,
+            old_path,
+            new_path,
+            &state,
+        )
+        .await?
+        .is_none()
+    {
+        crate::state::instances::commands::remove_project(
+            instance_id,
+            old_path,
+            &state,
+        )
+        .await?;
+    }
+
+    let content_set =
+        content_rows::get_applied_content_set(instance_id, &state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(
+                    "Instance has no applied content set".to_string(),
+                )
+            })?;
+    let _instance_lock = state.lock_instance_content(instance_id).await;
+    let mut tx = state.pool.begin_with("BEGIN IMMEDIATE").await?;
+    content_rows::set_pack_member_override_in_transaction(
+        member_id,
+        if pending_manual {
+            PackMemberMaterializationState::PendingManual
+        } else {
+            PackMemberMaterializationState::Present
+        },
+        PackMemberOverrideKind::None,
+        &mut tx,
+    )
+    .await?;
+    content_rows::bump_content_set_revision_in_transaction(
+        &content_set.id,
+        &mut tx,
+    )
+    .await?;
+    tx.commit().await?;
+    emit_content_changed(instance_id).await?;
+    Ok(restored_path)
+}
+
+pub(crate) async fn emit_content_changed(
+    instance_id: &str,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let content_set =
+        content_rows::get_applied_content_set(instance_id, &state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(
+                    "Instance has no applied content set".to_string(),
+                )
+            })?;
+    emit_instance(
+        instance_id,
+        InstancePayloadType::ContentChanged {
+            revision: content_set.revision,
+        },
+    )
+    .await
+}
+
+async fn content_mutation_target(
+    instance_id: &str,
+    content_id: &str,
+) -> crate::Result<content_rows::ContentMutationTarget> {
+    let state = State::get().await?;
+    content_rows::get_content_mutation_target(
+        instance_id,
+        content_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "The selected content no longer exists".to_string(),
+        )
+        .into()
+    })
+}
+
+fn curseforge_loader_type(loader: crate::state::ModLoader) -> Option<u32> {
+    match loader {
+        crate::state::ModLoader::Forge | crate::state::ModLoader::Cleanroom => {
+            Some(1)
+        }
+        crate::state::ModLoader::LiteLoader => Some(3),
+        crate::state::ModLoader::Fabric
+        | crate::state::ModLoader::LegacyFabric => Some(4),
+        crate::state::ModLoader::Quilt => Some(5),
+        crate::state::ModLoader::NeoForge => Some(6),
+        _ => None,
+    }
+}
+
+#[tracing::instrument]
+pub async fn update_managed_modrinth_version(
+    instance_id: &str,
+    version_id: &str,
+) -> crate::Result<crate::install::InstallJobSnapshot> {
+    let state = State::get().await?;
+    let metadata = crate::state::instances::commands::get_instance_metadata(
+        instance_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError("Unknown instance".to_string())
+    })?;
+
+    let post_install_edit = match &metadata.link {
+        crate::state::InstanceLink::ServerProjectModpack {
+            server_project_id,
+            content_project_id,
+            ..
+        } => Some(crate::install::InstallPostInstallEdit {
+            name: Some(metadata.instance.name.clone()),
+            icon_path: Some(metadata.instance.icon_path.clone()),
+            link: Some(crate::state::InstanceLink::ServerProjectModpack {
+                server_project_id: server_project_id.clone(),
+                content_project_id: content_project_id.clone(),
+                content_version_id: version_id.to_string(),
+            }),
+        }),
+        _ => None,
+    };
+
+    let project_id = match &metadata.link {
+        crate::state::InstanceLink::ModrinthModpack { project_id, .. } => {
+            project_id.clone()
+        }
+        crate::state::InstanceLink::ServerProjectModpack {
+            content_project_id,
+            ..
+        } => content_project_id.clone(),
+        _ => {
+            return Err(unmanaged_pack_error(&metadata.instance.id).into());
+        }
+    };
+
+    crate::install::install_pack_to_existing_instance(
+        metadata.instance.id,
+        crate::api::pack::install_from::CreatePackLocation::FromVersionId {
+            project_id,
+            version_id: version_id.to_string(),
+            title: metadata.instance.name.clone(),
+            icon_url: None,
+        },
+        post_install_edit,
+    )
+    .await
+}
+
+#[tracing::instrument]
+pub async fn repair_managed_modrinth(
+    instance_id: &str,
+) -> crate::Result<crate::install::InstallJobSnapshot> {
+    let state = State::get().await?;
+    let metadata = crate::state::instances::commands::get_instance_metadata(
+        instance_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError("Unknown instance".to_string())
+    })?;
+
+    let post_install_edit = match &metadata.link {
+        crate::state::InstanceLink::ServerProjectModpack { .. } => {
+            Some(crate::install::InstallPostInstallEdit {
+                name: Some(metadata.instance.name.clone()),
+                icon_path: Some(metadata.instance.icon_path.clone()),
+                link: Some(metadata.link.clone()),
+            })
+        }
+        _ => None,
+    };
+
+    let (project_id, version_id) = match &metadata.link {
+        crate::state::InstanceLink::ModrinthModpack {
+            project_id,
+            version_id,
+        } => (project_id.clone(), version_id.clone()),
+        crate::state::InstanceLink::ServerProjectModpack {
+            content_project_id,
+            content_version_id,
+            ..
+        } => (content_project_id.clone(), content_version_id.clone()),
+        _ => {
+            return Err(unmanaged_pack_error(&metadata.instance.id).into());
+        }
+    };
+
+    crate::install::install_pack_to_existing_instance(
+        metadata.instance.id,
+        crate::api::pack::install_from::CreatePackLocation::FromVersionId {
+            project_id,
+            version_id,
+            title: metadata.instance.name.clone(),
+            icon_url: None,
+        },
+        post_install_edit,
+    )
+    .await
+}
+
+fn unmanaged_pack_error(instance_id: &str) -> crate::ErrorKind {
+    crate::ErrorKind::InputError(format!(
+        "Instance {instance_id} is not a managed Modrinth pack, or has been disconnected."
+    ))
+}
+
+async fn get_instance_display_info(
+    instance_id: &str,
+    state: &State,
+) -> crate::Result<instance_rows::InstanceDisplayInfo> {
+    instance_rows::get_instance_display_info(instance_id, &state.pool)
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError("Unknown instance".to_string()).into()
+        })
+}

packages/app-lib/src/api/instance/run.rs

@@ -0,0 +1,516 @@
+use super::content::get_projects;
+use crate::server_address::ServerAddress;
+use crate::state::{
+    Credentials, InstanceInstallStage, InstanceLink, ProcessMetadata, Settings,
+    State,
+};
+use crate::util::fetch;
+use crate::util::io::IOError;
+use crate::util::mojang::mojang_service_url;
+use serde_json::json;
+use std::collections::HashMap;
+use std::time::Duration;
+use tokio::process::Command;
+use tracing::{info, warn};
+
+pub use crate::launcher::jvm_args::{GcLaunchIntent, GcLaunchReport};
+
+const DEFAULT_LAUNCH_PREPARATION_TIMEOUT: u64 = 60;
+const MIN_LAUNCH_PREPARATION_TIMEOUT: u64 = 30;
+const MAX_LAUNCH_PREPARATION_TIMEOUT: u64 = 600;
+
+#[derive(Debug, Clone)]
+pub enum QuickPlayType {
+    None,
+    Singleplayer(String),
+    Server(ServerAddress),
+}
+
+#[tracing::instrument]
+pub async fn run(
+    instance_id: &str,
+    quick_play_type: QuickPlayType,
+    offline_mode: bool,
+) -> crate::Result<ProcessMetadata> {
+    run_with_extra_launch_args(instance_id, quick_play_type, offline_mode, None)
+        .await
+}
+
+#[tracing::instrument]
+pub async fn run_with_extra_launch_args(
+    instance_id: &str,
+    quick_play_type: QuickPlayType,
+    offline_mode: bool,
+    extra_launch_args: Option<Vec<String>>,
+) -> crate::Result<ProcessMetadata> {
+    Ok(run_with_extra_launch_args_inner(
+        instance_id,
+        quick_play_type,
+        offline_mode,
+        extra_launch_args,
+        None,
+    )
+    .await?
+    .0)
+}
+
+/// Like [`run_with_extra_launch_args`], but additionally resolves a GC-args
+/// intent against the actual JVM and reports what was actually used (useful
+/// for surfacing strategy fallback / flag pruning to the user).
+#[tracing::instrument]
+pub async fn run_with_extra_launch_args_with_gc(
+    instance_id: &str,
+    quick_play_type: QuickPlayType,
+    offline_mode: bool,
+    extra_launch_args: Option<Vec<String>>,
+    gc_intent: Option<GcLaunchIntent>,
+) -> crate::Result<(ProcessMetadata, Option<GcLaunchReport>)> {
+    run_with_extra_launch_args_inner(
+        instance_id,
+        quick_play_type,
+        offline_mode,
+        extra_launch_args,
+        gc_intent,
+    )
+    .await
+}
+
+async fn run_with_extra_launch_args_inner(
+    instance_id: &str,
+    quick_play_type: QuickPlayType,
+    offline_mode: bool,
+    extra_launch_args: Option<Vec<String>>,
+    gc_intent: Option<GcLaunchIntent>,
+) -> crate::Result<(ProcessMetadata, Option<GcLaunchReport>)> {
+    let state = State::get().await?;
+    let launch_preparation_timeout =
+        crate::state::instances::commands::get_instance_launch_context(
+            instance_id,
+            &state.pool,
+        )
+        .await?
+        .and_then(|context| context.launch_overrides.launch_preparation_timeout)
+        .unwrap_or(DEFAULT_LAUNCH_PREPARATION_TIMEOUT)
+        .clamp(
+            MIN_LAUNCH_PREPARATION_TIMEOUT,
+            MAX_LAUNCH_PREPARATION_TIMEOUT,
+        );
+    let default_account = if offline_mode {
+        Credentials::get_offline_credential(&state.pool)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::LauncherError(
+                    "Offline mode requires an offline Minecraft account"
+                        .to_string(),
+                )
+                .as_error()
+            })?
+    } else {
+        Credentials::get_default_credential(&state.pool)
+            .await?
+            .ok_or_else(|| crate::ErrorKind::NoCredentialsError.as_error())?
+    };
+
+    tokio::time::timeout(
+        Duration::from_secs(launch_preparation_timeout),
+        run_credentials(
+            instance_id,
+            &default_account,
+            quick_play_type,
+            offline_mode,
+            extra_launch_args,
+            gc_intent,
+        ),
+    )
+    .await
+    .map_err(|_| {
+        crate::ErrorKind::LauncherError(
+            format!(
+                "Minecraft launch preparation timed out after {launch_preparation_timeout} seconds"
+            ),
+        )
+        .as_error()
+    })?
+}
+
+#[tracing::instrument(skip(credentials))]
+async fn run_credentials(
+    instance_id: &str,
+    credentials: &Credentials,
+    quick_play_type: QuickPlayType,
+    offline_mode: bool,
+    extra_launch_args: Option<Vec<String>>,
+    gc_intent: Option<GcLaunchIntent>,
+) -> crate::Result<(ProcessMetadata, Option<GcLaunchReport>)> {
+    let state = State::get().await?;
+    let settings = Settings::get(&state.pool).await?;
+    let context =
+        crate::state::instances::commands::get_instance_launch_context(
+            instance_id,
+            &state.pool,
+        )
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::OtherError(format!(
+                "Tried to run a nonexistent instance {instance_id}!"
+            ))
+        })?;
+
+    if offline_mode
+        && context.instance.install_stage != InstanceInstallStage::Installed
+    {
+        return Err(crate::ErrorKind::LauncherError(
+            "Offline mode can only launch fully downloaded instances"
+                .to_string(),
+        )
+        .as_error());
+    }
+
+    let pre_launch_hooks = context
+        .launch_overrides
+        .hooks
+        .pre_launch
+        .as_ref()
+        .or(settings.hooks.pre_launch.as_ref())
+        .filter(|hook_command| !hook_command.is_empty());
+    if let Some(hook) = pre_launch_hooks {
+        let mut cmd = shlex::split(hook)
+            .ok_or_else(|| {
+                crate::ErrorKind::LauncherError(format!(
+                    "Invalid pre-launch command: {hook}",
+                ))
+            })?
+            .into_iter();
+
+        if let Some(command) = cmd.next() {
+            let full_path = crate::util::io::canonicalize(
+                state.directories.resolve_game_dir(
+                    &context.instance.path,
+                    context.instance.game_dir_override.as_deref(),
+                ),
+            )?;
+            let mut command = Command::new(command);
+            command.args(cmd).current_dir(&full_path).kill_on_drop(true);
+            let result = command
+                .spawn()
+                .map_err(|e| IOError::with_path(e, &full_path))?
+                .wait()
+                .await
+                .map_err(IOError::from)?;
+
+            if !result.success() {
+                return Err(crate::ErrorKind::LauncherError(format!(
+                    "Non-zero exit code for pre-launch hook: {}",
+                    result.code().unwrap_or(-1)
+                ))
+                .as_error());
+            }
+        }
+    }
+
+    let java_args = if let Some(extra_launch_args) = extra_launch_args {
+        extra_launch_args
+    } else {
+        context
+            .launch_overrides
+            .extra_launch_args
+            .clone()
+            .unwrap_or(settings.extra_launch_args)
+    };
+    let wrapper = context
+        .launch_overrides
+        .hooks
+        .wrapper
+        .clone()
+        .or(settings.hooks.wrapper)
+        .filter(|hook_command| !hook_command.is_empty());
+    let mut memory = context.launch_overrides.memory.unwrap_or(settings.memory);
+    let resolution = context
+        .launch_overrides
+        .game_resolution
+        .unwrap_or(settings.game_resolution);
+    let maximize_window = context
+        .launch_overrides
+        .maximize_window
+        .unwrap_or(settings.maximize_window);
+    let env_args = context
+        .launch_overrides
+        .custom_env_vars
+        .clone()
+        .unwrap_or(settings.custom_env_vars);
+    let post_exit_hook = context
+        .launch_overrides
+        .hooks
+        .post_exit
+        .clone()
+        .or(settings.hooks.post_exit)
+        .filter(|hook_command| !hook_command.is_empty());
+
+    let mut mc_set_options: Vec<(String, String)> = vec![];
+    if let Some(fullscreen) = context.launch_overrides.force_fullscreen {
+        mc_set_options.push(("fullscreen".to_string(), fullscreen.to_string()));
+    } else if settings.force_fullscreen {
+        mc_set_options.push(("fullscreen".to_string(), "true".to_string()));
+    }
+
+    if credentials.is_microsoft()
+        && let Some(project_id) = server_play_project_id(&context.link)
+        && !project_id.trim().is_empty()
+    {
+        let server_id = uuid::Uuid::new_v4().to_string();
+        let join_url = mojang_service_url(
+            "https://sessionserver.mojang.com/session/minecraft/join",
+            state.mojang_auth_use_mirror(),
+        );
+        let join_result = fetch::INSECURE_REQWEST_CLIENT
+			.post(join_url.as_ref())
+			.json(&json!({
+				"accessToken": &credentials.access_token,
+				"selectedProfile": credentials.offline_profile.id.simple().to_string(),
+				"serverId": &server_id,
+			}))
+			.timeout(Duration::from_secs(5))
+			.send()
+			.await;
+
+        match join_result {
+            Ok(resp) if resp.status().is_success() => {
+                let result = fetch::post_json(
+                    concat!(
+                        env!("MODRINTH_API_BASE_URL"),
+                        "analytics/minecraft-server-play"
+                    ),
+                    json!({
+                        "project_id": project_id,
+                        "username": &credentials.offline_profile.name,
+                        "server_id": &server_id,
+                    }),
+                    &state.api_semaphore,
+                    &state.pool,
+                )
+                .await;
+
+                match result {
+                    Ok(()) => {
+                        info!(
+                            "Tracked server play for '{project_id}' in analytics"
+                        )
+                    }
+                    Err(err) => warn!("Failed to report server play: {err:?}"),
+                }
+            }
+            Ok(resp) => warn!(
+                "Failed to join Mojang session server: HTTP {}",
+                resp.status()
+            ),
+            Err(err) => warn!("Failed to join Mojang session server: {err:?}"),
+        }
+    }
+
+    if offline_mode {
+        crate::minecraft_skins::flush_pending_skin_change_for_profile(
+            credentials.offline_profile.id,
+        )
+        .await?;
+    } else {
+        crate::minecraft_skins::flush_pending_skin_change().await?;
+    }
+    if memory.optimize_before_launch
+        && crate::api::memory::optimization_supported()
+    {
+        tracing::info!("Optimizing memory before launching Minecraft");
+        crate::api::memory::optimize().await?;
+    }
+
+    if memory.automatic {
+        let instance_path = state.directories.resolve_game_dir(
+            &context.instance.path,
+            context.instance.game_dir_override.as_deref(),
+        );
+        memory.maximum = crate::api::jre::automatic_memory_max_mb_for_instance(
+            &instance_path,
+            matches!(
+                context.applied_content_set.loader,
+                crate::state::ModLoader::Forge
+                    | crate::state::ModLoader::Fabric
+                    | crate::state::ModLoader::Quilt
+                    | crate::state::ModLoader::NeoForge
+                    | crate::state::ModLoader::Cleanroom
+                    | crate::state::ModLoader::LiteLoader
+                    | crate::state::ModLoader::LegacyFabric
+                    | crate::state::ModLoader::Babric
+            ),
+        );
+        tracing::info!(
+            "Automatically allocated {} MiB of memory",
+            memory.maximum
+        );
+    }
+
+    let mut gc_report: Option<GcLaunchReport> = None;
+    let process = crate::launcher::launch_minecraft(
+        &java_args,
+        &env_args,
+        &mc_set_options,
+        &wrapper,
+        &memory,
+        &resolution,
+        maximize_window,
+        credentials,
+        post_exit_hook,
+        &context,
+        gc_intent,
+        &mut gc_report,
+        quick_play_type,
+        offline_mode,
+    )
+    .await?;
+    Ok((process, gc_report))
+}
+
+fn server_play_project_id(link: &InstanceLink) -> Option<&String> {
+    match link {
+        InstanceLink::ServerProject { project_id }
+        | InstanceLink::ServerProjectModpack {
+            server_project_id: project_id,
+            ..
+        } => Some(project_id),
+        InstanceLink::Unmanaged
+        | InstanceLink::ModrinthModpack { .. }
+        | InstanceLink::CurseForgeModpack { .. }
+        | InstanceLink::ImportedModpack { .. }
+        | InstanceLink::SharedInstance { .. } => None,
+    }
+}
+
+fn modrinth_pack_version_id(link: &InstanceLink) -> Option<&str> {
+    match link {
+        InstanceLink::ModrinthModpack { version_id, .. }
+        | InstanceLink::ServerProjectModpack {
+            content_version_id: version_id,
+            ..
+        } => Some(version_id),
+        InstanceLink::Unmanaged
+        | InstanceLink::ServerProject { .. }
+        | InstanceLink::CurseForgeModpack { .. }
+        | InstanceLink::ImportedModpack { .. }
+        | InstanceLink::SharedInstance { .. } => None,
+    }
+}
+
+fn playtime_api_url(base_url: &str) -> String {
+    format!("{}/analytics/playtime", base_url.trim_end_matches('/'))
+}
+
+pub async fn kill(instance_id: &str) -> crate::Result<()> {
+    let state = State::get().await?;
+    let processes =
+        crate::api::process::get_by_instance_id(instance_id).await?;
+
+    for process in processes {
+        state.process_manager.kill(process.uuid).await?;
+    }
+
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn try_update_playtime_by_instance_id(
+    instance_id: &str,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let context =
+        crate::state::instances::commands::get_instance_launch_context(
+            instance_id,
+            &state.pool,
+        )
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::OtherError(format!(
+                "Tried to update playtime for nonexistent instance {instance_id}!"
+            ))
+        })?;
+    let updated_recent_playtime = context.instance.recent_time_played;
+    let res = if updated_recent_playtime > 0 {
+        let modrinth_pack_version_id = modrinth_pack_version_id(&context.link);
+        let playtime_update_json = json!({
+            "seconds": updated_recent_playtime,
+            "loader": context.applied_content_set.loader.as_str(),
+            "game_version": &context.applied_content_set.game_version,
+            "parent": modrinth_pack_version_id,
+        });
+        let mut hashmap: HashMap<String, serde_json::Value> = HashMap::new();
+
+        for (_, project) in get_projects(instance_id, None).await? {
+            if let Some(metadata) = project.modrinth {
+                hashmap.insert(
+                    metadata.version_id.to_string(),
+                    playtime_update_json.clone(),
+                );
+            }
+        }
+
+        let playtime_url = playtime_api_url(env!("MODRINTH_API_BASE_URL"));
+        fetch::post_json(
+            &playtime_url,
+            serde_json::to_value(hashmap)?,
+            &state.api_semaphore,
+            &state.pool,
+        )
+        .await
+    } else {
+        Ok(())
+    };
+
+    if res.is_ok() {
+        crate::state::instances::commands::mark_instance_playtime_submitted(
+            &context.instance.id,
+            updated_recent_playtime,
+            &state.pool,
+        )
+        .await?;
+    }
+
+    res
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{modrinth_pack_version_id, playtime_api_url};
+    use crate::state::InstanceLink;
+
+    #[test]
+    fn playtime_parent_requires_an_explicit_modrinth_link() {
+        let modrinth = InstanceLink::ModrinthModpack {
+            project_id: "project".to_string(),
+            version_id: "version".to_string(),
+        };
+        let curseforge = InstanceLink::CurseForgeModpack {
+            project_id: "123".to_string(),
+            version_id: "456".to_string(),
+        };
+        let imported = InstanceLink::ImportedModpack {
+            project_id: Some("legacy-project".to_string()),
+            version_id: Some("legacy-version".to_string()),
+            name: None,
+            version_number: None,
+            filename: None,
+        };
+
+        assert_eq!(modrinth_pack_version_id(&modrinth), Some("version"));
+        assert_eq!(modrinth_pack_version_id(&curseforge), None);
+        assert_eq!(modrinth_pack_version_id(&imported), None);
+    }
+
+    #[test]
+    fn playtime_url_has_a_single_path_separator() {
+        assert_eq!(
+            playtime_api_url("https://api.modrinth.com"),
+            "https://api.modrinth.com/analytics/playtime"
+        );
+        assert_eq!(
+            playtime_api_url("https://api.modrinth.com/"),
+            "https://api.modrinth.com/analytics/playtime"
+        );
+    }
+}

packages/app-lib/src/api/instance/upgrade.rs

@@ -0,0 +1,966 @@
+use std::collections::HashMap;
+use std::sync::{Arc, LazyLock};
+
+use dashmap::DashMap;
+use tokio::sync::Mutex;
+
+use crate::state::instances::adapters::sqlite::content_rows;
+use crate::state::{
+    ContentSourceKind, InstanceLink, InstanceUpgradeAction,
+    InstanceUpgradeFixedConstraint, InstanceUpgradePlan,
+    InstanceUpgradeResolution, InstanceUpgradeResolutionBatchResult,
+    InstanceUpgradeResolutionResult, InstanceUpgradeSolutionChoice,
+    InstanceUpgradeSolutionKind, State,
+};
+
+use crate::install::{
+    InstallJobSnapshot, InstanceUpgradeExecution, InstanceUpgradeWatchBaseline,
+    SharedUpgradeMode,
+};
+
+struct StoredUpgradePlanState {
+    plan: InstanceUpgradePlan,
+    validation: crate::state::instances::commands::UpgradePlanRuntimeValidation,
+    execution_started: bool,
+}
+
+type StoredUpgradePlan = Arc<Mutex<StoredUpgradePlanState>>;
+
+static INSTANCE_UPGRADE_PLANS: LazyLock<DashMap<String, StoredUpgradePlan>> =
+    LazyLock::new(DashMap::new);
+
+#[tracing::instrument]
+pub async fn plan_instance_upgrade(
+    instance_id: &str,
+    target_environment: crate::state::InstanceUpgradeEnvironment,
+) -> crate::Result<InstanceUpgradePlan> {
+    let state = State::get().await?;
+    let creation_watch =
+        state.file_watcher.content_watch_snapshot(instance_id).await;
+    let (plan, source) = crate::state::instances::commands::create_instance_upgrade_plan_with_source(
+        instance_id,
+        target_environment,
+        &state,
+    )
+    .await?;
+    let mut validation =
+        crate::state::instances::commands::UpgradePlanRuntimeValidation::new(
+            source,
+            instance_id,
+            creation_watch,
+            &state,
+        )
+        .await;
+    validation.validate(&plan, &state).await?;
+    INSTANCE_UPGRADE_PLANS.insert(
+        plan.id.clone(),
+        Arc::new(Mutex::new(StoredUpgradePlanState {
+            plan: plan.clone(),
+            validation,
+            execution_started: false,
+        })),
+    );
+    Ok(plan)
+}
+
+#[tracing::instrument]
+pub async fn get_instance_upgrade_plan(
+    plan_id: &str,
+) -> crate::Result<InstanceUpgradePlan> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    if let Err(error) = ensure_current_revision(&mut stored, &state).await {
+        drop(stored);
+        INSTANCE_UPGRADE_PLANS.remove(plan_id);
+        return Err(error);
+    }
+    Ok(stored.plan.clone())
+}
+
+#[tracing::instrument]
+pub async fn update_instance_upgrade_resolution(
+    plan_id: &str,
+    resolution: InstanceUpgradeResolution,
+) -> crate::Result<InstanceUpgradePlan> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    let source = ensure_current_revision(&mut stored, &state).await?;
+    let mut plan = stored.plan.clone();
+    let item = plan
+        .items
+        .iter_mut()
+        .find(|item| item.content_id == resolution.content_id)
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Upgrade plan has no content item {}",
+                resolution.content_id
+            ))
+        })?;
+    item.resolution = resolution;
+    let (kind, constraints) = selected_kind_and_constraints(&plan);
+    crate::state::instances::commands::recompute_instance_upgrade_plan_from_source(
+        &mut plan,
+        &constraints,
+        kind,
+        source,
+        &state,
+    )
+    .await?;
+    stored.plan = plan.clone();
+    Ok(plan)
+}
+
+#[tracing::instrument(skip(resolutions))]
+pub async fn update_instance_upgrade_resolutions(
+    plan_id: &str,
+    resolutions: Vec<InstanceUpgradeResolution>,
+) -> crate::Result<InstanceUpgradeResolutionBatchResult> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    let source = ensure_current_revision(&mut stored, &state).await?;
+    let requested_count = resolutions.len();
+    let (requests, mut skipped) = normalize_batch_resolutions(resolutions);
+    let mut working_plan = stored.plan.clone();
+    let mut applied = Vec::new();
+    let mut failed = Vec::new();
+    let mut pending = vec![requests];
+
+    while let Some(chunk) = pending.pop() {
+        let mut applicable = Vec::new();
+        for resolution in chunk {
+            if !resolution_is_applicable(&working_plan, &resolution) {
+                skipped.push(InstanceUpgradeResolutionResult {
+                    content_id: resolution.content_id,
+                    code: Some("no_longer_applicable".to_string()),
+                    message: Some(
+                        "Resolution is no longer applicable".to_string(),
+                    ),
+                });
+            } else {
+                applicable.push(resolution);
+            }
+        }
+        if applicable.is_empty() {
+            continue;
+        }
+
+        let mut trial = working_plan.clone();
+        apply_resolutions(&mut trial, &applicable)?;
+        let (kind, constraints) = selected_kind_and_constraints(&trial);
+        match crate::state::instances::commands::recompute_instance_upgrade_plan_from_source(
+            &mut trial,
+            &constraints,
+            kind,
+            source.clone(),
+            &state,
+        )
+        .await
+        {
+            Ok(()) => {
+                applied.extend(applicable.iter().map(|resolution| {
+                    InstanceUpgradeResolutionResult {
+                        content_id: resolution.content_id.clone(),
+                        code: None,
+                        message: None,
+                    }
+                }));
+                working_plan = trial;
+            }
+            Err(error) if applicable.len() == 1 => {
+                failed.push(InstanceUpgradeResolutionResult {
+                    content_id: applicable[0].content_id.clone(),
+                    code: Some("resolution_failed".to_string()),
+                    message: Some(error.to_string()),
+                });
+            }
+            Err(_) => {
+                let midpoint = applicable.len() / 2;
+                let right = applicable[midpoint..].to_vec();
+                let left = applicable[..midpoint].to_vec();
+                pending.push(right);
+                pending.push(left);
+            }
+        }
+    }
+
+    if !applied.is_empty() {
+        stored.plan = working_plan.clone();
+    }
+    Ok(InstanceUpgradeResolutionBatchResult {
+        plan: working_plan,
+        requested_count,
+        applied,
+        skipped,
+        failed,
+    })
+}
+
+#[tracing::instrument]
+pub async fn reset_instance_upgrade_resolution(
+    plan_id: &str,
+    content_id: &str,
+) -> crate::Result<InstanceUpgradePlan> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    let source = ensure_current_revision(&mut stored, &state).await?;
+    let mut plan = stored.plan.clone();
+    let item = plan
+        .items
+        .iter_mut()
+        .find(|item| item.content_id == content_id)
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Upgrade plan has no content item {content_id}"
+            ))
+        })?;
+    item.resolution = automatic_resolution(item);
+    let (kind, constraints) = selected_kind_and_constraints(&plan);
+    crate::state::instances::commands::recompute_instance_upgrade_plan_from_source(
+        &mut plan,
+        &constraints,
+        kind,
+        source,
+        &state,
+    )
+    .await?;
+    stored.plan = plan.clone();
+    Ok(plan)
+}
+
+fn normalize_batch_resolutions(
+    resolutions: Vec<InstanceUpgradeResolution>,
+) -> (
+    Vec<InstanceUpgradeResolution>,
+    Vec<InstanceUpgradeResolutionResult>,
+) {
+    let mut by_content_id = HashMap::new();
+    let mut skipped = Vec::new();
+    for resolution in resolutions {
+        if by_content_id
+            .insert(resolution.content_id.clone(), resolution.clone())
+            .is_some()
+        {
+            skipped.push(InstanceUpgradeResolutionResult {
+                content_id: resolution.content_id,
+                code: Some("duplicate_request".to_string()),
+                message: Some(
+                    "Duplicate request replaced by its last value".to_string(),
+                ),
+            });
+        }
+    }
+    let mut normalized = by_content_id.into_values().collect::<Vec<_>>();
+    normalized.sort_by(|left, right| left.content_id.cmp(&right.content_id));
+    (normalized, skipped)
+}
+
+fn resolution_is_applicable(
+    plan: &InstanceUpgradePlan,
+    resolution: &InstanceUpgradeResolution,
+) -> bool {
+    plan.items.iter().any(|item| {
+        item.content_id == resolution.content_id
+            && item.resolution != *resolution
+    })
+}
+
+fn apply_resolutions(
+    plan: &mut InstanceUpgradePlan,
+    resolutions: &[InstanceUpgradeResolution],
+) -> crate::Result<()> {
+    for resolution in resolutions {
+        let item = plan
+            .items
+            .iter_mut()
+            .find(|item| item.content_id == resolution.content_id)
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Upgrade plan has no content item {}",
+                    resolution.content_id
+                ))
+            })?;
+        item.resolution = resolution.clone();
+    }
+    Ok(())
+}
+
+fn automatic_resolution(
+    item: &crate::state::InstanceUpgradeItem,
+) -> InstanceUpgradeResolution {
+    let action = if matches!(
+        item.status,
+        crate::state::InstanceUpgradeItemStatus::Unidentified
+            | crate::state::InstanceUpgradeItemStatus::UnsupportedContentType
+    ) {
+        InstanceUpgradeAction::Keep
+    } else {
+        InstanceUpgradeAction::Upgrade
+    };
+    InstanceUpgradeResolution {
+        content_id: item.content_id.clone(),
+        action,
+        allow_prerelease: false,
+        confirmed_prerelease_dependencies: Vec::new(),
+    }
+}
+
+#[tracing::instrument]
+pub async fn select_instance_upgrade_solution(
+    plan_id: &str,
+    choice: InstanceUpgradeSolutionChoice,
+) -> crate::Result<InstanceUpgradePlan> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    ensure_current_revision(&mut stored, &state).await?;
+    let mut plan = stored.plan.clone();
+    plan.selected_solution = match choice {
+        InstanceUpgradeSolutionChoice::Newest => plan.newest_solution.clone(),
+        InstanceUpgradeSolutionChoice::MinimalChange => {
+            plan.minimal_change_solution.clone()
+        }
+        InstanceUpgradeSolutionChoice::Custom => Some(
+            plan.selected_solution
+                .clone()
+                .filter(|solution| {
+                    solution.kind == InstanceUpgradeSolutionKind::Custom
+                })
+                .ok_or_else(|| {
+                    crate::ErrorKind::InputError(
+                        "No custom upgrade solution has been resolved"
+                            .to_string(),
+                    )
+                })?,
+        ),
+    };
+    plan.dependency_changes = plan
+        .selected_solution
+        .as_ref()
+        .map(|solution| solution.dependency_changes.clone())
+        .unwrap_or_default();
+    stored.plan = plan.clone();
+    Ok(plan)
+}
+
+#[tracing::instrument]
+pub async fn resolve_custom_instance_upgrade_solution(
+    plan_id: &str,
+    fixed_constraints: Vec<InstanceUpgradeFixedConstraint>,
+) -> crate::Result<InstanceUpgradePlan> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    let source = ensure_current_revision(&mut stored, &state).await?;
+    let mut plan = stored.plan.clone();
+    validate_fixed_constraints(&plan, &fixed_constraints)?;
+    crate::state::instances::commands::recompute_instance_upgrade_plan_from_source(
+        &mut plan,
+        &fixed_constraints,
+        InstanceUpgradeSolutionKind::Custom,
+        source,
+        &state,
+    )
+    .await?;
+    plan.custom_constraints = fixed_constraints;
+    stored.plan = plan.clone();
+    Ok(plan)
+}
+
+#[tracing::instrument]
+pub async fn execute_instance_upgrade(
+    plan_id: &str,
+    create_full_backup: bool,
+    shared_upgrade_mode: SharedUpgradeMode,
+    display_names: crate::install::InstanceUpgradeDisplayNames,
+) -> crate::Result<InstallJobSnapshot> {
+    let state = State::get().await?;
+    let handle = stored_plan_handle(plan_id)?;
+    let mut stored = handle.lock().await;
+    if stored.execution_started {
+        return Err(crate::ErrorKind::InputError(
+            "Upgrade plan execution has already started".to_string(),
+        )
+        .into());
+    }
+    let _execution_guard =
+        state.lock_instance_content(&stored.plan.instance_id).await;
+    let current_revision = content_rows::get_applied_content_set(
+        &stored.plan.instance_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "Instance has no applied content set".to_string(),
+        )
+    })?
+    .revision;
+    ensure_instance_upgrade_revision(
+        stored.plan.source_revision,
+        current_revision,
+    )?;
+    if !stored.plan.blocking_issues.is_empty() {
+        return Err(crate::ErrorKind::InputError(
+            "Upgrade plan still has blocking issues".to_string(),
+        )
+        .into());
+    }
+    let solution = stored.plan.selected_solution.clone().ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "Upgrade plan has no selected solution".to_string(),
+        )
+    })?;
+    let metadata = crate::state::instances::commands::get_instance_metadata(
+        &stored.plan.instance_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError("Unknown instance".to_string())
+    })?;
+    if !matches!(metadata.link, InstanceLink::Unmanaged)
+        || metadata.applied_content_set.source_kind != ContentSourceKind::Local
+    {
+        return Err(crate::ErrorKind::InputError(
+            "Only Local unmanaged instances can use upgrade execution"
+                .to_string(),
+        )
+        .into());
+    }
+    if state
+        .process_manager
+        .get_all()
+        .iter()
+        .any(|process| process.instance_id == stored.plan.instance_id)
+    {
+        return Err(crate::ErrorKind::InputError(
+            "Instance is currently running".to_string(),
+        )
+        .into());
+    }
+    let resolved_target_loader =
+        crate::launcher::get_loader_version_from_profile(
+            &stored.plan.target_environment.game_version,
+            stored.plan.target_environment.mod_loader,
+            stored.plan.target_environment.mod_loader_version.as_deref(),
+        )
+        .await?;
+    if stored.plan.target_environment.mod_loader
+        != crate::state::ModLoader::Vanilla
+        && resolved_target_loader.is_none()
+    {
+        return Err(crate::ErrorKind::InputError(
+            "Target loader version is no longer available".to_string(),
+        )
+        .into());
+    }
+    ensure_upgrade_disk_space(
+        &metadata,
+        &stored.plan.source_files,
+        create_full_backup,
+        shared_upgrade_mode,
+        &state,
+    )?;
+    ensure_upgrade_target_writable(
+        &state
+            .directories
+            .instances_dir()
+            .join(&metadata.instance.path),
+    )
+    .await?;
+    crate::state::instances::commands::validate_instance_upgrade_plan_source(
+        &stored.plan,
+        &state,
+    )
+    .await?;
+    let source_watch = state
+        .file_watcher
+        .content_watch_snapshot(&stored.plan.instance_id)
+        .await
+        .map(|snapshot| InstanceUpgradeWatchBaseline {
+            epoch: snapshot.epoch,
+            generation: snapshot.generation,
+            dirty_paths: snapshot.dirty_paths.into_iter().collect(),
+        });
+    if crate::install::store::list(false, &state)
+        .await?
+        .into_iter()
+        .any(|job| {
+            !job.status.is_finished()
+                && job.instance_id.as_deref()
+                    == Some(stored.plan.instance_id.as_str())
+        })
+    {
+        return Err(crate::ErrorKind::InputError(
+            "Instance already has an active install job".to_string(),
+        )
+        .into());
+    }
+    let instance_id = stored.plan.instance_id.clone();
+    let mut target_environment = stored.plan.target_environment.clone();
+    if let Some(loader) = resolved_target_loader {
+        target_environment.mod_loader_version = Some(loader.id);
+    }
+    let mut warnings = stored.plan.warnings.clone();
+    for warning in &solution.warnings {
+        if !warnings.contains(warning) {
+            warnings.push(warning.clone());
+        }
+    }
+    let execution = InstanceUpgradeExecution {
+        source_revision: stored.plan.source_revision,
+        source_files: stored.plan.source_files.clone(),
+        source_environment: stored.plan.source_environment.clone(),
+        target_environment,
+        items: stored.plan.items.clone(),
+        solution,
+        warnings,
+        source_watch,
+    };
+    stored.execution_started = true;
+    let result = crate::install::upgrade_unmanaged_instance(
+        instance_id,
+        plan_id.to_string(),
+        execution,
+        create_full_backup,
+        shared_upgrade_mode,
+        display_names,
+    )
+    .await;
+    if result.is_err() {
+        stored.execution_started = false;
+    }
+    result
+}
+
+pub async fn get_instance_post_upgrade_notice(
+    instance_id: &str,
+) -> crate::Result<Option<crate::state::InstancePostUpgradeNotice>> {
+    let state = State::get().await?;
+    crate::state::instances::commands::get_instance_post_upgrade_notice(
+        instance_id,
+        &state.pool,
+    )
+    .await
+}
+
+pub async fn dismiss_instance_post_upgrade_notice(
+    instance_id: &str,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    crate::state::instances::commands::dismiss_instance_post_upgrade_notice(
+        instance_id,
+        &state.pool,
+    )
+    .await
+}
+
+fn ensure_upgrade_disk_space(
+    metadata: &crate::state::InstanceMetadata,
+    source_files: &[crate::state::InstanceUpgradeSourceFile],
+    create_full_backup: bool,
+    shared_upgrade_mode: SharedUpgradeMode,
+    state: &State,
+) -> crate::Result<()> {
+    let instance_path = state
+        .directories
+        .instances_dir()
+        .join(&metadata.instance.path);
+    let canonical = crate::util::io::canonicalize(&instance_path)?;
+    let disks = sysinfo::Disks::new_with_refreshed_list();
+    let available = disks
+        .iter()
+        .filter(|disk| canonical.starts_with(disk.mount_point()))
+        .max_by_key(|disk| disk.mount_point().as_os_str().len())
+        .map(sysinfo::Disk::available_space);
+    let Some(available) = available else {
+        return Ok(());
+    };
+    let source_size = source_files
+        .iter()
+        .fold(0_u64, |total, file| total.saturating_add(file.size));
+    let copies = 1_u64
+        + u64::from(
+            create_full_backup
+                && shared_upgrade_mode == SharedUpgradeMode::Direct,
+        );
+    let required = source_size
+        .saturating_mul(copies)
+        .saturating_add(source_size / 10);
+    if available < required {
+        return Err(crate::ErrorKind::FSError(format!(
+            "Not enough free disk space for upgrade staging: need {required} bytes, have {available} bytes"
+        ))
+        .into());
+    }
+    Ok(())
+}
+
+async fn ensure_upgrade_target_writable(
+    path: &std::path::Path,
+) -> crate::Result<()> {
+    let probe = path.join(format!(
+        ".instance-upgrade-write-test-{}",
+        uuid::Uuid::new_v4()
+    ));
+    let file = tokio::fs::OpenOptions::new()
+        .write(true)
+        .create_new(true)
+        .open(&probe)
+        .await
+        .map_err(|error| {
+            crate::ErrorKind::FSError(format!(
+                "Upgrade target is not writable: {error}"
+            ))
+        })?;
+    drop(file);
+    tokio::fs::remove_file(&probe).await.map_err(|error| {
+        crate::ErrorKind::FSError(format!(
+            "Upgrade write probe could not be removed: {error}"
+        ))
+        .into()
+    })
+}
+
+fn stored_plan_handle(plan_id: &str) -> crate::Result<StoredUpgradePlan> {
+    INSTANCE_UPGRADE_PLANS
+        .get(plan_id)
+        .map(|entry| Arc::clone(entry.value()))
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "The instance upgrade plan has expired".to_string(),
+            )
+            .into()
+        })
+}
+
+async fn ensure_current_revision(
+    stored: &mut StoredUpgradePlanState,
+    state: &State,
+) -> crate::Result<crate::state::instances::commands::ReadOnlyUpgradeSource> {
+    let current_revision = content_rows::get_applied_content_set(
+        &stored.plan.instance_id,
+        &state.pool,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "Instance has no applied content set".to_string(),
+        )
+    })?
+    .revision;
+    if let Err(error) = ensure_instance_upgrade_revision(
+        stored.plan.source_revision,
+        current_revision,
+    ) {
+        return Err(error);
+    }
+    stored.validation.validate(&stored.plan, state).await
+}
+
+fn ensure_instance_upgrade_revision(
+    planned_revision: u64,
+    current_revision: u64,
+) -> crate::Result<()> {
+    if planned_revision == current_revision {
+        return Ok(());
+    }
+    Err(crate::ErrorKind::StaleInstanceUpgradePlan {
+        planned_revision,
+        current_revision,
+    }
+    .into())
+}
+
+fn selected_kind_and_constraints(
+    plan: &InstanceUpgradePlan,
+) -> (
+    InstanceUpgradeSolutionKind,
+    Vec<InstanceUpgradeFixedConstraint>,
+) {
+    let Some(solution) = plan.selected_solution.as_ref() else {
+        return (InstanceUpgradeSolutionKind::Newest, Vec::new());
+    };
+    if solution.kind != InstanceUpgradeSolutionKind::Custom {
+        return (solution.kind, Vec::new());
+    }
+    (
+        InstanceUpgradeSolutionKind::Custom,
+        plan.custom_constraints.clone(),
+    )
+}
+
+fn validate_fixed_constraints(
+    plan: &InstanceUpgradePlan,
+    constraints: &[InstanceUpgradeFixedConstraint],
+) -> crate::Result<()> {
+    let mut seen = HashMap::new();
+    for constraint in constraints {
+        if let Some(previous) = seen.insert(
+            constraint.content_id.as_str(),
+            constraint.version_id.as_str(),
+        ) && previous != constraint.version_id.as_str()
+        {
+            return Err(crate::ErrorKind::InputError(format!(
+                "Custom upgrade constraints select multiple versions for content {}",
+                constraint.content_id
+            ))
+            .into());
+        }
+        let root_exists = plan.items.iter().any(|item| {
+            !item.auto_dependency
+                && item.content_id == constraint.content_id
+                && item.provider == Some(constraint.provider)
+                && item.project_id.as_deref()
+                    == Some(constraint.project_id.as_str())
+        });
+        if !root_exists {
+            return Err(crate::ErrorKind::InputError(format!(
+				"Custom upgrade constraint does not match root content {} at {}:{}",
+				constraint.content_id,
+				constraint.provider.as_str(),
+				constraint.project_id
+			))
+			.into());
+        }
+    }
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn custom_fixed_constraint_preserves_content_id_through_serde() {
+        let input = serde_json::json!({
+            "contentId": "physical-iris",
+            "provider": "modrinth",
+            "projectId": "YL57xq9U",
+            "versionId": "Rhzf61g1"
+        });
+
+        let constraint: InstanceUpgradeFixedConstraint =
+            serde_json::from_value(input).unwrap();
+        let output = serde_json::to_value(constraint).unwrap();
+
+        assert_eq!(output["contentId"], "physical-iris");
+    }
+
+    #[test]
+    fn duplicate_custom_constraints_are_rejected_before_provider_work() {
+        let mut plan = empty_plan();
+        plan.items.push(crate::state::InstanceUpgradeItem {
+            content_id: "root".to_string(),
+            relative_path: "mods/root.jar".to_string(),
+            project_type: crate::state::ProjectType::Mod,
+            provider: Some(crate::state::ContentProvider::Modrinth),
+            project_id: Some("root".to_string()),
+            current_release_id: Some("old".to_string()),
+            current_enabled: true,
+            auto_dependency: false,
+            status: crate::state::InstanceUpgradeItemStatus::UpgradeAvailable,
+            resolution: crate::state::InstanceUpgradeResolution {
+                content_id: "root".to_string(),
+                action: crate::state::InstanceUpgradeAction::Upgrade,
+                allow_prerelease: false,
+                confirmed_prerelease_dependencies: Vec::new(),
+            },
+            candidate_release_ids: vec!["one".to_string(), "two".to_string()],
+        });
+        let constraints = vec![
+            InstanceUpgradeFixedConstraint {
+                content_id: "root".to_string(),
+                provider: crate::state::ContentProvider::Modrinth,
+                project_id: "root".to_string(),
+                version_id: "one".to_string(),
+            },
+            InstanceUpgradeFixedConstraint {
+                content_id: "root".to_string(),
+                provider: crate::state::ContentProvider::Modrinth,
+                project_id: "root".to_string(),
+                version_id: "two".to_string(),
+            },
+        ];
+        assert!(validate_fixed_constraints(&plan, &constraints).is_err());
+
+        let wrong_physical_root = vec![InstanceUpgradeFixedConstraint {
+            content_id: "different-root".to_string(),
+            provider: crate::state::ContentProvider::Modrinth,
+            project_id: "root".to_string(),
+            version_id: "one".to_string(),
+        }];
+        assert!(
+            validate_fixed_constraints(&plan, &wrong_physical_root).is_err()
+        );
+    }
+
+    #[test]
+    fn stale_upgrade_plan_revision_is_rejected() {
+        assert!(ensure_instance_upgrade_revision(4, 4).is_ok());
+        let error = ensure_instance_upgrade_revision(4, 5).unwrap_err();
+        assert!(error.to_string().contains("planned revision 4"));
+        assert!(error.to_string().contains("current revision 5"));
+    }
+
+    #[test]
+    fn custom_recompute_uses_only_explicitly_stored_constraints() {
+        let mut plan = empty_plan();
+        plan.custom_constraints = vec![InstanceUpgradeFixedConstraint {
+            content_id: "a".to_string(),
+            provider: crate::state::ContentProvider::Modrinth,
+            project_id: "a".to_string(),
+            version_id: "a-fixed".to_string(),
+        }];
+        plan.selected_solution = Some(crate::state::InstanceUpgradeSolution {
+            kind: InstanceUpgradeSolutionKind::Custom,
+            selections: vec![
+                crate::state::InstanceUpgradeSelection {
+                    content_id: "a".to_string(),
+                    provider: Some(crate::state::ContentProvider::Modrinth),
+                    project_id: Some("a".to_string()),
+                    current_release_id: Some("a-old".to_string()),
+                    target_release_id: Some("a-fixed".to_string()),
+                    action: crate::state::InstanceUpgradeAction::Upgrade,
+                    enabled: true,
+                },
+                crate::state::InstanceUpgradeSelection {
+                    content_id: "b".to_string(),
+                    provider: Some(crate::state::ContentProvider::Modrinth),
+                    project_id: Some("b".to_string()),
+                    current_release_id: Some("b-old".to_string()),
+                    target_release_id: Some("b-auto".to_string()),
+                    action: crate::state::InstanceUpgradeAction::Upgrade,
+                    enabled: true,
+                },
+            ],
+            dependency_changes: Vec::new(),
+            warnings: Vec::new(),
+        });
+        let (kind, constraints) = selected_kind_and_constraints(&plan);
+        assert_eq!(kind, InstanceUpgradeSolutionKind::Custom);
+        assert_eq!(constraints, plan.custom_constraints);
+        assert_eq!(constraints.len(), 1);
+        assert_eq!(constraints[0].project_id, "a");
+    }
+
+    #[test]
+    fn batch_requests_dedupe_by_content_with_last_value_and_stable_order() {
+        let request = |content_id: &str, action| InstanceUpgradeResolution {
+            content_id: content_id.to_string(),
+            action,
+            allow_prerelease: false,
+            confirmed_prerelease_dependencies: Vec::new(),
+        };
+        let (normalized, skipped) = normalize_batch_resolutions(vec![
+            request("b", InstanceUpgradeAction::Keep),
+            request("a", InstanceUpgradeAction::Disable),
+            request("b", InstanceUpgradeAction::Disable),
+        ]);
+        assert_eq!(
+            normalized
+                .iter()
+                .map(|item| item.content_id.as_str())
+                .collect::<Vec<_>>(),
+            ["a", "b"]
+        );
+        assert_eq!(normalized[1].action, InstanceUpgradeAction::Disable);
+        assert_eq!(skipped.len(), 1);
+    }
+
+    #[test]
+    fn batch_resolution_is_skipped_when_plan_already_has_requested_value() {
+        let mut plan = empty_plan();
+        plan.items.push(crate::state::InstanceUpgradeItem {
+            content_id: "root".to_string(),
+            relative_path: "mods/root.jar".to_string(),
+            project_type: crate::state::ProjectType::Mod,
+            provider: None,
+            project_id: None,
+            current_release_id: None,
+            current_enabled: true,
+            auto_dependency: false,
+            status: crate::state::InstanceUpgradeItemStatus::Unidentified,
+            resolution: InstanceUpgradeResolution {
+                content_id: "root".to_string(),
+                action: InstanceUpgradeAction::Keep,
+                allow_prerelease: false,
+                confirmed_prerelease_dependencies: Vec::new(),
+            },
+            candidate_release_ids: Vec::new(),
+        });
+        let request = plan.items[0].resolution.clone();
+        assert!(!resolution_is_applicable(&plan, &request));
+    }
+
+    #[tokio::test]
+    async fn per_plan_mutex_serializes_mutations_without_lost_update() {
+        let plan = Arc::new(Mutex::new(empty_plan()));
+        let acquired = Arc::new(tokio::sync::Notify::new());
+        let release = Arc::new(tokio::sync::Notify::new());
+        let first_plan = Arc::clone(&plan);
+        let first_acquired = Arc::clone(&acquired);
+        let first_release = Arc::clone(&release);
+        let first = tokio::spawn(async move {
+            let mut stored = first_plan.lock().await;
+            first_acquired.notify_one();
+            first_release.notified().await;
+            stored
+                .custom_constraints
+                .push(InstanceUpgradeFixedConstraint {
+                    content_id: "a".to_string(),
+                    provider: crate::state::ContentProvider::Modrinth,
+                    project_id: "a".to_string(),
+                    version_id: "a-one".to_string(),
+                });
+        });
+        acquired.notified().await;
+        let second_plan = Arc::clone(&plan);
+        let second = tokio::spawn(async move {
+            let mut stored = second_plan.lock().await;
+            stored
+                .custom_constraints
+                .push(InstanceUpgradeFixedConstraint {
+                    content_id: "b".to_string(),
+                    provider: crate::state::ContentProvider::Modrinth,
+                    project_id: "b".to_string(),
+                    version_id: "b-one".to_string(),
+                });
+        });
+        tokio::task::yield_now().await;
+        release.notify_one();
+        first.await.unwrap();
+        second.await.unwrap();
+        let stored = plan.lock().await;
+        assert_eq!(stored.custom_constraints.len(), 2);
+    }
+
+    fn empty_plan() -> InstanceUpgradePlan {
+        let environment = crate::state::InstanceUpgradeEnvironment {
+            game_version: "1.21.1".to_string(),
+            mod_loader: crate::state::ModLoader::Fabric,
+            mod_loader_version: None,
+            shader_runtime: crate::state::ShaderRuntime::Iris,
+        };
+        InstanceUpgradePlan {
+            id: "plan".to_string(),
+            instance_id: "instance".to_string(),
+            source_revision: 1,
+            source_files: Vec::new(),
+            source_environment: environment.clone(),
+            target_environment: environment,
+            items: Vec::new(),
+            dependency_changes: Vec::new(),
+            warnings: Vec::new(),
+            blocking_issues: Vec::new(),
+            newest_solution: None,
+            minimal_change_solution: None,
+            selected_solution: None,
+            custom_constraints: Vec::new(),
+        }
+    }
+}

packages/app-lib/src/api/mcarchive.rs

@@ -0,0 +1,447 @@
+use crate::State;
+use crate::util::fetch::INSECURE_REQWEST_CLIENT;
+use serde::{Deserialize, Serialize};
+use sha2::Digest;
+
+const API_BASE_URL: &str = "https://mcarchive.net/api/v1";
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct McArchiveGameVersion {
+    pub id: i64,
+    pub name: String,
+    #[serde(default, alias = "version_type")]
+    pub version_type: Option<String>,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct McArchiveFile {
+    pub uuid: String,
+    pub name: String,
+    #[serde(default)]
+    pub sha256: Option<String>,
+    #[serde(default, alias = "archive_url")]
+    pub archive_url: Option<String>,
+    #[serde(default, alias = "direct_url")]
+    pub direct_url: Option<String>,
+    #[serde(default, alias = "redirect_url")]
+    pub redirect_url: Option<String>,
+    #[serde(default, alias = "page_url")]
+    pub page_url: Option<String>,
+}
+
+impl McArchiveFile {
+    pub fn download_url(&self) -> Option<&str> {
+        self.archive_url
+            .as_deref()
+            .filter(|url| !url.trim().is_empty())
+            .or_else(|| {
+                self.direct_url
+                    .as_deref()
+                    .filter(|url| !url.trim().is_empty())
+            })
+    }
+
+    pub fn needs_manual_download(&self) -> bool {
+        !self.is_automatically_installable()
+    }
+
+    pub fn is_automatically_installable(&self) -> bool {
+        self.download_url().is_some()
+            && self
+                .sha256
+                .as_deref()
+                .is_some_and(|hash| !hash.trim().is_empty())
+    }
+
+    pub fn manual_download_url(&self) -> Option<&str> {
+        self.page_url
+            .as_deref()
+            .filter(|url| !url.trim().is_empty())
+            .or_else(|| {
+                self.redirect_url
+                    .as_deref()
+                    .filter(|url| !url.trim().is_empty())
+            })
+    }
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct McArchiveModVersion {
+    pub uuid: String,
+    pub name: String,
+    #[serde(default, alias = "game_versions")]
+    pub game_versions: Vec<McArchiveGameVersion>,
+    #[serde(default)]
+    pub files: Vec<McArchiveFile>,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct McArchiveMod {
+    #[serde(default)]
+    pub uuid: String,
+    pub slug: String,
+    pub name: String,
+    #[serde(default)]
+    pub summary: Option<String>,
+    #[serde(default)]
+    pub description: Option<String>,
+    #[serde(default, alias = "website", alias = "page_url")]
+    pub page_url: Option<String>,
+    #[serde(default, alias = "mod_versions")]
+    pub mod_versions: Vec<McArchiveModVersion>,
+}
+
+const SEARCH_FIELDS: &str = "{uuid,slug,name,description,website}";
+const MOD_FIELDS: &str = "{uuid,slug,name,description,website,mod_versions{uuid,name,page_url,description,game_versions{id,name},files{uuid,name,sha256,description,page_url,redirect_url,direct_url,archive_url}}}";
+const FILE_FIELDS: &str = "{uuid,name,sha256,description,page_url,redirect_url,direct_url,archive_url}";
+
+fn normalize_mod_identity(item: &mut McArchiveMod) {
+    if item.uuid.trim().is_empty() {
+        item.uuid = item.slug.clone();
+    }
+}
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(untagged)]
+enum Collection<T> {
+    Items(Vec<T>),
+    Wrapped { results: Vec<T> },
+    Data { data: Vec<T> },
+}
+
+impl<T> Collection<T> {
+    fn into_inner(self) -> Vec<T> {
+        match self {
+            Self::Items(items) => items,
+            Self::Wrapped { results } => results,
+            Self::Data { data } => data,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(untagged)]
+enum OneOrCollection<T> {
+    One(T),
+    Collection(Collection<T>),
+}
+
+impl<T> OneOrCollection<T> {
+    fn into_first(self) -> Option<T> {
+        match self {
+            Self::One(item) => Some(item),
+            Self::Collection(items) => items.into_inner().into_iter().next(),
+        }
+    }
+}
+
+pub async fn get_game_versions() -> crate::Result<Vec<McArchiveGameVersion>> {
+    get_collection("/game_versions", "{id,name}").await
+}
+
+pub async fn search_mods(
+    keyword: &str,
+    game_version: Option<&str>,
+) -> crate::Result<Vec<McArchiveMod>> {
+    let keyword = keyword.trim();
+    let mut url = format!(
+        "{API_BASE_URL}/mods/?keyword={}",
+        urlencoding::encode(keyword)
+    );
+    if let Some(game_version) = game_version
+        .map(str::trim)
+        .filter(|value| !value.is_empty())
+    {
+        url.push_str("&game_version=");
+        url.push_str(&urlencoding::encode(game_version));
+    }
+    let mut mods = get_json::<Collection<McArchiveMod>>(&url, SEARCH_FIELDS)
+        .await
+        .map(Collection::into_inner)?;
+    for item in &mut mods {
+        normalize_mod_identity(item);
+    }
+    Ok(mods)
+}
+
+pub async fn get_mod_by_slug(slug: &str) -> crate::Result<McArchiveMod> {
+    get_json(
+        &format!("{API_BASE_URL}/mods/by_slug/{}", urlencoding::encode(slug)),
+        MOD_FIELDS,
+    )
+    .await
+    .map(|mut item| {
+        normalize_mod_identity(&mut item);
+        item
+    })
+}
+
+pub async fn get_file_by_filename(
+    filename: &str,
+) -> crate::Result<Option<McArchiveFile>> {
+    get_optional(
+        &format!(
+            "{API_BASE_URL}/files/by_filename/{}",
+            urlencoding::encode(filename)
+        ),
+        FILE_FIELDS,
+    )
+    .await
+}
+
+pub async fn get_file_by_sha256(
+    sha256: &str,
+) -> crate::Result<Option<McArchiveFile>> {
+    get_optional(
+        &format!(
+            "{API_BASE_URL}/files/by_hash/sha256/{}",
+            urlencoding::encode(sha256)
+        ),
+        FILE_FIELDS,
+    )
+    .await
+}
+
+pub async fn download_file(file: &McArchiveFile) -> crate::Result<Vec<u8>> {
+    let url = file.download_url().ok_or_else(|| {
+        crate::ErrorKind::InputError(
+			"MCArchive does not expose a verifiable direct archive URL for this file"
+				.to_string(),
+		)
+    })?;
+    let state = State::get().await?;
+    let _permit = state.download_semaphore.0.acquire().await?;
+    let response = INSECURE_REQWEST_CLIENT
+        .get(url)
+        .send()
+        .await?
+        .error_for_status()?;
+    let bytes = response.bytes().await?.to_vec();
+    if bytes.is_empty() {
+        return Err(crate::ErrorKind::OtherError(
+            "MCArchive returned an empty file".to_string(),
+        )
+        .into());
+    }
+    let expected = file
+        .sha256
+        .as_deref()
+        .filter(|hash| !hash.is_empty())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "MCArchive does not publish a SHA-256 for {}",
+                file.name
+            ))
+        })?;
+    let actual = format!("{:x}", sha2::Sha256::digest(&bytes));
+    if !actual.eq_ignore_ascii_case(expected) {
+        return Err(crate::ErrorKind::OtherError(format!(
+            "MCArchive SHA-256 mismatch for {}",
+            file.name
+        ))
+        .into());
+    }
+    Ok(bytes)
+}
+
+async fn get_collection<T>(path: &str, fields: &str) -> crate::Result<Vec<T>>
+where
+    T: for<'de> Deserialize<'de>,
+{
+    get_json::<Collection<T>>(&format!("{API_BASE_URL}{path}"), fields)
+        .await
+        .map(Collection::into_inner)
+}
+
+async fn get_optional<T>(url: &str, fields: &str) -> crate::Result<Option<T>>
+where
+    T: for<'de> Deserialize<'de>,
+{
+    let state = State::get().await?;
+    let _permit = state.api_semaphore.0.acquire().await?;
+    let response = mcarchive_get(url).header("X-Fields", fields).send().await?;
+    if response.status() == reqwest::StatusCode::NOT_FOUND {
+        return Ok(None);
+    }
+    let response = response.error_for_status()?;
+    let value = response.json::<Option<OneOrCollection<T>>>().await?;
+    Ok(value.and_then(OneOrCollection::into_first))
+}
+
+async fn get_json<T>(url: &str, fields: &str) -> crate::Result<T>
+where
+    T: for<'de> Deserialize<'de>,
+{
+    let state = State::get().await?;
+    let _permit = state.api_semaphore.0.acquire().await?;
+    Ok(mcarchive_get(url)
+        .header("X-Fields", fields)
+        .send()
+        .await?
+        .error_for_status()?
+        .json()
+        .await?)
+}
+
+fn mcarchive_get(url: &str) -> reqwest::RequestBuilder {
+    INSECURE_REQWEST_CLIENT
+        .get(url)
+        .version(reqwest::Version::HTTP_11)
+        .header(reqwest::header::ACCEPT, "application/json")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn mcarchive_uses_string_uuid_identifiers_and_archive_url() {
+        let file: McArchiveFile = serde_json::from_value(serde_json::json!({
+            "uuid": "46d5c61e-02b4-4ca0-8b4b-7c965d2931bc",
+            "name": "ModLoader 1.6.2.zip",
+            "sha256": "abc",
+            "archive_url": "https://b2.mcarchive.net/file/modloader.zip",
+            "direct_url": "",
+            "redirect_url": "",
+            "page_url": ""
+        }))
+        .unwrap();
+        assert_eq!(file.uuid, "46d5c61e-02b4-4ca0-8b4b-7c965d2931bc");
+        assert_eq!(
+            file.download_url(),
+            Some("https://b2.mcarchive.net/file/modloader.zip")
+        );
+    }
+
+    #[test]
+    fn missing_urls_require_manual_download() {
+        let file = McArchiveFile {
+            uuid: "file".to_string(),
+            name: "mod.zip".to_string(),
+            sha256: None,
+            archive_url: Some(String::new()),
+            direct_url: None,
+            redirect_url: Some("https://example.invalid/download".to_string()),
+            page_url: Some("https://mcarchive.net/mod".to_string()),
+        };
+        assert!(file.needs_manual_download());
+        assert_eq!(
+            file.manual_download_url(),
+            Some("https://mcarchive.net/mod")
+        );
+    }
+
+    #[test]
+    fn hash_lookup_collections_return_the_first_matching_file() {
+        let response: Option<OneOrCollection<McArchiveFile>> =
+            serde_json::from_value(serde_json::json!([
+                {
+                    "uuid": "file-uuid",
+                    "name": "mod.jar",
+                    "sha256": "abc"
+                }
+            ]))
+            .unwrap();
+        assert_eq!(
+            response
+                .and_then(OneOrCollection::into_first)
+                .map(|file| file.uuid),
+            Some("file-uuid".to_string())
+        );
+    }
+
+    #[test]
+    fn mod_search_summaries_do_not_claim_to_include_versions() {
+        let mod_: McArchiveMod = serde_json::from_value(serde_json::json!({
+            "uuid": "mod-uuid",
+            "slug": "modloader",
+            "name": "ModLoader"
+        }))
+        .unwrap();
+
+        assert_eq!(mod_.slug, "modloader");
+        assert!(mod_.mod_versions.is_empty());
+    }
+
+    #[test]
+    fn real_mcarchive_search_payload_deserializes_without_versions() {
+        let payload = serde_json::json!([
+            {
+                "uuid": "ff38ccfe-24ca-4bc6-97ba-59d6b37b147a",
+                "slug": "modloader",
+                "name": "Modloader",
+                "description": "",
+                "website": ""
+            },
+            {
+                "uuid": "7b2abb02-ba79-4363-abbf-268b2024488d",
+                "slug": "modloadermp",
+                "name": "ModLoaderMP"
+            }
+        ]);
+        let mut mods: Vec<McArchiveMod> =
+            serde_json::from_value::<Collection<McArchiveMod>>(payload)
+                .unwrap()
+                .into_inner();
+        for item in &mut mods {
+            normalize_mod_identity(item);
+        }
+        assert_eq!(mods.len(), 2);
+        assert_eq!(mods[0].slug, "modloader");
+        assert_eq!(mods[0].uuid, "ff38ccfe-24ca-4bc6-97ba-59d6b37b147a");
+        assert!(mods[0].mod_versions.is_empty());
+        assert_eq!(mods[1].name, "ModLoaderMP");
+    }
+
+    #[test]
+    fn real_mcarchive_mod_payload_deserializes_nested_versions_and_files() {
+        let payload = serde_json::json!({
+            "uuid": "ff38ccfe-24ca-4bc6-97ba-59d6b37b147a",
+            "slug": "modloader",
+            "name": "Modloader",
+            "description": "",
+            "website": "",
+            "mod_versions": [{
+                "uuid": "52fbdb8f-6ae7-4dd6-8b02-cbfc54b5ce3e",
+                "name": "1.6.2",
+                "page_url": "",
+                "description": "",
+                "game_versions": [{"id": 9, "name": "1.6.2"}],
+                "files": [{
+                    "uuid": "e7830701-aca7-4e9b-a5b2-94aacbeef293",
+                    "name": "ModLoader 1.6.2.zip",
+                    "sha256": "0b14f5e261c9862989aa74313b59188cce10bea6724bae31130ce1e8e6a1c060",
+                    "description": "",
+                    "page_url": "",
+                    "redirect_url": "",
+                    "direct_url": "",
+                    "archive_url": "https://b2.mcarchive.net/file/mcarchive/example.zip"
+                }]
+            }]
+        });
+        let mut item: McArchiveMod = serde_json::from_value(payload).unwrap();
+        normalize_mod_identity(&mut item);
+        assert_eq!(item.mod_versions.len(), 1);
+        assert_eq!(item.mod_versions[0].game_versions[0].name, "1.6.2");
+        assert_eq!(
+            item.mod_versions[0].files[0].download_url(),
+            Some("https://b2.mcarchive.net/file/mcarchive/example.zip")
+        );
+    }
+
+    #[test]
+    fn missing_uuid_uses_slug_for_stable_search_identity() {
+        let mut item: McArchiveMod =
+            serde_json::from_value(serde_json::json!({
+                "slug": "modloader",
+                "name": "Modloader"
+            }))
+            .unwrap();
+        normalize_mod_identity(&mut item);
+        assert_eq!(item.uuid, "modloader");
+    }
+}

packages/app-lib/src/api/memory.rs

@@ -0,0 +1,320 @@
+use serde::Serialize;
+
+#[derive(Clone, Copy, Debug, Serialize)]
+pub struct MemoryOptimizationResult {
+    pub before_available_bytes: u64,
+    pub after_available_bytes: u64,
+    pub reclaimed_bytes: u64,
+    pub supported: bool,
+}
+
+pub fn optimization_supported() -> bool {
+    cfg!(target_os = "windows")
+}
+
+pub async fn optimize() -> crate::Result<MemoryOptimizationResult> {
+    tokio::task::spawn_blocking(optimize_blocking)
+        .await
+        .map_err(|error| {
+            crate::ErrorKind::OtherError(format!(
+                "Memory optimization task failed: {error}"
+            ))
+            .as_error()
+        })?
+}
+
+#[cfg(not(target_os = "windows"))]
+fn optimize_blocking() -> crate::Result<MemoryOptimizationResult> {
+    Ok(MemoryOptimizationResult {
+        before_available_bytes: 0,
+        after_available_bytes: 0,
+        reclaimed_bytes: 0,
+        supported: false,
+    })
+}
+
+#[cfg(target_os = "windows")]
+fn optimize_blocking() -> crate::Result<MemoryOptimizationResult> {
+    let before_available_bytes = super::jre::system_available_memory_bytes();
+    let direct_result = optimize_windows_memory();
+    let result = match direct_result {
+        Ok(()) => Ok(()),
+        Err(_error) => run_elevated_helper().map(|_| ()),
+    };
+
+    result.map_err(|error| {
+        crate::ErrorKind::OtherError(format!(
+            "Memory optimization was not completed: {error}"
+        ))
+        .as_error()
+    })?;
+
+    let after_available_bytes = super::jre::system_available_memory_bytes();
+    Ok(MemoryOptimizationResult {
+        before_available_bytes,
+        after_available_bytes,
+        reclaimed_bytes: after_available_bytes
+            .saturating_sub(before_available_bytes),
+        supported: true,
+    })
+}
+
+#[cfg(target_os = "windows")]
+fn run_elevated_helper() -> Result<(), String> {
+    use std::mem::size_of;
+    use std::os::windows::ffi::OsStrExt;
+    use windows::Win32::Foundation::{CloseHandle, WAIT_OBJECT_0};
+    use windows::Win32::System::Threading::{
+        GetExitCodeProcess, INFINITE, WaitForSingleObject,
+    };
+    use windows::Win32::UI::Shell::{
+        SEE_MASK_NOCLOSEPROCESS, SHELLEXECUTEINFOW, ShellExecuteExW,
+    };
+    use windows::core::{PCWSTR, w};
+
+    let mut executable = std::env::current_exe()
+        .map_err(|error| {
+            format!("Could not locate launcher executable: {error}")
+        })?
+        .into_os_string()
+        .encode_wide()
+        .collect::<Vec<_>>();
+    executable.push(0);
+    let arguments = "--memory-optimize\0".encode_utf16().collect::<Vec<_>>();
+    let mut execute_info = SHELLEXECUTEINFOW {
+        cbSize: size_of::<SHELLEXECUTEINFOW>() as u32,
+        fMask: SEE_MASK_NOCLOSEPROCESS,
+        lpVerb: w!("runas"),
+        lpFile: PCWSTR::from_raw(executable.as_ptr()),
+        lpParameters: PCWSTR::from_raw(arguments.as_ptr()),
+        // Run the elevated helper without a visible console window.
+        nShow: 0,
+        ..Default::default()
+    };
+
+    unsafe { ShellExecuteExW(&raw mut execute_info) }.map_err(|error| {
+        format!("Could not request administrator permission: {error}")
+    })?;
+
+    let process = execute_info.hProcess;
+    let result = (|| {
+        if unsafe { WaitForSingleObject(process, INFINITE) } != WAIT_OBJECT_0 {
+            return Err(
+                "Elevated memory optimization did not finish".to_string()
+            );
+        }
+
+        let mut exit_code = 0;
+        unsafe { GetExitCodeProcess(process, &mut exit_code) }.map_err(
+            |error| format!("Could not read elevated process status: {error}"),
+        )?;
+        if exit_code == 0 {
+            Ok(())
+        } else {
+            Err("Administrator permission was denied".to_string())
+        }
+    })();
+    unsafe { CloseHandle(process) }.map_err(|error| {
+        format!("Could not close elevated process handle: {error}")
+    })?;
+    result
+}
+
+#[cfg(target_os = "windows")]
+pub fn optimize_current_process_context() -> i32 {
+    match optimize_windows_memory() {
+        Ok(()) => 0,
+        Err(error) => {
+            tracing::error!("Elevated memory optimization failed: {error}");
+            1
+        }
+    }
+}
+
+#[cfg(target_os = "windows")]
+fn optimize_windows_memory() -> Result<(), String> {
+    use std::ffi::c_void;
+    use std::mem::size_of;
+    use std::ptr::null_mut;
+
+    #[repr(C)]
+    #[derive(Clone, Copy, Default)]
+    struct Luid {
+        low_part: u32,
+        high_part: i32,
+    }
+
+    #[repr(C)]
+    struct LuidAndAttributes {
+        luid: Luid,
+        attributes: u32,
+    }
+
+    #[repr(C)]
+    struct TokenPrivileges {
+        privilege_count: u32,
+        privileges: [LuidAndAttributes; 1],
+    }
+
+    #[repr(C)]
+    #[derive(Default)]
+    struct SystemFileCacheInformation {
+        current_size: usize,
+        peak_size: usize,
+        page_fault_count: u32,
+        minimum_working_set: usize,
+        maximum_working_set: usize,
+        current_size_including_transition_in_pages: usize,
+        peak_size_including_transition_in_pages: usize,
+        transition_repurpose_count: u32,
+        flags: u32,
+    }
+
+    #[repr(C)]
+    #[derive(Default)]
+    struct MemoryCombineInformationEx {
+        handle: isize,
+        pages_combined: usize,
+        flags: u32,
+    }
+
+    #[link(name = "kernel32")]
+    unsafe extern "system" {
+        fn GetCurrentProcess() -> *mut c_void;
+        fn CloseHandle(object: *mut c_void) -> i32;
+    }
+
+    #[link(name = "advapi32")]
+    unsafe extern "system" {
+        fn OpenProcessToken(
+            process_handle: *mut c_void,
+            desired_access: u32,
+            token_handle: *mut *mut c_void,
+        ) -> i32;
+        fn LookupPrivilegeValueW(
+            system_name: *const u16,
+            name: *const u16,
+            luid: *mut Luid,
+        ) -> i32;
+        fn AdjustTokenPrivileges(
+            token_handle: *mut c_void,
+            disable_all_privileges: i32,
+            new_state: *const TokenPrivileges,
+            buffer_length: u32,
+            previous_state: *mut TokenPrivileges,
+            return_length: *mut u32,
+        ) -> i32;
+    }
+
+    #[link(name = "ntdll")]
+    unsafe extern "system" {
+        fn NtSetSystemInformation(
+            system_information_class: u32,
+            system_information: *mut c_void,
+            system_information_length: u32,
+        ) -> i32;
+    }
+
+    const TOKEN_ADJUST_PRIVILEGES: u32 = 0x20;
+    const TOKEN_QUERY: u32 = 0x8;
+    const SE_PRIVILEGE_ENABLED: u32 = 0x2;
+
+    let process = unsafe { GetCurrentProcess() };
+    let mut token = null_mut();
+    if unsafe {
+        OpenProcessToken(
+            process,
+            TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY,
+            &raw mut token,
+        )
+    } == 0
+    {
+        return Err(std::io::Error::last_os_error().to_string());
+    }
+
+    let result = (|| {
+        for privilege in [
+            "SeProfileSingleProcessPrivilege",
+            "SeIncreaseQuotaPrivilege",
+        ] {
+            let mut wide = privilege.encode_utf16().collect::<Vec<_>>();
+            wide.push(0);
+            let mut luid = Luid::default();
+            if unsafe {
+                LookupPrivilegeValueW(null_mut(), wide.as_ptr(), &raw mut luid)
+            } == 0
+            {
+                return Err(std::io::Error::last_os_error().to_string());
+            }
+            let privileges = TokenPrivileges {
+                privilege_count: 1,
+                privileges: [LuidAndAttributes {
+                    luid,
+                    attributes: SE_PRIVILEGE_ENABLED,
+                }],
+            };
+            if unsafe {
+                AdjustTokenPrivileges(
+                    token,
+                    0,
+                    &raw const privileges,
+                    0,
+                    null_mut(),
+                    null_mut(),
+                )
+            } == 0
+            {
+                return Err(std::io::Error::last_os_error().to_string());
+            }
+        }
+
+        let mut statuses = Vec::with_capacity(7);
+        let mut info = 2_i32;
+        statuses.push(unsafe {
+            NtSetSystemInformation(
+                80,
+                (&raw mut info).cast(),
+                size_of::<i32>() as u32,
+            )
+        });
+        let mut cache = SystemFileCacheInformation {
+            minimum_working_set: usize::MAX,
+            maximum_working_set: usize::MAX,
+            ..Default::default()
+        };
+        statuses.push(unsafe {
+            NtSetSystemInformation(
+                81,
+                (&raw mut cache).cast(),
+                size_of::<SystemFileCacheInformation>() as u32,
+            )
+        });
+        for value in [3_i32, 4, 5] {
+            info = value;
+            statuses.push(unsafe {
+                NtSetSystemInformation(
+                    80,
+                    (&raw mut info).cast(),
+                    size_of::<i32>() as u32,
+                )
+            });
+        }
+        statuses.push(unsafe { NtSetSystemInformation(155, null_mut(), 0) });
+        let mut combine = MemoryCombineInformationEx::default();
+        statuses.push(unsafe {
+            NtSetSystemInformation(
+                130,
+                (&raw mut combine).cast(),
+                size_of::<MemoryCombineInformationEx>() as u32,
+            )
+        });
+
+        if statuses[0] < 0 && statuses[1] < 0 {
+            return Err("Administrator privileges are required".to_string());
+        }
+        Ok(())
+    })();
+
+    unsafe { CloseHandle(token) };
+    result
+}

packages/app-lib/src/api/metadata.rs

@@ -0,0 +1,139 @@
+use crate::State;
+use crate::state::{CacheBehaviour, CachedEntry};
+pub use daedalus::minecraft::VersionManifest;
+pub use daedalus::modded::Manifest;
+
+#[tracing::instrument]
+pub async fn get_minecraft_versions() -> crate::Result<VersionManifest> {
+    get_minecraft_versions_with_cache(None).await
+}
+
+pub async fn get_minecraft_versions_with_cache(
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<VersionManifest> {
+    let state = State::get().await?;
+    let minecraft_versions = CachedEntry::get_minecraft_manifest(
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::NoValueFor("minecraft versions".to_string())
+    })?;
+
+    Ok(minecraft_versions)
+}
+
+// #[tracing::instrument]
+pub async fn get_loader_versions(loader: &str) -> crate::Result<Manifest> {
+    match get_loader_versions_with_cache(
+        loader,
+        Some(CacheBehaviour::MustRevalidate),
+    )
+    .await
+    {
+        Ok(manifest) => Ok(manifest),
+        Err(refresh_error) => {
+            match get_loader_versions_with_cache(
+                loader,
+                Some(CacheBehaviour::CacheOnly),
+            )
+            .await
+            {
+                Ok(manifest) => {
+                    tracing::warn!(
+                        loader,
+                        error = %refresh_error,
+                        "Loader manifest refresh failed; serving cached data"
+                    );
+                    Ok(manifest)
+                }
+                Err(_) => Err(refresh_error),
+            }
+        }
+    }
+}
+
+pub async fn get_loader_versions_with_cache(
+    loader: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Manifest> {
+    let state = State::get().await?;
+    let cache_key =
+        daedalus::modded::loader_manifest_metadata(loader).cache_key;
+    let loaders = CachedEntry::get_loader_manifest(
+        &cache_key,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::NoValueFor(format!("{loader} loader versions"))
+    })?;
+
+    Ok(loaders.manifest)
+}
+
+pub async fn get_loader_versions_for_game(
+    loader: &str,
+    game_version: &str,
+) -> crate::Result<Manifest> {
+    match get_loader_versions_for_game_with_cache(
+        loader,
+        game_version,
+        Some(CacheBehaviour::MustRevalidate),
+    )
+    .await
+    {
+        Ok(manifest) => Ok(manifest),
+        Err(refresh_error) => {
+            match get_loader_versions_for_game_with_cache(
+                loader,
+                game_version,
+                Some(CacheBehaviour::CacheOnly),
+            )
+            .await
+            {
+                Ok(manifest) => {
+                    tracing::warn!(
+                        loader,
+                        game_version,
+                        error = %refresh_error,
+                        "Scoped loader metadata refresh failed; serving cached data"
+                    );
+                    Ok(manifest)
+                }
+                Err(_) => Err(refresh_error),
+            }
+        }
+    }
+}
+
+pub async fn get_loader_versions_for_game_with_cache(
+    loader: &str,
+    game_version: &str,
+    cache_behaviour: Option<CacheBehaviour>,
+) -> crate::Result<Manifest> {
+    let state = State::get().await?;
+    let cache_key = daedalus::modded::loader_manifest_metadata_for_game(
+        loader,
+        game_version,
+    )
+    .cache_key;
+    let loaders = CachedEntry::get_loader_manifest(
+        &cache_key,
+        cache_behaviour,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::NoValueFor(format!(
+            "{loader} loader versions for Minecraft {game_version}"
+        ))
+    })?;
+
+    Ok(loaders.manifest)
+}

packages/app-lib/src/api/minecraft_auth.rs

@@ -0,0 +1,274 @@
+//! Authentication flow interface
+
+use chrono::{DateTime, Utc};
+use reqwest::StatusCode;
+use serde::Serialize;
+use std::time::Duration;
+use uuid::Uuid;
+
+use crate::State;
+pub use crate::state::YggdrasilLoginResult;
+use crate::state::{
+    Credentials, MinecraftAccountType, MinecraftLoginFlow, MinecraftProfile,
+    YggdrasilAccount,
+};
+pub use crate::state::{MinecraftDeviceLoginFlow, MinecraftDeviceLoginPoll};
+use crate::util::fetch::INSECURE_REQWEST_CLIENT;
+use crate::util::mojang::{mojang_service_url, should_use_mojang_mirror};
+
+#[tracing::instrument]
+pub async fn check_reachable() -> crate::Result<()> {
+    let url = mojang_service_url(
+        "https://sessionserver.mojang.com/session/minecraft/hasJoined",
+        should_use_mojang_mirror(),
+    );
+    let resp = INSECURE_REQWEST_CLIENT
+        .get(url.as_ref())
+        .timeout(Duration::from_secs(5))
+        .send()
+        .await?;
+    if resp.status() == StatusCode::NO_CONTENT {
+        return Ok(());
+    }
+    resp.error_for_status()?;
+    Ok(())
+}
+
+pub async fn set_mojang_auth_use_mirror(
+    use_mirror: bool,
+    automatic: bool,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    state.set_mojang_auth_use_mirror(use_mirror);
+    if use_mirror && automatic {
+        tracing::info!(
+            "Mojang services are unreachable; routing Mojang service requests through the Fallen proxy"
+        );
+    }
+    Ok(())
+}
+
+#[derive(Clone, Debug, Serialize)]
+pub struct MojangServiceStatus {
+    pub service: &'static str,
+    pub url: &'static str,
+    pub reachable: bool,
+}
+
+const MOJANG_SERVICES: [(&str, &str); 5] = [
+    ("auth", "https://authserver.mojang.com/"),
+    ("account", "https://api.mojang.com/"),
+    (
+        "session",
+        "https://sessionserver.mojang.com/session/minecraft/hasJoined",
+    ),
+    ("services", "https://api.minecraftservices.com/"),
+    (
+        "profiles",
+        "https://api.mojang.com/users/profiles/minecraft/",
+    ),
+];
+
+#[tracing::instrument]
+pub async fn check_mojang_services() -> Vec<MojangServiceStatus> {
+    futures::future::join_all(MOJANG_SERVICES.map(
+        |(service, url)| async move {
+            let reachable = INSECURE_REQWEST_CLIENT
+                .get(url)
+                .timeout(Duration::from_secs(5))
+                .send()
+                .await
+                .is_ok();
+            MojangServiceStatus {
+                service,
+                url,
+                reachable,
+            }
+        },
+    ))
+    .await
+}
+
+#[tracing::instrument]
+pub async fn begin_login() -> crate::Result<MinecraftLoginFlow> {
+    let state = State::get().await?;
+
+    crate::state::login_begin(&state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn begin_browser_login() -> crate::Result<MinecraftLoginFlow> {
+    let state = State::get().await?;
+    crate::state::browser_login_begin(&state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn begin_device_login() -> crate::Result<MinecraftDeviceLoginFlow> {
+    crate::state::device_login_begin().await
+}
+
+#[tracing::instrument]
+pub async fn poll_device_login(
+    device_code: &str,
+) -> crate::Result<MinecraftDeviceLoginPoll> {
+    let state = State::get().await?;
+    crate::state::device_login_poll(device_code, &state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn finish_login(
+    code: &str,
+    state: &str,
+    flow: MinecraftLoginFlow,
+) -> crate::Result<Credentials> {
+    let app_state = State::get().await?;
+
+    crate::state::login_finish(code, state, flow, &app_state.pool).await
+}
+
+#[tracing::instrument]
+pub async fn add_offline_user(
+    username: &str,
+    uuid: Option<Uuid>,
+) -> crate::Result<Credentials> {
+    let state = State::get().await?;
+    let credentials = match uuid {
+        Some(uuid) => Credentials::offline_with_uuid(username, uuid)?,
+        None => Credentials::offline(username)?,
+    };
+
+    if uuid.is_some() {
+        let users = Credentials::get_all_without_refresh(&state.pool).await?;
+        if users.contains_key(&credentials.offline_profile.id) {
+            return Err(crate::ErrorKind::InputError(
+                "An account with this UUID already exists".to_string(),
+            )
+            .as_error());
+        }
+    }
+
+    credentials.upsert(&state.pool).await?;
+    Ok(credentials)
+}
+
+#[tracing::instrument(skip(password))]
+pub async fn begin_yggdrasil_login(
+    api_root: &str,
+    login: &str,
+    password: &str,
+) -> crate::Result<YggdrasilLoginResult> {
+    let state = State::get().await?;
+    crate::state::begin_yggdrasil_login(api_root, login, password, &state.pool)
+        .await
+}
+
+#[tracing::instrument]
+pub async fn finish_yggdrasil_login(
+    flow_id: uuid::Uuid,
+    profile_id: uuid::Uuid,
+) -> crate::Result<Credentials> {
+    let state = State::get().await?;
+    crate::state::finish_yggdrasil_login(flow_id, profile_id, &state.pool).await
+}
+
+pub fn normalize_yggdrasil_api_root(api_root: &str) -> crate::Result<String> {
+    crate::state::normalize_api_root(api_root)
+}
+
+#[tracing::instrument]
+pub async fn get_default_user(
+    offline_mode: bool,
+) -> crate::Result<Option<uuid::Uuid>> {
+    let state = State::get().await?;
+    let user = if offline_mode {
+        Credentials::get_offline_credential(&state.pool).await?
+    } else {
+        Credentials::get_active(&state.pool).await?
+    };
+    Ok(user.map(|user| user.offline_profile.id))
+}
+
+#[tracing::instrument]
+pub async fn set_default_user(user: uuid::Uuid) -> crate::Result<()> {
+    let state = State::get().await?;
+    let users = Credentials::get_all_without_refresh(&state.pool).await?;
+    let (_, mut user) = users.remove(&user).ok_or_else(|| {
+        crate::ErrorKind::OtherError(format!(
+            "Tried to get nonexistent user with ID {user}"
+        ))
+        .as_error()
+    })?;
+
+    user.active = true;
+    user.upsert(&state.pool).await?;
+
+    Ok(())
+}
+
+/// Remove a user account from the database
+#[tracing::instrument]
+pub async fn remove_user(uuid: uuid::Uuid) -> crate::Result<()> {
+    let state = State::get().await?;
+
+    let users = Credentials::get_all_without_refresh(&state.pool).await?;
+
+    if let Some((uuid, user)) = users.remove(&uuid) {
+        Credentials::remove(uuid, &state.pool).await?;
+
+        if user.active
+            && let Some((_, mut user)) = users.into_iter().next()
+        {
+            user.active = true;
+            user.upsert(&state.pool).await?;
+        }
+    }
+
+    Ok(())
+}
+
+#[derive(Serialize)]
+pub struct MinecraftUser {
+    pub profile: MinecraftProfile,
+    pub account_type: MinecraftAccountType,
+    pub access_token: String,
+    pub refresh_token: String,
+    pub expires: DateTime<Utc>,
+    pub active: bool,
+    pub yggdrasil: Option<YggdrasilAccount>,
+}
+
+impl MinecraftUser {
+    async fn from_credentials(credentials: Credentials) -> Self {
+        let profile = (*credentials.maybe_online_profile().await).clone();
+        Self {
+            profile,
+            account_type: credentials.account_type,
+            access_token: credentials.access_token,
+            refresh_token: credentials.refresh_token,
+            expires: credentials.expires,
+            active: credentials.active,
+            yggdrasil: credentials.yggdrasil,
+        }
+    }
+}
+
+/// Get a copy of the list of all user credentials with profile data ready for
+/// serialization.
+#[tracing::instrument]
+pub async fn users(offline_mode: bool) -> crate::Result<Vec<MinecraftUser>> {
+    let state = State::get().await?;
+    let users = if offline_mode {
+        Credentials::get_all_without_refresh(&state.pool).await?
+    } else {
+        Credentials::get_all(&state.pool).await?
+    };
+    let credentials = users
+        .into_iter()
+        .map(|x| x.1)
+        .filter(|credentials| !offline_mode || credentials.is_offline());
+    let mut hydrated_users = Vec::new();
+    for credentials in credentials {
+        hydrated_users.push(MinecraftUser::from_credentials(credentials).await);
+    }
+    Ok(hydrated_users)
+}

packages/app-lib/src/api/minecraft_news.rs

@@ -0,0 +1,121 @@
+//! Minecraft official news from the Minecraft website search API.
+use reqwest::Method;
+use serde::{Deserialize, Serialize};
+
+use crate::State;
+use crate::util::fetch::fetch_json;
+
+const MINECRAFT_NEWS_SEARCH_URL: &str = "https://net-secondary.web.minecraft-services.net/api/v1.0/en-us/search?pageSize=24&sortType=Recent&category=News&newsOnly=true&geography=USA";
+const MINECRAFT_ARTICLE_BASE: &str = "https://www.minecraft.net/en-us/article/";
+
+#[derive(Deserialize)]
+struct NewsSearchResponse {
+    result: NewsSearchResult,
+}
+
+#[derive(Deserialize)]
+struct NewsSearchResult {
+    results: Vec<NewsEntry>,
+}
+
+#[derive(Deserialize)]
+struct NewsEntry {
+    title: String,
+    #[serde(default)]
+    url: Option<String>,
+    #[serde(default)]
+    image: Option<String>,
+    #[serde(default)]
+    time: Option<i64>,
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct MinecraftNewsItem {
+    pub title: String,
+    pub category: Option<String>,
+    pub tag: Option<String>,
+    pub date: Option<String>,
+    pub image_url: Option<String>,
+    pub read_more_url: String,
+}
+
+pub async fn get_minecraft_news(
+    limit: usize,
+) -> crate::Result<Vec<MinecraftNewsItem>> {
+    let state = State::get().await?;
+    let news = fetch_json::<NewsSearchResponse>(
+        Method::GET,
+        MINECRAFT_NEWS_SEARCH_URL,
+        None,
+        None,
+        None,
+        &state.api_semaphore,
+        &state.pool,
+    )
+    .await?;
+
+    let mut items: Vec<MinecraftNewsItem> = news
+        .result
+        .results
+        .into_iter()
+        .filter_map(|entry| {
+            let read_more_url = article_url(entry.url.as_deref()?)?;
+            Some(MinecraftNewsItem {
+                title: entry.title,
+                category: None,
+                tag: None,
+                date: entry
+                    .time
+                    .and_then(|timestamp| {
+                        chrono::DateTime::from_timestamp(timestamp, 0)
+                    })
+                    .map(|timestamp| timestamp.to_rfc3339()),
+                image_url: entry.image,
+                read_more_url,
+            })
+        })
+        .collect();
+
+    items.sort_by(|a, b| b.date.cmp(&a.date));
+    items.truncate(limit);
+    Ok(items)
+}
+
+fn article_url(url: &str) -> Option<String> {
+    let parsed = url::Url::parse(url.trim()).ok()?;
+    if parsed.scheme() != "https"
+        || parsed.host_str() != Some("www.minecraft.net")
+    {
+        return None;
+    }
+    let article_id = parsed
+        .path_segments()?
+        .filter(|segment| !segment.is_empty())
+        .last()?;
+    url::Url::parse(MINECRAFT_ARTICLE_BASE)
+        .ok()?
+        .join(article_id)
+        .ok()
+        .map(|url| url.to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::article_url;
+
+    #[test]
+    fn derives_article_urls_from_search_results() {
+        assert_eq!(
+            article_url("https://www.minecraft.net/en-us/article/example"),
+            Some("https://www.minecraft.net/en-us/article/example".to_string())
+        );
+        assert_eq!(
+            article_url("https://www.minecraft.net/fr-fr/article/example"),
+            Some("https://www.minecraft.net/en-us/article/example".to_string())
+        );
+        assert_eq!(article_url("https://example.com/article/example"), None);
+        assert_eq!(article_url("javascript:alert(1)"), None);
+        assert_eq!(article_url("https://"), None);
+        assert_eq!(article_url("  "), None);
+    }
+}

packages/app-lib/src/api/minecraft_skins/offline.rs

@@ -0,0 +1,298 @@
+use std::{
+    io::{Cursor, Write},
+    path::Path,
+};
+
+use serde_json::json;
+use zip::{CompressionMethod, ZipWriter, write::SimpleFileOptions};
+
+use crate::{
+    ErrorKind, State,
+    state::minecraft_skins::{CustomMinecraftSkin, OfflineMinecraftSkin},
+};
+
+use super::{Credentials, png_util};
+
+pub(crate) const OFFLINE_SKIN_PACK_FILE_NAME: &str = "Axolotl Offline Skin.zip";
+pub(crate) const OFFLINE_SKIN_PACK_LEGACY_ID: &str = "Axolotl Offline Skin.zip";
+pub(crate) const OFFLINE_SKIN_PACK_MODERN_ID: &str =
+    "file/Axolotl Offline Skin.zip";
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct OfflineSkinPackOptions {
+    pub enabled_pack_id: Option<&'static str>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+struct MinecraftReleaseVersion {
+    major: u32,
+    minor: u32,
+    patch: u32,
+}
+
+impl MinecraftReleaseVersion {
+    fn parse(version: &str) -> Option<Self> {
+        let mut parts = version.split('.');
+        let major = leading_number(parts.next()?)?;
+        let minor = leading_number(parts.next()?)?;
+        let patch = parts.next().and_then(leading_number).unwrap_or(0);
+
+        Some(Self {
+            major,
+            minor,
+            patch,
+        })
+    }
+
+    fn supports_resource_packs(self) -> bool {
+        self.major > 1 || self.minor >= 6
+    }
+
+    fn uses_modern_pack_id(self) -> bool {
+        self.major > 1 || self.minor >= 13
+    }
+
+    fn uses_modern_player_texture_paths(self) -> bool {
+        self.major > 1
+            || self.minor > 19
+            || (self.minor == 19 && self.patch >= 3)
+    }
+
+    fn needs_legacy_skin_height(self) -> bool {
+        self.major == 1 && matches!(self.minor, 6 | 7)
+    }
+
+    fn resource_pack_format(self) -> u32 {
+        if self.major > 1 {
+            return 75;
+        }
+
+        match self.minor {
+            0..=8 => 1,
+            9..=10 => 2,
+            11..=12 => 3,
+            13..=14 => 4,
+            15 => 5,
+            16 if self.patch <= 1 => 5,
+            16 => 6,
+            17 => 7,
+            18 => 8,
+            19 if self.patch <= 2 => 9,
+            19 if self.patch == 3 => 12,
+            19 => 13,
+            20 if self.patch <= 1 => 15,
+            20 if self.patch == 2 => 18,
+            20 if self.patch <= 4 => 22,
+            20 => 32,
+            21 if self.patch <= 1 => 34,
+            21 if self.patch <= 3 => 42,
+            21 if self.patch == 4 => 46,
+            21 if self.patch == 5 => 55,
+            21 if self.patch == 6 => 63,
+            21 if self.patch <= 8 => 64,
+            21 if self.patch <= 10 => 69,
+            21 => 75,
+            _ => 75,
+        }
+    }
+}
+
+fn leading_number(value: &str) -> Option<u32> {
+    let digits = value
+        .chars()
+        .take_while(|character| character.is_ascii_digit())
+        .collect::<String>();
+    (!digits.is_empty()).then(|| digits.parse().ok()).flatten()
+}
+
+/// Builds (or removes) the resource pack that replaces vanilla's local default
+/// player texture with the selected offline skin.
+pub(crate) async fn prepare_offline_skin_resource_pack(
+    credentials: &Credentials,
+    instance_path: &Path,
+    game_version: &str,
+) -> crate::Result<OfflineSkinPackOptions> {
+    let resource_pack_dir = instance_path.join("resourcepacks");
+    let resource_pack_path =
+        resource_pack_dir.join(OFFLINE_SKIN_PACK_FILE_NAME);
+    let Some(version) = MinecraftReleaseVersion::parse(game_version) else {
+        remove_pack_if_present(&resource_pack_path).await?;
+        return Ok(OfflineSkinPackOptions {
+            enabled_pack_id: None,
+        });
+    };
+
+    if !credentials.is_offline() || !version.supports_resource_packs() {
+        remove_pack_if_present(&resource_pack_path).await?;
+        return Ok(OfflineSkinPackOptions {
+            enabled_pack_id: None,
+        });
+    }
+
+    let state = State::get().await?;
+    let Some(offline_skin) =
+        OfflineMinecraftSkin::get(credentials.offline_profile.id, &state.pool)
+            .await?
+    else {
+        remove_pack_if_present(&resource_pack_path).await?;
+        return Ok(OfflineSkinPackOptions {
+            enabled_pack_id: None,
+        });
+    };
+
+    let Some(saved_skin) = CustomMinecraftSkin::get_by_texture(
+        credentials.offline_profile.id,
+        &offline_skin.texture_key,
+        &state.pool,
+    )
+    .await?
+    else {
+        OfflineMinecraftSkin::clear(
+            credentials.offline_profile.id,
+            &state.pool,
+        )
+        .await?;
+        remove_pack_if_present(&resource_pack_path).await?;
+        return Ok(OfflineSkinPackOptions {
+            enabled_pack_id: None,
+        });
+    };
+
+    let mut texture = saved_skin.texture_blob(&state.pool).await?;
+    if version.needs_legacy_skin_height()
+        && png_util::dimensions(&texture)?.1 == 64
+    {
+        texture = png_util::to_legacy_client_texture(&texture)?.to_vec();
+    }
+
+    let zip_data = build_resource_pack(&texture, version)?;
+    tokio::fs::create_dir_all(&resource_pack_dir).await?;
+    tokio::fs::write(&resource_pack_path, zip_data).await?;
+
+    Ok(OfflineSkinPackOptions {
+        enabled_pack_id: Some(if version.uses_modern_pack_id() {
+            OFFLINE_SKIN_PACK_MODERN_ID
+        } else {
+            OFFLINE_SKIN_PACK_LEGACY_ID
+        }),
+    })
+}
+
+async fn remove_pack_if_present(path: &Path) -> crate::Result<()> {
+    match tokio::fs::remove_file(path).await {
+        Ok(()) => Ok(()),
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => Ok(()),
+        Err(error) => Err(error.into()),
+    }
+}
+
+fn build_resource_pack(
+    texture: &[u8],
+    version: MinecraftReleaseVersion,
+) -> crate::Result<Vec<u8>> {
+    let mut zip = ZipWriter::new(Cursor::new(Vec::new()));
+    let options = SimpleFileOptions::default()
+        .compression_method(CompressionMethod::Deflated);
+    let pack_format = version.resource_pack_format();
+    let metadata = json!({
+        "pack": {
+            "pack_format": pack_format,
+            "description": "Axolotl Launcher offline skin"
+        }
+    });
+
+    start_zip_file(&mut zip, "pack.mcmeta", options)?;
+    zip.write_all(&serde_json::to_vec(&metadata)?)?;
+
+    if version.uses_modern_player_texture_paths() {
+        for model in ["slim", "wide"] {
+            for skin_name in [
+                "alex", "ari", "efe", "kai", "makena", "noor", "steve",
+                "sunny", "zuri",
+            ] {
+                let path = format!(
+                    "assets/minecraft/textures/entity/player/{model}/{skin_name}.png"
+                );
+                start_zip_file(&mut zip, &path, options)?;
+                zip.write_all(texture)?;
+            }
+        }
+    } else {
+        // Replace both models. This keeps the standard offline UUID stable, so
+        // changing a skin cannot split single-player saves into a new player.
+        for path in [
+            "assets/minecraft/textures/entity/steve.png",
+            "assets/minecraft/textures/entity/alex.png",
+        ] {
+            start_zip_file(&mut zip, path, options)?;
+            zip.write_all(texture)?;
+        }
+    }
+
+    zip.finish().map(Cursor::into_inner).map_err(zip_error)
+}
+
+fn start_zip_file(
+    zip: &mut ZipWriter<Cursor<Vec<u8>>>,
+    path: &str,
+    options: SimpleFileOptions,
+) -> crate::Result<()> {
+    zip.start_file(path, options).map_err(zip_error)
+}
+
+fn zip_error(error: zip::result::ZipError) -> crate::Error {
+    ErrorKind::OtherError(format!(
+        "Failed to build offline skin resource pack: {error}"
+    ))
+    .as_error()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_release_versions_and_selects_pack_formats() {
+        let version = MinecraftReleaseVersion::parse("1.19.2").unwrap();
+        assert_eq!(version.resource_pack_format(), 9);
+        assert!(!version.uses_modern_player_texture_paths());
+
+        let version = MinecraftReleaseVersion::parse("1.19.3").unwrap();
+        assert_eq!(version.resource_pack_format(), 12);
+        assert!(version.uses_modern_player_texture_paths());
+
+        let version = MinecraftReleaseVersion::parse("1.21.8").unwrap();
+        assert_eq!(version.resource_pack_format(), 64);
+        assert!(version.uses_modern_pack_id());
+    }
+
+    #[test]
+    fn rejects_snapshot_versions_without_a_release_shape() {
+        assert_eq!(MinecraftReleaseVersion::parse("25w31a"), None);
+    }
+
+    #[test]
+    fn generated_pack_replaces_all_modern_default_player_textures() {
+        let texture = include_bytes!("assets/default/MissingNo.png");
+        let version = MinecraftReleaseVersion::parse("1.19.3").unwrap();
+        let pack = build_resource_pack(texture, version).unwrap();
+        let mut archive = zip::ZipArchive::new(Cursor::new(pack)).unwrap();
+
+        assert!(archive.by_name("pack.mcmeta").is_ok());
+        assert!(
+            archive
+                .by_name(
+                    "assets/minecraft/textures/entity/player/slim/alex.png"
+                )
+                .is_ok()
+        );
+        assert!(
+            archive
+                .by_name(
+                    "assets/minecraft/textures/entity/player/wide/zuri.png"
+                )
+                .is_ok()
+        );
+        assert_eq!(archive.len(), 19);
+    }
+}

packages/app-lib/src/api/minecraft_skins/png_util.rs

@@ -0,0 +1,482 @@
+//! Miscellaneous PNG utilities for Minecraft skins.
+
+use std::io::{BufRead, Cursor, Seek};
+use std::sync::Arc;
+
+use base64::Engine;
+use bytes::Bytes;
+use data_url::DataUrl;
+use futures::{Stream, TryStreamExt, future::Either, stream};
+use itertools::Itertools;
+use rgb::Rgba;
+use tokio::io::AsyncReadExt;
+use tokio_util::compat::FuturesAsyncReadCompatExt;
+use url::Url;
+
+use crate::{
+    ErrorKind, minecraft_skins::UrlOrBlob, util::fetch::INSECURE_REQWEST_CLIENT,
+};
+
+pub async fn url_to_data_stream(
+    url: &Url,
+) -> crate::Result<impl Stream<Item = Result<Bytes, reqwest::Error>> + use<>> {
+    if url.scheme() == "data" {
+        let data = DataUrl::process(url.as_str())?.decode_to_vec()?.0.into();
+
+        Ok(Either::Left(stream::once(async { Ok(data) })))
+    } else {
+        let response = INSECURE_REQWEST_CLIENT
+            .get(url.as_str())
+            .header("Accept", "image/png")
+            .timeout(std::time::Duration::from_secs(10))
+            .send()
+            .await
+            .and_then(|response| response.error_for_status())?;
+
+        Ok(Either::Right(response.bytes_stream()))
+    }
+}
+
+pub fn blob_to_data_url(png_data: impl AsRef<[u8]>) -> Option<Arc<Url>> {
+    let png_data = png_data.as_ref();
+
+    is_png(png_data).then(|| {
+        Url::parse(&format!(
+            "data:image/png;base64,{}",
+            base64::engine::general_purpose::STANDARD.encode(png_data)
+        ))
+        .unwrap()
+        .into()
+    })
+}
+
+pub fn is_png(png_data: &[u8]) -> bool {
+    /// The initial 8 bytes of a PNG file, used to identify it as such.
+    ///
+    /// Reference: <https://www.w3.org/TR/png-3/#3PNGsignature>
+    const PNG_SIGNATURE: &[u8] =
+        &[0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A];
+
+    png_data.starts_with(PNG_SIGNATURE)
+}
+
+pub fn dimensions(png_data: &[u8]) -> crate::Result<(u32, u32)> {
+    if !is_png(png_data) {
+        Err(ErrorKind::InvalidPng)?;
+    }
+
+    // Read the width and height fields from the IHDR chunk, which the
+    // PNG specification mandates to be the first in the file, just after
+    // the 8 signature bytes. See:
+    // https://www.w3.org/TR/png-3/#5DataRep
+    // https://www.w3.org/TR/png-3/#11IHDR
+    let width = u32::from_be_bytes(
+        png_data
+            .get(16..20)
+            .ok_or(ErrorKind::InvalidPng)?
+            .try_into()
+            .unwrap(),
+    );
+    let height = u32::from_be_bytes(
+        png_data
+            .get(20..24)
+            .ok_or(ErrorKind::InvalidPng)?
+            .try_into()
+            .unwrap(),
+    );
+
+    Ok((width, height))
+}
+
+/// Crops a modern 64x64 skin to the 64x32 layout understood by Minecraft
+/// 1.6 and 1.7 clients.
+pub(super) fn to_legacy_client_texture(
+    png_data: &[u8],
+) -> crate::Result<Bytes> {
+    let mut decoder = png::Decoder::new(Cursor::new(png_data));
+    decoder.set_transformations(png::Transformations::normalize_to_color8());
+    let mut png_reader = decoder.read_info()?;
+
+    if png_reader.info().width != 64 || png_reader.info().height != 64 {
+        Err(ErrorKind::InvalidSkinTexture)?;
+    }
+
+    let texture_buf = get_skin_texture_buffer(&mut png_reader, false)?;
+    let legacy_texture =
+        texture_buf.get(..64 * 32).ok_or(ErrorKind::InvalidPng)?;
+    let mut encoded_png = Vec::new();
+    let mut png_encoder = png::Encoder::new(&mut encoded_png, 64, 32);
+    png_encoder.set_color(png::ColorType::Rgba);
+    png_encoder.set_depth(png::BitDepth::Eight);
+    png_encoder.set_filter(png::Filter::NoFilter);
+    png_encoder.set_compression(png::Compression::Fast);
+
+    let png_buf = bytemuck::try_cast_slice(legacy_texture)
+        .map_err(|_| ErrorKind::InvalidPng)?;
+    let mut png_writer = png_encoder.write_header()?;
+    png_writer.write_image_data(png_buf)?;
+    png_writer.finish()?;
+
+    Ok(encoded_png.into())
+}
+
+/// Normalizes the texture of a Minecraft skin to the modern 64x64 format, handling legacy 64x32
+/// skins, doing "Notch transparency hack" and making inner parts opaque as the vanilla game client
+/// does. This function prioritizes PNG encoding speed over compression density, so the resulting
+/// textures are better suited for display purposes, not persistent storage or transmission.
+///
+/// The normalized, processed is returned texture as a byte array in PNG format.
+pub async fn normalize_skin_texture(
+    texture: &UrlOrBlob,
+) -> crate::Result<Bytes> {
+    let mut texture_data = Vec::with_capacity(8192);
+    Box::pin(
+        match texture {
+            UrlOrBlob::Url(url) => Either::Left(
+                url_to_data_stream(url)
+                    .await?
+                    .map_err(std::io::Error::other)
+                    .into_async_read(),
+            ),
+            UrlOrBlob::Blob(blob) => Either::Right(
+                stream::once({
+                    let blob = Bytes::clone(blob);
+                    async { Ok(blob) }
+                })
+                .into_async_read(),
+            ),
+        }
+        .compat(),
+    )
+    .read_to_end(&mut texture_data)
+    .await?;
+
+    let mut png_reader = {
+        let mut decoder = png::Decoder::new(Cursor::new(texture_data));
+        decoder
+            .set_transformations(png::Transformations::normalize_to_color8());
+        decoder.read_info()
+    }?;
+
+    // The code below assumes that the skin texture has valid dimensions.
+    // This also serves as a way to bail out early for obviously invalid or
+    // adversarial textures
+    if png_reader.info().width != 64
+        || ![64, 32].contains(&png_reader.info().height)
+    {
+        Err(ErrorKind::InvalidSkinTexture)?;
+    }
+
+    let is_legacy_skin = png_reader.info().height == 32;
+    let mut texture_buf =
+        get_skin_texture_buffer(&mut png_reader, is_legacy_skin)?;
+    if is_legacy_skin {
+        convert_legacy_skin_texture(&mut texture_buf, png_reader.info());
+        do_notch_transparency_hack(&mut texture_buf, png_reader.info());
+    }
+    make_inner_parts_opaque(&mut texture_buf, png_reader.info());
+
+    let mut encoded_png = vec![];
+
+    let mut png_encoder = png::Encoder::new(&mut encoded_png, 64, 64);
+    png_encoder.set_color(png::ColorType::Rgba);
+    png_encoder.set_depth(png::BitDepth::Eight);
+    png_encoder.set_filter(png::Filter::NoFilter);
+    png_encoder.set_compression(png::Compression::Fast);
+
+    // Keeping color space information properly set, to handle the occasional
+    // strange PNG with non-sRGB chromaticities and/or different grayscale spaces
+    // that keeps most people wondering, is what sets a carefully crafted image
+    // manipulation routine apart :)
+    if let Some(source_chromaticities) =
+        png_reader.info().source_chromaticities.as_ref().copied()
+    {
+        png_encoder.set_source_chromaticities(source_chromaticities);
+    }
+    if let Some(source_gamma) = png_reader.info().source_gamma.as_ref().copied()
+    {
+        png_encoder.set_source_gamma(source_gamma);
+    }
+    if let Some(source_srgb) = png_reader.info().srgb.as_ref().copied() {
+        png_encoder.set_source_srgb(source_srgb);
+    }
+
+    let png_buf = bytemuck::try_cast_slice(&texture_buf)
+        .map_err(|_| ErrorKind::InvalidPng)?;
+    let mut png_writer = png_encoder.write_header()?;
+    png_writer.write_image_data(png_buf)?;
+    png_writer.finish()?;
+
+    Ok(encoded_png.into())
+}
+
+/// Reads a skin texture and returns a 64x64 buffer in RGBA format.
+fn get_skin_texture_buffer<R: BufRead + Seek>(
+    png_reader: &mut png::Reader<R>,
+    is_legacy_skin: bool,
+) -> crate::Result<Vec<Rgba<u8>>> {
+    let output_buffer_size = png_reader
+        .output_buffer_size()
+        .expect("Reasonable skin texture size verified already");
+    let mut png_buf = if is_legacy_skin {
+        // Legacy skins have half the height, so duplicate the rows to
+        // turn them into a 64x64 texture
+        vec![0; output_buffer_size * 2]
+    } else {
+        // Modern skins are left as-is
+        vec![0; output_buffer_size]
+    };
+    png_reader.next_frame(&mut png_buf)?;
+
+    let mut texture_buf = match png_reader.output_color_type().0 {
+        png::ColorType::Grayscale => png_buf
+            .iter()
+            .map(|&value| Rgba {
+                r: value,
+                g: value,
+                b: value,
+                a: 255,
+            })
+            .collect_vec(),
+        png::ColorType::GrayscaleAlpha => png_buf
+            .chunks_exact(2)
+            .map(|chunk| Rgba {
+                r: chunk[0],
+                g: chunk[0],
+                b: chunk[0],
+                a: chunk[1],
+            })
+            .collect_vec(),
+        png::ColorType::Rgb => png_buf
+            .chunks_exact(3)
+            .map(|chunk| Rgba {
+                r: chunk[0],
+                g: chunk[1],
+                b: chunk[2],
+                a: 255,
+            })
+            .collect_vec(),
+        png::ColorType::Rgba => bytemuck::try_cast_vec(png_buf)
+            .map_err(|_| ErrorKind::InvalidPng)?,
+        _ => Err(ErrorKind::InvalidPng)?, // Cannot happen by PNG spec after transformations
+    };
+
+    // Make the added bottom half of the expanded legacy skin buffer transparent
+    if is_legacy_skin {
+        set_alpha(&mut texture_buf, png_reader.info(), 0, 32, 64, 64, 0);
+    }
+
+    Ok(texture_buf)
+}
+
+/// Converts a legacy skin texture (32x64 pixels) within a 64x64 buffer to the
+/// native 64x64 format used by modern Minecraft clients.
+///
+/// See also 25w16a's `SkinTextureDownloader#processLegacySkin` method.
+#[inline]
+fn convert_legacy_skin_texture(
+    texture_buf: &mut [Rgba<u8, u8>],
+    texture_info: &png::Info,
+) {
+    /// The skin faces the game client copies around, in order, when converting a
+    /// legacy skin to the native 64x64 format.
+    const FACE_COPY_PARAMETERS: &[(
+        usize,
+        usize,
+        isize,
+        isize,
+        usize,
+        usize,
+    )] = &[
+        (4, 16, 16, 32, 4, 4),
+        (8, 16, 16, 32, 4, 4),
+        (0, 20, 24, 32, 4, 12),
+        (4, 20, 16, 32, 4, 12),
+        (8, 20, 8, 32, 4, 12),
+        (12, 20, 16, 32, 4, 12),
+        (44, 16, -8, 32, 4, 4),
+        (48, 16, -8, 32, 4, 4),
+        (40, 20, 0, 32, 4, 12),
+        (44, 20, -8, 32, 4, 12),
+        (48, 20, -16, 32, 4, 12),
+        (52, 20, -8, 32, 4, 12),
+    ];
+
+    for (x, y, off_x, off_y, width, height) in FACE_COPY_PARAMETERS {
+        copy_rect_mirror_horizontally(
+            texture_buf,
+            texture_info,
+            *x,
+            *y,
+            *off_x,
+            *off_y,
+            *width,
+            *height,
+        )
+    }
+}
+
+/// Makes outer head layer transparent if every pixel has alpha greater or equal to 128.
+///
+/// See also 25w16a's `SkinTextureDownloader#doNotchTransparencyHack` method.
+fn do_notch_transparency_hack(
+    texture_buf: &mut [Rgba<u8, u8>],
+    texture_info: &png::Info,
+) {
+    // The skin part the game client makes transparent
+    let (x1, y1, x2, y2) = (32, 0, 64, 32);
+
+    for y in y1..y2 {
+        for x in x1..x2 {
+            if texture_buf[x + y * texture_info.width as usize].a < 128 {
+                return;
+            }
+        }
+    }
+
+    set_alpha(texture_buf, texture_info, x1, y1, x2, y2, 0);
+}
+
+/// Makes inner parts of a skin texture opaque.
+///
+/// See also 25w16a's `SkinTextureDownloader#processLegacySkin` method.
+#[inline]
+fn make_inner_parts_opaque(
+    texture_buf: &mut [Rgba<u8, u8>],
+    texture_info: &png::Info,
+) {
+    /// The skin parts the game client makes opaque.
+    const OPAQUE_PART_PARAMETERS: &[(usize, usize, usize, usize)] =
+        &[(0, 0, 32, 16), (0, 16, 64, 32), (16, 48, 48, 64)];
+
+    for (x1, y1, x2, y2) in OPAQUE_PART_PARAMETERS {
+        set_alpha(texture_buf, texture_info, *x1, *y1, *x2, *y2, 255);
+    }
+}
+
+/// Copies a `width` pixels wide, `height` pixels tall rectangle of pixels within `texture_buf`
+/// whose top-left corner is at coordinates `(x, y)` to a destination rectangle whose top-left
+/// corner is at coordinates `(x + off_x, y + off_y)`, while mirroring (i.e., flipping) the
+/// pixels horizontally.
+///
+/// Equivalent to Mojang's Blaze3D `NativeImage#copyRect(int, int, int, int, int, int,
+/// boolean, boolean)` method, but with the last two parameters fixed to `true` and `false`,
+/// respectively.
+#[allow(clippy::too_many_arguments)]
+fn copy_rect_mirror_horizontally(
+    texture_buf: &mut [Rgba<u8, u8>],
+    texture_info: &png::Info,
+    x: usize,
+    y: usize,
+    off_x: isize,
+    off_y: isize,
+    width: usize,
+    height: usize,
+) {
+    for row in 0..height {
+        for col in 0..width {
+            let src_x = x + col;
+            let src_y = y + row;
+            let dst_x = (x as isize + off_x) as usize + (width - 1 - col);
+            let dst_y = (y as isize + off_y) as usize + row;
+
+            texture_buf[dst_x + dst_y * texture_info.width as usize] =
+                texture_buf[src_x + src_y * texture_info.width as usize];
+        }
+    }
+}
+
+/// Sets alpha for every pixel of a rectangle within `texture_buf`
+/// whose top-left corner is at `(x1, y1)` and bottom-right corner is at `(x2 - 1, y2 - 1)`.
+fn set_alpha(
+    texture_buf: &mut [Rgba<u8, u8>],
+    texture_info: &png::Info,
+    x1: usize,
+    y1: usize,
+    x2: usize,
+    y2: usize,
+    alpha: u8,
+) {
+    for y in y1..y2 {
+        for x in x1..x2 {
+            texture_buf[x + y * texture_info.width as usize].a = alpha;
+        }
+    }
+}
+
+#[cfg(test)]
+#[tokio::test]
+async fn normalize_skin_texture_works() {
+    let decode_to_pixels = |png_data: &[u8]| {
+        let decoder = png::Decoder::new(Cursor::new(png_data));
+        let mut reader = decoder.read_info().expect("Failed to read PNG info");
+        let mut buffer =
+            vec![0; reader.output_buffer_size().expect("Skin size too large")];
+        reader
+            .next_frame(&mut buffer)
+            .expect("Failed to decode PNG");
+        (buffer, reader.info().clone())
+    };
+
+    let test_data = [
+        (
+            "legacy",
+            &include_bytes!("assets/test/legacy.png")[..],
+            &include_bytes!("assets/test/legacy_normalized.png")[..],
+        ),
+        (
+            "notch",
+            &include_bytes!("assets/test/notch.png")[..],
+            &include_bytes!("assets/test/notch_normalized.png")[..],
+        ),
+        (
+            "transparent",
+            &include_bytes!("assets/test/transparent.png")[..],
+            &include_bytes!("assets/test/transparent_normalized.png")[..],
+        ),
+    ];
+
+    for (skin_name, original_png_data, expected_normalized_png_data) in
+        test_data
+    {
+        let normalized_png_data =
+            normalize_skin_texture(&UrlOrBlob::Blob(original_png_data.into()))
+                .await
+                .expect("Failed to normalize skin texture");
+
+        let (normalized_pixels, normalized_info) =
+            decode_to_pixels(&normalized_png_data);
+        let (expected_pixels, expected_info) =
+            decode_to_pixels(expected_normalized_png_data);
+
+        // Check that dimensions match
+        assert_eq!(
+            normalized_info.width, expected_info.width,
+            "Widths don't match for {skin_name}"
+        );
+        assert_eq!(
+            normalized_info.height, expected_info.height,
+            "Heights don't match for {skin_name}"
+        );
+        assert_eq!(
+            normalized_info.color_type, expected_info.color_type,
+            "Color types don't match for {skin_name}"
+        );
+
+        // Check that pixel data matches
+        assert_eq!(
+            normalized_pixels, expected_pixels,
+            "Pixel data doesn't match for {skin_name}"
+        );
+    }
+}
+
+#[cfg(test)]
+#[test]
+fn creates_legacy_client_skin_texture() {
+    let texture = include_bytes!("assets/test/notch_normalized.png");
+    let legacy_texture =
+        to_legacy_client_texture(texture).expect("Failed to crop skin");
+
+    assert_eq!(dimensions(&legacy_texture).unwrap(), (64, 32));
+}

packages/app-lib/src/api/mod.rs

@@ -0,0 +1,96 @@
+//! API for interacting with Theseus
+pub mod ai;
+pub mod cache;
+pub mod content_favorites;
+pub mod content_search;
+pub mod curseforge;
+pub mod drop_classifier;
+pub mod friends;
+pub mod google_ip;
+pub mod handler;
+pub mod hongshi;
+pub mod instance;
+pub mod jre;
+pub(crate) mod loader_metadata;
+pub mod logs;
+pub mod mcarchive;
+pub mod memory;
+pub mod metadata;
+pub mod minecraft_auth;
+pub mod minecraft_news;
+pub mod minecraft_skins;
+pub mod mr_auth;
+pub mod multiplayer;
+pub mod pack;
+pub mod planet_minecraft;
+pub mod process;
+pub mod server_address;
+pub mod servers;
+pub mod settings;
+pub mod symlink;
+pub mod tags;
+pub mod terracotta;
+pub mod translation;
+pub mod worlds;
+
+pub mod data {
+    pub use crate::instance::McArchiveCoreInstallResult;
+    pub use crate::launcher::ExternalGameDirMode;
+    pub use crate::state::{
+        AppliedContentSetPatch, CacheBehaviour, CacheValueType, CachedEntry,
+        ContentFavorite, ContentFavoriteInput, ContentFavoriteProvider,
+        ContentFavoriteType, ContentFile, ContentItem, ContentItemCapabilities,
+        ContentItemOwner, ContentItemProject, ContentItemVersion,
+        ContentOwnershipKind, ContentProvider, ContentProviderRef,
+        ContentUpdatePlan, ContentUpdatePlanAction, ContentUpdateResolution,
+        ContentUpdateResolutionChoice, ContentUpdateScope, CoreComponent,
+        CoreComponentKind, CoreComponentSource, CoreJarPreview,
+        CreateDirectLinkInstance, CreateInstance, Credentials, Dependency,
+        DirectLinkSyncReport, DirectoryInfo, EditInstance,
+        ExternalMinecraftRoot, Hooks, InstanceContentPack,
+        InstanceContentSnapshot, InstanceContentSnapshotItem,
+        InstanceContentWarning, InstanceInstallCandidate,
+        InstanceInstallTarget, InstanceLaunchOverridesPatch, InstanceLink,
+        InstanceMetadata, InstancePostUpgradeNotice,
+        InstancePostUpgradeWarning, InstanceUpgradeAction,
+        InstanceUpgradeDependencyChange, InstanceUpgradeDependencyChangeKind,
+        InstanceUpgradeEnvironment, InstanceUpgradeFixedConstraint,
+        InstanceUpgradeIssue, InstanceUpgradeIssueCode, InstanceUpgradeItem,
+        InstanceUpgradeItemStatus, InstanceUpgradePlan,
+        InstanceUpgradeResolution, InstanceUpgradeResolutionBatchResult,
+        InstanceUpgradeResolutionResult, InstanceUpgradeSelection,
+        InstanceUpgradeSolution, InstanceUpgradeSolutionChoice,
+        InstanceUpgradeSolutionKind, JavaVersion, LinkedModpackInfo,
+        LoaderComponent, LoaderComponentKind, LoaderComponentRole,
+        ManualDownloadOperationKind, ManualDownloadState, MemorySettings,
+        ModLoader, ModrinthCredentials, Organization, OwnerType,
+        PackMemberMaterializationState, PackMemberOverrideKind,
+        PendingManualDownload, PrivacySettings, ProcessMetadata, Project,
+        ProjectType, ProjectV3, SearchResult, SearchResults, SearchResultsV3,
+        Settings, ShaderRuntime, TeamMember, Theme, User, UserFriend, Version,
+        WindowSize,
+    };
+    pub use ariadne::users::UserStatus;
+    pub use modrinth_content_management::{
+        ContentType, ResolutionPreferences, ResolveContentPlan,
+        ResolveContentRequest,
+    };
+}
+
+pub mod prelude {
+    pub use crate::{
+        State, ai,
+        data::*,
+        event::CommandPayload,
+        install, instance,
+        jre::{self, JdkVersionInfo},
+        metadata, minecraft_auth, mr_auth, pack, process, server_address,
+        servers, settings,
+        state::{ReleaseChannel, db_backup::app_db_backup_dir},
+        translation,
+        util::{
+            io::{IOError, canonicalize},
+            network::{is_network_metered, tcp_listen_any_loopback},
+        },
+    };
+}

packages/app-lib/src/api/mr_auth.rs

@@ -0,0 +1,45 @@
+use crate::state::ModrinthCredentials;
+
+#[tracing::instrument]
+pub fn authenticate_begin_flow() -> &'static str {
+    crate::state::get_login_url()
+}
+
+#[tracing::instrument]
+pub async fn authenticate_finish_flow(
+    code: &str,
+) -> crate::Result<ModrinthCredentials> {
+    let state = crate::State::get().await?;
+
+    let creds = crate::state::finish_login_flow(
+        code,
+        &state.api_semaphore,
+        &state.pool,
+    )
+    .await?;
+
+    creds.upsert(&state.pool).await?;
+    Ok(creds)
+}
+
+#[tracing::instrument]
+pub async fn logout() -> crate::Result<()> {
+    let state = crate::State::get().await?;
+    let current = ModrinthCredentials::get_active(&state.pool).await?;
+
+    if let Some(current) = current {
+        ModrinthCredentials::remove(&current.user_id, &state.pool).await?;
+    }
+
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn get_credentials() -> crate::Result<Option<ModrinthCredentials>> {
+    let state = crate::State::get().await?;
+    let current =
+        ModrinthCredentials::get_and_refresh(&state.pool, &state.api_semaphore)
+            .await?;
+
+    Ok(current)
+}

packages/app-lib/src/api/multiplayer.rs

@@ -0,0 +1,292 @@
+use eyre::bail;
+use serde::{Deserialize, Serialize};
+use std::sync::{
+    LazyLock,
+    atomic::{AtomicBool, Ordering},
+};
+use tokio::sync::Mutex;
+
+use super::{hongshi, terracotta};
+
+static ACTIVE_PROVIDER: LazyLock<Mutex<Option<MultiplayerProvider>>> =
+    LazyLock::new(|| Mutex::new(None));
+static MULTIPLAYER_OPERATION: LazyLock<Mutex<()>> =
+    LazyLock::new(|| Mutex::new(()));
+static SHUTTING_DOWN: AtomicBool = AtomicBool::new(false);
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum MultiplayerProvider {
+    Terracotta,
+    Hongshi,
+}
+
+impl std::fmt::Display for MultiplayerProvider {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Terracotta => formatter.write_str("terracotta"),
+            Self::Hongshi => formatter.write_str("hongshi"),
+        }
+    }
+}
+
+#[derive(Clone, Debug, Serialize)]
+pub struct MultiplayerProviderCapabilities {
+    pub provider: MultiplayerProvider,
+    pub supported: bool,
+    pub can_host: bool,
+    pub can_join: bool,
+    pub requires_local_port: bool,
+    pub unsupported_reason: Option<String>,
+}
+
+#[derive(Clone, Debug, Serialize)]
+pub struct MultiplayerState {
+    pub active_provider: Option<MultiplayerProvider>,
+    pub providers: Vec<MultiplayerProviderCapabilities>,
+    pub terracotta: terracotta::TerracottaState,
+    pub hongshi: hongshi::HongshiState,
+}
+
+#[derive(Clone, Debug, Deserialize)]
+#[serde(tag = "provider", rename_all = "snake_case")]
+pub enum MultiplayerHostRequest {
+    Terracotta {
+        player_name: String,
+        room_code: Option<String>,
+    },
+    Hongshi {
+        local_port: u16,
+        node_name: Option<String>,
+        instance_id: Option<String>,
+    },
+}
+
+#[derive(Clone, Debug, Deserialize)]
+pub struct MultiplayerJoinRequest {
+    pub provider: MultiplayerProvider,
+    pub player_name: String,
+    pub room_code: String,
+}
+
+pub async fn claim_provider(provider: MultiplayerProvider) -> eyre::Result<()> {
+    if SHUTTING_DOWN.load(Ordering::Relaxed) {
+        bail!("the launcher is shutting down");
+    }
+
+    let mut active = ACTIVE_PROVIDER.lock().await;
+    if let Some(current) = *active
+        && current != provider
+    {
+        bail!("{current} multiplayer is already running");
+    }
+    *active = Some(provider);
+    Ok(())
+}
+
+pub async fn release_provider(provider: MultiplayerProvider) {
+    let mut active = ACTIVE_PROVIDER.lock().await;
+    if *active == Some(provider) {
+        *active = None;
+    }
+}
+
+pub async fn get_state() -> MultiplayerState {
+    let active_provider = *ACTIVE_PROVIDER.lock().await;
+    let terracotta = terracotta::get_state().await;
+    let hongshi = hongshi::get_state().await;
+    MultiplayerState {
+        active_provider,
+        providers: vec![
+            MultiplayerProviderCapabilities {
+                provider: MultiplayerProvider::Terracotta,
+                supported: terracotta::terracotta_platform_key()
+                    != "unsupported",
+                can_host: true,
+                can_join: true,
+                requires_local_port: false,
+                unsupported_reason: None,
+            },
+            MultiplayerProviderCapabilities {
+                provider: MultiplayerProvider::Hongshi,
+                supported: hongshi.supported,
+                can_host: true,
+                can_join: false,
+                requires_local_port: true,
+                unsupported_reason: (!hongshi.supported).then(|| {
+                    "RedStone is not supported on this platform".to_string()
+                }),
+            },
+        ],
+        terracotta,
+        hongshi,
+    }
+}
+
+async fn stop_provider(provider: MultiplayerProvider) -> eyre::Result<()> {
+    match provider {
+        MultiplayerProvider::Terracotta => terracotta::stop_terracotta().await,
+        MultiplayerProvider::Hongshi => hongshi::stop().await,
+    }
+}
+
+pub async fn switch_provider(
+    provider: MultiplayerProvider,
+) -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    let active = *ACTIVE_PROVIDER.lock().await;
+    if let Some(current) = active
+        && current != provider
+    {
+        stop_provider(current).await?;
+    }
+    Ok(())
+}
+
+pub async fn prepare_terracotta() -> eyre::Result<()> {
+    prepare_terracotta_with_options(None, true).await
+}
+
+pub async fn prepare_terracotta_with_options(
+    binary_path: Option<String>,
+    auto_download: bool,
+) -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    claim_provider(MultiplayerProvider::Terracotta).await?;
+    if terracotta::get_state().await.http_port.is_some() {
+        return Ok(());
+    }
+    if let Err(error) =
+        terracotta::start_terracotta(binary_path, auto_download).await
+    {
+        release_provider(MultiplayerProvider::Terracotta).await;
+        return Err(error);
+    }
+    Ok(())
+}
+
+pub async fn stop_terracotta_compat() -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    terracotta::stop_terracotta().await
+}
+
+pub async fn reset_terracotta_compat() -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    terracotta::reset_state().await
+}
+
+pub async fn host(request: MultiplayerHostRequest) -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    match request {
+        MultiplayerHostRequest::Terracotta {
+            player_name,
+            room_code,
+        } => {
+            let already_running =
+                terracotta::get_state().await.http_port.is_some();
+            claim_provider(MultiplayerProvider::Terracotta).await?;
+            let result = async {
+                if !already_running {
+                    terracotta::start_terracotta(None, true).await?;
+                }
+                terracotta::start_hosting(room_code, player_name).await
+            }
+            .await;
+            if result.is_err() && !already_running {
+                let _ = terracotta::stop_terracotta().await;
+            }
+            result
+        }
+        MultiplayerHostRequest::Hongshi {
+            local_port,
+            node_name,
+            instance_id,
+        } => hongshi::start(local_port, node_name, instance_id).await,
+    }
+}
+
+pub async fn join(request: MultiplayerJoinRequest) -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    if request.provider != MultiplayerProvider::Terracotta {
+        bail!(
+            "RedStone guests connect directly with the public server address"
+        );
+    }
+    let already_running = terracotta::get_state().await.http_port.is_some();
+    claim_provider(MultiplayerProvider::Terracotta).await?;
+    let result = async {
+        if !already_running {
+            terracotta::start_terracotta(None, true).await?;
+        }
+        terracotta::start_joining(request.room_code, request.player_name).await
+    }
+    .await;
+    if result.is_err() && !already_running {
+        let _ = terracotta::stop_terracotta().await;
+    }
+    result
+}
+
+pub async fn stop() -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    let provider = { *ACTIVE_PROVIDER.lock().await };
+    if let Some(provider) = provider {
+        stop_provider(provider).await?;
+    }
+    Ok(())
+}
+
+pub async fn reset() -> eyre::Result<()> {
+    let _operation = MULTIPLAYER_OPERATION.lock().await;
+    let provider = { *ACTIVE_PROVIDER.lock().await };
+    match provider {
+        Some(MultiplayerProvider::Terracotta) => {
+            terracotta::reset_state().await
+        }
+        Some(MultiplayerProvider::Hongshi) => hongshi::stop().await,
+        None => Ok(()),
+    }
+}
+
+pub async fn observe_minecraft_log(
+    instance_id: &str,
+    instance_name: &str,
+    process_id: &str,
+    message: &str,
+) {
+    hongshi::observe_minecraft_log(
+        instance_id,
+        instance_name,
+        process_id,
+        message,
+    )
+    .await;
+}
+
+pub async fn minecraft_process_finished(instance_id: &str) {
+    hongshi::minecraft_process_finished(instance_id).await;
+}
+
+pub async fn shutdown() -> eyre::Result<()> {
+    SHUTTING_DOWN.store(true, Ordering::Relaxed);
+    stop().await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn active_provider_snapshot_does_not_hold_the_mutex() {
+        *ACTIVE_PROVIDER.lock().await = Some(MultiplayerProvider::Hongshi);
+        let provider = { *ACTIVE_PROVIDER.lock().await };
+        let mut active = tokio::time::timeout(
+            std::time::Duration::from_millis(100),
+            ACTIVE_PROVIDER.lock(),
+        )
+        .await
+        .expect("provider mutex should be released before stopping");
+        assert_eq!(provider, Some(MultiplayerProvider::Hongshi));
+        *active = None;
+    }
+}

packages/app-lib/src/api/pack/archive_util.rs

@@ -0,0 +1,293 @@
+//! Shared helpers for extracting content from local modpack archives.
+
+use std::path::{Component, Path, PathBuf};
+
+use super::detect::decode_zip_entry_name;
+use crate::util::io;
+use tokio_util::sync::CancellationToken;
+
+const EXTRACTION_SIZE_LIMIT: u64 = 8 * 1024 * 1024 * 1024;
+
+fn archive_error(error: zip::result::ZipError) -> crate::Error {
+    crate::ErrorKind::InputError(format!("Modpack archive is invalid: {error}"))
+        .into()
+}
+
+pub(crate) fn safe_relative_path(value: &str) -> crate::Result<String> {
+    let path = Path::new(value);
+    if value.is_empty()
+        || path.is_absolute()
+        || path
+            .components()
+            .any(|component| !matches!(component, Component::Normal(_)))
+    {
+        return Err(crate::ErrorKind::InputError(
+            "Modpack archive contains an invalid file path".to_string(),
+        )
+        .into());
+    }
+    Ok(path.to_string_lossy().replace('\\', "/"))
+}
+
+/// Extracts every file under `prefix` in the archive into `target_dir`,
+/// preserving the directory structure below the prefix. Returns the number of
+/// files written.
+pub(crate) async fn extract_archive_subdir(
+    archive_path: PathBuf,
+    prefix: String,
+    target_dir: PathBuf,
+) -> crate::Result<u32> {
+    tokio::task::spawn_blocking(move || {
+        extract_archive_subdir_sync(&archive_path, &prefix, &target_dir, None)
+    })
+    .await?
+}
+
+pub(crate) async fn extract_archive_subdir_for_instance(
+    instance_id: String,
+    cancellation: CancellationToken,
+    archive_path: PathBuf,
+    prefix: String,
+    target_dir: PathBuf,
+) -> crate::Result<u32> {
+    run_blocking_instance_write(
+        instance_id,
+        cancellation,
+        move |cancellation| {
+            extract_archive_subdir_sync(
+                &archive_path,
+                &prefix,
+                &target_dir,
+                Some(cancellation),
+            )
+        },
+    )
+    .await
+}
+
+pub(crate) async fn run_blocking_instance_write<T, F>(
+    instance_id: String,
+    cancellation: CancellationToken,
+    operation: F,
+) -> crate::Result<T>
+where
+    T: Send + 'static,
+    F: FnOnce(&CancellationToken) -> crate::Result<T> + Send + 'static,
+{
+    let state = crate::State::get().await?;
+    let instance_lock =
+        state.lock_instance_content_exclusive(&instance_id).await;
+    tokio::task::spawn_blocking(move || {
+        let _instance_lock = instance_lock;
+        operation(&cancellation)
+    })
+    .await?
+}
+
+fn extract_archive_subdir_sync(
+    archive_path: &Path,
+    prefix: &str,
+    target_dir: &Path,
+    cancellation: Option<&CancellationToken>,
+) -> crate::Result<u32> {
+    let file = std::fs::File::open(archive_path)
+        .map_err(|error| io::IOError::with_path(error, archive_path))?;
+    let mut archive = zip::ZipArchive::new(file).map_err(archive_error)?;
+    let mut files_written = 0_u32;
+    let mut total_size = 0_u64;
+    for index in 0..archive.len() {
+        check_cancellation(cancellation)?;
+        let mut entry = archive.by_index(index).map_err(archive_error)?;
+        let entry_name = decode_zip_entry_name(entry.name_raw());
+        if entry.is_dir() || !entry_name.starts_with(prefix) {
+            continue;
+        }
+        let relative = &entry_name[prefix.len()..];
+        if relative.is_empty() {
+            continue;
+        }
+        total_size = total_size.saturating_add(entry.size());
+        if total_size > EXTRACTION_SIZE_LIMIT {
+            return Err(crate::ErrorKind::InputError(
+                "Modpack archive contents exceed the extraction limit"
+                    .to_string(),
+            )
+            .into());
+        }
+        let target = target_dir.join(safe_relative_path(relative)?);
+        if let Some(parent) = target.parent() {
+            std::fs::create_dir_all(parent)
+                .map_err(|error| io::IOError::with_path(error, parent))?;
+        }
+        let mut output = std::fs::File::create(&target)
+            .map_err(|error| io::IOError::with_path(error, &target))?;
+        copy_with_cancellation(&mut entry, &mut output, cancellation, &target)?;
+        files_written = files_written.saturating_add(1);
+    }
+    Ok(files_written)
+}
+
+pub(crate) fn check_cancellation(
+    cancellation: Option<&CancellationToken>,
+) -> crate::Result<()> {
+    if cancellation.is_some_and(CancellationToken::is_cancelled) {
+        return Err(crate::ErrorKind::OtherError(
+            "Install was canceled".to_string(),
+        )
+        .into());
+    }
+    Ok(())
+}
+
+pub(crate) fn copy_with_cancellation<R, W>(
+    reader: &mut R,
+    writer: &mut W,
+    cancellation: Option<&CancellationToken>,
+    target: &Path,
+) -> crate::Result<u64>
+where
+    R: std::io::Read,
+    W: std::io::Write,
+{
+    let mut buffer = [0_u8; 64 * 1024];
+    let mut written = 0_u64;
+    loop {
+        check_cancellation(cancellation)?;
+        let count = reader
+            .read(&mut buffer)
+            .map_err(|error| io::IOError::with_path(error, target))?;
+        if count == 0 {
+            return Ok(written);
+        }
+        check_cancellation(cancellation)?;
+        writer
+            .write_all(&buffer[..count])
+            .map_err(|error| io::IOError::with_path(error, target))?;
+        written = written.saturating_add(count as u64);
+    }
+}
+
+/// Extracts a single archive entry to the given target file path.
+pub(crate) async fn extract_archive_entry_to_file(
+    archive_path: PathBuf,
+    entry_name: String,
+    target: PathBuf,
+) -> crate::Result<()> {
+    tokio::task::spawn_blocking(move || {
+        let file = std::fs::File::open(&archive_path)
+            .map_err(|error| io::IOError::with_path(error, &archive_path))?;
+        let mut archive = zip::ZipArchive::new(file).map_err(archive_error)?;
+        let index = (0..archive.len())
+            .find(|&index| {
+                archive
+                    .by_index_raw(index)
+                    .map(|entry| {
+                        decode_zip_entry_name(entry.name_raw()) == entry_name
+                    })
+                    .unwrap_or(false)
+            })
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Modpack archive is missing {entry_name}"
+                ))
+            })?;
+        let mut entry = archive.by_index(index).map_err(archive_error)?;
+        if let Some(parent) = target.parent() {
+            std::fs::create_dir_all(parent)
+                .map_err(|error| io::IOError::with_path(error, parent))?;
+        }
+        let mut output = std::fs::File::create(&target)
+            .map_err(|error| io::IOError::with_path(error, &target))?;
+        std::io::copy(&mut entry, &mut output)
+            .map_err(|error| io::IOError::with_path(error, &target))?;
+        Ok(())
+    })
+    .await?
+}
+
+/// Reads a single archive entry into a string, tolerating GB18030-encoded
+/// file contents produced by Chinese packaging tools.
+pub(crate) async fn read_archive_entry_to_string(
+    archive_path: PathBuf,
+    entry_name: String,
+) -> crate::Result<String> {
+    tokio::task::spawn_blocking(move || {
+        let file = std::fs::File::open(&archive_path)
+            .map_err(|error| io::IOError::with_path(error, &archive_path))?;
+        let mut archive = zip::ZipArchive::new(file).map_err(archive_error)?;
+        let index = super::detect::find_entry_index(&mut archive, &entry_name)?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Modpack archive is missing {entry_name}"
+                ))
+            })?;
+        let mut entry = archive.by_index(index).map_err(archive_error)?;
+        let mut contents = Vec::new();
+        std::io::Read::read_to_end(&mut entry, &mut contents)?;
+        Ok(match String::from_utf8(contents) {
+            Ok(value) => value,
+            Err(error) => {
+                let (decoded, _, _) =
+                    encoding_rs::GB18030.decode(error.as_bytes());
+                decoded.into_owned()
+            }
+        })
+    })
+    .await?
+}
+
+/// Allocates a unique scratch directory for extracting nested pack content.
+pub(crate) async fn create_import_scratch_dir(
+    state: &crate::State,
+) -> crate::Result<PathBuf> {
+    let dir = state
+        .directories
+        .caches_dir()
+        .join("modpack-import")
+        .join(uuid::Uuid::new_v4().to_string());
+    io::create_dir_all(&dir).await?;
+    Ok(dir)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    struct CancelOnRead {
+        cancellation: CancellationToken,
+        read: bool,
+    }
+
+    impl std::io::Read for CancelOnRead {
+        fn read(&mut self, buffer: &mut [u8]) -> std::io::Result<usize> {
+            if self.read {
+                return Ok(0);
+            }
+            self.read = true;
+            self.cancellation.cancel();
+            let count = buffer.len().min(1024);
+            buffer[..count].fill(1);
+            Ok(count)
+        }
+    }
+
+    #[test]
+    fn blocking_copy_stops_before_writing_after_cancellation() {
+        let cancellation = CancellationToken::new();
+        let mut reader = CancelOnRead {
+            cancellation: cancellation.clone(),
+            read: false,
+        };
+        let mut output = Vec::new();
+        let error = copy_with_cancellation(
+            &mut reader,
+            &mut output,
+            Some(&cancellation),
+            Path::new("override.bin"),
+        )
+        .unwrap_err();
+
+        assert!(error.to_string().contains("Install was canceled"));
+        assert!(output.is_empty());
+    }
+}

packages/app-lib/src/api/pack/detect.rs

@@ -0,0 +1,464 @@
+//! Local modpack file format detection.
+//!
+//! Detects the modpack format of a local archive by inspecting its contents
+//! rather than its file extension, checking both the archive root and a single
+//! wrapping folder, mirroring the detection behavior of PCL.
+
+use std::io::Read;
+use std::path::Path;
+
+use tracing::debug;
+
+pub const MRPACK_MANIFEST: &str = "modrinth.index.json";
+pub const CURSEFORGE_MANIFEST: &str = "manifest.json";
+pub const MCBBS_MANIFEST: &str = "mcbbs.packmeta";
+pub const HMCL_MANIFEST: &str = "modpack.json";
+pub const MMC_MANIFEST: &str = "mmc-pack.json";
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LocalPackFormat {
+    Mrpack,
+    CurseForge,
+    Mcbbs,
+    Hmcl,
+    MmcExport,
+    LauncherBundled,
+    PlainArchive,
+    InstanceFolder,
+}
+
+impl LocalPackFormat {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Self::Mrpack => "Modrinth",
+            Self::CurseForge => "CurseForge",
+            Self::Mcbbs => "MCBBS",
+            Self::Hmcl => "HMCL",
+            Self::MmcExport => "MultiMC",
+            Self::LauncherBundled => "launcher bundle",
+            Self::PlainArchive => "game folder archive",
+            Self::InstanceFolder => "instance folder",
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct DetectedLocalPack {
+    pub format: LocalPackFormat,
+    /// Prefix of the folder containing the pack's key files, either empty or
+    /// a single path segment ending in `/`.
+    pub base_folder: String,
+    /// For [`LocalPackFormat::LauncherBundled`], the archive entry of the
+    /// nested modpack file.
+    pub inner_pack_entry: Option<String>,
+    /// For [`LocalPackFormat::PlainArchive`], the version id matched under
+    /// `versions/<id>/<id>.json`.
+    pub plain_version_id: Option<String>,
+}
+
+/// Decodes a zip entry name, tolerating archives produced by Chinese tools
+/// that store GB18030-encoded names without the UTF-8 flag.
+pub fn decode_zip_entry_name(raw: &[u8]) -> String {
+    match std::str::from_utf8(raw) {
+        Ok(name) => name.to_string(),
+        Err(_) => {
+            let (decoded, _, _) = encoding_rs::GB18030.decode(raw);
+            decoded.into_owned()
+        }
+    }
+}
+
+pub async fn detect_local_pack(
+    path: &Path,
+) -> crate::Result<DetectedLocalPack> {
+    let path = path.to_path_buf();
+    tokio::task::spawn_blocking(move || detect_local_pack_sync(&path)).await?
+}
+
+fn open_error(path: &Path, error: impl std::fmt::Display) -> crate::Error {
+    if path
+        .extension()
+        .is_some_and(|ext| ext.eq_ignore_ascii_case("rar"))
+    {
+        crate::ErrorKind::InputError(
+            "RAR modpack archives are not supported; please repackage the modpack as a zip file".to_string(),
+        )
+        .into()
+    } else {
+        crate::ErrorKind::InputError(format!(
+            "Failed to open modpack archive: {error}"
+        ))
+        .into()
+    }
+}
+
+pub fn detect_local_pack_sync(path: &Path) -> crate::Result<DetectedLocalPack> {
+    let file =
+        std::fs::File::open(path).map_err(|error| open_error(path, error))?;
+    let mut archive =
+        zip::ZipArchive::new(file).map_err(|error| open_error(path, error))?;
+
+    let total_entries = archive.len();
+    debug!(
+        "detect_local_pack_sync: path={} total_zip_entries={}",
+        path.display(),
+        total_entries
+    );
+
+    let mut names = Vec::with_capacity(archive.len());
+    for index in 0..archive.len() {
+        let entry = archive.by_index_raw(index).map_err(|error| {
+            crate::ErrorKind::InputError(format!(
+                "Failed to read modpack archive entry: {error}"
+            ))
+        })?;
+        if entry.encrypted() {
+            return Err(crate::ErrorKind::InputError(
+                "Encrypted modpack archives are not supported".to_string(),
+            )
+            .into());
+        }
+        let name = decode_zip_entry_name(entry.name_raw());
+        debug!(
+            "detect_local_pack_sync: scanning entry[{}] name={}",
+            index, name
+        );
+        names.push(name);
+    }
+
+    let bases = candidate_bases(&names);
+    debug!(
+        "detect_local_pack_sync: path={} candidate_bases={:?}",
+        path.display(),
+        bases
+    );
+
+    for base in &bases {
+        debug!(
+            "detect_local_pack_sync: path={} trying base={:?}",
+            path.display(),
+            base
+        );
+        if let Some(detected) = detect_at_base(&mut archive, &names, base)? {
+            debug!(
+                "detect_local_pack_sync: path={} base={:?} matched format={:?}",
+                path.display(),
+                base,
+                detected.format
+            );
+            return Ok(detected);
+        }
+        debug!(
+            "detect_local_pack_sync: path={} base={:?} no format matched",
+            path.display(),
+            base
+        );
+    }
+
+    debug!(
+        "detect_local_pack_sync: path={} trying detect_plain_archive",
+        path.display()
+    );
+    if let Some(detected) = detect_plain_archive(&names) {
+        debug!(
+            "detect_local_pack_sync: path={} matched PlainArchive version_id={:?}",
+            path.display(),
+            detected.plain_version_id
+        );
+        return Ok(detected);
+    }
+
+    debug!(
+        "detect_local_pack_sync: path={} trying detect_instance_folder",
+        path.display()
+    );
+    if let Some(detected) = detect_instance_folder(&names) {
+        debug!(
+            "detect_local_pack_sync: path={} matched InstanceFolder",
+            path.display()
+        );
+        return Ok(detected);
+    }
+
+    debug!(
+        "detect_local_pack_sync: path={} no format matched at all",
+        path.display()
+    );
+    Err(crate::ErrorKind::InputError(
+        "Unrecognized modpack format: no known pack manifest was found in the archive"
+            .to_string(),
+    )
+    .into())
+}
+
+/// The archive root, followed by each distinct single wrapping folder.
+fn candidate_bases(names: &[String]) -> Vec<String> {
+    let mut bases = vec![String::new()];
+    for name in names {
+        if let Some((first, rest)) = name.split_once('/')
+            && !rest.is_empty()
+            && !rest.contains('/')
+        {
+            let base = format!("{first}/");
+            if !bases.contains(&base) {
+                bases.push(base);
+            }
+        }
+    }
+    bases
+}
+
+pub(crate) fn detect_at_base<R: std::io::Read + std::io::Seek>(
+    archive: &mut zip::ZipArchive<R>,
+    names: &[String],
+    base: &str,
+) -> crate::Result<Option<DetectedLocalPack>> {
+    let has = |file: &str| -> bool {
+        let target = format!("{base}{file}");
+        let found = names.iter().any(|name| name == &target);
+        debug!(
+            "detect_at_base: base={:?} has({}) target={} result={}",
+            base, file, target, found
+        );
+        found
+    };
+    let detected = |format: LocalPackFormat| DetectedLocalPack {
+        format,
+        base_folder: base.to_string(),
+        inner_pack_entry: None,
+        plain_version_id: None,
+    };
+
+    // MCBBS and MultiMC packs may also contain a manifest.json, so both must
+    // be checked before the CurseForge manifest.
+    if has(MCBBS_MANIFEST) {
+        debug!(
+            "detect_at_base: matched MCBBS via mcbbs.packmeta at base={:?}",
+            base
+        );
+        return Ok(Some(detected(LocalPackFormat::Mcbbs)));
+    }
+    if has(MMC_MANIFEST) {
+        debug!(
+            "detect_at_base: matched MmcExport via mmc-pack.json at base={:?}",
+            base
+        );
+        return Ok(Some(detected(LocalPackFormat::MmcExport)));
+    }
+    if has(MRPACK_MANIFEST) {
+        debug!(
+            "detect_at_base: matched Mrpack via modrinth.index.json at base={:?}",
+            base
+        );
+        return Ok(Some(detected(LocalPackFormat::Mrpack)));
+    }
+    if has(CURSEFORGE_MANIFEST) {
+        // A manifest.json with an `addons` array is the MCBBS variant. An
+        // unreadable manifest.json (e.g. an unrelated mod config inside a
+        // zipped game folder) does not abort detection of other formats.
+        match read_entry_json(archive, &format!("{base}{CURSEFORGE_MANIFEST}"))
+        {
+            Ok(manifest) => {
+                let has_addons = manifest
+                    .get("addons")
+                    .is_some_and(|value| !value.is_null());
+                debug!(
+                    "detect_at_base: matched CurseForge/MCBBS via manifest.json at base={:?} addons={}",
+                    base, has_addons
+                );
+                return Ok(Some(detected(if has_addons {
+                    LocalPackFormat::Mcbbs
+                } else {
+                    LocalPackFormat::CurseForge
+                })));
+            }
+            Err(error) => {
+                tracing::warn!(
+                    "Ignoring unparsable manifest.json at {base:?} during modpack detection: {error}"
+                );
+            }
+        }
+    }
+    if has(HMCL_MANIFEST) {
+        debug!(
+            "detect_at_base: matched Hmcl via modpack.json at base={:?}",
+            base
+        );
+        return Ok(Some(detected(LocalPackFormat::Hmcl)));
+    }
+    for inner in ["modpack.zip", "modpack.mrpack"] {
+        if has(inner) {
+            debug!(
+                "detect_at_base: matched LauncherBundled via {} at base={:?}",
+                inner, base
+            );
+            return Ok(Some(DetectedLocalPack {
+                format: LocalPackFormat::LauncherBundled,
+                base_folder: base.to_string(),
+                inner_pack_entry: Some(format!("{base}{inner}")),
+                plain_version_id: None,
+            }));
+        }
+    }
+
+    debug!("detect_at_base: no format matched at base={:?}", base);
+    Ok(None)
+}
+
+/// Finds an entry index by its decoded name, so lookups stay consistent with
+/// [`decode_zip_entry_name`] even for archives with GB18030-encoded names.
+pub(crate) fn find_entry_index<R: std::io::Read + std::io::Seek>(
+    archive: &mut zip::ZipArchive<R>,
+    entry_name: &str,
+) -> crate::Result<Option<usize>> {
+    for index in 0..archive.len() {
+        let entry = archive.by_index_raw(index).map_err(|error| {
+            crate::ErrorKind::InputError(format!(
+                "Failed to read modpack archive entry: {error}"
+            ))
+        })?;
+        if decode_zip_entry_name(entry.name_raw()).replace('\\', "/")
+            == entry_name
+        {
+            return Ok(Some(index));
+        }
+    }
+    Ok(None)
+}
+
+fn read_entry_json<R: std::io::Read + std::io::Seek>(
+    archive: &mut zip::ZipArchive<R>,
+    entry_name: &str,
+) -> crate::Result<serde_json::Value> {
+    let index = find_entry_index(archive, entry_name)?.ok_or_else(|| {
+        crate::ErrorKind::InputError(format!(
+            "Modpack archive is missing {entry_name}"
+        ))
+    })?;
+    let mut entry = archive.by_index(index).map_err(|error| {
+        crate::ErrorKind::InputError(format!(
+            "Failed to read {entry_name} from modpack archive: {error}"
+        ))
+    })?;
+    let mut contents = Vec::new();
+    entry.read_to_end(&mut contents)?;
+    // Windows tools often prepend a UTF-8 BOM; serde_json rejects it.
+    let contents = contents
+        .strip_prefix(&[0xEF, 0xBB, 0xBF])
+        .unwrap_or(&contents);
+    Ok(serde_json::from_slice(contents)?)
+}
+
+/// Looks for a `versions/<id>/<id>.json` structure marking a zipped-up game
+/// folder, returning the prefix of the folder containing `versions`.
+fn detect_plain_archive(names: &[String]) -> Option<DetectedLocalPack> {
+    for name in names {
+        let segments: Vec<&str> = name.split('/').collect();
+        if segments.len() < 3 {
+            continue;
+        }
+        let json = segments[segments.len() - 1];
+        let version = segments[segments.len() - 2];
+        let marker = segments[segments.len() - 3];
+        let is_match = marker == "versions"
+            && !version.is_empty()
+            && json
+                .strip_suffix(".json")
+                .is_some_and(|stem| stem == version);
+        debug!(
+            "detect_plain_archive: checking entry={} marker={} version={} json={} is_match={}",
+            name, marker, version, json, is_match
+        );
+        if is_match {
+            let base = segments[..segments.len() - 3].join("/");
+            let base = if base.is_empty() {
+                base
+            } else {
+                format!("{base}/")
+            };
+            debug!(
+                "detect_plain_archive: matched version={} base={:?}",
+                version, base
+            );
+            return Some(DetectedLocalPack {
+                format: LocalPackFormat::PlainArchive,
+                base_folder: base,
+                inner_pack_entry: None,
+                plain_version_id: Some(version.to_string()),
+            });
+        }
+    }
+    debug!("detect_plain_archive: no versions pattern matched");
+    None
+}
+
+/// Looks for a `mods` folder containing `.jar` files, marking a simple instance folder.
+fn detect_instance_folder(names: &[String]) -> Option<DetectedLocalPack> {
+    // First, collect all paths that contain a "mods" segment
+    let mut mods_folders = std::collections::HashSet::new();
+
+    for name in names {
+        let segments: Vec<&str> = name.split('/').collect();
+        for i in 0..segments.len() {
+            if segments[i] == "mods" {
+                let base = segments[..i].join("/");
+                let base = if base.is_empty() {
+                    base
+                } else {
+                    format!("{base}/")
+                };
+                debug!(
+                    "detect_instance_folder: found mods folder at entry={} base={:?}",
+                    name, base
+                );
+                mods_folders.insert(base);
+            }
+        }
+    }
+
+    debug!(
+        "detect_instance_folder: found {} unique mods folder(s)",
+        mods_folders.len()
+    );
+
+    if mods_folders.is_empty() {
+        debug!("detect_instance_folder: no mods folder found");
+        return None;
+    }
+
+    // Now check each mods folder to see if there's at least one .jar file in it
+    for base in &mods_folders {
+        let mut jar_files: Vec<String> = Vec::new();
+        for name in names {
+            let name_without_base =
+                name.strip_prefix(base.as_str()).unwrap_or(name);
+            let segments: Vec<&str> = name_without_base.split('/').collect();
+            if segments.len() == 2
+                && segments[0] == "mods"
+                && segments[1].to_lowercase().ends_with(".jar")
+            {
+                jar_files.push(name.clone());
+            }
+        }
+        let has_jar = !jar_files.is_empty();
+        debug!(
+            "detect_instance_folder: base={:?} has_jar={} jar_files={:?}",
+            base, has_jar, jar_files
+        );
+        if has_jar {
+            debug!(
+                "detect_instance_folder: matched InstanceFolder at base={:?}",
+                base
+            );
+            return Some(DetectedLocalPack {
+                format: LocalPackFormat::InstanceFolder,
+                base_folder: base.clone(),
+                inner_pack_entry: None,
+                plain_version_id: None,
+            });
+        }
+    }
+
+    debug!("detect_instance_folder: no mods folder with .jar files found");
+    None
+}

packages/app-lib/src/api/pack/import/atlauncher.rs

@@ -0,0 +1,277 @@
+use std::{collections::HashMap, path::PathBuf};
+
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    State,
+    install::{InstallPhaseDetails, InstallProgressReporter},
+    pack::{
+        self,
+        import::{self, finish_import},
+        install_from::CreatePackDescription,
+    },
+    prelude::ModLoader,
+    state::{
+        AppliedContentSetPatch, EditInstance, InstanceInstallStage,
+        InstanceLink,
+    },
+    util::io,
+};
+
+#[derive(Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ATInstance {
+    pub id: String, // minecraft version id ie: 1.12.1, not a name
+    pub launcher: ATLauncher,
+    pub java_version: ATJavaVersion,
+}
+#[derive(Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ATLauncher {
+    pub name: String,
+    pub pack: String,
+    pub version: String, // ie: 1.6
+    pub loader_version: ATLauncherLoaderVersion,
+
+    pub modrinth_project: Option<ATLauncherModrinthProject>,
+    pub modrinth_version: Option<ATLauncherModrinthVersion>,
+    pub modrinth_manifest: Option<pack::install_from::PackFormat>,
+}
+
+#[derive(Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ATJavaVersion {
+    pub major_version: u8,
+    pub component: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct ATLauncherLoaderVersion {
+    pub r#type: String,
+    pub version: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ATLauncherModrinthProject {
+    pub id: String,
+    pub slug: String,
+    pub project_type: String,
+    pub team: String,
+    pub client_side: Option<String>,
+    pub server_side: Option<String>,
+    pub categories: Vec<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+pub struct ATLauncherModrinthVersion {
+    pub id: String,
+    pub project_id: String,
+    pub name: String,
+    pub version_number: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct ATLauncherModrinthVersionFile {
+    pub hashes: HashMap<String, String>,
+    pub url: String,
+    pub filename: String,
+    pub primary: bool,
+    pub size: u64,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct ATLauncherModrinthVersionDependency {
+    pub project_id: Option<String>,
+    pub version_id: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct ATLauncherMod {
+    pub name: String,
+    pub version: String,
+    pub file: String,
+
+    pub modrinth_project: Option<ATLauncherModrinthProject>,
+    pub modrinth_version: Option<ATLauncherModrinthVersion>,
+}
+
+// Check if folder has a instance.json that parses
+pub async fn is_valid_atlauncher(instance_folder: PathBuf) -> bool {
+    let instance = serde_json::from_str::<ATInstance>(
+        &io::read_any_encoding_to_string(
+            &instance_folder.join("instance.json"),
+        )
+        .await
+        .unwrap_or(("".into(), encoding_rs::UTF_8))
+        .0,
+    );
+
+    if let Err(e) = instance {
+        tracing::warn!(
+            "Could not parse instance.json at {}: {}",
+            instance_folder.display(),
+            e
+        );
+        false
+    } else {
+        true
+    }
+}
+
+#[tracing::instrument]
+
+pub async fn import_atlauncher_dir(
+    atlauncher_base_path: PathBuf,
+    atlauncher_instance_path: PathBuf,
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    let atinstance = serde_json::from_str::<ATInstance>(
+        &io::read_any_encoding_to_string(
+            &atlauncher_instance_path.join("instance.json"),
+        )
+        .await
+        .unwrap_or(("".into(), encoding_rs::UTF_8))
+        .0,
+    )?;
+
+    let icon_path_primary = atlauncher_instance_path.join("instance.png");
+    let safe_pack_name = atinstance
+        .launcher
+        .pack
+        .replace(|c: char| !c.is_alphanumeric(), "")
+        .to_lowercase();
+    let icon_path_secondary = atlauncher_base_path
+        .join("configs")
+        .join("images")
+        .join(safe_pack_name + ".png");
+    let icon = match (icon_path_primary.exists(), icon_path_secondary.exists())
+    {
+        (true, _) => import::recache_icon(icon_path_primary).await?,
+        (_, true) => import::recache_icon(icon_path_secondary).await?,
+        _ => None,
+    };
+
+    let description = CreatePackDescription {
+        icon,
+        override_title: Some(atinstance.launcher.name.clone()),
+        project_id: None,
+        version_id: None,
+        instance_id: instance_id.to_string(),
+        source_filename: None,
+    };
+
+    let backup_name = format!(
+        "ATLauncher-{}",
+        atlauncher_instance_path
+            .file_name()
+            .map(|name| name.to_string_lossy())
+            .unwrap_or_default()
+    );
+    let minecraft_folder = atlauncher_instance_path;
+
+    import_atlauncher_unmanaged(
+        instance_id,
+        minecraft_folder,
+        backup_name,
+        description,
+        atinstance,
+        reporter,
+        details,
+        symlink,
+    )
+    .await?;
+    Ok(())
+}
+
+async fn import_atlauncher_unmanaged(
+    instance_id: &str,
+    minecraft_folder: PathBuf,
+    backup_name: String,
+    description: CreatePackDescription,
+    atinstance: ATInstance,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    let mod_loader = format!(
+        "\"{}\"",
+        atinstance.launcher.loader_version.r#type.to_lowercase()
+    );
+    let mod_loader: ModLoader = serde_json::from_str::<ModLoader>(&mod_loader)
+        .map_err(|_| {
+            crate::ErrorKind::InputError(format!(
+                "Could not parse mod loader type: {mod_loader}"
+            ))
+        })?;
+
+    let game_version = atinstance.id;
+
+    let loader_version = if mod_loader != ModLoader::Vanilla {
+        crate::launcher::get_loader_version_from_profile(
+            &game_version,
+            mod_loader,
+            Some(&atinstance.launcher.loader_version.version),
+        )
+        .await?
+    } else {
+        None
+    };
+
+    let link = match (&description.project_id, &description.version_id) {
+        (Some(project_id), Some(version_id)) => {
+            Some(InstanceLink::ModrinthModpack {
+                project_id: project_id.clone(),
+                version_id: version_id.clone(),
+            })
+        }
+        _ => None,
+    };
+    crate::api::instance::edit(
+        instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(
+                description
+                    .override_title
+                    .clone()
+                    .unwrap_or_else(|| backup_name.to_string()),
+            ),
+            icon_path: Some(
+                description
+                    .icon
+                    .clone()
+                    .map(|x| x.to_string_lossy().to_string()),
+            ),
+            link,
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind: None,
+                game_version: Some(game_version.clone()),
+                protocol_version: Some(None),
+                loader: Some(mod_loader),
+                loader_version: Some(loader_version.clone().map(|x| x.id)),
+            }),
+            ..EditInstance::default()
+        },
+    )
+    .await?;
+
+    // Moves .minecraft folder over (ie: overrides such as resourcepacks, mods, etc)
+    let state = State::get().await?;
+    finish_import(
+        instance_id,
+        minecraft_folder,
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await?;
+    Ok(())
+}

packages/app-lib/src/api/pack/import/axolotl.rs

@@ -0,0 +1,178 @@
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+use crate::{
+    State,
+    install::{InstallPhaseDetails, InstallProgressReporter},
+    state::{
+        AppliedContentSetPatch, ContentSourceKind, EditInstance,
+        InstanceInstallStage, InstanceLaunchOverridesPatch, ModLoader,
+        ReleaseChannel, instances::InstanceLaunchOverridesData,
+    },
+    util::io,
+};
+
+use super::{ImportOverrides, finish_import, generic, recache_icon};
+
+const CONFIG_FILE_NAME: &str = "axolotl_config.json";
+const CONFIG_SCHEMA_VERSION: u32 = 1;
+
+#[derive(Deserialize, Clone, Debug)]
+#[serde(rename_all = "snake_case")]
+pub struct AxolotlConfigFile {
+    pub schema_version: u32,
+    pub instance_id: String,
+    pub path: String,
+    pub generated_at: chrono::DateTime<chrono::Utc>,
+    pub name: String,
+    pub icon_path: Option<String>,
+    pub update_channel: String,
+    pub symlink_target: Option<String>,
+    pub groups: Vec<String>,
+    pub content_set: AxolotlContentSet,
+    pub link: crate::state::instances::InstanceLink,
+    pub launch_overrides: InstanceLaunchOverridesData,
+}
+
+#[derive(Deserialize, Clone, Debug)]
+#[serde(rename_all = "snake_case")]
+pub struct AxolotlContentSet {
+    pub source_kind: String,
+    pub game_version: String,
+    pub protocol_version: Option<u32>,
+    pub loader: String,
+    pub loader_version: Option<String>,
+}
+
+/// Imports an Axolotl instance by reading `axolotl_config.json` and applying
+/// the migratable fields to the new profile. Invalid or unsupported configs
+/// fall back to the generic instance import so the game files still arrive.
+pub(crate) async fn import_axolotl(
+    source_path: PathBuf,
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+    overrides: &ImportOverrides,
+) -> crate::Result<()> {
+    let config_path = source_path.join(CONFIG_FILE_NAME);
+    let content = io::read_any_encoding_to_string(&config_path)
+        .await
+        .unwrap_or_else(|error| {
+            tracing::warn!(
+                "Axolotl import: could not read {}: {error}; falling back to generic import",
+                config_path.display()
+            );
+            (String::new(), encoding_rs::UTF_8)
+        })
+        .0;
+
+    let config = match serde_json::from_str::<AxolotlConfigFile>(&content) {
+        Ok(config) => config,
+        Err(error) => {
+            tracing::warn!(
+                "Axolotl import: invalid config {}: {error}; falling back to generic import",
+                config_path.display()
+            );
+            return generic::import_generic(
+                source_path,
+                instance_id,
+                reporter,
+                details,
+                symlink,
+                overrides,
+                None,
+            )
+            .await;
+        }
+    };
+    tracing::debug!(
+        "Axolotl import: config instance_id={} path={} generated_at={} symlink_target={:?}",
+        config.instance_id,
+        config.path,
+        config.generated_at,
+        config.symlink_target
+    );
+
+    if config.schema_version != CONFIG_SCHEMA_VERSION
+        || config.content_set.game_version.trim().is_empty()
+    {
+        tracing::warn!(
+            "Axolotl import: unsupported schema or missing game version for {}; falling back to generic import",
+            config_path.display()
+        );
+        return generic::import_generic(
+            source_path,
+            instance_id,
+            reporter,
+            details,
+            symlink,
+            overrides,
+            None,
+        )
+        .await;
+    }
+
+    let icon = match config.icon_path.as_ref() {
+        Some(path) => recache_icon(source_path.join(path)).await?,
+        None => None,
+    };
+    let source_kind =
+        ContentSourceKind::from_str(&config.content_set.source_kind)
+            .unwrap_or(ContentSourceKind::Local);
+    let loader = ModLoader::try_from_string(&config.content_set.loader)?;
+    let update_channel = ReleaseChannel::from_key(&config.update_channel);
+
+    let state = State::get().await?;
+    crate::state::edit_instance(
+        instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(config.name.clone()),
+            icon_path: Some(icon.map(|p| p.to_string_lossy().to_string())),
+            update_channel: Some(update_channel),
+            groups: Some(config.groups.clone()),
+            link: Some(config.link.clone()),
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind: Some(source_kind),
+                game_version: Some(config.content_set.game_version.clone()),
+                protocol_version: Some(config.content_set.protocol_version),
+                loader: Some(loader),
+                loader_version: Some(config.content_set.loader_version.clone()),
+            }),
+            launch_overrides: Some(InstanceLaunchOverridesPatch {
+                java_path: Some(config.launch_overrides.java_path.clone()),
+                extra_launch_args: Some(
+                    config.launch_overrides.extra_launch_args.clone(),
+                ),
+                custom_env_vars: Some(
+                    config.launch_overrides.custom_env_vars.clone(),
+                ),
+                memory: Some(config.launch_overrides.memory),
+                force_fullscreen: Some(
+                    config.launch_overrides.force_fullscreen,
+                ),
+                maximize_window: Some(config.launch_overrides.maximize_window),
+                game_resolution: Some(config.launch_overrides.game_resolution),
+                launch_preparation_timeout: Some(
+                    config.launch_overrides.launch_preparation_timeout,
+                ),
+                hooks: Some(config.launch_overrides.hooks.clone()),
+            }),
+            ..EditInstance::default()
+        },
+        &state.pool,
+    )
+    .await?;
+
+    finish_import(
+        instance_id,
+        source_path,
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await
+}

packages/app-lib/src/api/pack/import/curseforge.rs

@@ -0,0 +1,275 @@
+use std::path::PathBuf;
+
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    State,
+    install::{InstallPhaseDetails, InstallProgressReporter},
+    prelude::ModLoader,
+    state::{AppliedContentSetPatch, EditInstance, InstanceInstallStage},
+    util::{
+        fetch::{fetch, write_cached_icon},
+        io,
+    },
+};
+
+use super::{finish_import, instance_json, recache_icon};
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct MinecraftInstance {
+    pub name: Option<String>,
+    pub base_mod_loader: Option<MinecraftInstanceModLoader>,
+    pub profile_image_path: Option<PathBuf>,
+    pub installed_modpack: Option<InstalledModpack>,
+    pub game_version: String, // Minecraft game version. Non-prioritized, use this if Vanilla
+}
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct MinecraftInstanceModLoader {
+    pub name: String,
+}
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InstalledModpack {
+    pub thumbnail_url: Option<String>,
+}
+
+fn parse_curseforge_loader(
+    loader_name: &str,
+    game_version: &str,
+) -> Option<(ModLoader, String)> {
+    let loader_name = loader_name.trim();
+    if loader_name.eq_ignore_ascii_case("labymod")
+        || loader_name.to_ascii_lowercase().starts_with("labymod-")
+    {
+        return None;
+    }
+    let family = crate::api::curseforge::loader_family(loader_name);
+    let loader = match family {
+        "forge" => ModLoader::Forge,
+        "fabric" => ModLoader::Fabric,
+        "quilt" => ModLoader::Quilt,
+        "neo" | "neoforge" => ModLoader::NeoForge,
+        _ => return None,
+    };
+    let detected_version =
+        loader_name.strip_prefix(family)?.strip_prefix('-')?.trim();
+    if detected_version.is_empty() {
+        return None;
+    }
+    let version = instance_json::normalize_imported_loader_version(
+        loader.as_str(),
+        game_version,
+        detected_version,
+    );
+    (!version.is_empty()).then_some((loader, version))
+}
+
+// Check if folder has a minecraftinstance.json that parses
+pub async fn is_valid_curseforge(instance_folder: PathBuf) -> bool {
+    let minecraft_instance = serde_json::from_str::<MinecraftInstance>(
+        &io::read_any_encoding_to_string(
+            &instance_folder.join("minecraftinstance.json"),
+        )
+        .await
+        .unwrap_or(("".into(), encoding_rs::UTF_8))
+        .0,
+    );
+    minecraft_instance.is_ok()
+}
+
+pub async fn import_curseforge(
+    curseforge_instance_folder: PathBuf, // instance's folder
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    // Load minecraftinstance.json
+    let minecraft_instance = serde_json::from_str::<MinecraftInstance>(
+        &io::read_any_encoding_to_string(
+            &curseforge_instance_folder.join("minecraftinstance.json"),
+        )
+        .await
+        .unwrap_or(("".into(), encoding_rs::UTF_8))
+        .0,
+    )?;
+    let override_title = minecraft_instance.name;
+    let backup_name = format!(
+        "Curseforge-{}",
+        curseforge_instance_folder
+            .file_name()
+            .map_or("Unknown".to_string(), |a| a.to_string_lossy().to_string())
+    );
+
+    let state = State::get().await?;
+    // Recache Curseforge Icon if it exists
+    let mut icon = None;
+
+    if let Some(icon_path) = minecraft_instance.profile_image_path.clone() {
+        icon = recache_icon(icon_path).await?;
+    } else if let Some(InstalledModpack {
+        thumbnail_url: Some(thumbnail_url),
+    }) = minecraft_instance.installed_modpack.clone()
+    {
+        let icon_bytes = fetch(
+            &thumbnail_url,
+            None,
+            None,
+            None,
+            &state.fetch_semaphore,
+            &state.pool,
+        )
+        .await?;
+        let filename = thumbnail_url.rsplit('/').next_back();
+        if let Some(filename) = filename {
+            icon = Some(
+                write_cached_icon(
+                    filename,
+                    &state.directories.caches_dir(),
+                    icon_bytes,
+                    &state.io_semaphore,
+                )
+                .await?,
+            );
+        }
+    }
+
+    // base mod loader is always None for vanilla
+    if let Some(instance_mod_loader) = minecraft_instance.base_mod_loader {
+        let game_version = minecraft_instance.game_version;
+
+        let parsed_loader =
+            parse_curseforge_loader(&instance_mod_loader.name, &game_version);
+        let (mod_loader, requested_loader_version) = parsed_loader.ok_or_else(|| {
+			let loader_name = instance_mod_loader.name.trim();
+			let message = if loader_name.eq_ignore_ascii_case("labymod")
+				|| loader_name.to_ascii_lowercase().starts_with("labymod-")
+			{
+				"Unsupported loader LabyMod: Axolotl does not install, update, or repair LabyMod instances".to_string()
+			} else {
+				format!(
+					"Unsupported loader {loader_name}: the instance was not imported as Vanilla"
+				)
+			};
+			crate::ErrorKind::InputError(message)
+		})?;
+
+        let loader_version = crate::launcher::get_loader_version_from_profile(
+            &game_version,
+            mod_loader,
+            Some(&requested_loader_version),
+        )
+        .await?;
+        if loader_version.is_none() {
+            return Err(crate::ErrorKind::InputError(format!(
+				"CurseForge instance loader version {requested_loader_version} is not available for {} {game_version}",
+				mod_loader.as_str(),
+			))
+			.into());
+        }
+
+        crate::api::instance::edit(
+            instance_id,
+            EditInstance {
+                install_stage: Some(InstanceInstallStage::PackInstalling),
+                name: Some(
+                    override_title
+                        .clone()
+                        .unwrap_or_else(|| backup_name.to_string()),
+                ),
+                icon_path: Some(
+                    icon.clone().map(|x| x.to_string_lossy().to_string()),
+                ),
+                content_set_patch: Some(AppliedContentSetPatch {
+                    source_kind: None,
+                    game_version: Some(game_version.clone()),
+                    protocol_version: Some(None),
+                    loader: Some(mod_loader),
+                    loader_version: Some(loader_version.clone().map(|x| x.id)),
+                }),
+                ..EditInstance::default()
+            },
+        )
+        .await?;
+    } else {
+        crate::api::instance::edit(
+            instance_id,
+            EditInstance {
+                name: Some(
+                    override_title
+                        .clone()
+                        .unwrap_or_else(|| backup_name.to_string()),
+                ),
+                icon_path: Some(
+                    icon.clone().map(|x| x.to_string_lossy().to_string()),
+                ),
+                content_set_patch: Some(AppliedContentSetPatch {
+                    source_kind: None,
+                    game_version: Some(minecraft_instance.game_version.clone()),
+                    protocol_version: Some(None),
+                    loader: Some(ModLoader::Vanilla),
+                    loader_version: Some(None),
+                }),
+                ..EditInstance::default()
+            },
+        )
+        .await?;
+    }
+
+    // Copy in contained folders as overrides
+    let state = State::get().await?;
+    finish_import(
+        instance_id,
+        curseforge_instance_folder,
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await?;
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_supported_curseforge_instance_loaders() {
+        for (name, game_version, loader, version) in [
+            ("forge-47.4.22", "1.20.1", ModLoader::Forge, "47.4.22"),
+            (
+                "fabric-0.16.10-1.21.1",
+                "1.21.1",
+                ModLoader::Fabric,
+                "0.16.10",
+            ),
+            ("quilt-0.26.4-1.20.1", "1.20.1", ModLoader::Quilt, "0.26.4"),
+            (
+                "neoforge-21.4.157",
+                "1.21.4",
+                ModLoader::NeoForge,
+                "21.4.157",
+            ),
+        ] {
+            assert_eq!(
+                parse_curseforge_loader(name, game_version),
+                Some((loader, version.to_string())),
+                "{name}"
+            );
+        }
+    }
+
+    #[test]
+    fn rejects_unknown_curseforge_instance_loader() {
+        assert_eq!(parse_curseforge_loader("unknown-1.0", "1.20.1"), None);
+    }
+
+    #[test]
+    fn rejects_labymod_curseforge_instance_loader() {
+        assert_eq!(parse_curseforge_loader("labymod-4.4.20", "1.20.1"), None);
+    }
+}

packages/app-lib/src/api/pack/import/direct_link.rs

@@ -0,0 +1,948 @@
+use std::path::{Path, PathBuf};
+
+use serde_json::Value;
+
+use super::{ImportLauncherType, generic, hmcl, instance_json, pcl};
+use crate::state::ModLoader;
+
+const TEMP_IMPORT_DIR: &str = "axolotl-launcher-import";
+
+#[derive(Clone, Debug)]
+pub(crate) struct ResolvedDirectLink {
+    pub launcher: ImportLauncherType,
+    pub launcher_root: PathBuf,
+    pub dot_minecraft: PathBuf,
+    /// Resolved `versions/<id>` directory of the linked installation; carried
+    /// as part of the resolution contract even though current consumers
+    /// derive their paths from `dot_minecraft`/`version_json` directly.
+    #[allow(dead_code)]
+    pub version_dir: PathBuf,
+    pub version_json: PathBuf,
+    pub version_id: String,
+    pub game_version: String,
+    pub loader: ModLoader,
+    /// Detected loader version of the linked document. Directly associated
+    /// instances display no loader version (the loader is managed by the
+    /// external launcher), so this is not persisted anywhere yet.
+    #[allow(dead_code)]
+    pub loader_version: Option<String>,
+}
+
+/// The launcher's dialect and root used to resolve a traditional
+/// `.minecraft/versions/<id>` directory. The root is intentionally separate
+/// from the game directory: PCL stores its settings beside the executable,
+/// while its `.minecraft` may be a sibling directory.
+#[derive(Clone, Debug)]
+pub(crate) struct DirectLinkSource {
+    pub launcher: ImportLauncherType,
+    pub launcher_root: PathBuf,
+}
+
+/// Identifies the launcher that owns an externally selected version folder.
+///
+/// Direct-link Settings receives `.minecraft` roots rather than launcher
+/// executables, so the normal import scanner cannot infer PCL from its
+/// executable alone. Probe the selected root and its parent, where portable
+/// PCL/PCL-CE installations keep their executable and `PCL` configuration.
+/// HMCL is only selected when its configuration actually references the
+/// supplied game directory; an unrelated `.hmcl` folder must not relabel a
+/// generic Minecraft installation.
+pub(crate) fn detect_direct_link_source(
+    dot_minecraft: &Path,
+    version_dir: &Path,
+) -> DirectLinkSource {
+    for launcher_root in [
+        dot_minecraft.parent().map(Path::to_path_buf),
+        Some(dot_minecraft.to_path_buf()),
+    ]
+    .into_iter()
+    .flatten()
+    {
+        if super::pe_info::folder_has_product(
+            &launcher_root,
+            "Plain Craft Launcher",
+        ) {
+            let launcher =
+                if launcher_root.join("PCL").join("config.v1.yml").is_file() {
+                    ImportLauncherType::PCL2CE
+                } else {
+                    ImportLauncherType::PCL2
+                };
+            return DirectLinkSource {
+                launcher,
+                launcher_root,
+            };
+        }
+
+        if super::hmcl::config_exists(&launcher_root)
+            && super::hmcl::configured_game_dir(
+                &launcher_root,
+                dot_minecraft,
+                version_dir,
+            )
+            .is_some()
+        {
+            return DirectLinkSource {
+                launcher: ImportLauncherType::HMCL,
+                launcher_root,
+            };
+        }
+    }
+
+    DirectLinkSource {
+        launcher: ImportLauncherType::Generic,
+        launcher_root: dot_minecraft.to_path_buf(),
+    }
+}
+
+/// Returns the stable user-facing group for a directly linked `.minecraft`
+/// root. The complete normalized path is used as the group name so two roots
+/// with the same display folder name remain distinct.
+pub(crate) fn direct_link_group(dot_minecraft: &Path) -> Option<String> {
+    let path = dot_minecraft.to_string_lossy().trim().to_string();
+    (!path.is_empty()).then_some(path)
+}
+
+impl ResolvedDirectLink {
+    pub(crate) fn launcher_key(&self) -> &'static str {
+        launcher_key(self.launcher)
+            .expect("resolved direct links always use a supported launcher")
+    }
+}
+
+/// Resolves the same launcher identity used by the existing import flow into
+/// persistent paths for a read-only direct association.
+///
+/// The conventional repository layout follows HMCL
+/// `DefaultGameRepositoryLayout.getInstanceRoot/getInstanceJson` at commit
+/// `083dbb18ade1c935e2e56d0bdefcd718be1e2ed6`: shared root plus
+/// `versions/<id>/<id>.json`. PCL's fallback follows
+/// `ModMinecraft.McInstance.GetJsonPath` at commit
+/// `639de1b48a44326cbd5465579295cecf23d9056a`: prefer the same-name JSON,
+/// otherwise inspect JSON files in the version directory. PCL-CE keeps the
+/// same version-folder model in `Modules/Minecraft/McInstance.cs` at commit
+/// `aa3b81c6afb3cd1896dda271578b002066512177`.
+pub(crate) async fn resolve_direct_link(
+    launcher_type: ImportLauncherType,
+    base_path: PathBuf,
+    instance_folder: String,
+    instance_path: Option<String>,
+) -> crate::Result<ResolvedDirectLink> {
+    if launcher_key(launcher_type).is_none()
+        && launcher_type != ImportLauncherType::Unknown
+    {
+        return Err(unsupported_launcher(launcher_type));
+    }
+
+    reject_temporary_import_path(&base_path)?;
+    if let Some(instance_path) = instance_path.as_deref() {
+        reject_temporary_import_path(Path::new(instance_path))?;
+    }
+
+    if launcher_type == ImportLauncherType::Unknown {
+        return resolve_unknown(
+            base_path,
+            instance_folder,
+            instance_path.as_deref(),
+        )
+        .await;
+    }
+
+    resolve_known(
+        launcher_type,
+        base_path,
+        &instance_folder,
+        instance_path.as_deref(),
+    )
+}
+
+async fn resolve_unknown(
+    base_path: PathBuf,
+    instance_folder: String,
+    instance_path: Option<&str>,
+) -> crate::Result<ResolvedDirectLink> {
+    // Match the selected scan result before assigning a dialect. Merely having
+    // HMCL/PCL configuration beside a Generic version must not relabel that
+    // version and route it through the wrong launch merger.
+    if let Ok(instances) = Box::pin(super::get_importable_instances(
+        ImportLauncherType::HMCL,
+        base_path.clone(),
+    ))
+    .await
+        && selection_matches(&instances, &instance_folder, instance_path)
+        && let Ok(resolved) = resolve_known(
+            ImportLauncherType::HMCL,
+            base_path.clone(),
+            &instance_folder,
+            instance_path,
+        )
+    {
+        return Ok(resolved);
+    }
+
+    // The existing PCL scanner intentionally merges legacy PCL and PCL-CE
+    // config sources. Recover the source dialect after matching the selected
+    // scan item so PCL-CE is not always mislabeled as the first PCL variant.
+    if let Ok(instances) = Box::pin(super::get_importable_instances(
+        ImportLauncherType::PCL2,
+        base_path.clone(),
+    ))
+    .await
+        && selection_matches(&instances, &instance_folder, instance_path)
+    {
+        let launcher_type = pcl_dialect(&instance_folder, instance_path);
+        if let Ok(resolved) = resolve_known(
+            launcher_type,
+            base_path.clone(),
+            &instance_folder,
+            instance_path,
+        ) {
+            return Ok(resolved);
+        }
+    }
+
+    resolve_known(
+        ImportLauncherType::Generic,
+        base_path,
+        &instance_folder,
+        instance_path,
+    )
+    .map_err(|_| {
+        crate::ErrorKind::InputError(
+            "Could not resolve a traditional .minecraft instance as HMCL, PCL2, PCL2CE, or Generic"
+                .to_string(),
+        )
+        .into()
+    })
+}
+
+fn selection_matches(
+    instances: &[super::ImportableInstance],
+    instance_folder: &str,
+    instance_path: Option<&str>,
+) -> bool {
+    instances.iter().any(|candidate| {
+        if let Some(selected) = instance_path {
+            paths_match(Path::new(selected), Path::new(&candidate.path))
+                || candidate.version_path.as_deref().is_some_and(
+                    |version_path| {
+                        paths_match(
+                            Path::new(selected),
+                            Path::new(version_path),
+                        )
+                    },
+                )
+        } else {
+            candidate.name == instance_folder
+        }
+    })
+}
+
+fn pcl_dialect(
+    instance_folder: &str,
+    instance_path: Option<&str>,
+) -> ImportLauncherType {
+    let pcl_sources = pcl::get_pcl_instances();
+    let pcl_ce_sources = pcl::get_pclce_instances();
+    pcl_dialect_from_sources(
+        instance_folder,
+        instance_path,
+        &pcl_sources,
+        &pcl_ce_sources,
+    )
+}
+
+fn pcl_dialect_from_sources(
+    instance_folder: &str,
+    instance_path: Option<&str>,
+    pcl_sources: &[(String, String)],
+    pcl_ce_sources: &[(String, String)],
+) -> ImportLauncherType {
+    let config_name = split_config_name(instance_folder).0;
+    let source_matches = |sources: &[(String, String)]| {
+        sources.iter().any(|(name, path)| {
+            if let Some(selected) = instance_path {
+                path_contains(Path::new(path), Path::new(selected))
+            } else {
+                name == config_name
+            }
+        })
+    };
+    let pcl_matches = source_matches(pcl_sources);
+    let pcl_ce_matches = source_matches(pcl_ce_sources);
+
+    if pcl_ce_matches && !pcl_matches {
+        ImportLauncherType::PCL2CE
+    } else {
+        // Preserve the existing importer's legacy-PCL-first precedence for
+        // duplicate config names and the launcher's local `.minecraft` entry.
+        ImportLauncherType::PCL2
+    }
+}
+
+fn resolve_known(
+    launcher_type: ImportLauncherType,
+    base_path: PathBuf,
+    instance_folder: &str,
+    instance_path: Option<&str>,
+) -> crate::Result<ResolvedDirectLink> {
+    let launcher_root = canonicalize_checked(&base_path)?;
+    let (dot_minecraft, version_dir) = if let Some(instance_path) =
+        instance_path
+    {
+        let version_dir = canonicalize_checked(Path::new(instance_path))?;
+        let dot_minecraft = compatible_game_dir(&base_path, &version_dir)?;
+        (canonicalize_checked(&dot_minecraft)?, version_dir)
+    } else {
+        let source =
+            resolve_source_path(launcher_type, &base_path, instance_folder)?;
+        resolve_repository_paths(&source, instance_folder)?
+    };
+
+    reject_temporary_import_path(&launcher_root)?;
+    reject_temporary_import_path(&dot_minecraft)?;
+    reject_temporary_import_path(&version_dir)?;
+
+    let version_json = discover_version_json(&version_dir)?;
+    let version_json = canonicalize_checked(&version_json)?;
+    let version_id = version_json
+        .file_stem()
+        .and_then(|stem| stem.to_str())
+        .filter(|stem| !stem.is_empty())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Version JSON has no usable file stem: {}",
+                version_json.display()
+            ))
+            .as_error()
+        })?
+        .to_string();
+    let info = instance_json::detect(&version_dir).ok_or_else(|| {
+        crate::ErrorKind::InputError(format!(
+            "Could not detect Minecraft version from {}",
+            version_json.display()
+        ))
+        .as_error()
+    })?;
+    let loader = info
+        .loader
+        .as_deref()
+        .map(ModLoader::try_from_string)
+        .transpose()?
+        .unwrap_or(ModLoader::Vanilla);
+
+    Ok(ResolvedDirectLink {
+        launcher: launcher_type,
+        launcher_root,
+        dot_minecraft,
+        version_dir,
+        version_json,
+        version_id,
+        game_version: info.vanilla_name,
+        loader,
+        loader_version: info.loader_version,
+    })
+}
+
+fn resolve_source_path(
+    launcher_type: ImportLauncherType,
+    base_path: &Path,
+    instance_folder: &str,
+) -> crate::Result<PathBuf> {
+    let (config_name, rest) = split_config_name(instance_folder);
+    let target = if rest.is_empty() { config_name } else { rest };
+
+    let game_dir = match launcher_type {
+        ImportLauncherType::HMCL => {
+            hmcl::get_instance_path(base_path, config_name)
+                .map(PathBuf::from)
+                .map(|path| {
+                    if path.is_absolute() {
+                        path
+                    } else {
+                        base_path.join(path)
+                    }
+                })
+                .unwrap_or_else(|| base_path.to_path_buf())
+        }
+        ImportLauncherType::PCL2 | ImportLauncherType::PCL2CE => {
+            find_pcl_source(config_name, &pcl::get_pcl_instances())
+                .or_else(|| {
+                    find_pcl_source(config_name, &pcl::get_pclce_instances())
+                })
+                .map(PathBuf::from)
+                .or_else(|| {
+                    (config_name == ".minecraft")
+                        .then(|| base_path.join(".minecraft"))
+                        .filter(|path| path.is_dir())
+                })
+                .unwrap_or_else(|| base_path.to_path_buf())
+        }
+        ImportLauncherType::Generic => base_path.to_path_buf(),
+        _ => return Err(unsupported_launcher(launcher_type)),
+    };
+
+    Ok(resolve_instance_path(&game_dir, target))
+}
+
+fn resolve_repository_paths(
+    source: &Path,
+    instance_folder: &str,
+) -> crate::Result<(PathBuf, PathBuf)> {
+    let source = canonicalize_checked(source)?;
+    if source
+        .parent()
+        .and_then(Path::file_name)
+        .is_some_and(|name| name.eq_ignore_ascii_case("versions"))
+    {
+        let dot_minecraft = source
+            .parent()
+            .and_then(Path::parent)
+            .ok_or_else(|| invalid_version_directory(&source))?;
+        return Ok((canonicalize_checked(dot_minecraft)?, source));
+    }
+
+    let (_, dot_minecraft) = generic::resolve_dotminecraft(&source);
+    let dot_minecraft = canonicalize_checked(&dot_minecraft)?;
+    let target = split_config_name(instance_folder).1;
+    let target = if target.is_empty() {
+        Path::new(instance_folder)
+            .strip_prefix("versions")
+            .unwrap_or_else(|_| Path::new(instance_folder))
+    } else {
+        Path::new(target)
+            .strip_prefix("versions")
+            .unwrap_or_else(|_| Path::new(target))
+    };
+    let version_dir = dot_minecraft.join("versions").join(target);
+    if !version_dir.is_dir() {
+        return Err(invalid_version_directory(&version_dir));
+    }
+
+    Ok((dot_minecraft, canonicalize_checked(&version_dir)?))
+}
+
+fn compatible_game_dir(
+    base_path: &Path,
+    version_dir: &Path,
+) -> crate::Result<PathBuf> {
+    if version_dir
+        .parent()
+        .and_then(Path::file_name)
+        .is_some_and(|name| name.eq_ignore_ascii_case("versions"))
+    {
+        return version_dir
+            .parent()
+            .and_then(Path::parent)
+            .map(Path::to_path_buf)
+            .ok_or_else(|| invalid_version_directory(version_dir));
+    }
+
+    let (_, dot_minecraft) = generic::resolve_dotminecraft(base_path);
+    Ok(dot_minecraft)
+}
+
+/// Returns whether a file is a Minecraft version manifest rather than a JSON
+/// sidecar produced by the game or a launcher. Version folders often contain
+/// files such as `usercache.json`; those must not make a copied PCL instance
+/// appear ambiguous.
+fn is_minecraft_version_manifest(path: &Path) -> bool {
+    let Ok(contents) = std::fs::read_to_string(path) else {
+        return false;
+    };
+    let Ok(value) = serde_json::from_str::<Value>(&contents) else {
+        return false;
+    };
+    let Some(object) = value.as_object() else {
+        return false;
+    };
+
+    object
+        .get("id")
+        .and_then(Value::as_str)
+        .is_some_and(|id| !id.trim().is_empty())
+        && [
+            "arguments",
+            "assetIndex",
+            "assets",
+            "clientVersion",
+            "downloads",
+            "inheritsFrom",
+            "jar",
+            "libraries",
+            "mainClass",
+            "minecraftArguments",
+        ]
+        .iter()
+        .any(|field| object.contains_key(*field))
+}
+
+/// Returns whether a version directory contains at least one usable Minecraft
+/// version manifest. This lets a root scan ignore launcher bookkeeping folders
+/// that are not launchable instances.
+pub(crate) fn has_minecraft_version_manifest(version_dir: &Path) -> bool {
+    std::fs::read_dir(version_dir).is_ok_and(|entries| {
+        entries.flatten().map(|entry| entry.path()).any(|path| {
+            path.is_file()
+                && path.extension().is_some_and(|extension| {
+                    extension.eq_ignore_ascii_case("json")
+                })
+                && is_minecraft_version_manifest(&path)
+        })
+    })
+}
+
+/// Finds the actual manifest selected by upstream launchers: a valid
+/// same-name manifest first, then the sole valid manifest in the version
+/// directory. Ambiguous folders are rejected instead of guessing which
+/// manifest the UI intended.
+pub(crate) fn discover_version_json(
+    version_dir: &Path,
+) -> crate::Result<PathBuf> {
+    let folder_name = version_dir
+        .file_name()
+        .and_then(|name| name.to_str())
+        .ok_or_else(|| invalid_version_directory(version_dir))?;
+    let same_name = version_dir.join(format!("{folder_name}.json"));
+    if same_name.is_file() && is_minecraft_version_manifest(&same_name) {
+        return Ok(same_name);
+    }
+
+    let mut json_files = std::fs::read_dir(version_dir)
+        .map_err(|error| {
+            crate::ErrorKind::FSError(format!(
+                "Failed to inspect version directory {}: {error}",
+                version_dir.display()
+            ))
+        })?
+        .filter_map(Result::ok)
+        .map(|entry| entry.path())
+        .filter(|path| {
+            path.is_file()
+                && path.extension().is_some_and(|extension| {
+                    extension.eq_ignore_ascii_case("json")
+                })
+                && is_minecraft_version_manifest(path)
+        })
+        .collect::<Vec<_>>();
+    json_files.sort();
+
+    match json_files.as_slice() {
+        [only] => Ok(only.clone()),
+        [] => Err(crate::ErrorKind::InputError(format!(
+            "No Minecraft version JSON found in {}",
+            version_dir.display()
+        ))
+        .into()),
+        _ => Err(crate::ErrorKind::InputError(format!(
+            "Multiple Minecraft version JSON files found in {}; expected a same-name JSON or one unique fallback",
+            version_dir.display()
+        ))
+        .into()),
+    }
+}
+
+fn launcher_key(launcher_type: ImportLauncherType) -> Option<&'static str> {
+    match launcher_type {
+        ImportLauncherType::HMCL => Some("hmcl"),
+        ImportLauncherType::PCL2 => Some("pcl2"),
+        ImportLauncherType::PCL2CE => Some("pcl2_ce"),
+        ImportLauncherType::Generic => Some("generic"),
+        _ => None,
+    }
+}
+
+fn reject_temporary_import_path(path: &Path) -> crate::Result<()> {
+    let temporary_root = std::env::temp_dir().join(TEMP_IMPORT_DIR);
+    if path.starts_with(&temporary_root) {
+        return Err(crate::ErrorKind::InputError(
+            "Direct association is unavailable for extracted launcher archives because the temporary folder is deleted after import"
+                .to_string(),
+        )
+        .into());
+    }
+    Ok(())
+}
+
+fn canonicalize_checked(path: &Path) -> crate::Result<PathBuf> {
+    let canonical = crate::util::io::canonicalize(path)?;
+    reject_temporary_import_path(&canonical)?;
+    Ok(canonical)
+}
+
+fn paths_match(left: &Path, right: &Path) -> bool {
+    match (
+        crate::util::io::canonicalize(left),
+        crate::util::io::canonicalize(right),
+    ) {
+        (Ok(left), Ok(right)) => left == right,
+        _ => left == right,
+    }
+}
+
+fn path_contains(root: &Path, selected: &Path) -> bool {
+    match (
+        crate::util::io::canonicalize(root),
+        crate::util::io::canonicalize(selected),
+    ) {
+        (Ok(root), Ok(selected)) => selected.starts_with(root),
+        _ => selected.starts_with(root),
+    }
+}
+
+fn unsupported_launcher(launcher_type: ImportLauncherType) -> crate::Error {
+    crate::ErrorKind::InputError(format!(
+        "Direct association does not support launcher {launcher_type}; expected HMCL, PCL2, PCL2CE, Generic, or Unknown"
+    ))
+    .into()
+}
+
+fn invalid_version_directory(path: &Path) -> crate::Error {
+    crate::ErrorKind::InputError(format!(
+        "Expected a traditional .minecraft version directory at {}",
+        path.display()
+    ))
+    .into()
+}
+
+/// Splits an instance folder identity like `name` or `Version:1.12.2` into
+/// (config name, version part); PCL and HMCL instance identities use this
+/// shape.
+fn split_config_name(name: &str) -> (&str, &str) {
+    name.split_once(':').unwrap_or((name, ""))
+}
+
+/// Resolves the folder of an instance from a base path and its scan identity.
+fn resolve_instance_path(base_path: &Path, instance_folder: &str) -> PathBuf {
+    if let Ok(rest) = Path::new(instance_folder).strip_prefix("versions") {
+        return base_path.join("versions").join(rest);
+    }
+    if base_path
+        .file_name()
+        .map(|n| n.to_string_lossy().to_string())
+        .as_deref()
+        == Some(instance_folder)
+    {
+        base_path.to_path_buf()
+    } else {
+        base_path.join(instance_folder)
+    }
+}
+
+/// Finds the game directory of a PCL/PCL-CE instance from its scan sources
+/// (registry entries or CE config).
+fn find_pcl_source(
+    instance_name: &str,
+    sources: &[(String, String)],
+) -> Option<PathBuf> {
+    sources
+        .iter()
+        .find(|(name, _)| name == instance_name)
+        .map(|(_, path)| PathBuf::from(path))
+        .filter(|path| path.is_dir())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+    use tempfile::TempDir;
+
+    fn write_json(version_dir: &Path, file_stem: &str) {
+        std::fs::create_dir_all(version_dir).unwrap();
+        std::fs::write(
+            version_dir.join(format!("{file_stem}.json")),
+            serde_json::to_vec_pretty(&json!({
+                "id": file_stem,
+                "mainClass": "net.minecraft.client.main.Main",
+                "type": "release"
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+    }
+
+    #[tokio::test]
+    async fn resolves_normal_versions_layout() {
+        let root = TempDir::new().unwrap();
+        let version_dir = root.path().join("versions/1.20.1");
+        write_json(&version_dir, "1.20.1");
+
+        let resolved = resolve_direct_link(
+            ImportLauncherType::Generic,
+            root.path().to_path_buf(),
+            "versions/1.20.1".to_string(),
+            None,
+        )
+        .await
+        .unwrap();
+
+        assert_eq!(resolved.launcher, ImportLauncherType::Generic);
+        assert_eq!(
+            resolved.dot_minecraft,
+            crate::util::io::canonicalize(root.path()).unwrap()
+        );
+        assert_eq!(resolved.version_id, "1.20.1");
+        assert_eq!(
+            resolved.version_dir,
+            crate::util::io::canonicalize(&version_dir).unwrap()
+        );
+    }
+
+    #[test]
+    fn identifies_hmcl_only_when_it_owns_the_game_directory() {
+        let root = TempDir::new().unwrap();
+        let game_dir = root.path().join("game");
+        std::fs::create_dir_all(game_dir.join("versions")).unwrap();
+        let hmcl_dir = root.path().join(".hmcl");
+        std::fs::create_dir_all(&hmcl_dir).unwrap();
+        std::fs::write(
+            hmcl_dir.join("hmcl.json"),
+            serde_json::to_vec(&json!({
+                "configurations": {
+                    "default": { "gameDir": game_dir.to_string_lossy() }
+                }
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let source = detect_direct_link_source(
+            &game_dir,
+            &game_dir.join("versions").join("demo"),
+        );
+        assert_eq!(source.launcher, ImportLauncherType::HMCL);
+        assert_eq!(source.launcher_root, root.path());
+    }
+
+    #[tokio::test]
+    async fn resolves_compatible_mode_from_game_dir_and_version_path() {
+        let root = TempDir::new().unwrap();
+        let version_dir = root.path().join("versions/1.12.2-forge");
+        write_json(&version_dir, "1.12.2-forge");
+
+        let resolved = resolve_direct_link(
+            ImportLauncherType::PCL2,
+            root.path().to_path_buf(),
+            "Friendly PCL Name".to_string(),
+            Some(version_dir.to_string_lossy().to_string()),
+        )
+        .await
+        .unwrap();
+
+        assert_eq!(resolved.launcher_key(), "pcl2");
+        assert_eq!(
+            resolved.dot_minecraft,
+            crate::util::io::canonicalize(root.path()).unwrap()
+        );
+        assert_eq!(resolved.version_id, "1.12.2-forge");
+    }
+
+    #[tokio::test]
+    async fn unique_json_fallback_uses_actual_stem_not_display_name() {
+        let root = TempDir::new().unwrap();
+        let version_dir = root.path().join("versions/ui-folder");
+        std::fs::create_dir_all(&version_dir).unwrap();
+        std::fs::write(
+            version_dir.join("actual-version-id.json"),
+            serde_json::to_vec_pretty(&json!({
+                "id": "actual-version-id",
+                "clientVersion": "1.20.1",
+                "mainClass": "net.minecraft.client.main.Main",
+                "type": "release"
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let resolved = resolve_direct_link(
+            ImportLauncherType::Generic,
+            root.path().to_path_buf(),
+            "versions/ui-folder".to_string(),
+            None,
+        )
+        .await
+        .unwrap();
+
+        assert_eq!(resolved.version_id, "actual-version-id");
+        assert!(resolved.version_json.ends_with("actual-version-id.json"));
+    }
+
+    #[test]
+    fn ignores_runtime_json_when_finding_a_copied_pcl_instance() {
+        let root = TempDir::new().unwrap();
+        let version_dir =
+            root.path().join("versions").join("1.19.2 - 64bit - copy");
+        write_json(&version_dir, "1.19.2 - 64bit");
+        std::fs::write(
+            version_dir.join("usercache.json"),
+            r#"[{"name":"player","uuid":"example"}]"#,
+        )
+        .unwrap();
+
+        assert!(has_minecraft_version_manifest(&version_dir));
+        assert_eq!(
+            discover_version_json(&version_dir).unwrap(),
+            version_dir.join("1.19.2 - 64bit.json")
+        );
+    }
+
+    #[test]
+    fn rejects_a_pcl_bookkeeping_directory_without_a_version_manifest() {
+        let root = TempDir::new().unwrap();
+        let version_dir = root.path().join("versions").join("Sodium Plus");
+        std::fs::create_dir_all(version_dir.join("PCL")).unwrap();
+        std::fs::write(
+            version_dir.join("PCL").join("config.v1.yml"),
+            "VersionVanilla: 1.21.1\n",
+        )
+        .unwrap();
+
+        assert!(!has_minecraft_version_manifest(&version_dir));
+    }
+
+    #[tokio::test]
+    async fn rejects_temporary_launcher_import_directory() {
+        let error = resolve_direct_link(
+            ImportLauncherType::Generic,
+            std::env::temp_dir().join(TEMP_IMPORT_DIR).join("extracted"),
+            "versions/1.20.1".to_string(),
+            None,
+        )
+        .await
+        .unwrap_err();
+
+        assert!(error.to_string().contains("temporary"));
+    }
+
+    #[tokio::test]
+    async fn rejects_unsupported_launcher_before_touching_paths() {
+        let error = resolve_direct_link(
+            ImportLauncherType::MultiMC,
+            PathBuf::from("missing"),
+            "instance".to_string(),
+            None,
+        )
+        .await
+        .unwrap_err();
+
+        assert!(error.to_string().contains("does not support"));
+    }
+
+    #[test]
+    fn maps_pcl_and_hmcl_to_distinct_persistent_dialects() {
+        assert_eq!(launcher_key(ImportLauncherType::HMCL), Some("hmcl"));
+        assert_eq!(launcher_key(ImportLauncherType::PCL2), Some("pcl2"));
+        assert_eq!(launcher_key(ImportLauncherType::PCL2CE), Some("pcl2_ce"));
+    }
+
+    #[test]
+    fn groups_direct_links_by_their_complete_path() {
+        assert_eq!(
+            direct_link_group(&Path::new("A").join(".minecraft")),
+            Some(
+                Path::new("A")
+                    .join(".minecraft")
+                    .to_string_lossy()
+                    .to_string()
+            )
+        );
+        assert_eq!(
+            direct_link_group(Path::new(".minecraft")),
+            Some(".minecraft".to_string())
+        );
+    }
+
+    #[test]
+    fn unknown_recovers_pcl_ce_dialect_from_selected_source_path() {
+        let root = TempDir::new().unwrap();
+        let pcl_root = root.path().join("pcl");
+        let pcl_ce_root = root.path().join("pcl-ce");
+        let selected = pcl_ce_root.join("versions/1.21.1");
+        std::fs::create_dir_all(&pcl_root).unwrap();
+        std::fs::create_dir_all(&selected).unwrap();
+        let pcl_sources = vec![(
+            "Legacy".to_string(),
+            pcl_root.to_string_lossy().to_string(),
+        )];
+        let pcl_ce_sources = vec![(
+            "Community".to_string(),
+            pcl_ce_root.to_string_lossy().to_string(),
+        )];
+
+        assert_eq!(
+            pcl_dialect_from_sources(
+                "1.21.1",
+                Some(selected.to_string_lossy().as_ref()),
+                &pcl_sources,
+                &pcl_ce_sources,
+            ),
+            ImportLauncherType::PCL2CE
+        );
+    }
+
+    #[tokio::test]
+    async fn unknown_prefers_detected_hmcl_over_generic() {
+        let root = TempDir::new().unwrap();
+        let game_dir = root.path().join("game");
+        let version_dir = game_dir.join("versions/1.20.4");
+        write_json(&version_dir, "1.20.4");
+        std::fs::create_dir_all(root.path().join(".hmcl")).unwrap();
+        std::fs::write(
+            root.path().join(".hmcl/hmcl.json"),
+            serde_json::to_vec_pretty(&json!({
+                "configurations": {
+                    "HMCL Profile": { "gameDir": game_dir }
+                }
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let resolved = resolve_direct_link(
+            ImportLauncherType::Unknown,
+            root.path().to_path_buf(),
+            "HMCL Profile:versions/1.20.4".to_string(),
+            None,
+        )
+        .await
+        .unwrap();
+
+        assert_eq!(resolved.launcher, ImportLauncherType::HMCL);
+        assert_eq!(resolved.launcher_key(), "hmcl");
+    }
+
+    #[tokio::test]
+    async fn unknown_does_not_relabel_unmatched_generic_as_hmcl() {
+        let root = TempDir::new().unwrap();
+        let hmcl_game = root.path().join("hmcl-game");
+        write_json(&hmcl_game.join("versions/hmcl"), "1.20.1");
+        std::fs::create_dir_all(root.path().join(".hmcl")).unwrap();
+        std::fs::write(
+            root.path().join(".hmcl/hmcl.json"),
+            serde_json::to_vec_pretty(&json!({
+                "configurations": {
+                    "HMCL Profile": { "gameDir": hmcl_game }
+                }
+            }))
+            .unwrap(),
+        )
+        .unwrap();
+
+        let generic_version = root.path().join("versions/generic");
+        write_json(&generic_version, "1.20.4");
+        let resolved = resolve_direct_link(
+            ImportLauncherType::Unknown,
+            root.path().to_path_buf(),
+            // Deliberately collide with the HMCL candidate's display identity;
+            // the explicitly selected path must take precedence.
+            "HMCL Profile:versions/hmcl".to_string(),
+            Some(generic_version.to_string_lossy().to_string()),
+        )
+        .await
+        .unwrap();
+
+        assert_eq!(resolved.launcher, ImportLauncherType::Generic);
+        assert_eq!(resolved.launcher_key(), "generic");
+    }
+}

packages/app-lib/src/api/pack/import/gdlauncher.rs

@@ -0,0 +1,130 @@
+use std::path::PathBuf;
+
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    State,
+    install::{InstallPhaseDetails, InstallProgressReporter},
+    prelude::ModLoader,
+    state::{AppliedContentSetPatch, EditInstance, InstanceInstallStage},
+    util::io,
+};
+
+use super::{finish_import, recache_icon};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct GDLauncherConfig {
+    pub background: Option<String>,
+    pub loader: GDLauncherLoader,
+    // pub mods: Vec<GDLauncherMod>,
+}
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct GDLauncherLoader {
+    pub loader_type: ModLoader,
+    pub loader_version: Option<String>,
+    pub mc_version: String,
+    pub source: Option<String>,
+    pub source_name: Option<String>,
+}
+
+// Check if folder has a config.json that parses
+pub async fn is_valid_gdlauncher(instance_folder: PathBuf) -> bool {
+    let config = serde_json::from_str::<GDLauncherConfig>(
+        &io::read_any_encoding_to_string(&instance_folder.join("config.json"))
+            .await
+            .unwrap_or(("".into(), encoding_rs::UTF_8))
+            .0,
+    );
+    config.is_ok()
+}
+
+pub async fn import_gdlauncher(
+    gdlauncher_instance_folder: PathBuf, // instance's folder
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    // Load config.json
+    let config = serde_json::from_str::<GDLauncherConfig>(
+        &io::read_any_encoding_to_string(
+            &gdlauncher_instance_folder.join("config.json"),
+        )
+        .await
+        .unwrap_or(("".into(), encoding_rs::UTF_8))
+        .0,
+    )?;
+    let override_title = config.loader.source_name;
+    let backup_name = format!(
+        "GDLauncher-{}",
+        gdlauncher_instance_folder
+            .file_name()
+            .map_or("Unknown".to_string(), |a| a.to_string_lossy().to_string())
+    );
+
+    // Re-cache icon
+    let icon = config
+        .background
+        .clone()
+        .map(|b| gdlauncher_instance_folder.join(b));
+    let icon = if let Some(icon) = icon {
+        recache_icon(icon).await?
+    } else {
+        None
+    };
+
+    let game_version = config.loader.mc_version;
+    let mod_loader = config.loader.loader_type;
+    let loader_version = config.loader.loader_version;
+
+    let loader_version = if mod_loader != ModLoader::Vanilla {
+        crate::launcher::get_loader_version_from_profile(
+            &game_version,
+            mod_loader,
+            loader_version.as_deref(),
+        )
+        .await?
+    } else {
+        None
+    };
+
+    crate::api::instance::edit(
+        instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(
+                override_title
+                    .clone()
+                    .unwrap_or_else(|| backup_name.to_string()),
+            ),
+            icon_path: Some(
+                icon.clone().map(|x| x.to_string_lossy().to_string()),
+            ),
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind: None,
+                game_version: Some(game_version.clone()),
+                protocol_version: Some(None),
+                loader: Some(mod_loader),
+                loader_version: Some(loader_version.clone().map(|x| x.id)),
+            }),
+            ..EditInstance::default()
+        },
+    )
+    .await?;
+
+    // Copy in contained folders as overrides
+    let state = State::get().await?;
+    finish_import(
+        instance_id,
+        gdlauncher_instance_folder,
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await?;
+
+    Ok(())
+}

packages/app-lib/src/api/pack/import/generic.rs

@@ -0,0 +1,465 @@
+use std::{
+    collections::HashMap,
+    path::{Path, PathBuf},
+};
+
+use super::{ImportOverrides, instance_json};
+use crate::{
+    State,
+    install::{InstallPhaseDetails, InstallProgressReporter},
+    launcher::get_loader_version_from_profile,
+    pack::{
+        import::finish_import,
+        install_from::{self, CreatePackDescription, PackDependency},
+    },
+    state::ModLoader,
+};
+
+/// Import a generic launcher instance folder into an Axolotl profile.
+///
+/// Runs in four stages: resolve the source folder, validate that it contains
+/// a detectable Minecraft version, register the instance metadata, then copy
+/// (or symlink) the files into the profile.
+pub async fn import_generic(
+    instance_folder: PathBuf,
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+    overrides: &ImportOverrides,
+    instance_path: Option<PathBuf>, // For compatible mode: path to versions/<version>/
+) -> crate::Result<()> {
+    let (name, dotminecraft, json_path) = if let Some(ref inst_path) =
+        instance_path
+    {
+        let name = inst_path
+            .file_name()
+            .map(|n| n.to_string_lossy().to_string())
+            .unwrap_or_else(|| "imported".to_string());
+        tracing::debug!(
+            "import_generic: compatible mode - dotminecraft={}, json_path={}",
+            instance_folder.display(),
+            inst_path.display()
+        );
+        (name, instance_folder.to_path_buf(), inst_path.to_path_buf())
+    } else {
+        let (name, dotminecraft) = resolve_dotminecraft(&instance_folder);
+        let json_path = dotminecraft.clone(); // JSON detection will scan dotminecraft
+        (name, dotminecraft, json_path)
+    };
+
+    let info = detect_instance_info(&json_path, overrides).await?;
+    register_instance(instance_id, &name, &info).await?;
+    copy_instance_files(instance_id, &dotminecraft, reporter, details, symlink)
+        .await
+}
+
+/// Stage 1 — resolve the name and the `.minecraft` directory of an imported
+/// instance folder. Falls back to the folder itself when there is no nested
+/// `.minecraft` subdirectory.
+pub(crate) fn resolve_dotminecraft(
+    instance_folder: &Path,
+) -> (String, PathBuf) {
+    let name = instance_folder
+        .file_name()
+        .map(|n| n.to_string_lossy().to_string())
+        .unwrap_or_else(|| "imported".to_string());
+
+    let dotminecraft = instance_folder.join(".minecraft");
+    if dotminecraft.is_dir() {
+        tracing::debug!(
+            "import_generic: using .minecraft subdir at {}",
+            dotminecraft.display()
+        );
+        (name, dotminecraft)
+    } else {
+        tracing::debug!(
+            "import_generic: using folder directly at {}",
+            instance_folder.display()
+        );
+        (name, instance_folder.to_path_buf())
+    }
+}
+
+/// Stage 2 — validate the folder contains a Minecraft version JSON.
+async fn detect_instance_info(
+    dotminecraft: &Path,
+    overrides: &ImportOverrides,
+) -> crate::Result<instance_json::InstanceInfo> {
+    tracing::debug!(
+        "import_generic: about to detect instance_json at dotminecraft={}",
+        dotminecraft.display()
+    );
+    let Some(mut info) = instance_json::detect(dotminecraft) else {
+        let Some(game_version) = overrides
+            .game_version
+            .as_ref()
+            .filter(|version| !version.trim().is_empty())
+        else {
+            tracing::warn!(
+                "import_generic: instance_json::detect returned None for {}",
+                dotminecraft.display()
+            );
+            return Err(crate::ErrorKind::InputError(
+                "Could not detect Minecraft version. Make sure the folder contains a valid version JSON."
+                    .into(),
+            )
+            .into());
+        };
+        return Ok(instance_json::InstanceInfo {
+            vanilla_name: game_version.clone(),
+            loader: overrides
+                .loader
+                .filter(|loader| *loader != ModLoader::Vanilla)
+                .map(|loader| loader.as_str().to_string()),
+            loader_version: overrides
+                .loader_version
+                .clone()
+                .filter(|version| !version.is_empty() && version != "latest"),
+            adjuncts: Vec::new(),
+        });
+    };
+
+    if let Some(game_version) = overrides
+        .game_version
+        .as_ref()
+        .filter(|version| !version.trim().is_empty())
+    {
+        info.vanilla_name.clone_from(game_version);
+    }
+    if let Some(loader) = overrides.loader {
+        if loader == ModLoader::Vanilla {
+            info.loader = None;
+            info.loader_version = None;
+            info.adjuncts.clear();
+        } else {
+            info.loader = Some(loader.as_str().to_string());
+            info.loader_version = None;
+        }
+    }
+    if let Some(loader_version) = overrides
+        .loader_version
+        .as_ref()
+        .filter(|version| !version.is_empty() && *version != "latest")
+    {
+        info.loader_version = Some(loader_version.clone());
+    }
+
+    Ok(info)
+}
+
+/// Stage 3 — register the instance metadata (name, game version, loaders)
+/// with the app database.
+async fn register_instance(
+    instance_id: &str,
+    name: &str,
+    info: &instance_json::InstanceInfo,
+) -> crate::Result<()> {
+    tracing::debug!(
+        "import_generic: detect result: vanilla_name={} loader={:?} loader_version={:?}",
+        info.vanilla_name,
+        info.loader,
+        info.loader_version
+    );
+
+    let description = CreatePackDescription {
+        icon: None,
+        override_title: Some(name.to_string()),
+        project_id: None,
+        version_id: None,
+        instance_id: instance_id.to_string(),
+        source_filename: None,
+    };
+    let dependencies = build_dependencies(info).await?;
+
+    tracing::debug!(
+        "import_generic: setting instance info with dependencies={:?}",
+        dependencies
+    );
+    install_from::set_instance_information(
+        instance_id.to_string(),
+        &description,
+        "Imported from folder",
+        None,
+        &dependencies,
+        false,
+    )
+    .await?;
+    Ok(())
+}
+
+/// Builds the dependency map from the detected game version and loader,
+/// resolving the loader version from the metadata API when it is missing.
+async fn build_dependencies(
+    info: &instance_json::InstanceInfo,
+) -> crate::Result<HashMap<PackDependency, String>> {
+    let mut dependencies =
+        HashMap::from([(PackDependency::Minecraft, info.vanilla_name.clone())]);
+    let Some(ref loader) = info.loader else {
+        tracing::debug!("import_generic: no loader detected, will be Vanilla");
+        return Ok(dependencies);
+    };
+    let components = std::iter::once((
+        loader.as_str(),
+        info.loader_version.as_ref(),
+    ))
+    .chain(info.adjuncts.iter().filter_map(|(loader, version)| {
+        (loader != "optifabric").then_some((loader.as_str(), version.as_ref()))
+    }));
+    for (loader, version) in components {
+        if loader.eq_ignore_ascii_case("labymod") {
+            return Err(crate::ErrorKind::InputError(
+                "Unsupported loader LabyMod: Axolotl does not install, update, or repair LabyMod instances"
+                    .to_string(),
+            )
+            .into());
+        }
+        let dep = loader_dependency(loader).ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Unsupported loader {loader}: the instance was not imported as Vanilla"
+            ))
+            .as_error()
+        })?;
+        let loader_version = resolve_loader_version(
+            &info.vanilla_name,
+            loader,
+            version.map(String::as_str),
+        )
+        .await;
+        match loader_version {
+            Some(version) => {
+                dependencies.insert(dep, version);
+            }
+            None => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "Could not resolve {loader} for Minecraft {}; the instance was not imported as Vanilla",
+                    info.vanilla_name
+                ))
+                .into());
+            }
+        }
+    }
+    if let Some((_, version)) = info
+        .adjuncts
+        .iter()
+        .find(|(loader, _)| loader == "optifabric")
+    {
+        let version = version.as_ref().ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "Imported OptiFabric component is missing its version"
+                    .to_string(),
+            )
+        })?;
+        dependencies.insert(PackDependency::OptiFabric, version.clone());
+    }
+    Ok(dependencies)
+}
+
+/// Maps a detected loader name to a dependency the launcher can install.
+fn loader_dependency(loader: &str) -> Option<PackDependency> {
+    match loader {
+        "forge" => Some(PackDependency::Forge),
+        "neoforge" => Some(PackDependency::NeoForge),
+        "fabric" => Some(PackDependency::FabricLoader),
+        "quilt" => Some(PackDependency::QuiltLoader),
+        "optifine" => Some(PackDependency::OptiFine),
+        "cleanroom" => Some(PackDependency::Cleanroom),
+        "lite_loader" | "liteloader" => Some(PackDependency::LiteLoader),
+        "legacy_fabric" | "legacyfabric" => Some(PackDependency::LegacyFabric),
+        _ => None,
+    }
+}
+
+/// Resolves a missing loader version by asking the metadata API for the
+/// latest version compatible with the detected game version.
+async fn resolve_loader_version(
+    game_version: &str,
+    loader: &str,
+    requested_version: Option<&str>,
+) -> Option<String> {
+    if requested_version
+        .is_some_and(|version| !version.is_empty() && version != "latest")
+    {
+        return requested_version.map(str::to_string);
+    }
+    let mod_loader = match loader {
+        "forge" => Some(ModLoader::Forge),
+        "neoforge" => Some(ModLoader::NeoForge),
+        "fabric" => Some(ModLoader::Fabric),
+        "quilt" => Some(ModLoader::Quilt),
+        "optifine" => Some(ModLoader::OptiFine),
+        "cleanroom" => Some(ModLoader::Cleanroom),
+        "lite_loader" | "liteloader" => Some(ModLoader::LiteLoader),
+        "legacy_fabric" | "legacyfabric" => Some(ModLoader::LegacyFabric),
+        _ => None,
+    }?;
+    tracing::debug!(
+        "import_generic: loader={} has no version, resolving latest for game_version={}",
+        loader,
+        game_version
+    );
+    match get_loader_version_from_profile(game_version, mod_loader, None).await
+    {
+        Ok(Some(lv)) => {
+            tracing::debug!(
+                "import_generic: resolved latest loader version: {}",
+                lv.id
+            );
+            Some(lv.id)
+        }
+        Ok(None) => {
+            tracing::warn!(
+                "import_generic: no loader version found for {} {}",
+                mod_loader.as_str(),
+                game_version
+            );
+            None
+        }
+        Err(e) => {
+            tracing::warn!(
+                "import_generic: failed to resolve loader version: {e}",
+            );
+            None
+        }
+    }
+}
+
+/// Stage 4 — copy (or symlink) the source files into the instance profile.
+async fn copy_instance_files(
+    instance_id: &str,
+    dotminecraft: &Path,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    tracing::debug!(
+        "import_generic: finishing import for instance_id={}",
+        instance_id
+    );
+    finish_import(
+        instance_id,
+        dotminecraft.to_path_buf(),
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn loader_dependency_maps_supported_loaders() {
+        assert_eq!(loader_dependency("forge"), Some(PackDependency::Forge));
+        assert_eq!(
+            loader_dependency("neoforge"),
+            Some(PackDependency::NeoForge)
+        );
+        assert_eq!(
+            loader_dependency("fabric"),
+            Some(PackDependency::FabricLoader)
+        );
+        assert_eq!(
+            loader_dependency("quilt"),
+            Some(PackDependency::QuiltLoader)
+        );
+        assert_eq!(
+            loader_dependency("optifine"),
+            Some(PackDependency::OptiFine)
+        );
+        assert_eq!(
+            loader_dependency("cleanroom"),
+            Some(PackDependency::Cleanroom)
+        );
+        assert_eq!(
+            loader_dependency("lite_loader"),
+            Some(PackDependency::LiteLoader)
+        );
+        assert_eq!(
+            loader_dependency("legacy_fabric"),
+            Some(PackDependency::LegacyFabric)
+        );
+    }
+
+    #[test]
+    fn loader_dependency_rejects_unsupported_loaders() {
+        for loader in ["labymod", "unknown", "vanilla"] {
+            assert_eq!(loader_dependency(loader), None, "{loader}");
+        }
+    }
+
+    #[tokio::test]
+    async fn detect_overrides_replace_missing_detection() {
+        let directory = tempfile::tempdir().unwrap();
+        let overrides = ImportOverrides {
+            game_version: Some("1.20.1".to_string()),
+            loader: Some(ModLoader::Fabric),
+            loader_version: Some("0.15.11".to_string()),
+        };
+
+        let info = detect_instance_info(directory.path(), &overrides)
+            .await
+            .unwrap();
+
+        assert_eq!(info.vanilla_name, "1.20.1");
+        assert_eq!(info.loader.as_deref(), Some("fabric"));
+        assert_eq!(info.loader_version.as_deref(), Some("0.15.11"));
+    }
+
+    #[tokio::test]
+    async fn detect_overrides_ignore_blank_and_latest_loader_version() {
+        let directory = tempfile::tempdir().unwrap();
+        for loader_version in ["", "latest"] {
+            let overrides = ImportOverrides {
+                game_version: Some("1.20.1".to_string()),
+                loader: Some(ModLoader::Fabric),
+                loader_version: Some(loader_version.to_string()),
+            };
+
+            let info = detect_instance_info(directory.path(), &overrides)
+                .await
+                .unwrap();
+
+            assert_eq!(info.loader_version, None);
+        }
+    }
+
+    #[tokio::test]
+    async fn build_dependencies_uses_override_values() {
+        let info = instance_json::InstanceInfo {
+            vanilla_name: "1.20.1".to_string(),
+            loader: Some("fabric".to_string()),
+            loader_version: Some("0.15.11".to_string()),
+            adjuncts: Vec::new(),
+        };
+
+        let dependencies = build_dependencies(&info).await.unwrap();
+
+        assert_eq!(
+            dependencies.get(&PackDependency::Minecraft),
+            Some(&"1.20.1".to_string())
+        );
+        assert_eq!(
+            dependencies.get(&PackDependency::FabricLoader),
+            Some(&"0.15.11".to_string())
+        );
+    }
+
+    #[tokio::test]
+    async fn labymod_and_unknown_loaders_never_become_vanilla() {
+        for loader in ["labymod", "unknown_loader"] {
+            let info = instance_json::InstanceInfo {
+                vanilla_name: "1.20.1".to_string(),
+                loader: Some(loader.to_string()),
+                loader_version: Some("1.0".to_string()),
+                adjuncts: Vec::new(),
+            };
+            let error = build_dependencies(&info).await.unwrap_err();
+            assert!(error.to_string().contains("Unsupported loader"));
+        }
+    }
+}

packages/app-lib/src/api/pack/import/hmcl.rs

@@ -0,0 +1,116 @@
+use std::{
+    collections::HashMap,
+    path::{Path, PathBuf},
+};
+
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize)]
+struct HmclConfig {
+    configurations: HashMap<String, HmclConfiguration>,
+}
+
+#[derive(Debug, Deserialize)]
+struct HmclConfiguration {
+    #[serde(rename = "gameDir")]
+    game_dir: String,
+}
+
+fn find_config(base_path: &Path) -> Option<std::path::PathBuf> {
+    let path = base_path.join(".hmcl").join("hmcl.json");
+    if path.exists() {
+        return Some(path);
+    }
+    None
+}
+
+pub fn config_exists(base_path: &Path) -> bool {
+    find_config(base_path).is_some()
+}
+
+pub fn get_instances(base_path: &Path) -> Vec<(String, String)> {
+    let Some(config_path) = find_config(base_path) else {
+        return Vec::new();
+    };
+
+    let Ok(content) = std::fs::read_to_string(&config_path) else {
+        tracing::warn!(
+            "hmcl: failed to read config at {}",
+            config_path.display()
+        );
+        return Vec::new();
+    };
+
+    let config: HmclConfig = match serde_json::from_str(&content) {
+        Ok(c) => c,
+        Err(e) => {
+            tracing::warn!(
+                "hmcl: failed to parse config at {}: {e}",
+                config_path.display()
+            );
+            return Vec::new();
+        }
+    };
+
+    let mut instances = Vec::new();
+    for (key, entry) in &config.configurations {
+        let game_dir = PathBuf::from(&entry.game_dir);
+        let resolved = if game_dir.is_absolute() {
+            game_dir
+        } else {
+            base_path.join(&game_dir)
+        };
+        if resolved.is_dir() {
+            instances
+                .push((key.clone(), resolved.to_string_lossy().to_string()));
+        }
+    }
+    instances.sort_by(|a, b| a.0.cmp(&b.0));
+    instances
+}
+
+pub fn get_instance_path(
+    base_path: &Path,
+    instance_key: &str,
+) -> Option<String> {
+    // Reuse get_instances() to avoid parsing the config file twice.
+    get_instances(base_path)
+        .into_iter()
+        .find(|(key, _)| key == instance_key)
+        .map(|(_, path)| path)
+}
+
+/// Returns the configured HMCL game directory when it explicitly owns either
+/// the shared `.minecraft` root or this version directory. An explicit entry
+/// wins over content-folder heuristics, which cannot distinguish a newly
+/// created isolated instance from a shared one.
+pub fn configured_game_dir(
+    base_path: &Path,
+    dot_minecraft: &Path,
+    version_dir: &Path,
+) -> Option<PathBuf> {
+    let game_dirs = get_instances(base_path)
+        .into_iter()
+        .map(|(_, game_dir)| PathBuf::from(game_dir))
+        .collect::<Vec<_>>();
+    game_dirs
+        .iter()
+        .find(|game_dir| paths_match(game_dir, version_dir))
+        .cloned()
+        .or_else(|| {
+            game_dirs
+                .iter()
+                .find(|game_dir| paths_match(game_dir, dot_minecraft))
+                .cloned()
+        })
+}
+
+fn paths_match(left: &Path, right: &Path) -> bool {
+    match (
+        crate::util::io::canonicalize(left),
+        crate::util::io::canonicalize(right),
+    ) {
+        (Ok(left), Ok(right)) => left == right,
+        _ => left == right,
+    }
+}

packages/app-lib/src/api/pack/import/hmcl_config.rs

@@ -0,0 +1,89 @@
+//! HMCL data directory discovery.
+//!
+//! HMCL stores its configuration (`launcher-settings.json`) in a data directory
+//! that depends on how the launcher was installed.  This module finds that
+//! directory's root (the `.hmcl` folder itself, not its `config` subfolder)
+//! with a three‑priority strategy:
+//!
+//! 1. Portable mode — `{launcher_dir}/.hmcl/config/launcher-settings.json`
+//! 2. System install — platform‑specific application data directory
+//! 3. Environment variable — `$HMCL_DATA_DIR`
+
+use std::path::{Path, PathBuf};
+
+/// Try to locate the HMCL data directory root by probing the three priority
+/// levels in order.  Returns the first root that contains
+/// `config/launcher-settings.json`, or `None` if none does.
+pub fn find_hmcl_data_dir(launcher_dir: &Path) -> Option<PathBuf> {
+    // 1. Portable mode — side‑car `.hmcl` folder next to the launcher jar
+    let portable = launcher_dir.join(".hmcl");
+    if portable.join("config/launcher-settings.json").exists() {
+        return Some(portable);
+    }
+
+    // 2. System install — standard platform data directory
+    if let Some(system_dir) = system_data_dir()
+        && system_dir.join("config/launcher-settings.json").exists()
+    {
+        return Some(system_dir);
+    }
+
+    // 3. Environment variable override
+    if let Ok(env_dir) = std::env::var("HMCL_DATA_DIR") {
+        let env_path = PathBuf::from(env_dir);
+        if env_path.join("config/launcher-settings.json").exists() {
+            return Some(env_path);
+        }
+    }
+
+    None
+}
+
+/// Return the platform‑specific HMCL data directory root for a system
+/// install.
+fn system_data_dir() -> Option<PathBuf> {
+    #[cfg(target_os = "windows")]
+    {
+        dirs::data_dir().map(|d| d.join(".hmcl"))
+    }
+    #[cfg(target_os = "macos")]
+    {
+        dirs::data_dir().map(|d| d.join("hmcl"))
+    }
+    #[cfg(not(any(target_os = "windows", target_os = "macos")))]
+    {
+        dirs::data_dir().map(|d| d.join("hmcl"))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    #[test]
+    fn test_system_data_dir_is_some() {
+        // On any real OS this should return a path (it may or may not exist).
+        assert!(system_data_dir().is_some());
+    }
+
+    #[test]
+    fn test_find_hmcl_data_dir_returns_none_for_bogus_path() {
+        let bogus = Path::new("/tmp/this-does-not-exist-12345");
+        assert!(find_hmcl_data_dir(bogus).is_none());
+    }
+
+    #[test]
+    fn test_portable_mode_returns_hmcl_root() {
+        let dir = tempdir().expect("temp dir");
+        let config = dir.path().join(".hmcl/config");
+        std::fs::create_dir_all(&config).expect("create config dir");
+        std::fs::write(config.join("launcher-settings.json"), "{}")
+            .expect("write settings");
+
+        assert_eq!(
+            find_hmcl_data_dir(dir.path()),
+            Some(dir.path().join(".hmcl"))
+        );
+    }
+}

packages/app-lib/src/api/pack/import/instance_json.rs

@@ -0,0 +1,840 @@
+use std::path::Path;
+
+use serde_json::Value;
+use tracing::debug;
+
+pub struct InstanceInfo {
+    pub vanilla_name: String,
+    pub loader: Option<String>,
+    pub loader_version: Option<String>,
+    pub adjuncts: Vec<(String, Option<String>)>,
+}
+
+fn find_json(path: &Path) -> Option<(String, String)> {
+    let name = path.file_name()?.to_string_lossy().to_string();
+    let primary = path.join(format!("{name}.json"));
+    debug!(
+        "instance_json: path={} looking for primary={}",
+        path.display(),
+        primary.display()
+    );
+    if primary.exists() {
+        debug!(
+            "instance_json: path={} json={} (by name match)",
+            path.display(),
+            primary.display()
+        );
+        let content = std::fs::read_to_string(&primary).ok()?;
+        debug!(
+            "instance_json: path={} primary content (len={}, first_200={:?})",
+            path.display(),
+            content.len(),
+            &content[..content.len().min(200)]
+        );
+        return Some((name, content));
+    }
+    debug!(
+        "instance_json: path={} primary={} NOT FOUND, enumerating directory",
+        path.display(),
+        primary.display()
+    );
+    let mut json_files = Vec::new();
+    if let Ok(dir) = std::fs::read_dir(path) {
+        for entry in dir.flatten() {
+            let p = entry.path();
+            debug!(
+                "instance_json: path={} entry={}",
+                path.display(),
+                p.display()
+            );
+            if p.extension().map(|e| e == "json").unwrap_or(false) {
+                json_files.push(p);
+            }
+        }
+    }
+    debug!(
+        "instance_json: path={} found {} json files",
+        path.display(),
+        json_files.len()
+    );
+    if json_files.len() == 1 {
+        debug!(
+            "instance_json: path={} json={} (sole json fallback)",
+            path.display(),
+            json_files[0].display()
+        );
+        let content = std::fs::read_to_string(&json_files[0]).ok()?;
+        debug!(
+            "instance_json: path={} sole json content (len={}, first_200={:?})",
+            path.display(),
+            content.len(),
+            &content[..content.len().min(200)]
+        );
+        let name = json_files[0]
+            .file_stem()
+            .map(|n| n.to_string_lossy().to_string())
+            .unwrap_or(name);
+        return Some((name, content));
+    }
+    // Multiple JSONs: try each one, return the first with a valid version.
+    // A single unreadable or malformed candidate must not abort the loop.
+    for jf in &json_files {
+        let Ok(content) = std::fs::read_to_string(jf) else {
+            debug!(
+                "instance_json: path={} json={} unreadable, trying next",
+                path.display(),
+                jf.display()
+            );
+            continue;
+        };
+        debug!(
+            "instance_json: path={} trying json={} (len={}, first_200={:?})",
+            path.display(),
+            jf.display(),
+            content.len(),
+            &content[..content.len().min(200)]
+        );
+        let Ok(json) = serde_json::from_str::<serde_json::Value>(&content)
+        else {
+            debug!(
+                "instance_json: path={} json={} invalid JSON, trying next",
+                path.display(),
+                jf.display()
+            );
+            continue;
+        };
+        let version = extract_version(&json, &content, None);
+        if !version.is_empty() {
+            let fname = jf
+                .file_stem()
+                .map(|n| n.to_string_lossy().to_string())
+                .unwrap_or_else(|| name.clone());
+            debug!(
+                "instance_json: path={} json={} (multiple-json pick, version={})",
+                path.display(),
+                jf.display(),
+                version
+            );
+            return Some((fname, content));
+        }
+    }
+    debug!(
+        "instance_json: path={} multiple={} json files, none yielded a version",
+        path.display(),
+        json_files.len()
+    );
+    None
+}
+
+pub fn detect(path: &Path) -> Option<InstanceInfo> {
+    let (name, content) = find_json(path)?;
+    let json: Value = match serde_json::from_str(&content) {
+        Ok(v) => v,
+        Err(e) => {
+            debug!("instance_json: path={} parse_err={}", path.display(), e);
+            return None;
+        }
+    };
+    let mut vanilla_name = extract_version(&json, &content, Some(&name));
+    debug!(
+        "instance_json: path={} extract_version returned {:?}",
+        path.display(),
+        vanilla_name
+    );
+    if vanilla_name.is_empty() {
+        debug!(
+            "instance_json: path={} version empty or Unknown",
+            path.display()
+        );
+        return None;
+    }
+    vanilla_name = normalize_version(&vanilla_name);
+    let loader = detect_loader(&content, &json).map(|(loader, version)| {
+        let version = version.map(|version| {
+            normalize_imported_loader_version(&loader, &vanilla_name, &version)
+        });
+        (loader, version)
+    });
+    let adjuncts = detect_adjuncts(
+        &content,
+        loader.as_ref().map(|(loader, _)| loader.as_str()),
+    )
+    .into_iter()
+    .map(|(loader, version)| {
+        let version = version.map(|version| {
+            normalize_imported_loader_version(&loader, &vanilla_name, &version)
+        });
+        (loader, version)
+    })
+    .collect();
+    debug!(
+        "instance_json: path={} version={} loader={:?}",
+        path.display(),
+        vanilla_name,
+        loader.as_ref().map(|(t, _)| t.as_str())
+    );
+    Some(InstanceInfo {
+        vanilla_name,
+        loader: loader.as_ref().map(|(t, _)| t.clone()),
+        loader_version: loader.and_then(|(_, v)| v),
+        adjuncts,
+    })
+}
+
+fn normalize_version(raw: &str) -> String {
+    let mut v = raw.to_string();
+    if (v.starts_with("20.") || v.starts_with("21.")) && !v.starts_with("1.") {
+        v = format!("1.{v}");
+    }
+    v = v.replace("_unobfuscated", "");
+    v = v.replace(" Unobfuscated", "");
+    v.trim().to_string()
+}
+
+pub(crate) fn normalize_imported_loader_version(
+    loader: &str,
+    game_version: &str,
+    detected_version: &str,
+) -> String {
+    let detected_version = detected_version.trim();
+    let without_family = match loader {
+        "fabric" | "legacy_fabric" => detected_version
+            .strip_prefix("fabric-loader-")
+            .or_else(|| detected_version.strip_prefix("fabric-")),
+        "quilt" => detected_version
+            .strip_prefix("quilt-loader-")
+            .or_else(|| detected_version.strip_prefix("quilt-")),
+        "forge" => detected_version.strip_prefix("forge-"),
+        "neoforge" => detected_version
+            .strip_prefix("neoforge-")
+            .or_else(|| detected_version.strip_prefix("neo-")),
+        _ => None,
+    }
+    .unwrap_or(detected_version);
+
+    match loader {
+        "fabric" | "legacy_fabric" | "quilt" => without_family
+            .strip_suffix(&format!("-{game_version}"))
+            .unwrap_or(without_family)
+            .to_string(),
+        "forge" | "neoforge" => {
+            let stripped = without_family
+                .strip_prefix(&format!("{game_version}-"))
+                .unwrap_or(without_family);
+            // Legacy Forge (e.g. 1.7.10) embeds the MC version as a trailing
+            // suffix: `1.7.10-10.13.4.1614-1.7.10` -> `10.13.4.1614`. Strip it so
+            // the id matches the metadata manifest. When the suffix is absent
+            // (modern `1.20.1-47.4.22`), keep the already prefix-stripped
+            // version rather than reverting to the raw detected value.
+            stripped
+                .strip_suffix(&format!("-{game_version}"))
+                .unwrap_or(stripped)
+                .to_string()
+        }
+        _ => without_family.to_string(),
+    }
+}
+
+fn extract_version(
+    json: &Value,
+    json_str: &str,
+    folder_name: Option<&str>,
+) -> String {
+    // ① PCL download record clientVersion
+    if let Some(v) = json.get("clientVersion").and_then(|v| v.as_str())
+        && !v.is_empty()
+    {
+        debug!("extract_version: method=① clientVersion value={}", v);
+        return v.to_string();
+    }
+
+    // ② HMCL patches[].version (id == "game")
+    if let Some(patches) = json.get("patches").and_then(|v| v.as_array()) {
+        for patch in patches {
+            if patch.get("id").and_then(|v| v.as_str()) == Some("game")
+                && let Some(ver) = patch.get("version").and_then(|v| v.as_str())
+                && !ver.is_empty()
+            {
+                debug!(
+                    "extract_version: method=② patches.game.version value={}",
+                    ver
+                );
+                return ver.to_string();
+            }
+        }
+    }
+
+    // ③ arguments.game --fml.mcVersion (Forge/NeoForge)
+    if let Some(args) = json
+        .get("arguments")
+        .and_then(|v| v.get("game"))
+        .and_then(|v| v.as_array())
+    {
+        let mut mark = false;
+        for arg in args {
+            if mark && let Some(v) = arg.as_str() {
+                debug!("extract_version: method=③ --fml.mcVersion value={}", v);
+                return v.to_string();
+            }
+            if arg.as_str() == Some("--fml.mcVersion") {
+                mark = true;
+            }
+        }
+    }
+
+    // ④ inheritsFrom (version inheritance) — must come before the `jar`
+    // field, which is not always a version name.
+    if let Some(v) = json.get("inheritsFrom").and_then(|v| v.as_str())
+        && !v.is_empty()
+    {
+        debug!("extract_version: method=④ inheritsFrom value={}", v);
+        return v.to_string();
+    }
+
+    // ⑤ libraries string regex fallback (Forge/OptiFine/FabricLike lib versions)
+    // Use the original JSON string (from find_json) instead of re-serializing
+    // the parsed Value, which would allocate a fresh string unnecessarily.
+    if let Some(v) = extract_version_from_libraries(json_str) {
+        debug!("extract_version: method=⑤ libraries value={}", v);
+        return v;
+    }
+
+    // ⑥ JSON id field → extract leading version
+    if let Some(id) = json.get("id").and_then(|v| v.as_str())
+        && let Some(v) = extract_version_from_id(id)
+    {
+        debug!("extract_version: method=⑥ id id={} value={}", id, v);
+        return v;
+    }
+
+    // ⑦ jar field (legacy versions store the base game in `jar`)
+    if let Some(v) = json.get("jar").and_then(|v| v.as_str())
+        && !v.is_empty()
+    {
+        debug!("extract_version: method=⑦ jar value={}", v);
+        return v.to_string();
+    }
+
+    // ⑧ folder name fallback (renamed / non-standard instances)
+    if let Some(name) = folder_name
+        && let Some(v) = extract_version_from_id(name)
+    {
+        debug!("extract_version: method=⑧ folder_name value={}", v);
+        return v;
+    }
+
+    debug!("extract_version: method=✗ all methods failed");
+    String::new()
+}
+
+/// Extracts Minecraft version from library artifact coordinates in the JSON string.
+/// Matches PCLCE's approach scanning for Forge/OptiFine/FabricLike lib entries.
+/// Order: NeoForge before Forge (NeoForge JSON often also contains forge references).
+fn extract_version_from_libraries(content: &str) -> Option<String> {
+    // NeoForge: net.neoforged:neoforge:1.20.1-44.0.3 → "1.20.1"
+    // Try known Maven coordinate formats (neoforge before forge).
+    for needle in [
+        "net.neoforged:neoforge:",
+        "net.neoforged.neoforge:neoforge:",
+        "net.neoforged.fml:modern:",
+    ] {
+        if let Some(pos) = content.find(needle) {
+            let after = &content[pos + needle.len()..];
+            if let Some(end) = after.find(&['"', ',', '\n', '}'] as &[char]) {
+                let ver = &after[..end];
+                if let Some(dash) = ver.find('-') {
+                    return Some(ver[..dash].to_string());
+                }
+                return Some(ver.to_string());
+            }
+        }
+    }
+    // Forge: minecraftforge:forge:1.8.9-11.15.1.1722 → "1.8.9"
+    //        net.minecraftforge:forge:1.21.1-52.0.0 (modern Forge, 1.13+)
+    for needle in ["minecraftforge:forge:", "net.minecraftforge:forge:"] {
+        if let Some(pos) = content.find(needle) {
+            let after = &content[pos + needle.len()..];
+            if let Some(end) = after.find(&['"', ',', '\n', '}'] as &[char]) {
+                let ver = &after[..end];
+                if let Some(dash) = ver.find('-') {
+                    return Some(ver[..dash].to_string());
+                }
+                return Some(ver.to_string());
+            }
+        }
+    }
+    // OptiFine: optifine:OptiFine:1.8.9_HD_U_H5 → "1.8.9"
+    if let Some(pos) = content.find("optifine:OptiFine:") {
+        let after = &content[pos + "optifine:OptiFine:".len()..];
+        if let Some(end) = after.find(&['"', ',', '\n', '}'] as &[char]) {
+            let ver = &after[..end];
+            if let Some(underscore) = ver.find('_') {
+                return Some(ver[..underscore].to_string());
+            }
+            return Some(ver.to_string());
+        }
+    }
+    // Fabric-like: net.fabricmc:fabric-loader:0.15.11-1.20.1 → "1.20.1"
+    if let Some(pos) = content.find("net.fabricmc:fabric-loader:") {
+        let after = &content[pos + "net.fabricmc:fabric-loader:".len()..];
+        if let Some(end) = after.find(&['"', ',', '\n', '}'] as &[char]) {
+            let ver = &after[..end];
+            if let Some(dash) = ver.rfind('-') {
+                return Some(ver[dash + 1..].to_string());
+            }
+        }
+    }
+    None
+}
+
+/// Extracts leading version number from the instance id.
+/// e.g. "1.8.9-forge-11.15.1.1722" → "1.8.9"
+/// Skips hash-like ids (≥32 chars, no separators).
+fn extract_version_from_id(id: &str) -> Option<String> {
+    let ver = id.trim();
+    if ver.is_empty() {
+        return None;
+    }
+    if ver.len() >= 32
+        && !ver.contains('.')
+        && !ver.contains('-')
+        && !ver.contains('_')
+    {
+        return None;
+    }
+    if let Some(first_sep) = ver.find(['-', '_', ' ']) {
+        let candidate = &ver[..first_sep];
+        if candidate.starts_with("1.") || candidate.starts_with('2') {
+            return Some(candidate.to_string());
+        }
+    }
+    if ver.starts_with("1.") || ver.starts_with('2') {
+        return Some(ver.to_string());
+    }
+    None
+}
+
+///参考自PCL启动器
+fn detect_loader(
+    content: &str,
+    json: &Value,
+) -> Option<(String, Option<String>)> {
+    let lower = content.to_lowercase();
+
+    // LabyMod
+    if lower.contains("labymod_data") {
+        let version = json
+            .get("labymod_data")
+            .and_then(|v| v.get("version"))
+            .and_then(|v| v.as_str())
+            .map(|s| s.to_string());
+        return Some(("labymod".into(), version));
+    }
+
+    // Legacy Fabric
+    if lower.contains("net.legacyfabric:intermediary") {
+        let version = try_extract_version_from_needle(
+            content,
+            "net.fabricmc:fabric-loader:",
+            None,
+        );
+        return Some(("legacy_fabric".into(), version));
+    }
+
+    // Fabric
+    if lower.contains("net.fabricmc:fabric-loader") {
+        let version = try_extract_version_from_needle(
+            content,
+            "net.fabricmc:fabric-loader:",
+            None,
+        );
+        return Some(("fabric".into(), version));
+    }
+
+    // Quilt
+    if lower.contains("org.quiltmc:quilt-loader") {
+        let version = try_extract_version_from_needle(
+            content,
+            "org.quiltmc:quilt-loader:",
+            None,
+        );
+        return Some(("quilt".into(), version));
+    }
+
+    // Cleanroom
+    if lower.contains("com.cleanroommc:cleanroom:") {
+        let version = try_extract_version_from_needle(
+            content,
+            "com.cleanroommc:cleanroom:",
+            None,
+        );
+        return Some(("cleanroom".into(), version));
+    }
+
+    // Forge
+    if lower.contains("minecraftforge") && !lower.contains("net.neoforge") {
+        let version = try_extract_version_from_needle(
+            content,
+            "minecraftforge:forge:",
+            None,
+        )
+        .or_else(|| {
+            try_extract_version_from_needle(
+                content,
+                "net.minecraftforge:forge:",
+                None,
+            )
+        })
+        .or_else(|| {
+            try_extract_version_from_needle(
+                content,
+                "net.minecraftforge:fmlloader:",
+                None,
+            )
+        });
+        return Some(("forge".into(), version));
+    }
+
+    // NeoForge
+    if lower.contains("net.neoforge") {
+        let version = try_extract_version_from_needle(
+            content,
+            "net.neoforged:neoforge:",
+            None,
+        )
+        .or_else(|| {
+            try_extract_version_from_needle(
+                content,
+                "net.neoforged.neoforge:neoforge:",
+                None,
+            )
+        });
+        return Some(("neoforge".into(), version));
+    }
+
+    // OptiFine
+    if lower.contains("optifine") {
+        let version = try_extract_version_from_needle(
+            content,
+            "optifine:OptiFine:",
+            None,
+        );
+        if version.is_some() {
+            return Some(("optifine".into(), version));
+        }
+    }
+
+    // LiteLoader
+    if lower.contains("liteloader") {
+        return Some(("lite_loader".into(), None));
+    }
+
+    debug!("detect_loader: no known loader library found in JSON content");
+    None
+}
+
+fn detect_adjuncts(
+    content: &str,
+    primary_loader: Option<&str>,
+) -> Vec<(String, Option<String>)> {
+    let lower = content.to_ascii_lowercase();
+    let mut adjuncts = Vec::new();
+    if primary_loader != Some("lite_loader") && lower.contains("liteloader") {
+        adjuncts.push(("lite_loader".to_string(), None));
+    }
+    if primary_loader != Some("optifine") && lower.contains("optifine") {
+        let version = try_extract_version_from_needle(
+            content,
+            "optifine:OptiFine:",
+            None,
+        )
+        .or_else(|| {
+            try_extract_version_from_needle(&lower, "optifine:optifine:", None)
+        });
+        if version.is_some() {
+            adjuncts.push(("optifine".to_string(), version));
+        }
+    }
+    if lower.contains("optifabric") {
+        let version = try_extract_version_from_needle(
+            &lower,
+            "me.modmuss50:optifabric:",
+            None,
+        )
+        .or_else(|| {
+            try_extract_version_from_needle(
+                &lower,
+                "optifabric:optifabric:",
+                None,
+            )
+        });
+        adjuncts.push(("optifabric".to_string(), version));
+    }
+    adjuncts
+}
+
+/// Extracts the loader version string from JSON content by finding a needle
+/// and reading until a terminator character.
+fn try_extract_version_from_needle(
+    content: &str,
+    needle: &str,
+    split_at: Option<char>,
+) -> Option<String> {
+    let pos = content.find(needle)?;
+    let after = &content[pos + needle.len()..];
+    let end = after.find(&['"', ',', '\n', '}'] as &[char])?;
+    let ver = &after[..end];
+    if let Some(ch) = split_at
+        && let Some(pos) = ver.rfind(ch)
+    {
+        Some(ver[pos + 1..].to_string())
+    } else {
+        Some(ver.to_string())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn detect_from_json(content: &str) -> Option<(String, Option<String>)> {
+        let json: Value = serde_json::from_str(content).expect("test JSON");
+        detect_loader(content, &json)
+    }
+
+    fn assert_loader(
+        content: &str,
+        expected: &str,
+        expected_version: Option<&str>,
+    ) {
+        let (loader, version) = detect_from_json(content)
+            .unwrap_or_else(|| panic!("expected loader {expected}, got None"));
+        assert_eq!(loader, expected);
+        assert_eq!(version.as_deref(), expected_version);
+    }
+
+    #[test]
+    fn test_forge() {
+        assert_loader(
+            r#"{
+                "id": "1.21.1-forge-52.0.0",
+                "libraries": [
+                    {
+                        "name": "net.minecraftforge:forge:1.21.1-52.0.0"
+                    }
+                ]
+            }"#,
+            "forge",
+            Some("1.21.1-52.0.0"),
+        );
+    }
+
+    #[test]
+    fn normalizes_imported_loader_versions_for_central_resolution() {
+        for (loader, game_version, detected, expected) in [
+            ("fabric", "1.20.1", "0.15.11-1.20.1", "0.15.11"),
+            ("quilt", "1.20.1", "0.26.4-1.20.1", "0.26.4"),
+            (
+                "forge",
+                "1.7.10",
+                "1.7.10-10.13.4.1614-1.7.10",
+                "10.13.4.1614",
+            ),
+            ("forge", "1.20.1", "1.20.1-47.4.22", "47.4.22"),
+            ("neoforge", "1.20.1", "1.20.1-44.0.3", "44.0.3"),
+            ("neoforge", "1.21.4", "21.4.157", "21.4.157"),
+        ] {
+            assert_eq!(
+                normalize_imported_loader_version(
+                    loader,
+                    game_version,
+                    detected
+                ),
+                expected,
+                "{loader} {game_version} {detected}"
+            );
+        }
+    }
+
+    #[test]
+    fn test_neoforge() {
+        assert_loader(
+            r#"{
+                "id": "1.20.1-neoforge-44.0.3",
+                "libraries": [
+                    {
+                        "name": "net.neoforged:neoforge:1.20.1-44.0.3"
+                    }
+                ]
+            }"#,
+            "neoforge",
+            Some("1.20.1-44.0.3"),
+        );
+    }
+
+    #[test]
+    fn test_fabric() {
+        assert_loader(
+            r#"{
+                "id": "1.20.1-fabric-0.15.11",
+                "libraries": [
+                    {
+                        "name": "net.fabricmc:fabric-loader:0.15.11-1.20.1"
+                    }
+                ]
+            }"#,
+            "fabric",
+            Some("0.15.11-1.20.1"),
+        );
+    }
+
+    #[test]
+    fn test_quilt() {
+        assert_loader(
+            r#"{
+                "id": "1.20.1-quilt-0.26.4",
+                "libraries": [
+                    {
+                        "name": "org.quiltmc:quilt-loader:0.26.4-1.20.1"
+                    }
+                ]
+            }"#,
+            "quilt",
+            Some("0.26.4-1.20.1"),
+        );
+    }
+
+    #[test]
+    fn test_optifine() {
+        assert_loader(
+            r#"{
+                "id": "1.8.9-OptiFine",
+                "libraries": [
+                    {
+                        "name": "optifine:OptiFine:1.8.9_HD_U_H5"
+                    }
+                ]
+            }"#,
+            "optifine",
+            Some("1.8.9_HD_U_H5"),
+        );
+    }
+
+    #[test]
+    fn detects_forge_with_liteloader_and_optifine_adjuncts() {
+        let content = r#"{
+            "id": "1.12.2-forge-combined",
+            "libraries": [
+                { "name": "net.minecraftforge:forge:1.12.2-14.23.5.2860" },
+                { "name": "com.mumfrey:liteloader:1.12.2-SNAPSHOT" },
+                { "name": "optifine:OptiFine:1.12.2_HD_U_G5" }
+            ]
+        }"#;
+        let json: Value = serde_json::from_str(content).unwrap();
+        let primary = detect_loader(content, &json).unwrap();
+        let adjuncts = detect_adjuncts(content, Some(&primary.0));
+
+        assert_eq!(primary.0, "forge");
+        assert_eq!(
+            adjuncts,
+            vec![
+                ("lite_loader".to_string(), None),
+                ("optifine".to_string(), Some("1.12.2_HD_U_G5".to_string())),
+            ]
+        );
+    }
+
+    #[test]
+    fn test_legacy_fabric() {
+        assert_loader(
+            r#"{
+                "id": "1.8.9-legacy-fabric-0.13.1.4",
+                "libraries": [
+                    {
+                        "name": "net.legacyfabric:intermediary:1.8.9"
+                    },
+                    {
+                        "name": "net.fabricmc:fabric-loader:0.13.1.4-1.8.9"
+                    }
+                ]
+            }"#,
+            "legacy_fabric",
+            Some("0.13.1.4-1.8.9"),
+        );
+    }
+
+    #[test]
+    fn test_cleanroom() {
+        assert_loader(
+            r#"{
+                "id": "1.12.2-cleanroom-7.1.0",
+                "libraries": [
+                    {
+                        "name": "com.cleanroommc:cleanroom:1.12.2-7.1.0"
+                    }
+                ]
+            }"#,
+            "cleanroom",
+            Some("1.12.2-7.1.0"),
+        );
+    }
+
+    #[test]
+    fn test_labymod() {
+        assert_loader(
+            r#"{
+                "id": "1.20.1-labymod",
+                "labymod_data": {
+                    "version": "4.4.20"
+                }
+            }"#,
+            "labymod",
+            Some("4.4.20"),
+        );
+    }
+
+    #[test]
+    fn test_lite_loader() {
+        assert_loader(
+            r#"{
+                "id": "1.12.2-LiteLoader-1.12.2-SNAPSHOT",
+                "libraries": [
+                    {
+                        "name": "com.mumfrey:liteloader:1.12.2"
+                    }
+                ]
+            }"#,
+            "lite_loader",
+            None,
+        );
+    }
+
+    #[test]
+    fn test_no_loader() {
+        assert!(detect_from_json(r#"{"id": "1.20.4"}"#).is_none());
+    }
+
+    #[test]
+    fn test_detect_end_to_end() {
+        let dir = tempfile::tempdir().expect("temp dir");
+        let instance = dir.path().join(".minecraft");
+        std::fs::create_dir(&instance).expect("create .minecraft dir");
+        std::fs::write(
+            instance.join(".minecraft.json"),
+            r#"{
+                "id": "1.20.1-fabric-0.15.11",
+                "libraries": [
+                    {
+                        "name": "net.fabricmc:fabric-loader:0.15.11-1.20.1"
+                    }
+                ]
+            }"#,
+        )
+        .expect("write instance json");
+
+        let info = detect(&instance).expect("detect should succeed");
+        assert_eq!(info.vanilla_name, "1.20.1");
+        assert_eq!(info.loader.as_deref(), Some("fabric"));
+        assert_eq!(info.loader_version.as_deref(), Some("0.15.11"));
+    }
+}

packages/app-lib/src/api/pack/import/mmc.rs

@@ -0,0 +1,440 @@
+use std::path::{Path, PathBuf};
+
+use serde::{Deserialize, Serialize, de};
+
+use crate::{
+    State,
+    install::{InstallPhaseDetails, InstallProgressReporter},
+    pack::{
+        import::{self, finish_import},
+        install_from::{self, CreatePackDescription, PackDependency},
+    },
+    util::io,
+};
+
+// instance.cfg
+// https://github.com/PrismLauncher/PrismLauncher/blob/develop/launcher/minecraft/MinecraftInstance.cpp
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+#[serde(untagged)]
+enum MMCInstanceEnum {
+    General(MMCInstanceGeneral),
+    Instance(MMCInstance),
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+struct MMCInstanceGeneral {
+    pub general: MMCInstance,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+pub struct MMCInstance {
+    pub java_path: Option<String>,
+    pub jvm_args: Option<String>,
+
+    #[serde(default)]
+    #[serde(deserialize_with = "deserialize_optional_bool")]
+    pub managed_pack: Option<bool>,
+
+    #[serde(rename = "ManagedPackID")]
+    pub managed_pack_id: Option<String>,
+    pub managed_pack_type: Option<MMCManagedPackType>,
+    #[serde(rename = "ManagedPackVersionID")]
+    pub managed_pack_version_id: Option<String>,
+    pub managed_pack_version_name: Option<String>,
+
+    #[serde(rename = "iconKey")]
+    pub icon_key: Option<String>,
+    #[serde(rename = "name")]
+    pub name: Option<String>,
+}
+
+// serde_ini reads 'true' and 'false' as strings, so we need to convert them to booleans
+fn deserialize_optional_bool<'de, D>(
+    deserializer: D,
+) -> Result<Option<bool>, D::Error>
+where
+    D: de::Deserializer<'de>,
+{
+    let s = Option::<String>::deserialize(deserializer)?;
+    match s {
+        Some(string) => match string.as_str() {
+            "true" => Ok(Some(true)),
+            "false" => Ok(Some(false)),
+            _ => Err(de::Error::custom("expected 'true' or 'false'")),
+        },
+        None => Ok(None),
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "lowercase")]
+pub enum MMCManagedPackType {
+    Modrinth,
+    Flame,
+    ATLauncher,
+    #[serde(other)]
+    Unknown,
+}
+
+// mmc-pack.json
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct MMCPack {
+    components: Vec<MMCComponent>,
+    format_version: u32,
+}
+
+// https://github.com/PrismLauncher/PrismLauncher/blob/develop/launcher/minecraft/Component.h
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct MMCComponent {
+    pub uid: String,
+
+    #[serde(default)]
+    pub version: Option<String>,
+    #[serde(default)]
+    pub dependency_only: bool,
+
+    #[serde(default)]
+    pub important: bool,
+    #[serde(default)]
+    pub disabled: bool,
+
+    pub cached_name: Option<String>,
+    pub cached_version: Option<String>,
+
+    #[serde(default)]
+    pub cached_requires: Vec<MMCComponentRequirement>,
+    #[serde(default)]
+    pub cached_conflicts: Vec<MMCComponentRequirement>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct MMCComponentRequirement {
+    pub uid: String,
+    pub equals_version: Option<String>,
+    pub suggests: Option<String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+#[serde(untagged)]
+enum MMCLauncherEnum {
+    General(MMCLauncherGeneral),
+    Instance(MMCLauncher),
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+struct MMCLauncherGeneral {
+    pub general: MMCLauncher,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "PascalCase")]
+pub struct MMCLauncher {
+    instance_dir: String,
+}
+
+// Checks if if its a folder, and the folder contains instance.cfg and mmc-pack.json, and they both parse
+#[tracing::instrument]
+pub async fn is_valid_mmc(instance_folder: PathBuf) -> bool {
+    let instance_cfg = instance_folder.join("instance.cfg");
+    let mmc_pack = instance_folder.join("mmc-pack.json");
+
+    let Ok((mmc_pack, _)) = io::read_any_encoding_to_string(&mmc_pack).await
+    else {
+        return false;
+    };
+
+    load_instance_cfg(&instance_cfg).await.is_ok()
+        && serde_json::from_str::<MMCPack>(&mmc_pack).is_ok()
+}
+
+#[tracing::instrument]
+pub async fn get_instances_subpath(config: PathBuf) -> Option<String> {
+    let launcher = io::read_any_encoding_to_string(&config).await.ok()?.0;
+    let launcher: MMCLauncherEnum = serde_ini::from_str(&launcher).ok()?;
+    match launcher {
+        MMCLauncherEnum::General(p) => Some(p.general.instance_dir),
+        MMCLauncherEnum::Instance(p) => Some(p.instance_dir),
+    }
+}
+
+// Loading the INI (instance.cfg) file
+async fn load_instance_cfg(file_path: &Path) -> crate::Result<MMCInstance> {
+    match serde_ini::from_str::<MMCInstanceEnum>(
+        &io::read_any_encoding_to_string(file_path).await?.0,
+    )? {
+        MMCInstanceEnum::General(instance_cfg) => Ok(instance_cfg.general),
+        MMCInstanceEnum::Instance(instance_cfg) => Ok(instance_cfg),
+    }
+}
+
+// #[tracing::instrument]
+pub(crate) async fn import_mmc_instance_dir(
+    mmc_instance_path: PathBuf,
+    icons_dir: Option<PathBuf>,
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    let mmc_pack = serde_json::from_str::<MMCPack>(
+        &io::read_any_encoding_to_string(
+            &mmc_instance_path.join("mmc-pack.json"),
+        )
+        .await?
+        .0,
+    )?;
+
+    let instance_cfg =
+        load_instance_cfg(&mmc_instance_path.join("instance.cfg")).await?;
+
+    // Re-cache icon
+    let icon = if let Some(icon_key) = instance_cfg.icon_key {
+        let mut icon = None;
+        for icon_dir in
+            icons_dir.iter().chain(std::iter::once(&mmc_instance_path))
+        {
+            let icon_path = icon_dir.join(&icon_key);
+            icon = import::recache_icon(icon_path).await?;
+            if icon.is_none() {
+                let icon_path = icon_dir.join(format!("{icon_key}.png"));
+                icon = import::recache_icon(icon_path).await?;
+            }
+            if icon.is_some() {
+                break;
+            }
+        }
+        icon
+    } else {
+        None
+    };
+
+    // Create description from instance.cfg
+    let mut description = CreatePackDescription {
+        icon,
+        override_title: instance_cfg.name,
+        project_id: None,
+        version_id: None,
+        instance_id: instance_id.to_string(),
+        source_filename: None,
+    };
+
+    let mut minecraft_folder = mmc_instance_path.join("minecraft");
+    if !minecraft_folder.is_dir() {
+        minecraft_folder = mmc_instance_path.join(".minecraft");
+        if !minecraft_folder.is_dir() {
+            return Err(crate::ErrorKind::InputError(
+                "Instance is missing Minecraft directory".to_string(),
+            )
+            .into());
+        }
+    }
+
+    // Managed pack
+    if instance_cfg.managed_pack.unwrap_or(false) {
+        match instance_cfg.managed_pack_type {
+            Some(MMCManagedPackType::Modrinth) => {
+                description.project_id = instance_cfg.managed_pack_id;
+                description.version_id = instance_cfg.managed_pack_version_id;
+
+                // Modrinth Managed Pack
+                // Kept separate as we may in the future want to add special handling for modrinth managed packs
+                import_mmc_unmanaged(instance_id, minecraft_folder, "Imported Modrinth Modpack".to_string(), description, mmc_pack, reporter, details, symlink).await?;
+            }
+            Some(MMCManagedPackType::Flame | MMCManagedPackType::ATLauncher) => {
+                // For flame/atlauncher managed packs
+                // Treat as unmanaged, but with 'minecraft' folder instead of '.minecraft'
+                import_mmc_unmanaged(instance_id, minecraft_folder, "Imported Modpack".to_string(), description, mmc_pack, reporter, details, symlink).await?;
+            },
+            Some(_) => {
+                // For managed packs that aren't modrinth, flame, atlauncher
+                // Treat as unmanaged
+                import_mmc_unmanaged(instance_id, minecraft_folder, "ImportedModpack".to_string(), description, mmc_pack, reporter, details, symlink).await?;
+            },
+            _ => return Err(crate::ErrorKind::InputError("Instance is managed, but managed pack type not specified in instance.cfg".to_string()).into())
+        }
+    } else {
+        // Directly import unmanaged pack
+        import_mmc_unmanaged(
+            instance_id,
+            minecraft_folder,
+            "Imported Modpack".to_string(),
+            description,
+            mmc_pack,
+            reporter,
+            details,
+            symlink,
+        )
+        .await?;
+    }
+    Ok(())
+}
+
+async fn import_mmc_unmanaged(
+    instance_id: &str,
+    minecraft_folder: PathBuf,
+    backup_name: String,
+    description: CreatePackDescription,
+    mmc_pack: MMCPack,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    let dependencies = mmc_dependencies(&mmc_pack)?;
+
+    install_from::set_instance_information(
+        instance_id.to_string(),
+        &description,
+        &backup_name,
+        None,
+        &dependencies,
+        false,
+    )
+    .await?;
+
+    // Moves .minecraft folder over (ie: overrides such as resourcepacks, mods, etc)
+    let state = State::get().await?;
+    finish_import(
+        instance_id,
+        minecraft_folder,
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await?;
+    Ok(())
+}
+
+fn mmc_dependencies(
+    mmc_pack: &MMCPack,
+) -> crate::Result<std::collections::HashMap<PackDependency, String>> {
+    let mut dependencies = std::collections::HashMap::new();
+    let has_legacy_fabric = mmc_pack.components.iter().any(|component| {
+        component
+            .uid
+            .to_ascii_lowercase()
+            .starts_with("net.legacyfabric")
+    });
+    let has_cleanroom = mmc_pack.components.iter().any(|component| {
+        component
+            .uid
+            .to_ascii_lowercase()
+            .starts_with("com.cleanroommc")
+    });
+    for component in &mmc_pack.components {
+        let uid = component.uid.to_ascii_lowercase();
+        if uid.contains("labymod") {
+            return Err(crate::ErrorKind::InputError(
+				"Unsupported loader LabyMod: Axolotl does not install, update, or repair LabyMod instances"
+					.to_string(),
+			)
+			.into());
+        }
+        let dependency = if uid.starts_with("net.fabricmc.fabric-loader") {
+            Some(if has_legacy_fabric {
+                PackDependency::LegacyFabric
+            } else {
+                PackDependency::FabricLoader
+            })
+        } else if uid.starts_with("net.legacyfabric") {
+            Some(PackDependency::LegacyFabric)
+        } else if uid.starts_with("net.minecraftforge") {
+            (!has_cleanroom).then_some(PackDependency::Forge)
+        } else if uid.starts_with("net.neoforged") {
+            Some(PackDependency::NeoForge)
+        } else if uid.starts_with("org.quiltmc.quilt-loader") {
+            Some(PackDependency::QuiltLoader)
+        } else if uid.starts_with("com.cleanroommc") {
+            Some(PackDependency::Cleanroom)
+        } else if uid.contains("liteloader") {
+            Some(PackDependency::LiteLoader)
+        } else if uid.contains("optifabric") {
+            Some(PackDependency::OptiFabric)
+        } else if uid.contains("optifine") {
+            Some(PackDependency::OptiFine)
+        } else if uid.starts_with("net.minecraft") {
+            Some(PackDependency::Minecraft)
+        } else {
+            None
+        };
+        if let Some(dependency) = dependency {
+            let version = component
+                .version
+                .clone()
+                .filter(|v| !v.is_empty())
+                .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "MultiMC component {} is missing its version",
+                    component.uid
+                ))
+            })?;
+            dependencies.insert(dependency, version);
+        }
+    }
+    Ok(dependencies)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn component(uid: &str, version: &str) -> MMCComponent {
+        MMCComponent {
+            uid: uid.to_string(),
+            version: Some(version.to_string()),
+            dependency_only: false,
+            important: true,
+            disabled: false,
+            cached_name: None,
+            cached_version: None,
+            cached_requires: Vec::new(),
+            cached_conflicts: Vec::new(),
+        }
+    }
+
+    #[test]
+    fn dependencies_preserve_legacy_fabric_and_optifine_components() {
+        let pack = MMCPack {
+            format_version: 1,
+            components: vec![
+                component("net.minecraft", "1.8.9"),
+                component("net.legacyfabric.intermediary", "1.8.9"),
+                component("net.fabricmc.fabric-loader", "0.13.1.4"),
+                component("optifine.OptiFine", "1.8.9_HD_U_M6_pre2"),
+                component("optifabric.OptiFabric", "1.13.16"),
+            ],
+        };
+        let dependencies = mmc_dependencies(&pack).unwrap();
+
+        assert_eq!(
+            dependencies.get(&PackDependency::LegacyFabric),
+            Some(&"0.13.1.4".to_string())
+        );
+        assert_eq!(
+            dependencies.get(&PackDependency::OptiFine),
+            Some(&"1.8.9_HD_U_M6_pre2".to_string())
+        );
+        assert_eq!(
+            dependencies.get(&PackDependency::OptiFabric),
+            Some(&"1.13.16".to_string())
+        );
+    }
+
+    #[test]
+    fn dependencies_reject_labymod_components() {
+        let pack = MMCPack {
+            format_version: 1,
+            components: vec![component("net.labymod.LabyMod", "4.4.20")],
+        };
+
+        assert!(mmc_dependencies(&pack).is_err());
+    }
+}

packages/app-lib/src/api/pack/import/modrinth_app.rs

@@ -0,0 +1,254 @@
+use std::{collections::HashMap, path::PathBuf};
+
+use sqlx::{
+    Row,
+    sqlite::{SqliteConnectOptions, SqlitePoolOptions},
+};
+
+use crate::{
+    State,
+    api::pack::{
+        import::finish_import,
+        install_from::{self, CreatePackDescription, PackDependency},
+    },
+    install::{InstallPhaseDetails, InstallProgressReporter},
+};
+
+async fn open_source_db(
+    base_path: &PathBuf,
+) -> crate::Result<sqlx::SqlitePool> {
+    let db_path = base_path.join("app.db");
+    let options = SqliteConnectOptions::new()
+        .filename(db_path)
+        .read_only(true)
+        .create_if_missing(false);
+
+    Ok(SqlitePoolOptions::new()
+        .max_connections(1)
+        .connect_with(options)
+        .await?)
+}
+
+async fn source_config_dir(
+    base_path: &PathBuf,
+    pool: &sqlx::SqlitePool,
+) -> crate::Result<PathBuf> {
+    let custom_dir: Option<String> =
+        sqlx::query_scalar("SELECT custom_dir FROM settings WHERE id = 0")
+            .fetch_optional(pool)
+            .await?
+            .flatten();
+    Ok(custom_dir.map_or_else(|| base_path.clone(), PathBuf::from))
+}
+
+async fn has_table(
+    pool: &sqlx::SqlitePool,
+    table: &str,
+) -> crate::Result<bool> {
+    let count: i64 = sqlx::query_scalar(
+        "SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = ?",
+    )
+    .bind(table)
+    .fetch_one(pool)
+    .await?;
+    Ok(count > 0)
+}
+
+pub async fn get_importable_instances_with_paths(
+    base_path: PathBuf,
+) -> crate::Result<Vec<(String, PathBuf)>> {
+    let pool = open_source_db(&base_path).await?;
+    let config_dir = source_config_dir(&base_path, &pool).await?;
+    let profiles_dir = config_dir.join("profiles");
+    let rows = if has_table(&pool, "instances").await? {
+        sqlx::query("SELECT path FROM instances ORDER BY name COLLATE NOCASE")
+            .fetch_all(&pool)
+            .await?
+    } else {
+        sqlx::query("SELECT path FROM profiles ORDER BY name COLLATE NOCASE")
+            .fetch_all(&pool)
+            .await?
+    };
+
+    Ok(rows
+        .into_iter()
+        .filter_map(|row| {
+            let path = row.try_get::<String, _>("path").ok()?;
+            let full = profiles_dir.join(&path);
+            full.is_dir().then_some((path, full))
+        })
+        .collect())
+}
+
+pub async fn get_importable_instances(
+    base_path: PathBuf,
+) -> crate::Result<Vec<String>> {
+    get_importable_instances_with_paths(base_path)
+        .await
+        .map(|v| v.into_iter().map(|(n, _)| n).collect())
+}
+
+fn dependencies(
+    game_version: String,
+    loader: String,
+    loader_version: Option<String>,
+) -> crate::Result<HashMap<PackDependency, String>> {
+    let mut dependencies =
+        HashMap::from([(PackDependency::Minecraft, game_version)]);
+    let loader = loader.trim().to_ascii_lowercase();
+    if loader == "vanilla" || loader.is_empty() {
+        return Ok(dependencies);
+    }
+    if loader == "labymod" || loader.starts_with("labymod-") {
+        return Err(crate::ErrorKind::InputError(
+            "Unsupported loader LabyMod: Axolotl does not install, update, or repair LabyMod instances"
+                .to_string(),
+        )
+        .into());
+    }
+
+    let dependency = match loader.as_str() {
+        "fabric" => PackDependency::FabricLoader,
+        "forge" => PackDependency::Forge,
+        "neoforge" | "neo_forge" => PackDependency::NeoForge,
+        "quilt" => PackDependency::QuiltLoader,
+        "optifine" => PackDependency::OptiFine,
+        "cleanroom" => PackDependency::Cleanroom,
+        "lite_loader" | "liteloader" => PackDependency::LiteLoader,
+        "legacy_fabric" | "legacyfabric" => PackDependency::LegacyFabric,
+        _ => {
+            return Err(crate::ErrorKind::InputError(format!(
+                "Unsupported loader {loader}: the instance was not imported as Vanilla"
+            ))
+            .into());
+        }
+    };
+    let loader_version = loader_version
+        .filter(|version| !version.trim().is_empty())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Modrinth source instance is missing the {loader} version and was not imported as Vanilla"
+            ))
+        })?;
+    dependencies.insert(dependency, loader_version);
+    Ok(dependencies)
+}
+
+pub async fn import_instance(
+    base_path: PathBuf,
+    instance_path: String,
+    instance_id: &str,
+    reporter: InstallProgressReporter,
+    details: InstallPhaseDetails,
+    symlink: bool,
+) -> crate::Result<()> {
+    let pool = open_source_db(&base_path).await?;
+    let config_dir = source_config_dir(&base_path, &pool).await?;
+    let source = config_dir.join("profiles").join(&instance_path);
+
+    let (name, game_version, loader, loader_version, icon_path) = if has_table(
+        &pool,
+        "instances",
+    )
+    .await?
+    {
+        let row = sqlx::query(
+                "SELECT i.name, s.game_version, s.loader, s.loader_version, i.icon_path \
+                 FROM instances i JOIN instance_content_sets s \
+                 ON s.id = i.applied_content_set_id WHERE i.path = ?",
+            )
+            .bind(&instance_path)
+            .fetch_one(&pool)
+            .await?;
+        (
+            row.try_get("name")?,
+            row.try_get("game_version")?,
+            row.try_get("loader")?,
+            row.try_get("loader_version")?,
+            row.try_get::<Option<String>, _>("icon_path")?,
+        )
+    } else {
+        let row = sqlx::query(
+            "SELECT name, game_version, mod_loader AS loader, \
+                 mod_loader_version AS loader_version, icon_path \
+                 FROM profiles WHERE path = ?",
+        )
+        .bind(&instance_path)
+        .fetch_one(&pool)
+        .await?;
+        (
+            row.try_get("name")?,
+            row.try_get("game_version")?,
+            row.try_get("loader")?,
+            row.try_get("loader_version")?,
+            row.try_get::<Option<String>, _>("icon_path")?,
+        )
+    };
+
+    let icon = match icon_path {
+        Some(path) => super::recache_icon(config_dir.join(path)).await?,
+        None => None,
+    };
+    let description = CreatePackDescription {
+        icon,
+        override_title: Some(name),
+        project_id: None,
+        version_id: None,
+        instance_id: instance_id.to_string(),
+        source_filename: None,
+    };
+    install_from::set_instance_information(
+        instance_id.to_string(),
+        &description,
+        "Imported from Modrinth source installation",
+        None,
+        &dependencies(game_version, loader, loader_version)?,
+        false,
+    )
+    .await?;
+
+    let state = State::get().await?;
+    finish_import(
+        instance_id,
+        source,
+        &state.io_semaphore,
+        reporter,
+        details,
+        symlink,
+    )
+    .await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn source_dependencies_preserve_supported_loaders() {
+        let dependencies = dependencies(
+            "1.12.2".to_string(),
+            "cleanroom".to_string(),
+            Some("0.6.11-alpha".to_string()),
+        )
+        .unwrap();
+
+        assert_eq!(
+            dependencies.get(&PackDependency::Cleanroom),
+            Some(&"0.6.11-alpha".to_string())
+        );
+    }
+
+    #[test]
+    fn source_dependencies_reject_labymod_and_missing_versions() {
+        for result in [
+            dependencies(
+                "1.20.1".to_string(),
+                "labymod".to_string(),
+                Some("4.4.20".to_string()),
+            ),
+            dependencies("1.12.2".to_string(), "lite_loader".to_string(), None),
+        ] {
+            assert!(result.is_err());
+        }
+    }
+}

packages/app-lib/src/api/pack/import/pcl.rs

@@ -0,0 +1,109 @@
+use std::path::{Path, PathBuf};
+
+use serde::Deserialize;
+
+#[cfg(target_os = "windows")]
+pub fn read_pcl_registry() -> Option<String> {
+    use winreg::enums::HKEY_CURRENT_USER;
+    let hkcu = winreg::RegKey::predef(HKEY_CURRENT_USER);
+    let key = hkcu.open_subkey("SOFTWARE\\PCL").ok()?;
+    let value: String = key.get_value("LaunchFolders").ok()?;
+    tracing::debug!(raw = %value, "read_pcl_registry: read LaunchFolders from HKCU\\SOFTWARE\\PCL");
+    Some(value)
+}
+
+#[cfg(not(target_os = "windows"))]
+pub fn read_pcl_registry() -> Option<String> {
+    None
+}
+
+#[derive(Debug, Deserialize)]
+struct PclCeConfig {
+    #[serde(rename = "LaunchFolders")]
+    launch_folders: Option<String>,
+}
+
+fn read_pclce_config() -> Option<String> {
+    let path = dirs::data_dir()?.join("PCLCE").join("config.v1.json");
+    tracing::debug!(path = %path.display(), "read_pclce_config: attempting to read config file");
+    let content = std::fs::read_to_string(&path).inspect_err(|e| {
+        tracing::debug!(path = %path.display(), error = %e, "read_pclce_config: failed to read file");
+    }).ok()?;
+    let config: PclCeConfig = serde_json::from_str(&content).inspect_err(|e| {
+        tracing::debug!(path = %path.display(), error = %e, "read_pclce_config: failed to parse JSON");
+    }).ok()?;
+    let launch_folders = config.launch_folders.as_deref().unwrap_or("");
+    tracing::debug!(launch_folders = %launch_folders, "read_pclce_config: parsed LaunchFolders");
+    config.launch_folders
+}
+
+fn parse_pcl_folders(raw: &str) -> Vec<(String, String)> {
+    let mut result = Vec::new();
+    for entry in raw.split('|') {
+        let entry = entry.trim();
+        if entry.is_empty() {
+            continue;
+        }
+        if let Some((name, path)) = entry.split_once('>') {
+            let path = PathBuf::from(path.trim());
+            let exists = path.is_dir();
+            tracing::debug!(
+                entry = %entry,
+                name = %name.trim(),
+                path = %path.display(),
+                exists = exists,
+                "parse_pcl_folders: entry"
+            );
+            if exists {
+                result.push((
+                    name.trim().to_string(),
+                    path.to_string_lossy().to_string(),
+                ));
+            }
+        } else {
+            tracing::debug!(entry = %entry, "parse_pcl_folders: malformed entry (no '>' separator)");
+        }
+    }
+    result.sort_by(|a, b| a.0.cmp(&b.0));
+    tracing::debug!(count = result.len(), raw = %raw, "parse_pcl_folders: done");
+    result
+}
+
+pub fn config_exists() -> bool {
+    let exists = read_pclce_config().is_some();
+    tracing::debug!(exists = exists, "config_exists");
+    exists
+}
+
+pub fn get_pcl_instances() -> Vec<(String, String)> {
+    let raw = read_pcl_registry().unwrap_or_default();
+    let instances = parse_pcl_folders(&raw);
+    tracing::info!(count = instances.len(), "get_pcl_instances");
+    instances
+}
+
+pub fn get_pclce_instances() -> Vec<(String, String)> {
+    let raw = read_pclce_config().unwrap_or_default();
+    let instances = parse_pcl_folders(&raw);
+    tracing::info!(count = instances.len(), "get_pclce_instances");
+    instances
+}
+
+/// Checks if a `.minecraft` folder exists next to the launcher (i.e. at
+/// `base_path/.minecraft`) and returns it as a `(name, path)` pair suitable
+/// for merging into the GameDir list.
+pub fn get_local_dotminecraft(base_path: &Path) -> Option<(String, String)> {
+    let dot_mc = base_path.join(".minecraft");
+    if dot_mc.is_dir() {
+        tracing::debug!(
+            path = %dot_mc.display(),
+            "get_local_dotminecraft: found .minecraft next to launcher"
+        );
+        Some((
+            ".minecraft".to_string(),
+            dot_mc.to_string_lossy().to_string(),
+        ))
+    } else {
+        None
+    }
+}

packages/app-lib/src/api/pack/import/pe_info.rs

@@ -0,0 +1,148 @@
+#[cfg(target_os = "windows")]
+mod imp {
+    use std::ffi::OsStr;
+    use std::os::windows::ffi::OsStrExt;
+    use std::path::Path;
+
+    pub fn get_product_name(path: &Path) -> Option<String> {
+        use windows::Win32::Storage::FileSystem::{
+            GetFileVersionInfoSizeW, GetFileVersionInfoW, VerQueryValueW,
+        };
+        use windows::core::PCWSTR;
+
+        let wide: Vec<u16> = path
+            .as_os_str()
+            .encode_wide()
+            .chain(std::iter::once(0))
+            .collect();
+
+        let mut unused = 0u32;
+        let size = unsafe {
+            GetFileVersionInfoSizeW(
+                PCWSTR::from_raw(wide.as_ptr()),
+                Some(&raw mut unused),
+            )
+        };
+        if size == 0 {
+            return None;
+        }
+
+        let mut buffer = vec![0u8; size as usize];
+
+        let ok = unsafe {
+            GetFileVersionInfoW(
+                PCWSTR::from_raw(wide.as_ptr()),
+                Some(0),
+                size,
+                buffer.as_mut_ptr() as *mut _,
+            )
+        };
+        if ok.is_err() {
+            return None;
+        }
+
+        let sub = OsStr::new("\\VarFileInfo\\Translation")
+            .encode_wide()
+            .chain(std::iter::once(0))
+            .collect::<Vec<u16>>();
+
+        let mut lang_ptr = std::ptr::null_mut::<std::ffi::c_void>();
+        let mut lang_len = 0u32;
+
+        let ok = unsafe {
+            VerQueryValueW(
+                buffer.as_ptr() as *const _,
+                PCWSTR::from_raw(sub.as_ptr()),
+                &raw mut lang_ptr,
+                &raw mut lang_len,
+            )
+        };
+        if ok.0 == 0 || lang_len == 0 || lang_ptr.is_null() {
+            return None;
+        }
+
+        // lang_len from VerQueryValueW(Translation) is in bytes, not characters
+        let lang_len_u16 = (lang_len / 2) as usize;
+        if lang_len_u16 < 2 {
+            return None;
+        }
+        let lang = unsafe {
+            std::slice::from_raw_parts(lang_ptr as *const u16, lang_len_u16)
+        };
+        let block = format!(
+            "\\StringFileInfo\\{:04x}{:04x}\\ProductName",
+            lang[0], lang[1]
+        );
+        let block_wide: Vec<u16> = OsStr::new(&block)
+            .encode_wide()
+            .chain(std::iter::once(0))
+            .collect();
+
+        let mut val_ptr = std::ptr::null_mut::<std::ffi::c_void>();
+        let mut val_len = 0u32;
+
+        let ok = unsafe {
+            VerQueryValueW(
+                buffer.as_ptr() as *const _,
+                PCWSTR::from_raw(block_wide.as_ptr()),
+                &raw mut val_ptr,
+                &raw mut val_len,
+            )
+        };
+        if ok.0 == 0 || val_len == 0 || val_ptr.is_null() {
+            return None;
+        }
+
+        let slice = unsafe {
+            std::slice::from_raw_parts(
+                val_ptr as *const u16,
+                val_len as usize - 1,
+            )
+        };
+        String::from_utf16(slice).ok()
+    }
+
+    pub fn folder_has_product(base_path: &Path, product_name: &str) -> bool {
+        if !base_path.is_dir() {
+            return false;
+        }
+        let Ok(read_dir) = std::fs::read_dir(base_path) else {
+            return false;
+        };
+        for entry in read_dir.flatten() {
+            let p = entry.path();
+            if p.extension().map(|e| e == "exe").unwrap_or(false)
+                && let Some(product) = get_product_name(&p)
+                && product.contains(product_name)
+            {
+                return true;
+            }
+        }
+        false
+    }
+}
+
+#[cfg(not(target_os = "windows"))]
+mod imp {
+    use std::path::Path;
+    pub fn folder_has_product(_base_path: &Path, _product_name: &str) -> bool {
+        false
+    }
+}
+
+pub use imp::folder_has_product;
+
+pub fn folder_has_product_result(
+    path: &std::path::Path,
+    product_name: &str,
+) -> Result<bool, String> {
+    #[cfg(target_os = "windows")]
+    {
+        Ok(folder_has_product(path, product_name))
+    }
+    #[cfg(not(target_os = "windows"))]
+    {
+        let _ = (path, product_name);
+        Err("PE detection is only available on Windows".to_string())
+    }
+}

packages/app-lib/src/api/pack/install_from.rs

@@ -0,0 +1,774 @@
+use crate::State;
+use crate::api::pack::detect::detect_local_pack_sync;
+use crate::data::ModLoader;
+use crate::install::{
+    InstallErrorContext, InstallJobEventKind, InstallPhaseDetails,
+    InstallPhaseId, InstallProgress, InstallProgressReporter,
+};
+use crate::state::{
+    AppliedContentSetPatch, CacheBehaviour, CachedEntry, ContentSourceKind,
+    EditInstance, InstanceInstallStage, InstanceLink, LoaderComponent,
+    LoaderComponentKind, LoaderComponentRole, ModrinthProjectId,
+    ModrinthVersionId, SideType,
+};
+use crate::util::fetch::{
+    ContentValidation, DownloadMeta, DownloadReason, DownloadRequest,
+    FetchProgressFn, Integrity, ResourceClass, download_to_path, fetch,
+    sha1_file_async, write_cached_icon,
+};
+use path_util::SafeRelativeUtf8UnixPathBuf;
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+use std::future::Future;
+
+use std::path::{Component, Path, PathBuf};
+use std::pin::Pin;
+
+use zip::ZipArchive;
+
+#[derive(Serialize, Deserialize, Eq, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct PackFormat {
+    pub game: String,
+    pub format_version: i32,
+    pub version_id: String,
+    pub name: String,
+    pub summary: Option<String>,
+    pub files: Vec<PackFile>,
+    pub dependencies: HashMap<PackDependency, String>,
+}
+
+#[derive(Serialize, Deserialize, Clone, Eq, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct PackFile {
+    pub path: SafeRelativeUtf8UnixPathBuf,
+    pub hashes: HashMap<PackFileHash, String>,
+    pub env: Option<HashMap<EnvType, SideType>>,
+    pub downloads: Vec<String>,
+    pub file_size: u32,
+}
+
+#[derive(Serialize, Deserialize, Clone, Eq, PartialEq, Hash)]
+#[serde(rename_all = "camelCase", from = "String")]
+pub enum PackFileHash {
+    Sha1,
+    Sha512,
+    Unknown(String),
+}
+
+impl From<String> for PackFileHash {
+    fn from(s: String) -> Self {
+        match s.as_str() {
+            "sha1" => PackFileHash::Sha1,
+            "sha512" => PackFileHash::Sha512,
+            _ => PackFileHash::Unknown(s),
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize, Clone, Eq, PartialEq, Hash)]
+#[serde(rename_all = "camelCase")]
+pub enum EnvType {
+    Client,
+    Server,
+}
+
+#[derive(Serialize, Deserialize, Clone, Copy, Hash, PartialEq, Eq, Debug)]
+pub enum PackDependency {
+    #[serde(rename = "forge")]
+    Forge,
+
+    #[serde(rename = "neoforge")]
+    #[serde(alias = "neo-forge")]
+    NeoForge,
+
+    #[serde(rename = "fabric-loader")]
+    FabricLoader,
+
+    #[serde(rename = "quilt-loader")]
+    QuiltLoader,
+
+    #[serde(rename = "optifine")]
+    OptiFine,
+
+    #[serde(rename = "cleanroom")]
+    Cleanroom,
+
+    #[serde(rename = "lite_loader", alias = "liteloader")]
+    LiteLoader,
+
+    #[serde(rename = "legacy_fabric", alias = "legacyfabric")]
+    LegacyFabric,
+
+    #[serde(rename = "optifabric")]
+    OptiFabric,
+
+    #[serde(rename = "minecraft")]
+    Minecraft,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "camelCase", tag = "type")]
+pub enum CreatePackLocation {
+    // Create a pack from a modrinth version ID (such as a modpack)
+    FromVersionId {
+        project_id: String,
+        version_id: String,
+        title: String,
+        icon_url: Option<String>,
+    },
+    // Create a pack from a file (such as an .mrpack for installing from a file, or a folder name for importing)
+    FromFile {
+        path: PathBuf,
+    },
+}
+
+#[derive(Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct CreatePackInstance {
+    pub name: String, // the name of the instance and relative path
+    pub game_version: String, // the game version of the instance
+    pub modloader: ModLoader, // the modloader to use
+    pub loader_version: Option<String>, // the modloader version to use, set to "latest", "stable", or the ID of your chosen loader. defaults to latest
+    pub icon: Option<PathBuf>,          // the icon for the instance
+    pub icon_url: Option<String>, // the URL icon for an instance during import
+    pub link: Option<InstanceLink>,
+    pub unknown_file: bool, // true when pack file isn't found on Modrinth via hash lookup
+    pub skip_install_profile: Option<bool>,
+    pub no_watch: Option<bool>,
+}
+
+// default
+impl Default for CreatePackInstance {
+    fn default() -> Self {
+        CreatePackInstance {
+            name: "Untitled".to_string(),
+            game_version: "1.19.4".to_string(),
+            modloader: ModLoader::Vanilla,
+            loader_version: None,
+            icon: None,
+            icon_url: None,
+            link: None,
+            unknown_file: false,
+            skip_install_profile: Some(true),
+            no_watch: Some(false),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub enum CreatePackFile {
+    Bytes(bytes::Bytes),
+    // Local packs can be larger than available memory, so keep them file-backed.
+    Path(PathBuf),
+}
+
+#[derive(Clone)]
+pub struct CreatePack {
+    pub file: CreatePackFile,
+    pub description: CreatePackDescription,
+}
+
+// The hash lookup only gates the unknown-pack warning, so avoid a long blocking scan for huge local packs.
+const MAX_LOCAL_FILE_HASH_LOOKUP_SIZE: u64 = 1024 * 1024 * 1024;
+
+#[derive(Clone, Debug)]
+pub struct CreatePackDescription {
+    pub icon: Option<PathBuf>,
+    pub override_title: Option<String>,
+    pub project_id: Option<String>,
+    pub version_id: Option<String>,
+    pub instance_id: String,
+    pub source_filename: Option<String>,
+}
+
+pub async fn get_instance_from_pack(
+    location: CreatePackLocation,
+) -> crate::Result<CreatePackInstance> {
+    match location {
+        CreatePackLocation::FromVersionId {
+            project_id,
+            version_id,
+            title,
+            icon_url,
+        } => Ok(CreatePackInstance {
+            name: title,
+            icon_url,
+            link: Some(InstanceLink::ModrinthModpack {
+                project_id,
+                version_id,
+            }),
+            ..Default::default()
+        }),
+        CreatePackLocation::FromFile { path } => {
+            let file_name = path
+                .file_stem()
+                .unwrap_or_default()
+                .to_string_lossy()
+                .to_string();
+
+            // Validate ZIP structure before proceeding — fail fast on corrupt archives
+            // rather than discovering the error later during extraction.
+            let file = std::fs::File::open(&path)
+                .map_err(crate::ErrorKind::StdIOError)?;
+            ZipArchive::new(file).map_err(|e| {
+                crate::ErrorKind::InputError(format!(
+                    "Invalid or corrupt modpack archive ({}): {e}",
+                    path.display()
+                ))
+            })?;
+
+            // Scan ZIP entry names to detect pack format (no extraction, just
+            // reads the central directory). This tells us what kind of content
+            // we're dealing with before any expensive operations.
+            let _has_known_manifest = detect_local_pack_sync(&path).is_ok();
+
+            let is_known_file = if tokio::fs::metadata(&path).await?.len()
+                <= MAX_LOCAL_FILE_HASH_LOOKUP_SIZE
+            {
+                let state = State::get().await?;
+                let (_, hash) = sha1_file_async(&path).await?;
+                match CachedEntry::get_file_many(
+                    &[&hash],
+                    Some(CacheBehaviour::StaleWhileRevalidateSkipOffline),
+                    &state.pool,
+                    &state.api_semaphore,
+                )
+                .await
+                {
+                    Ok(files) => !files.is_empty(),
+                    Err(err) => {
+                        tracing::warn!(
+                            "Failed to check Modrinth file hash for {}: {}",
+                            path.display(),
+                            err
+                        );
+                        false
+                    }
+                }
+            } else {
+                false
+            };
+
+            Ok(CreatePackInstance {
+                name: file_name,
+                unknown_file: !is_known_file,
+                ..Default::default()
+            })
+        }
+    }
+}
+
+#[tracing::instrument(skip(reporter))]
+#[allow(clippy::too_many_arguments)]
+pub(crate) async fn generate_pack_from_version_id_with_reporter(
+    project_id: String,
+    version_id: String,
+    title: String,
+    icon_url: Option<String>,
+    instance_id: String,
+    reason: DownloadReason,
+    reporter: InstallProgressReporter,
+) -> crate::Result<CreatePack> {
+    let state = State::get().await?;
+    let has_icon_url = icon_url.is_some();
+
+    let version = CachedEntry::get_version(
+        &ModrinthVersionId::new(version_id.clone())?,
+        Some(CacheBehaviour::Bypass),
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "Invalid version ID specified!".to_string(),
+        )
+    })?;
+
+    // Update instance with correct loader and game version from the API version metadata,
+    // so the UI shows accurate info while the pack file is still downloading.
+    if let Some(game_version) = version.game_versions.first() {
+        let loader = version
+            .loaders
+            .first()
+            .map(|loader| ModLoader::try_from_string(loader))
+            .transpose()?
+            .unwrap_or(ModLoader::Vanilla);
+        let game_version = game_version.clone();
+        crate::api::instance::edit(
+            &instance_id,
+            EditInstance {
+                content_set_patch: Some(AppliedContentSetPatch {
+                    source_kind: None,
+                    game_version: Some(game_version),
+                    protocol_version: Some(None),
+                    loader: Some(loader),
+                    loader_version: None,
+                }),
+                ..EditInstance::default()
+            },
+        )
+        .await?;
+    }
+
+    let pack_file = version
+        .files
+        .iter()
+        .find(|file| file.primary)
+        .or_else(|| version.files.first())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "Specified version has no files".to_string(),
+            )
+        })?;
+    let file_name = Path::new(&pack_file.filename);
+    if file_name.components().count() != 1
+        || !matches!(file_name.components().next(), Some(Component::Normal(_)))
+    {
+        return Err(crate::ErrorKind::InputError(
+            "Modrinth returned an invalid modpack file name".to_string(),
+        )
+        .into());
+    }
+    let hash = pack_file.hashes.get("sha1");
+    let pack_path = state
+        .directories
+        .caches_dir()
+        .join("modpacks")
+        .join(&project_id)
+        .join(&version_id)
+        .join(file_name);
+
+    let metadata =
+        crate::api::instance::get(&instance_id)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Unknown instance {instance_id}"
+                ))
+            })?;
+
+    let download_meta = DownloadMeta {
+        reason,
+        game_version: metadata.applied_content_set.game_version.clone(),
+        loader: metadata.applied_content_set.loader.as_str().to_string(),
+        dependent_on: Some(version_id.clone()),
+    };
+
+    let details = InstallPhaseDetails::Modpack {
+        project_id: Some(project_id.clone()),
+        version_id: Some(version_id.clone()),
+        title: Some(title.clone()),
+    };
+    let mut last_reported_bytes = 0_u64;
+    let mut progress =
+        |current: u64,
+         total: u64|
+         -> Pin<Box<dyn Future<Output = crate::Result<()>> + Send>> {
+            let min_delta = (total / 200).max(256 * 1024);
+            if current < total
+                && current.saturating_sub(last_reported_bytes) < min_delta
+            {
+                return Box::pin(async { Ok(()) });
+            }
+
+            last_reported_bytes = current;
+            let reporter = reporter.clone();
+            let details = details.clone();
+            Box::pin(async move {
+                reporter
+                    .update(
+                        InstallPhaseId::DownloadingPackFile,
+                        Some(InstallProgress {
+                            current,
+                            total,
+                            secondary: None,
+                        }),
+                        details,
+                    )
+                    .await?;
+                Ok(())
+            })
+        };
+    let progress = Some(&mut progress as &mut FetchProgressFn<'_>);
+
+    let context = InstallErrorContext::new("download modpack file")
+        .urls(vec![pack_file.url.clone()])
+        .maybe_expected_hash(hash.cloned())
+        .expected_size(pack_file.size as u64)
+        .target_path(pack_path.display().to_string())
+        .project_id(project_id.clone())
+        .version_id(version_id.clone())
+        .build();
+    reporter.set_context(context).await?;
+    let item_path = pack_path.display().to_string();
+    reporter
+        .update_with_events(
+            InstallPhaseId::DownloadingPackFile,
+            Some(InstallProgress {
+                current: 0,
+                total: pack_file.size.max(1) as u64,
+                secondary: None,
+            }),
+            details.clone(),
+            vec![InstallJobEventKind::ContentFileQueued {
+                path: item_path,
+                bytes_total: Some(pack_file.size as u64),
+                max_attempts: 5,
+            }],
+        )
+        .await?;
+    reporter.persist().await?;
+    let download_result = download_to_path(
+        DownloadRequest::new(&pack_file.url, ResourceClass::Modpack)
+            .with_integrity(Integrity {
+                size: Some(pack_file.size as u64),
+                sha1: hash.cloned(),
+                sha512: pack_file.hashes.get("sha512").cloned(),
+                content: ContentValidation::Jar,
+                ..Integrity::default()
+            })
+            .with_h2_range_concurrency(16)
+            .with_download_meta(download_meta)
+            .with_install_tracking(
+                reporter.clone(),
+                pack_path.display().to_string(),
+                pack_file.filename.clone(),
+            ),
+        &pack_path,
+        &state.download_semaphore,
+        &state.pool,
+        progress,
+    )
+    .await?;
+    if download_result.attempts > 0 {
+        reporter
+            .record_download_metrics(
+                download_result.source.as_str(),
+                download_result.fallback_count as u64,
+            )
+            .await?;
+    }
+
+    reporter
+        .update(InstallPhaseId::ResolvingPack, None, details.clone())
+        .await?;
+
+    let project = CachedEntry::get_project(
+        &ModrinthProjectId::new(version.project_id.clone())?,
+        None,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(
+            "Invalid project ID specified!".to_string(),
+        )
+    })?;
+
+    // Only fetch the pack icon when icon_url is provided (new profile).
+    // When installing to an existing profile (e.g. server projects),
+    // icon_url is None and we preserve the profile's existing icon.
+    let icon = if has_icon_url {
+        if let Some(icon_url) = project.icon_url {
+            let state = State::get().await?;
+            reporter
+                .set_context(
+                    InstallErrorContext::new("download modpack icon")
+                        .urls(vec![icon_url.clone()])
+                        .project_id(project_id.clone())
+                        .version_id(version_id.clone())
+                        .build(),
+                )
+                .await?;
+            let icon_bytes = fetch(
+                &icon_url,
+                None,
+                None,
+                None,
+                &state.fetch_semaphore,
+                &state.pool,
+            )
+            .await?;
+
+            let filename = icon_url.rsplit('/').next();
+
+            if let Some(filename) = filename {
+                Some(
+                    write_cached_icon(
+                        filename,
+                        &state.directories.caches_dir(),
+                        icon_bytes,
+                        &state.io_semaphore,
+                    )
+                    .await?,
+                )
+            } else {
+                None
+            }
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
+    // Set the icon immediately so the UI shows it during download.
+    if let Some(ref icon_path) = icon {
+        let _ = crate::api::instance::edit_icon(
+            &instance_id,
+            Some(icon_path.as_path()),
+        )
+        .await;
+    }
+
+    Ok(CreatePack {
+        file: CreatePackFile::Path(pack_path),
+        description: CreatePackDescription {
+            icon,
+            override_title: Some(title),
+            project_id: Some(project_id),
+            version_id: Some(version_id),
+            instance_id,
+            source_filename: None,
+        },
+    })
+}
+
+#[tracing::instrument]
+
+pub async fn generate_pack_from_file(
+    path: PathBuf,
+    instance_id: String,
+) -> crate::Result<CreatePack> {
+    let source_filename =
+        path.file_name().map(|x| x.to_string_lossy().to_string());
+
+    Ok(CreatePack {
+        file: CreatePackFile::Path(path),
+        description: CreatePackDescription {
+            icon: None,
+            override_title: None,
+            project_id: None,
+            version_id: None,
+            instance_id,
+            source_filename,
+        },
+    })
+}
+
+/// Sets generated instance attributes to the pack ones.
+/// This includes the pack name, icon, game version, loader version, and loader
+pub async fn set_instance_information(
+    instance_id: String,
+    description: &CreatePackDescription,
+    backup_name: &str,
+    pack_version_id: Option<&str>,
+    dependencies: &HashMap<PackDependency, String>,
+    _ignore_lock: bool,
+) -> crate::Result<()> {
+    let mut game_version: Option<&String> = None;
+    for (key, value) in dependencies {
+        if *key == PackDependency::Minecraft {
+            game_version = Some(value);
+        }
+    }
+
+    let Some(game_version) = game_version else {
+        return Err(crate::ErrorKind::InputError(
+            "Pack did not specify Minecraft version".to_string(),
+        )
+        .into());
+    };
+
+    let primary_dependencies = [
+        (PackDependency::Forge, ModLoader::Forge),
+        (PackDependency::NeoForge, ModLoader::NeoForge),
+        (PackDependency::FabricLoader, ModLoader::Fabric),
+        (PackDependency::QuiltLoader, ModLoader::Quilt),
+        (PackDependency::Cleanroom, ModLoader::Cleanroom),
+        (PackDependency::LegacyFabric, ModLoader::LegacyFabric),
+    ]
+    .into_iter()
+    .filter(|(dependency, _)| dependencies.contains_key(dependency))
+    .collect::<Vec<_>>();
+    if primary_dependencies.len() > 1 {
+        return Err(crate::ErrorKind::InputError(format!(
+            "Pack declares incompatible primary loaders: {}",
+            primary_dependencies
+                .iter()
+                .map(|(_, loader)| loader.as_str())
+                .collect::<Vec<_>>()
+                .join(", ")
+        ))
+        .into());
+    }
+
+    let primary_loader = primary_dependencies
+        .first()
+        .map(|(_, loader)| *loader)
+        .unwrap_or(ModLoader::Vanilla);
+    let mut components = vec![LoaderComponent::new_primary(
+        instance_id.clone(),
+        primary_loader,
+        None,
+    )];
+    if let Some((dependency, loader)) = primary_dependencies.first() {
+        let version = resolve_pack_loader_version(
+            dependencies,
+            *dependency,
+            *loader,
+            game_version,
+        )
+        .await?;
+        components[0].version = Some(version);
+        components[0].provider_metadata = Some(serde_json::json!({
+            "source": "pack"
+        }));
+    }
+    for (dependency, loader, kind) in [
+        (
+            PackDependency::LiteLoader,
+            ModLoader::LiteLoader,
+            LoaderComponentKind::LiteLoader,
+        ),
+        (
+            PackDependency::OptiFine,
+            ModLoader::OptiFine,
+            LoaderComponentKind::OptiFine,
+        ),
+    ] {
+        if dependencies.contains_key(&dependency) {
+            let version = resolve_pack_loader_version(
+                dependencies,
+                dependency,
+                loader,
+                game_version,
+            )
+            .await?;
+            components.push(LoaderComponent {
+                instance_id: instance_id.clone(),
+                kind,
+                version: Some(version),
+                role: LoaderComponentRole::Adjunct,
+                provider_metadata: Some(serde_json::json!({
+                    "source": "pack"
+                })),
+            });
+        }
+    }
+    if let Some(version) = dependencies
+        .get(&PackDependency::OptiFabric)
+        .filter(|version| !version.trim().is_empty())
+    {
+        components.push(LoaderComponent {
+            instance_id: instance_id.clone(),
+            kind: LoaderComponentKind::OptiFabric,
+            version: Some(version.clone()),
+            role: LoaderComponentRole::Adjunct,
+            provider_metadata: Some(serde_json::json!({
+                "projectId": crate::install::runner::OPTIFABRIC_CURSEFORGE_PROJECT_ID,
+                "provider": "curseforge",
+                "source": "pack"
+            })),
+        });
+    }
+    crate::install::runner::validate_loader_components(&components)?;
+    let (mod_loader, loader_version) =
+        crate::state::project_loader_components(&components)?;
+
+    let link = match (&description.project_id, &description.version_id) {
+        (Some(project_id), Some(version_id)) => {
+            Some(InstanceLink::ModrinthModpack {
+                project_id: project_id.clone(),
+                version_id: version_id.clone(),
+            })
+        }
+        _ if description.source_filename.is_some() => {
+            Some(InstanceLink::ImportedModpack {
+                project_id: None,
+                version_id: None,
+                name: Some(backup_name.to_string()),
+                version_number: pack_version_id.map(ToString::to_string),
+                filename: description.source_filename.clone(),
+            })
+        }
+        _ => None,
+    };
+    let source_kind = match &link {
+        Some(InstanceLink::ModrinthModpack { .. }) => {
+            Some(ContentSourceKind::ModrinthModpack)
+        }
+        Some(InstanceLink::ImportedModpack { .. }) => {
+            Some(ContentSourceKind::ImportedModpack)
+        }
+        _ => None,
+    };
+    crate::api::instance::edit(
+        &instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(
+                description
+                    .override_title
+                    .clone()
+                    .unwrap_or_else(|| backup_name.to_string()),
+            ),
+            icon_path: description
+                .icon
+                .as_ref()
+                .map(|icon| Some(icon.to_string_lossy().to_string())),
+            link,
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind,
+                game_version: Some(game_version.clone()),
+                protocol_version: Some(None),
+                loader: Some(mod_loader),
+                loader_version: Some(loader_version),
+            }),
+            ..EditInstance::default()
+        },
+    )
+    .await?;
+    let state = State::get().await?;
+    crate::state::instances::commands::replace_instance_loader_components(
+        &instance_id,
+        &components,
+        &state.pool,
+    )
+    .await?;
+    Ok(())
+}
+
+async fn resolve_pack_loader_version(
+    dependencies: &HashMap<PackDependency, String>,
+    dependency: PackDependency,
+    loader: ModLoader,
+    game_version: &str,
+) -> crate::Result<String> {
+    let requested = dependencies
+        .get(&dependency)
+        .filter(|version| !version.trim().is_empty())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Pack is missing the {} version",
+                loader.as_str()
+            ))
+        })?;
+    crate::launcher::get_loader_version_from_profile(
+        game_version,
+        loader,
+        Some(requested),
+    )
+    .await?
+    .map(|version| version.id)
+    .ok_or_else(|| {
+        crate::ErrorKind::InputError(format!(
+            "Loader version {requested} is not available for {} {game_version}",
+            loader.as_str()
+        ))
+        .into()
+    })
+}

packages/app-lib/src/api/pack/install_hmcl.rs

@@ -0,0 +1,362 @@
+//! Installer for HMCL modpacks.
+//!
+//! HMCL packs are zips carrying a `modpack.json` with the pack name and game
+//! version, optionally with an MCBBS-style `addons` array declaring loaders;
+//! bundled content ships in a `minecraft/` folder that maps onto the
+//! instance's game directory.
+
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+use super::archive_util;
+use crate::State;
+use crate::data::ModLoader;
+use crate::install::{
+    InstallPhaseDetails, InstallPhaseId, InstallProgressReporter,
+};
+use crate::pack::detect::HMCL_MANIFEST;
+use crate::state::{
+    AppliedContentSetPatch, ContentSourceKind, EditInstance,
+    InstanceInstallStage, InstanceLink,
+};
+
+#[derive(Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+struct HmclManifest {
+    #[serde(default)]
+    name: Option<String>,
+    #[serde(default)]
+    version: Option<String>,
+    #[serde(default)]
+    game_version: Option<String>,
+    #[serde(default)]
+    addons: Vec<HmclAddon>,
+}
+
+#[derive(Deserialize, Debug)]
+struct HmclAddon {
+    id: String,
+    version: String,
+}
+
+pub(crate) async fn install_hmcl_pack_with_reporter(
+    instance_id: String,
+    archive_path: PathBuf,
+    base_folder: String,
+    source_filename: Option<String>,
+    reporter: InstallProgressReporter,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let manifest_json = archive_util::read_archive_entry_to_string(
+        archive_path.clone(),
+        format!("{base_folder}{HMCL_MANIFEST}"),
+    )
+    .await?;
+    let manifest: HmclManifest = serde_json::from_str(&manifest_json)?;
+
+    let mut game_version = manifest
+        .game_version
+        .clone()
+        .filter(|version| !version.trim().is_empty());
+    let mut loader = ModLoader::Vanilla;
+    let mut loader_version = None;
+    let mut optifine_version = None;
+    let mut lite_loader_version = None;
+    for addon in &manifest.addons {
+        match addon.id.to_ascii_lowercase().as_str() {
+            "game" => {
+                if game_version.is_none() {
+                    game_version = Some(addon.version.clone());
+                }
+            }
+            "forge" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "HMCL modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Forge;
+                loader_version = Some(addon.version.clone());
+            }
+            "neoforge" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "HMCL modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::NeoForge;
+                loader_version = Some(addon.version.clone());
+            }
+            "fabric" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "HMCL modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Fabric;
+                loader_version = Some(addon.version.clone());
+            }
+            "quilt" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "HMCL modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Quilt;
+                loader_version = Some(addon.version.clone());
+            }
+            "cleanroom" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "HMCL modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Cleanroom;
+                loader_version = Some(addon.version.clone());
+            }
+            "legacy_fabric" | "legacyfabric" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "HMCL modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::LegacyFabric;
+                loader_version = Some(addon.version.clone());
+            }
+            "lite_loader" | "liteloader" => {
+                lite_loader_version = Some(addon.version.clone());
+            }
+            "optifine" => optifine_version = Some(addon.version.clone()),
+            "labymod" => {
+                return Err(crate::ErrorKind::InputError(
+                    "Unsupported loader LabyMod: Axolotl does not install, update, or repair LabyMod instances"
+                        .to_string(),
+                )
+                .into());
+            }
+            other => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "Unsupported HMCL loader component {other} {}",
+                    addon.version
+                ))
+                .into());
+            }
+        }
+    }
+    let Some(game_version) = game_version else {
+        return Err(crate::ErrorKind::InputError(
+            "HMCL modpack did not specify a Minecraft version".to_string(),
+        )
+        .into());
+    };
+
+    let mut lite_loader_as_adjunct = None;
+    if let Some(lite_loader_version) = lite_loader_version {
+        match loader {
+            ModLoader::Vanilla => {
+                loader = ModLoader::LiteLoader;
+                loader_version = Some(lite_loader_version);
+            }
+            ModLoader::Forge => {
+                lite_loader_as_adjunct = Some(lite_loader_version);
+            }
+            _ => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "LiteLoader is not supported with {}",
+                    loader.as_str()
+                ))
+                .into());
+            }
+        }
+    }
+
+    let mut optifine_as_mod = None;
+    let mut requires_optifabric = false;
+    if let Some(optifine_version) = optifine_version {
+        match loader {
+            ModLoader::Vanilla => {
+                loader = ModLoader::OptiFine;
+                loader_version = Some(optifine_version);
+            }
+            ModLoader::Forge | ModLoader::NeoForge => {
+                optifine_as_mod = Some(optifine_version);
+            }
+            ModLoader::Fabric | ModLoader::LegacyFabric => {
+                optifine_as_mod = Some(optifine_version);
+                requires_optifabric = true;
+            }
+            _ => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "OptiFine is not supported with {}",
+                    loader.as_str()
+                ))
+                .into());
+            }
+        }
+    }
+
+    let pack_name = manifest
+        .name
+        .clone()
+        .filter(|name| !name.trim().is_empty())
+        .or_else(|| {
+            source_filename.as_ref().map(|name| {
+                std::path::Path::new(name)
+                    .file_stem()
+                    .unwrap_or_default()
+                    .to_string_lossy()
+                    .to_string()
+            })
+        })
+        .unwrap_or_else(|| "HMCL Modpack".to_string());
+    let pack_details = InstallPhaseDetails::Modpack {
+        project_id: None,
+        version_id: None,
+        title: Some(pack_name.clone()),
+    };
+    reporter
+        .update(InstallPhaseId::ResolvingPack, None, pack_details.clone())
+        .await?;
+
+    let lite_loader_as_adjunct = if let Some(requested_version) =
+        lite_loader_as_adjunct
+    {
+        Some(
+			crate::launcher::get_loader_version_from_profile(
+				&game_version,
+				ModLoader::LiteLoader,
+				Some(&requested_version),
+			)
+			.await?
+			.ok_or_else(|| {
+				crate::ErrorKind::InputError(format!(
+					"No LiteLoader version {requested_version} supports Minecraft {game_version}"
+				))
+			})?,
+		)
+    } else {
+        None
+    };
+    let optifabric_version = if requires_optifabric {
+        Some(
+            crate::install::runner::resolve_optifabric_version(&game_version)
+                .await?,
+        )
+    } else {
+        None
+    };
+
+    let resolved_loader_version = if loader != ModLoader::Vanilla {
+        crate::launcher::get_loader_version_from_profile(
+            &game_version,
+            loader,
+            loader_version.as_deref(),
+        )
+        .await?
+    } else {
+        None
+    };
+
+    crate::api::instance::edit(
+        &instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(pack_name.clone()),
+            link: Some(InstanceLink::ImportedModpack {
+                project_id: None,
+                version_id: None,
+                name: Some(pack_name.clone()),
+                version_number: manifest.version.clone(),
+                filename: source_filename,
+            }),
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind: Some(ContentSourceKind::ImportedModpack),
+                game_version: Some(game_version.clone()),
+                protocol_version: Some(None),
+                loader: Some(loader),
+                loader_version: Some(
+                    resolved_loader_version.map(|version| version.id),
+                ),
+            }),
+            ..EditInstance::default()
+        },
+    )
+    .await?;
+
+    let minecraft_install =
+        super::parallel_minecraft_install::ParallelMinecraftInstall::start(
+            instance_id.clone(),
+            reporter.clone(),
+        );
+
+    reporter
+        .update(
+            InstallPhaseId::ExtractingOverrides,
+            None,
+            pack_details.clone(),
+        )
+        .await?;
+    let instance_path =
+        crate::api::instance::get_full_path(&instance_id).await?;
+    archive_util::extract_archive_subdir_for_instance(
+        instance_id.clone(),
+        reporter.cancellation_token(),
+        archive_path,
+        format!("{base_folder}minecraft/"),
+        instance_path.clone(),
+    )
+    .await?;
+
+    minecraft_install.join().await?;
+
+    if let Some(lite_loader_version) = lite_loader_as_adjunct {
+        super::install_mcbbs::install_liteloader_component(
+            &state,
+            &instance_id,
+            &game_version,
+            loader,
+            &lite_loader_version,
+        )
+        .await?;
+    }
+    if let Some(optifine_version) = optifine_as_mod {
+        super::install_mcbbs::install_optifine_mod(
+            &state,
+            &instance_id,
+            reporter.cancellation_token(),
+            &game_version,
+            &optifine_version,
+            &instance_path,
+        )
+        .await?;
+        super::install_mcbbs::record_optifine_component(
+            &instance_id,
+            &optifine_version,
+        )
+        .await?;
+    }
+    if let Some(optifabric_version) = optifabric_version {
+        super::install_mcbbs::install_optifabric_component(
+            &instance_id,
+            &game_version,
+            &optifabric_version,
+        )
+        .await?;
+    }
+
+    reporter.clear_context().await?;
+    Ok(())
+}

packages/app-lib/src/api/pack/install_mcbbs.rs

@@ -0,0 +1,615 @@
+//! Installer for MCBBS modpacks.
+//!
+//! MCBBS packs are zips carrying either an `mcbbs.packmeta` file or a
+//! `manifest.json` with an `addons` array. Game and loader versions come from
+//! the addons list, bundled content ships in `overrides/`, and optional
+//! launch settings come from `launchInfo`.
+
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+use super::archive_util;
+use crate::State;
+use crate::data::ModLoader;
+use crate::install::{
+    InstallPhaseDetails, InstallPhaseId, InstallProgressReporter,
+};
+use crate::pack::detect::{CURSEFORGE_MANIFEST, MCBBS_MANIFEST};
+use crate::state::{
+    AppliedContentSetPatch, ContentSourceKind, EditInstance,
+    InstanceInstallStage, InstanceLaunchOverridesPatch, InstanceLink,
+};
+
+#[derive(Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+struct McbbsManifest {
+    #[serde(default)]
+    name: Option<String>,
+    #[serde(default)]
+    version: Option<String>,
+    #[serde(default)]
+    addons: Vec<McbbsAddon>,
+    #[serde(default)]
+    files: Vec<McbbsFile>,
+    #[serde(default)]
+    launch_info: Option<McbbsLaunchInfo>,
+}
+
+#[derive(Deserialize, Debug)]
+struct McbbsAddon {
+    id: String,
+    version: String,
+}
+
+/// A `files` entry; `curse` entries carry CurseForge project/file ids while
+/// `addition` entries ship inside the overrides folder and need no download.
+#[derive(Deserialize, Debug)]
+struct McbbsFile {
+    #[serde(default, rename = "type")]
+    type_: Option<String>,
+    #[serde(default, alias = "projectID", alias = "projectId")]
+    project_id: Option<u32>,
+    #[serde(default, alias = "fileID", alias = "fileId")]
+    file_id: Option<u32>,
+}
+
+#[derive(Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+struct McbbsLaunchInfo {
+    #[serde(default)]
+    java_argument: Option<serde_json::Value>,
+}
+
+fn join_arguments(value: &serde_json::Value) -> Vec<String> {
+    match value {
+        serde_json::Value::String(value) => vec![value.clone()],
+        serde_json::Value::Array(values) => values
+            .iter()
+            .filter_map(|value| value.as_str().map(str::to_string))
+            .collect(),
+        _ => Vec::new(),
+    }
+}
+
+pub(crate) async fn install_mcbbs_pack_with_reporter(
+    instance_id: String,
+    archive_path: PathBuf,
+    base_folder: String,
+    source_filename: Option<String>,
+    reporter: InstallProgressReporter,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+
+    let manifest_json = match archive_util::read_archive_entry_to_string(
+        archive_path.clone(),
+        format!("{base_folder}{MCBBS_MANIFEST}"),
+    )
+    .await
+    {
+        Ok(contents) => contents,
+        Err(_) => {
+            archive_util::read_archive_entry_to_string(
+                archive_path.clone(),
+                format!("{base_folder}{CURSEFORGE_MANIFEST}"),
+            )
+            .await?
+        }
+    };
+    let manifest: McbbsManifest = serde_json::from_str(&manifest_json)?;
+
+    let mut game_version = None;
+    let mut loader = ModLoader::Vanilla;
+    let mut loader_version = None;
+    let mut optifine_version = None;
+    let mut lite_loader_version = None;
+    for addon in &manifest.addons {
+        match addon.id.to_ascii_lowercase().as_str() {
+            "game" => game_version = Some(addon.version.clone()),
+            "forge" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCBBS modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Forge;
+                loader_version = Some(addon.version.clone());
+            }
+            "neoforge" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCBBS modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::NeoForge;
+                loader_version = Some(addon.version.clone());
+            }
+            "fabric" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCBBS modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Fabric;
+                loader_version = Some(addon.version.clone());
+            }
+            "quilt" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCBBS modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Quilt;
+                loader_version = Some(addon.version.clone());
+            }
+            "cleanroom" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCBBS modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::Cleanroom;
+                loader_version = Some(addon.version.clone());
+            }
+            "legacy_fabric" | "legacyfabric" => {
+                if loader != ModLoader::Vanilla {
+                    return Err(crate::ErrorKind::InputError(
+                        "MCBBS modpack declares multiple primary loaders"
+                            .to_string(),
+                    )
+                    .into());
+                }
+                loader = ModLoader::LegacyFabric;
+                loader_version = Some(addon.version.clone());
+            }
+            "lite_loader" | "liteloader" => {
+                lite_loader_version = Some(addon.version.clone());
+            }
+            "optifine" => optifine_version = Some(addon.version.clone()),
+            "labymod" => {
+                return Err(crate::ErrorKind::InputError(
+                    "Unsupported loader LabyMod: Axolotl does not install, update, or repair LabyMod instances"
+                        .to_string(),
+                )
+                .into());
+            }
+            other => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "Unsupported MCBBS loader component {other} {}",
+                    addon.version
+                ))
+                .into());
+            }
+        }
+    }
+    let Some(game_version) = game_version else {
+        return Err(crate::ErrorKind::InputError(
+            "MCBBS modpack did not specify a Minecraft version".to_string(),
+        )
+        .into());
+    };
+
+    let mut lite_loader_as_adjunct = None;
+    if let Some(lite_loader_version) = lite_loader_version {
+        match loader {
+            ModLoader::Vanilla => {
+                loader = ModLoader::LiteLoader;
+                loader_version = Some(lite_loader_version);
+            }
+            ModLoader::Forge => {
+                lite_loader_as_adjunct = Some(lite_loader_version);
+            }
+            _ => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "LiteLoader is not supported with {}",
+                    loader.as_str()
+                ))
+                .into());
+            }
+        }
+    }
+
+    let mut optifine_as_mod = None;
+    let mut requires_optifabric = false;
+    if let Some(optifine_version) = optifine_version {
+        match loader {
+            ModLoader::Vanilla => {
+                loader = ModLoader::OptiFine;
+                loader_version = Some(optifine_version);
+            }
+            ModLoader::Forge | ModLoader::NeoForge => {
+                optifine_as_mod = Some(optifine_version);
+            }
+            ModLoader::Fabric | ModLoader::LegacyFabric => {
+                optifine_as_mod = Some(optifine_version);
+                requires_optifabric = true;
+            }
+            _ => {
+                return Err(crate::ErrorKind::InputError(format!(
+                    "OptiFine is not supported with {}",
+                    loader.as_str()
+                ))
+                .into());
+            }
+        }
+    }
+
+    let pack_name = manifest
+        .name
+        .clone()
+        .filter(|name| !name.trim().is_empty())
+        .or_else(|| {
+            source_filename.as_ref().map(|name| {
+                std::path::Path::new(name)
+                    .file_stem()
+                    .unwrap_or_default()
+                    .to_string_lossy()
+                    .to_string()
+            })
+        })
+        .unwrap_or_else(|| "MCBBS Modpack".to_string());
+    let pack_details = InstallPhaseDetails::Modpack {
+        project_id: None,
+        version_id: None,
+        title: Some(pack_name.clone()),
+    };
+    reporter
+        .update(InstallPhaseId::ResolvingPack, None, pack_details.clone())
+        .await?;
+
+    let lite_loader_as_adjunct = if let Some(requested_version) =
+        lite_loader_as_adjunct
+    {
+        Some(
+			crate::launcher::get_loader_version_from_profile(
+				&game_version,
+				ModLoader::LiteLoader,
+				Some(&requested_version),
+			)
+			.await?
+			.ok_or_else(|| {
+				crate::ErrorKind::InputError(format!(
+					"No LiteLoader version {requested_version} supports Minecraft {game_version}"
+				))
+			})?,
+		)
+    } else {
+        None
+    };
+    let optifabric_version = if requires_optifabric {
+        Some(
+            crate::install::runner::resolve_optifabric_version(&game_version)
+                .await?,
+        )
+    } else {
+        None
+    };
+
+    let resolved_loader_version = if loader != ModLoader::Vanilla {
+        crate::launcher::get_loader_version_from_profile(
+            &game_version,
+            loader,
+            loader_version.as_deref(),
+        )
+        .await?
+    } else {
+        None
+    };
+
+    let launch_overrides =
+        manifest.launch_info.as_ref().and_then(|launch_info| {
+            let jvm_args = launch_info
+                .java_argument
+                .as_ref()
+                .map(join_arguments)
+                .filter(|args| !args.is_empty())?;
+            Some(InstanceLaunchOverridesPatch {
+                extra_launch_args: Some(Some(jvm_args)),
+                ..InstanceLaunchOverridesPatch::default()
+            })
+        });
+
+    crate::api::instance::edit(
+        &instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(pack_name.clone()),
+            link: Some(InstanceLink::ImportedModpack {
+                project_id: None,
+                version_id: None,
+                name: Some(pack_name.clone()),
+                version_number: manifest.version.clone(),
+                filename: source_filename,
+            }),
+            launch_overrides,
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind: Some(ContentSourceKind::ImportedModpack),
+                game_version: Some(game_version.clone()),
+                protocol_version: Some(None),
+                loader: Some(loader),
+                loader_version: Some(
+                    resolved_loader_version.map(|version| version.id),
+                ),
+            }),
+            ..EditInstance::default()
+        },
+    )
+    .await?;
+
+    let minecraft_install =
+        super::parallel_minecraft_install::ParallelMinecraftInstall::start(
+            instance_id.clone(),
+            reporter.clone(),
+        );
+
+    let curse_files = manifest
+        .files
+        .iter()
+        .filter(|file| {
+            file.type_
+                .as_deref()
+                .is_none_or(|kind| kind.eq_ignore_ascii_case("curse"))
+        })
+        .filter_map(|file| {
+            Some(crate::api::curseforge::CurseForgeManifestFile {
+                project_id: file.project_id?,
+                file_id: file.file_id?,
+                required: true,
+            })
+        })
+        .collect::<Vec<_>>();
+    if !curse_files.is_empty() {
+        let content_loader = (loader != ModLoader::Vanilla
+            && loader != ModLoader::OptiFine)
+            .then(|| loader.as_str().to_string());
+        crate::api::curseforge::install_local_manifest_files(
+            &instance_id,
+            curse_files,
+            false,
+            &game_version,
+            content_loader.as_deref(),
+            pack_details.clone(),
+            &reporter,
+        )
+        .await?;
+    }
+
+    reporter
+        .update(
+            InstallPhaseId::ExtractingOverrides,
+            None,
+            pack_details.clone(),
+        )
+        .await?;
+    let instance_path =
+        crate::api::instance::get_full_path(&instance_id).await?;
+    archive_util::extract_archive_subdir_for_instance(
+        instance_id.clone(),
+        reporter.cancellation_token(),
+        archive_path,
+        format!("{base_folder}overrides/"),
+        instance_path.clone(),
+    )
+    .await?;
+
+    minecraft_install.join().await?;
+
+    if let Some(lite_loader_version) = lite_loader_as_adjunct {
+        install_liteloader_component(
+            &state,
+            &instance_id,
+            &game_version,
+            loader,
+            &lite_loader_version,
+        )
+        .await?;
+    }
+    if let Some(optifine_version) = optifine_as_mod {
+        install_optifine_mod(
+            &state,
+            &instance_id,
+            reporter.cancellation_token(),
+            &game_version,
+            &optifine_version,
+            &instance_path,
+        )
+        .await?;
+        record_optifine_component(&instance_id, &optifine_version).await?;
+    }
+    if let Some(optifabric_version) = optifabric_version {
+        install_optifabric_component(
+            &instance_id,
+            &game_version,
+            &optifabric_version,
+        )
+        .await?;
+    }
+
+    reporter.clear_context().await?;
+    Ok(())
+}
+
+pub(crate) async fn record_optifine_component(
+    instance_id: &str,
+    version: &str,
+) -> crate::Result<()> {
+    record_loader_component(
+        instance_id,
+        crate::state::LoaderComponentKind::OptiFine,
+        version,
+        Some(serde_json::json!({ "source": "pack" })),
+    )
+    .await
+}
+
+pub(crate) async fn record_loader_component(
+    instance_id: &str,
+    kind: crate::state::LoaderComponentKind,
+    version: &str,
+    provider_metadata: Option<serde_json::Value>,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let metadata =
+        crate::api::instance::get(instance_id)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Unknown instance {instance_id}"
+                ))
+            })?;
+    let mut components = metadata.loader_components;
+    components.retain(|component| component.kind != kind);
+    components.push(crate::state::LoaderComponent {
+        instance_id: instance_id.to_string(),
+        kind,
+        version: Some(version.to_string()),
+        role: crate::state::LoaderComponentRole::Adjunct,
+        provider_metadata,
+    });
+    crate::state::instances::commands::replace_instance_loader_components(
+        instance_id,
+        &components,
+        &state.pool,
+    )
+    .await
+}
+
+pub(crate) async fn install_liteloader_component(
+    state: &State,
+    instance_id: &str,
+    game_version: &str,
+    primary_loader: ModLoader,
+    resolved_version: &daedalus::modded::LoaderVersion,
+) -> crate::Result<()> {
+    let metadata =
+        crate::api::instance::get(instance_id)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Unknown instance {instance_id}"
+                ))
+            })?;
+    let version = crate::install::runner::install_liteloader_adjunct_resolved(
+        state,
+        &metadata,
+        game_version,
+        primary_loader,
+        resolved_version,
+    )
+    .await?;
+    record_loader_component(
+        instance_id,
+        crate::state::LoaderComponentKind::LiteLoader,
+        &version,
+        Some(serde_json::json!({ "source": "pack" })),
+    )
+    .await
+}
+
+pub(crate) async fn install_optifabric_component(
+    instance_id: &str,
+    game_version: &str,
+    version: &str,
+) -> crate::Result<()> {
+    let version = crate::install::runner::install_optifabric_file(
+        instance_id,
+        game_version,
+        version,
+    )
+    .await?;
+    record_loader_component(
+        instance_id,
+        crate::state::LoaderComponentKind::OptiFabric,
+        &version,
+        Some(serde_json::json!({
+            "projectId": crate::install::runner::OPTIFABRIC_CURSEFORGE_PROJECT_ID,
+            "provider": "curseforge"
+        })),
+    )
+    .await
+}
+
+/// Installs OptiFine into the instance's mods folder for packs that pair it
+/// with Forge or NeoForge. Requires the instance's Minecraft install to have
+/// completed so the client jar and a Java runtime are available.
+pub(crate) async fn install_optifine_mod(
+    state: &State,
+    instance_id: &str,
+    cancellation: tokio_util::sync::CancellationToken,
+    game_version: &str,
+    optifine_version: &str,
+    instance_path: &std::path::Path,
+) -> crate::Result<()> {
+    let metadata =
+        crate::api::instance::get(instance_id)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::InputError(format!(
+                    "Unknown instance {instance_id}"
+                ))
+            })?;
+    let version_jar = match &metadata.applied_content_set.loader_version {
+        Some(loader_version) => format!("{game_version}-{loader_version}"),
+        None => game_version.to_string(),
+    };
+    let loader_client_jar = state
+        .directories
+        .version_dir(&version_jar)
+        .join(format!("{version_jar}.jar"));
+    let client_jar = if loader_client_jar.is_file() {
+        loader_client_jar
+    } else {
+        state
+            .directories
+            .version_dir(game_version)
+            .join(format!("{game_version}.jar"))
+    };
+
+    let (manifest, version_index) =
+        crate::launcher::resolve_minecraft_manifest(game_version, state)
+            .await?;
+    let version_info = crate::launcher::download::download_version_info(
+        state,
+        &manifest.versions[version_index],
+        ModLoader::Vanilla,
+        None,
+        None,
+        None,
+        None,
+    )
+    .await?;
+    let java_key = version_info
+        .java_version
+        .as_ref()
+        .map_or(8, |java| java.major_version);
+    let java = crate::api::jre::find_java_for_version(java_key)
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::LauncherError(format!(
+                "No Java {java_key} runtime is available for the OptiFine installer"
+            ))
+        })?;
+
+    crate::launcher::optifine::install_optifine_as_mod(
+        state,
+        instance_id,
+        cancellation,
+        std::path::Path::new(&java.path),
+        game_version,
+        optifine_version,
+        &client_jar,
+        &instance_path.join("mods"),
+    )
+    .await?;
+    Ok(())
+}

packages/app-lib/src/api/pack/install_mmc_zip.rs

@@ -0,0 +1,63 @@
+//! Installer for MultiMC/Prism export zips.
+//!
+//! Export zips carry the same `mmc-pack.json` + `instance.cfg` layout as an
+//! installed MMC instance, so the archive is extracted to a scratch directory
+//! and imported through the existing MMC instance importer.
+
+use std::path::PathBuf;
+
+use super::archive_util;
+use crate::State;
+use crate::install::{
+    InstallPhaseDetails, InstallPhaseId, InstallProgressReporter,
+};
+use crate::pack::import::ImportLauncherType;
+
+pub(crate) async fn install_mmc_zip_with_reporter(
+    instance_id: String,
+    archive_path: PathBuf,
+    base_folder: String,
+    source_filename: Option<String>,
+    reporter: InstallProgressReporter,
+) -> crate::Result<()> {
+    let state = State::get().await?;
+    let details = InstallPhaseDetails::Import {
+        launcher_type: ImportLauncherType::MultiMC,
+        instance_folder: source_filename.unwrap_or_else(|| {
+            archive_path
+                .file_name()
+                .map(|name| name.to_string_lossy().to_string())
+                .unwrap_or_else(|| "MultiMC pack".to_string())
+        }),
+    };
+    reporter
+        .update(InstallPhaseId::ExtractingOverrides, None, details.clone())
+        .await?;
+
+    let scratch = archive_util::create_import_scratch_dir(&state).await?;
+    let result = async {
+        archive_util::extract_archive_subdir(
+            archive_path,
+            base_folder,
+            scratch.clone(),
+        )
+        .await?;
+        crate::pack::import::mmc::import_mmc_instance_dir(
+            scratch.clone(),
+            Some(scratch.clone()),
+            &instance_id,
+            reporter.clone(),
+            details,
+            false, // zip imports don't support symlinks
+        )
+        .await
+    }
+    .await;
+    if let Err(error) = tokio::fs::remove_dir_all(&scratch).await {
+        tracing::warn!(
+            "Failed to clean up modpack import scratch directory {}: {error}",
+            scratch.display()
+        );
+    }
+    result
+}

packages/app-lib/src/api/pack/install_plain_archive.rs

@@ -0,0 +1,312 @@
+//! Installer for plain zipped-up game folders.
+//!
+//! These archives have no pack manifest at all — they are a `.minecraft`
+//! folder (optionally wrapped in extra directories) identified by a
+//! `versions/<id>/<id>.json` structure. The version JSON is inspected to
+//! guess the game version and loader, and the folder contents become the
+//! instance's game directory.
+
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+use super::archive_util;
+use crate::data::ModLoader;
+use crate::install::{
+    InstallPhaseDetails, InstallPhaseId, InstallProgressReporter,
+};
+use crate::state::{
+    AppliedContentSetPatch, ContentSourceKind, EditInstance,
+    InstanceInstallStage, InstanceLink,
+};
+
+#[derive(Deserialize, Debug, Default)]
+#[serde(rename_all = "camelCase")]
+struct PlainVersionJson {
+    #[serde(default)]
+    id: Option<String>,
+    #[serde(default)]
+    inherits_from: Option<String>,
+    #[serde(default)]
+    libraries: Vec<PlainLibrary>,
+}
+
+#[derive(Deserialize, Debug)]
+struct PlainLibrary {
+    #[serde(default)]
+    name: Option<String>,
+}
+
+fn looks_like_game_version(value: &str) -> bool {
+    let mut parts = value.split('.');
+    parts.next().is_some_and(|part| part.parse::<u32>().is_ok())
+        && value.split('.').skip(1).all(|part| {
+            part.split('-')
+                .next()
+                .is_some_and(|part| part.parse::<u32>().is_ok())
+        })
+}
+
+struct DetectedTarget {
+    game_version: String,
+    loader: ModLoader,
+    loader_version: Option<String>,
+}
+
+fn detect_target(version_json: &PlainVersionJson) -> Option<DetectedTarget> {
+    let mut game_version = version_json
+        .inherits_from
+        .clone()
+        .filter(|value| looks_like_game_version(value));
+    let mut loader = ModLoader::Vanilla;
+    let mut loader_version = None;
+
+    for library in &version_json.libraries {
+        let Some(name) = &library.name else {
+            continue;
+        };
+        let parts: Vec<&str> = name.split(':').collect();
+        if parts.len() < 3 {
+            continue;
+        }
+        let (group, artifact, version) = (parts[0], parts[1], parts[2]);
+        match (group, artifact) {
+            ("net.fabricmc", "fabric-loader") => {
+                loader = ModLoader::Fabric;
+                loader_version = Some(version.to_string());
+            }
+            ("org.quiltmc", "quilt-loader") => {
+                loader = ModLoader::Quilt;
+                loader_version = Some(version.to_string());
+            }
+            ("net.neoforged", "neoforge" | "forge") => {
+                loader = ModLoader::NeoForge;
+                loader_version = Some(version.to_string());
+            }
+            ("net.minecraftforge", "forge" | "fmlloader") => {
+                loader = ModLoader::Forge;
+                // Forge versions are usually stored as `<mc>-<forge>`.
+                let forge_version = version
+                    .split_once('-')
+                    .map(|(mc, forge)| {
+                        if game_version.is_none() && looks_like_game_version(mc)
+                        {
+                            game_version = Some(mc.to_string());
+                        }
+                        forge.to_string()
+                    })
+                    .unwrap_or_else(|| version.to_string());
+                loader_version = Some(forge_version);
+            }
+            ("optifine", "OptiFine") if loader == ModLoader::Vanilla => {
+                loader = ModLoader::OptiFine;
+                // OptiFine library versions look like `<mc>_HD_U_I6`.
+                loader_version = Some(
+                    version
+                        .split_once('_')
+                        .map(|(_, of)| of.to_string())
+                        .unwrap_or_else(|| version.to_string()),
+                );
+            }
+            _ => {}
+        }
+    }
+
+    if game_version.is_none()
+        && let Some(id) = &version_json.id
+        && looks_like_game_version(id)
+    {
+        game_version = Some(id.clone());
+    }
+
+    game_version.map(|game_version| DetectedTarget {
+        game_version,
+        loader,
+        loader_version,
+    })
+}
+
+/// Reads every `versions/<id>/<id>.json` under the base folder. Archives of
+/// modded installs usually contain both the vanilla and the modded version
+/// folder, so all candidates are needed to pick the right one.
+async fn read_version_candidates(
+    archive_path: PathBuf,
+    base_folder: String,
+) -> crate::Result<Vec<(String, PlainVersionJson)>> {
+    tokio::task::spawn_blocking(move || {
+        let file = std::fs::File::open(&archive_path).map_err(|error| {
+            crate::util::io::IOError::with_path(error, &archive_path)
+        })?;
+        let mut archive = zip::ZipArchive::new(file).map_err(|error| {
+            crate::ErrorKind::InputError(format!(
+                "Modpack archive is invalid: {error}"
+            ))
+        })?;
+        let versions_prefix = format!("{base_folder}versions/");
+        let mut candidates = Vec::new();
+        for index in 0..archive.len() {
+            let name = {
+                let entry = archive.by_index_raw(index).map_err(|error| {
+                    crate::ErrorKind::InputError(format!(
+                        "Failed to read modpack archive entry: {error}"
+                    ))
+                })?;
+                crate::pack::detect::decode_zip_entry_name(entry.name_raw())
+            };
+            let Some(rest) = name.strip_prefix(&versions_prefix) else {
+                continue;
+            };
+            let mut segments = rest.split('/');
+            let (Some(id), Some(json), None) =
+                (segments.next(), segments.next(), segments.next())
+            else {
+                continue;
+            };
+            if json.strip_suffix(".json") != Some(id) {
+                continue;
+            }
+            let id = id.to_string();
+            let mut entry = archive.by_index(index).map_err(|error| {
+                crate::ErrorKind::InputError(format!(
+                    "Failed to read modpack archive entry: {error}"
+                ))
+            })?;
+            let mut contents = Vec::new();
+            std::io::Read::read_to_end(&mut entry, &mut contents)?;
+            if let Ok(parsed) =
+                serde_json::from_slice::<PlainVersionJson>(&contents)
+            {
+                candidates.push((id, parsed));
+            }
+        }
+        Ok(candidates)
+    })
+    .await?
+}
+
+pub(crate) async fn install_plain_archive_with_reporter(
+    instance_id: String,
+    archive_path: PathBuf,
+    base_folder: String,
+    version_id: String,
+    source_filename: Option<String>,
+    reporter: InstallProgressReporter,
+) -> crate::Result<()> {
+    let candidates =
+        read_version_candidates(archive_path.clone(), base_folder.clone())
+            .await?;
+    let mut targets: Vec<(String, DetectedTarget)> = candidates
+        .iter()
+        .filter_map(|(id, json)| {
+            detect_target(json).map(|target| (id.clone(), target))
+        })
+        .collect();
+    let selected = targets
+        .iter()
+        .position(|(_, target)| target.loader != ModLoader::Vanilla)
+        .map(|index| targets.remove(index))
+        .or_else(|| {
+            if targets.is_empty() {
+                None
+            } else {
+                Some(targets.remove(0))
+            }
+        });
+    let Some((selected_id, target)) = selected else {
+        return Err(crate::ErrorKind::InputError(format!(
+            "Could not determine the Minecraft version of archived instance {version_id}"
+        ))
+        .into());
+    };
+
+    let pack_name = if selected_id.trim().is_empty() {
+        source_filename
+            .as_ref()
+            .map(|name| {
+                std::path::Path::new(name)
+                    .file_stem()
+                    .unwrap_or_default()
+                    .to_string_lossy()
+                    .to_string()
+            })
+            .unwrap_or_else(|| "Imported Instance".to_string())
+    } else {
+        selected_id.clone()
+    };
+    let pack_details = InstallPhaseDetails::Modpack {
+        project_id: None,
+        version_id: None,
+        title: Some(pack_name.clone()),
+    };
+    reporter
+        .update(InstallPhaseId::ResolvingPack, None, pack_details.clone())
+        .await?;
+
+    let resolved_loader_version = if target.loader != ModLoader::Vanilla {
+        crate::launcher::get_loader_version_from_profile(
+            &target.game_version,
+            target.loader,
+            target.loader_version.as_deref(),
+        )
+        .await?
+    } else {
+        None
+    };
+
+    crate::api::instance::edit(
+        &instance_id,
+        EditInstance {
+            install_stage: Some(InstanceInstallStage::PackInstalling),
+            name: Some(pack_name.clone()),
+            link: Some(InstanceLink::ImportedModpack {
+                project_id: None,
+                version_id: None,
+                name: Some(pack_name),
+                version_number: None,
+                filename: source_filename,
+            }),
+            content_set_patch: Some(AppliedContentSetPatch {
+                source_kind: Some(ContentSourceKind::ImportedModpack),
+                game_version: Some(target.game_version.clone()),
+                protocol_version: Some(None),
+                loader: Some(target.loader),
+                loader_version: Some(
+                    resolved_loader_version.map(|version| version.id),
+                ),
+            }),
+            ..EditInstance::default()
+        },
+    )
+    .await?;
+
+    reporter
+        .update(
+            InstallPhaseId::ExtractingOverrides,
+            None,
+            pack_details.clone(),
+        )
+        .await?;
+    let instance_path =
+        crate::api::instance::get_full_path(&instance_id).await?;
+    archive_util::extract_archive_subdir_for_instance(
+        instance_id.clone(),
+        reporter.cancellation_token(),
+        archive_path,
+        base_folder,
+        instance_path.clone(),
+    )
+    .await?;
+
+    let local_source =
+        crate::launcher::download::LocalRuntimeSource::discover(&instance_path);
+    crate::launcher::install_minecraft_for_instance_id_with_local_source(
+        &instance_id,
+        local_source,
+        false,
+        Some(reporter.clone()),
+        crate::launcher::InstanceCompletionPolicy::DeferToInstallJob,
+    )
+    .await?;
+    reporter.clear_context().await?;
+    Ok(())
+}

packages/app-lib/src/api/pack/mod.rs

@@ -0,0 +1,10 @@
+pub(crate) mod archive_util;
+pub mod detect;
+pub mod import;
+pub mod install_from;
+pub(crate) mod install_hmcl;
+pub(crate) mod install_mcbbs;
+pub(crate) mod install_mmc_zip;
+pub mod install_mrpack;
+pub(crate) mod install_plain_archive;
+pub(crate) mod parallel_minecraft_install;

packages/app-lib/src/api/pack/parallel_minecraft_install.rs

@@ -0,0 +1,65 @@
+use crate::install::InstallProgressReporter;
+use tokio_util::sync::CancellationToken;
+
+/// Owns a Minecraft core installation that runs alongside pack content work.
+/// Dropping the guard cancels the task so an importer cannot leave a core
+/// download running after its content installation fails.
+pub(crate) struct ParallelMinecraftInstall {
+    cancel: CancellationToken,
+    task: Option<tokio::task::JoinHandle<crate::Result<()>>>,
+}
+
+impl ParallelMinecraftInstall {
+    pub(crate) fn start(
+        instance_id: String,
+        reporter: InstallProgressReporter,
+    ) -> Self {
+        let cancel = CancellationToken::new();
+        let task_cancel = cancel.clone();
+        let parallel_reporter = reporter.with_parallel_output();
+        let task = tokio::spawn(async move {
+            tokio::select! {
+                _ = task_cancel.cancelled() => {
+                    tracing::debug!(
+                        instance_id = %instance_id,
+                        "Parallel Minecraft install aborted before completion"
+                    );
+                    Ok(())
+                }
+                result = crate::launcher::install_minecraft_for_instance_id_with_reporter(
+                    &instance_id,
+                    false,
+                    Some(parallel_reporter),
+                    crate::launcher::InstanceCompletionPolicy::DeferToInstallJob,
+                ) => result,
+            }
+        });
+
+        Self {
+            cancel,
+            task: Some(task),
+        }
+    }
+
+    /// Cancels the core install and waits until the task has stopped.
+    pub(crate) async fn abort(mut self) {
+        self.cancel.cancel();
+        if let Some(task) = self.task.take() {
+            let _ = task.await;
+        }
+    }
+
+    /// Waits for the core install to finish without cancelling it.
+    pub(crate) async fn join(mut self) -> crate::Result<()> {
+        if let Some(task) = self.task.take() {
+            task.await??;
+        }
+        Ok(())
+    }
+}
+
+impl Drop for ParallelMinecraftInstall {
+    fn drop(&mut self) {
+        self.cancel.cancel();
+    }
+}

packages/app-lib/src/api/planet_minecraft.rs

@@ -0,0 +1,231 @@
+use crate::State;
+use crate::util::fetch::INSECURE_REQWEST_CLIENT;
+use bytes::Bytes;
+use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
+
+const CONNECTOR_URL_ENV: &str = "AXOLOTL_PLANET_MINECRAFT_CONNECTOR_URL";
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PlanetMinecraftProject {
+    pub id: String,
+    pub title: String,
+    pub page_url: String,
+    #[serde(default)]
+    pub summary: Option<String>,
+    #[serde(default)]
+    pub versions: Vec<PlanetMinecraftVersion>,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PlanetMinecraftVersion {
+    pub id: String,
+    pub name: String,
+    pub game_versions: Vec<String>,
+    pub download: PlanetMinecraftDownload,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PlanetMinecraftDownload {
+    pub page_url: String,
+    #[serde(default)]
+    pub file_name: Option<String>,
+    #[serde(default)]
+    pub direct_url: Option<String>,
+    #[serde(default)]
+    pub sha256: Option<String>,
+}
+
+#[derive(Clone, Debug, Serialize)]
+#[serde(tag = "state", rename_all = "snake_case")]
+pub enum PlanetMinecraftInstallRoute {
+    Automatic {
+        direct_url: String,
+        sha256: String,
+        file_name: Option<String>,
+    },
+    Manual {
+        page_url: String,
+        file_name: Option<String>,
+    },
+}
+
+impl PlanetMinecraftDownload {
+    pub fn install_route(&self) -> PlanetMinecraftInstallRoute {
+        match (
+            self.direct_url.as_deref().filter(|url| {
+                !url.trim().is_empty() && validated_download_url(url).is_ok()
+            }),
+            self.sha256
+                .as_deref()
+                .filter(|hash| !hash.trim().is_empty()),
+        ) {
+            (Some(direct_url), Some(sha256)) => {
+                PlanetMinecraftInstallRoute::Automatic {
+                    direct_url: direct_url.to_string(),
+                    sha256: sha256.to_string(),
+                    file_name: self.file_name.clone(),
+                }
+            }
+            _ => PlanetMinecraftInstallRoute::Manual {
+                page_url: self.page_url.clone(),
+                file_name: self.file_name.clone(),
+            },
+        }
+    }
+}
+
+pub fn connector_base_url() -> crate::Result<String> {
+    let value = std::env::var(CONNECTOR_URL_ENV).map_err(|_| {
+        crate::ErrorKind::InputError(
+            "Planet Minecraft connector is not configured".to_string(),
+        )
+    })?;
+    let url = reqwest::Url::parse(&value).map_err(|_| {
+        crate::ErrorKind::InputError(
+            "Planet Minecraft connector URL is invalid".to_string(),
+        )
+    })?;
+    if url.scheme() != "https" {
+        return Err(crate::ErrorKind::InputError(
+            "Planet Minecraft connector must use HTTPS".to_string(),
+        )
+        .into());
+    }
+    Ok(value.trim_end_matches('/').to_string())
+}
+
+pub async fn search_projects(
+    query: &str,
+    game_version: Option<&str>,
+) -> crate::Result<Vec<PlanetMinecraftProject>> {
+    let mut url = format!(
+        "{}/projects?query={}",
+        connector_base_url()?,
+        urlencoding::encode(query)
+    );
+    if let Some(game_version) = game_version.filter(|value| !value.is_empty()) {
+        url.push_str(&format!(
+            "&game_version={}",
+            urlencoding::encode(game_version)
+        ));
+    }
+    connector_get(&url).await
+}
+
+pub async fn get_project(id: &str) -> crate::Result<PlanetMinecraftProject> {
+    connector_get(&format!(
+        "{}/projects/{}",
+        connector_base_url()?,
+        urlencoding::encode(id)
+    ))
+    .await
+}
+
+pub async fn download_verified_file(
+    direct_url: &str,
+    expected_sha256: &str,
+) -> crate::Result<Bytes> {
+    let url = validated_download_url(direct_url)?;
+    if expected_sha256.trim().is_empty() {
+        return Err(crate::ErrorKind::InputError(
+            "Planet Minecraft downloads require a SHA-256".to_string(),
+        )
+        .into());
+    }
+    let state = State::get().await?;
+    let _permit = state.api_semaphore.0.acquire().await?;
+    let bytes = INSECURE_REQWEST_CLIENT
+        .get(url)
+        .send()
+        .await?
+        .error_for_status()?
+        .bytes()
+        .await?;
+    if bytes.is_empty() {
+        return Err(crate::ErrorKind::InputError(
+            "Planet Minecraft returned an empty file".to_string(),
+        )
+        .into());
+    }
+    let actual = format!("{:x}", Sha256::digest(&bytes));
+    if !actual.eq_ignore_ascii_case(expected_sha256.trim()) {
+        return Err(crate::ErrorKind::OtherError(
+            "Planet Minecraft SHA-256 mismatch".to_string(),
+        )
+        .into());
+    }
+    Ok(bytes)
+}
+
+fn validated_download_url(value: &str) -> crate::Result<reqwest::Url> {
+    let url = reqwest::Url::parse(value).map_err(|_| {
+        crate::ErrorKind::InputError(
+            "Planet Minecraft download URL is invalid".to_string(),
+        )
+    })?;
+    if url.scheme() != "https" {
+        return Err(crate::ErrorKind::InputError(
+            "Planet Minecraft download URL must use HTTPS".to_string(),
+        )
+        .into());
+    }
+    Ok(url)
+}
+
+async fn connector_get<T>(url: &str) -> crate::Result<T>
+where
+    T: for<'de> Deserialize<'de>,
+{
+    let state = State::get().await?;
+    let _permit = state.api_semaphore.0.acquire().await?;
+    Ok(INSECURE_REQWEST_CLIENT
+        .get(url)
+        .send()
+        .await?
+        .error_for_status()?
+        .json()
+        .await?)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn downloads_without_a_hash_remain_manual() {
+        let download = PlanetMinecraftDownload {
+            page_url: "https://www.planetminecraft.com/mod/example".to_string(),
+            file_name: Some("example.jar".to_string()),
+            direct_url: Some("https://host.example/example.jar".to_string()),
+            sha256: None,
+        };
+        assert!(matches!(
+            download.install_route(),
+            PlanetMinecraftInstallRoute::Manual { .. }
+        ));
+    }
+
+    #[test]
+    fn direct_downloads_require_https() {
+        assert!(validated_download_url("http://example.com/file.jar").is_err());
+        assert!(validated_download_url("https://example.com/file.jar").is_ok());
+    }
+
+    #[test]
+    fn non_https_direct_downloads_fall_back_to_manual_import() {
+        let download = PlanetMinecraftDownload {
+            page_url: "https://www.planetminecraft.com/mod/example".to_string(),
+            file_name: Some("example.jar".to_string()),
+            direct_url: Some("http://host.example/example.jar".to_string()),
+            sha256: Some("abc".to_string()),
+        };
+        assert!(matches!(
+            download.install_route(),
+            PlanetMinecraftInstallRoute::Manual { .. }
+        ));
+    }
+}

packages/app-lib/src/api/process.rs

@@ -0,0 +1,82 @@
+//! Theseus process management interface
+
+use crate::state::ProcessMetadata;
+pub use crate::{
+    State,
+    state::{Hooks, MemorySettings, Settings, WindowSize},
+};
+use uuid::Uuid;
+
+// Gets each running stored process in the state
+#[tracing::instrument]
+pub async fn get_all() -> crate::Result<Vec<ProcessMetadata>> {
+    let state = State::get().await?;
+    let processes = state.process_manager.get_all();
+    Ok(processes)
+}
+
+pub async fn resolve_instance_id(instance: &str) -> crate::Result<String> {
+    let state = State::get().await?;
+    resolve_instance_id_with_state(instance, &state)
+        .await?
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(format!(
+                "Unknown instance id or path: {instance}"
+            ))
+            .as_error()
+        })
+}
+
+async fn resolve_instance_id_with_state(
+    instance: &str,
+    state: &State,
+) -> crate::Result<Option<String>> {
+    sqlx::query_scalar!(
+        "
+		SELECT id
+		FROM instances
+		WHERE id = ? OR path = ?
+		ORDER BY CASE WHEN id = ? THEN 0 ELSE 1 END
+		LIMIT 1
+		",
+        instance,
+        instance,
+        instance,
+    )
+    .fetch_optional(&state.pool)
+    .await
+    .map_err(Into::into)
+}
+
+// Gets the UUID of each stored process in the state by instance id
+#[tracing::instrument]
+pub async fn get_by_instance_id(
+    instance_id: &str,
+) -> crate::Result<Vec<ProcessMetadata>> {
+    let state = State::get().await?;
+    let processes = state
+        .process_manager
+        .get_all()
+        .into_iter()
+        .filter(|x| x.instance_id == instance_id)
+        .collect();
+    Ok(processes)
+}
+
+// Kill a child process stored in the state by UUID, as a string
+#[tracing::instrument]
+pub async fn kill(uuid: Uuid) -> crate::Result<()> {
+    let state = State::get().await?;
+    state.process_manager.kill(uuid).await?;
+
+    Ok(())
+}
+
+// Wait for a child process stored in the state by UUID
+#[tracing::instrument]
+pub async fn wait_for(uuid: Uuid) -> crate::Result<()> {
+    let state = State::get().await?;
+    state.process_manager.wait_for(uuid).await?;
+
+    Ok(())
+}

packages/app-lib/src/api/server_address.rs

@@ -0,0 +1,195 @@
+use crate::{Error, ErrorKind, Result};
+use std::fmt::Display;
+use std::mem;
+use std::net::{Ipv4Addr, Ipv6Addr};
+use tokio::sync::Semaphore;
+
+#[derive(Debug, Clone)]
+pub enum ServerAddress {
+    Unresolved(String),
+    Resolved {
+        original_host: String,
+        original_port: u16,
+        resolved_host: String,
+        resolved_port: u16,
+    },
+}
+
+impl ServerAddress {
+    pub async fn resolve(&mut self) -> Result<()> {
+        match self {
+            Self::Unresolved(address) => {
+                let (host, port) = parse_server_address(address)?;
+                let (resolved_host, resolved_port) =
+                    resolve_server_address(host, port).await?;
+                *self = Self::Resolved {
+                    original_host: if host.len() == address.len() {
+                        mem::take(address)
+                    } else {
+                        host.to_owned()
+                    },
+                    original_port: port,
+                    resolved_host,
+                    resolved_port,
+                }
+            }
+            Self::Resolved { .. } => {}
+        }
+        Ok(())
+    }
+
+    pub fn require_resolved(&self) -> Result<(&str, u16)> {
+        match self {
+            Self::Resolved {
+                resolved_host,
+                resolved_port,
+                ..
+            } => Ok((resolved_host, *resolved_port)),
+            Self::Unresolved(address) => Err(ErrorKind::InputError(format!(
+                "Unexpected unresolved server address: {address}"
+            ))
+            .into()),
+        }
+    }
+}
+
+impl Display for ServerAddress {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Unresolved(address) => write!(f, "{address}"),
+            Self::Resolved {
+                resolved_host,
+                resolved_port,
+                ..
+            } => {
+                if resolved_host.contains(':') {
+                    write!(f, "[{resolved_host}]:{resolved_port}")
+                } else {
+                    write!(f, "{resolved_host}:{resolved_port}")
+                }
+            }
+        }
+    }
+}
+
+pub fn parse_server_address(address: &str) -> Result<(&str, u16)> {
+    parse_server_address_inner(address)
+        .map_err(|e| Error::from(ErrorKind::InputError(e)))
+}
+
+// Reimplementation of Guava's HostAndPort#fromString with a default port of 25565
+fn parse_server_address_inner(
+    address: &str,
+) -> std::result::Result<(&str, u16), String> {
+    let (host, port_str) = if address.starts_with("[") {
+        let (Some(colon_index), Some(close_bracket_index)) =
+            (address.find(':'), address.rfind(']'))
+        else {
+            return Err(format!("Invalid bracketed host/port: {address}"));
+        };
+        if close_bracket_index <= colon_index {
+            return Err(format!("Invalid bracketed host/port: {address}"));
+        }
+
+        let host = &address[1..close_bracket_index];
+        if close_bracket_index + 1 == address.len() {
+            (host, "")
+        } else {
+            if address.as_bytes().get(close_bracket_index + 1).copied()
+                != Some(b':')
+            {
+                return Err(format!(
+                    "Only a colon may follow a close bracket: {address}"
+                ));
+            }
+            let port_str = &address[close_bracket_index + 2..];
+            for c in port_str.chars() {
+                if !c.is_ascii_digit() {
+                    return Err(format!("Port must be numeric: {address}"));
+                }
+            }
+            (host, port_str)
+        }
+    } else {
+        if let Some((host, port)) = address.split_once(':')
+            && !port.contains(':')
+        {
+            (host, port)
+        } else {
+            (address, "")
+        }
+    };
+
+    let mut port = None;
+    if !port_str.is_empty() {
+        if port_str.starts_with('+') {
+            return Err(format!("Unparsable port number: {port_str}"));
+        }
+        port = port_str.parse::<u16>().ok();
+        if port.is_none() {
+            return Err(format!("Unparsable port number: {port_str}"));
+        }
+    }
+
+    Ok((host, port.unwrap_or(25565)))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::parse_server_address_inner;
+
+    #[test]
+    fn parses_ipv4_server_addresses() {
+        for (address, expected) in [
+            ("192.0.2.1", ("192.0.2.1", 25565)),
+            ("192.0.2.1:25566", ("192.0.2.1", 25566)),
+        ] {
+            assert_eq!(parse_server_address_inner(address), Ok(expected));
+        }
+    }
+
+    #[test]
+    fn parses_ipv6_server_addresses() {
+        for (address, expected) in [
+            ("2001:db8::1", ("2001:db8::1", 25565)),
+            ("[2001:db8::1]", ("2001:db8::1", 25565)),
+            ("[2001:db8::1]:25566", ("2001:db8::1", 25566)),
+        ] {
+            assert_eq!(parse_server_address_inner(address), Ok(expected));
+        }
+    }
+}
+
+pub async fn resolve_server_address(
+    host: &str,
+    port: u16,
+) -> Result<(String, u16)> {
+    static SIMULTANEOUS_DNS_QUERIES: Semaphore = Semaphore::const_new(24);
+
+    if port != 25565
+        || host.parse::<Ipv4Addr>().is_ok()
+        || host.parse::<Ipv6Addr>().is_ok()
+    {
+        return Ok((host.to_owned(), port));
+    }
+
+    let _permit = SIMULTANEOUS_DNS_QUERIES.acquire().await?;
+    let resolver = hickory_resolver::TokioResolver::builder_tokio()?.build();
+    Ok(
+        match resolver.srv_lookup(format!("_minecraft._tcp.{host}")).await {
+            Err(e)
+                if e.proto()
+                    .as_ref()
+                    .is_some_and(|x| x.kind().is_no_records_found()) =>
+            {
+                None
+            }
+            Err(e) => return Err(e.into()),
+            Ok(lookup) => lookup
+                .into_iter()
+                .next()
+                .map(|r| (r.target().to_string(), r.port())),
+        }
+        .unwrap_or_else(|| (host.to_owned(), port)),
+    )
+}

packages/app-lib/src/api/servers.rs

@@ -0,0 +1,23 @@
+//! Managed dedicated Minecraft servers: manifests, downloads, and process control.
+//! Each server lives in its own directory under the launcher's `servers` folder
+//! and is described by an `axolotl-server.json` manifest.
+
+mod files;
+mod forge;
+mod lifecycle;
+mod logs;
+mod manage;
+mod manifest;
+mod modpack;
+mod ports;
+
+pub use self::files::{download_file, read_file, write_file};
+pub use self::forge::install_forge;
+pub use self::lifecycle::{
+    kill, resize_console, send_command, send_console_input, start, stop,
+};
+pub use self::logs::{clear_log, get_log_buffer};
+pub use self::manage::{create, delete, get, list, set_icon, update_settings};
+pub use self::manifest::{ModpackInfo, ServerInfo, ServerManifest};
+pub use self::modpack::install_modpack;
+pub use self::ports::{PortProcessInfo, kill_port_process, port_process};

packages/app-lib/src/api/servers/files.rs

@@ -0,0 +1,200 @@
+//! Reading, writing, and downloading files inside a server's directory.
+
+use std::path::{Path, PathBuf};
+
+use futures::StreamExt;
+use sha1_smol::Sha1;
+
+use crate::event::ServerPayloadType;
+use crate::event::emit::emit_server;
+use crate::util::io::{self, IOError};
+use crate::{ErrorKind, Result};
+
+use super::manifest::server_path;
+
+const DOWNLOAD_PROGRESS_STEP: u64 = 512 * 1024;
+
+pub async fn read_file(server_id: &str, file: &str) -> Result<String> {
+    let path = resolve_server_file(server_id, file).await?;
+    let bytes = io::read(&path).await?;
+    let text = String::from_utf8_lossy(&bytes).into_owned();
+    Ok(text)
+}
+
+pub async fn write_file(
+    server_id: &str,
+    file: &str,
+    contents: &str,
+) -> Result<()> {
+    let path = resolve_server_file(server_id, file).await?;
+    io::write(&path, contents).await?;
+    Ok(())
+}
+
+pub async fn download_file(
+    server_id: &str,
+    url: &str,
+    filename: &str,
+    expected_sha1: Option<String>,
+) -> Result<()> {
+    let dir = server_path(server_id).await?;
+    download_to_dir(server_id, &dir, url, filename, expected_sha1).await
+}
+
+/// Downloads a URL into a nested, relative path inside the server directory
+/// (for example `mods/sodium.jar`), creating parent directories as needed.
+/// The relative path is validated against traversal; a plain filename behaves
+/// identically to [`download_file`].
+pub(super) async fn download_to_dir(
+    server_id: &str,
+    dir: &Path,
+    url: &str,
+    rel_path: &str,
+    expected_sha1: Option<String>,
+) -> Result<()> {
+    let destination = safe_relative_join(dir, rel_path)?;
+    let partial = destination.with_extension("part");
+
+    if let Some(parent) = destination.parent() {
+        io::create_dir_all(parent).await?;
+    }
+
+    let client = reqwest::Client::builder()
+        .user_agent(crate::launcher_user_agent())
+        .build()
+        .map_err(|e| ErrorKind::NetworkError(e.to_string()))?;
+    let response = client
+        .get(url)
+        .send()
+        .await
+        .and_then(|r| r.error_for_status())?;
+    let total = response.content_length();
+    let mut stream = response.bytes_stream();
+
+    let mut file = tokio::fs::File::create(&partial)
+        .await
+        .map_err(|e| IOError::with_path(e, &partial))?;
+    let mut hasher = Sha1::new();
+    let mut downloaded: u64 = 0;
+    let mut last_reported: u64 = 0;
+    while let Some(chunk) = stream.next().await {
+        let chunk = chunk?;
+        tokio::io::AsyncWriteExt::write_all(&mut file, &chunk)
+            .await
+            .map_err(|e| IOError::with_path(e, &partial))?;
+        hasher.update(&chunk);
+        downloaded += chunk.len() as u64;
+        if downloaded - last_reported >= DOWNLOAD_PROGRESS_STEP {
+            last_reported = downloaded;
+            emit_server(
+                server_id,
+                ServerPayloadType::DownloadProgress { downloaded, total },
+            )
+            .await
+            .ok();
+        }
+    }
+    drop(file);
+
+    if let Some(expected) = expected_sha1.as_deref() {
+        let actual = hasher.digest().to_string();
+        if !actual.eq_ignore_ascii_case(expected) {
+            let _ = tokio::fs::remove_file(&partial).await;
+            return Err(ErrorKind::NetworkError(format!(
+                "Download checksum mismatch for {rel_path}: expected {expected}, got {actual}"
+            ))
+            .as_error());
+        }
+    }
+
+    tokio::fs::rename(&partial, &destination)
+        .await
+        .map_err(|e| IOError::with_path(e, &destination))?;
+    emit_server(
+        server_id,
+        ServerPayloadType::DownloadProgress {
+            downloaded,
+            total: Some(downloaded.max(total.unwrap_or(0))),
+        },
+    )
+    .await
+    .ok();
+    Ok(())
+}
+
+async fn resolve_server_file(server_id: &str, file: &str) -> Result<PathBuf> {
+    let dir = server_path(server_id).await?;
+    safe_join(&dir, file)
+}
+
+fn safe_join(dir: &Path, file: &str) -> Result<PathBuf> {
+    if file.is_empty()
+        || file.contains('\\')
+        || file.starts_with('/')
+        || file
+            .split('/')
+            .any(|segment| segment == ".." || segment.is_empty())
+    {
+        return Err(ErrorKind::InputError(format!(
+            "Invalid file name: {file}"
+        ))
+        .as_error());
+    }
+    Ok(dir.join(file))
+}
+
+/// Joins a relative path that may contain `/` separators but never escapes the
+/// server directory (no `..`, empty segments, or absolute/Windows roots).
+pub(super) fn safe_relative_join(dir: &Path, rel: &str) -> Result<PathBuf> {
+    let is_windows_drive_root =
+        rel.as_bytes().get(1).is_some_and(|byte| *byte == b':')
+            && rel.as_bytes().first().is_some_and(u8::is_ascii_alphabetic);
+    if rel.is_empty()
+        || Path::new(rel).is_absolute()
+        || is_windows_drive_root
+        || rel.starts_with('/')
+        || rel.starts_with('\\')
+        || rel.split(['/', '\\']).any(|segment| {
+            segment.is_empty() || segment == ".." || segment == "."
+        })
+    {
+        return Err(ErrorKind::InputError(format!("Invalid file path: {rel}"))
+            .as_error());
+    }
+    Ok(dir.join(rel))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn safe_join_rejects_traversal() {
+        let dir = Path::new("/tmp/servers/a");
+        assert!(safe_join(dir, "server.properties").is_ok());
+        assert!(safe_join(dir, "../secret").is_err());
+        assert!(safe_join(dir, "/etc/passwd").is_err());
+        assert!(safe_join(dir, "a//b").is_err());
+        assert!(safe_join(dir, "").is_err());
+    }
+
+    #[test]
+    fn safe_relative_join_allows_nested_paths() {
+        let dir = Path::new("/tmp/servers/a");
+        assert_eq!(
+            safe_relative_join(dir, "mods/sodium.jar").unwrap(),
+            dir.join("mods/sodium.jar")
+        );
+        assert_eq!(
+            safe_relative_join(dir, "config/foo/bar.toml").unwrap(),
+            dir.join("config/foo/bar.toml")
+        );
+        assert!(safe_relative_join(dir, "mods/../secret").is_err());
+        assert!(safe_relative_join(dir, "../secret").is_err());
+        assert!(safe_relative_join(dir, "/etc/passwd").is_err());
+        assert!(safe_relative_join(dir, "C:/windows/system32").is_err());
+        assert!(safe_relative_join(dir, "mods//double.jar").is_err());
+        assert!(safe_relative_join(dir, "mods/./dot.jar").is_err());
+        assert!(safe_relative_join(dir, "").is_err());
+    }
+}

packages/app-lib/src/api/servers/forge.rs

@@ -0,0 +1,120 @@
+//! Forge server installation: downloading the official installer and running it
+//! headlessly to materialize the server launcher (run script, `@args` files, and
+//! the mod loader) into a managed server directory.
+//!
+//! Forge ships a bootstrapper rather than a ready-to-run jar. The launcher jar is
+//! produced by `java -jar forge-installer.jar --installServer <dir>`, which lays
+//! down the loader, its libraries, and the `@args` launch files. The regular
+//! `servers.start` flow then boots that output (see `lifecycle::forge_launch_args`).
+
+use tokio::process::Command;
+
+use crate::event::ServerPayloadType;
+use crate::event::emit::emit_server;
+use crate::util::io::IOError;
+use crate::{ErrorKind, Result};
+
+use super::files::download_to_dir;
+use super::manifest::{
+    InstallState, read_manifest, server_path, write_manifest,
+};
+
+const FORGE_MAVEN: &str =
+    "https://maven.minecraftforge.net/net/minecraftforge/forge";
+
+/// Downloads the Forge installer for `mc_version`/`build` into the server dir
+/// and runs it headlessly (`--installServer`) to lay down the launcher. The
+/// server is left unstarted; the caller (frontend wizard) writes `eula.txt` and
+/// the regular `servers.start` flow boots it.
+pub async fn install_forge(
+    server_id: &str,
+    mc_version: &str,
+    build: &str,
+    java_path: Option<String>,
+) -> Result<()> {
+    let dir = server_path(server_id).await?;
+
+    let mut manifest = read_manifest(&dir).await?;
+    manifest.install_state = Some(InstallState::Incomplete);
+    manifest.install_error = None;
+    write_manifest(&dir, &manifest).await?;
+    drop(manifest);
+
+    let installer_name = format!("forge-{mc_version}-{build}-installer.jar");
+    let installer_url =
+        format!("{FORGE_MAVEN}/{mc_version}-{build}/{installer_name}");
+
+    log(
+        server_id,
+        &format!("Downloading Forge installer ({installer_name})"),
+    )
+    .await?;
+    download_to_dir(server_id, &dir, &installer_url, &installer_name, None)
+        .await?;
+
+    let installer_path = dir.join(&installer_name);
+    let java = java_path.clone().unwrap_or_else(|| "java".to_string());
+
+    log(server_id, "Running Forge installer (this may take a while)").await?;
+    let output = Command::new(&java)
+        .arg("-jar")
+        .arg(&installer_path)
+        .arg("--installServer")
+        .arg(&dir)
+        .current_dir(&dir)
+        .stdout(std::process::Stdio::piped())
+        .stderr(std::process::Stdio::piped())
+        .output()
+        .await
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!(
+                "Failed to run Forge installer: {e}"
+            ))
+            .as_error()
+        })?;
+
+    // The installer is verbose; surface a condensed tail so failures are diagnosable.
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    for line in stderr.lines().rev().take(20) {
+        log(server_id, line).await.ok();
+    }
+
+    if !output.status.success() {
+        let mut manifest = read_manifest(&dir).await?;
+        manifest.install_state = Some(InstallState::Failed);
+        manifest.install_error =
+            Some("Forge installer exited with an error".to_string());
+        write_manifest(&dir, &manifest).await?;
+        return Err(ErrorKind::LauncherError(
+			"Forge installer failed. Check that the selected Java version supports this game version."
+				.to_string(),
+		)
+		.as_error());
+    }
+
+    // Ensure eula.txt exists (eula=false) so the manual-start gate can offer it
+    // without booting the jar.
+    let eula_path = dir.join("eula.txt");
+    if !eula_path.exists() {
+        tokio::fs::write(&eula_path, "eula=false\n")
+            .await
+            .map_err(|e| IOError::with_path(e, &eula_path))?;
+    }
+
+    let mut manifest = read_manifest(&dir).await?;
+    manifest.install_state = None;
+    manifest.install_error = None;
+    write_manifest(&dir, &manifest).await?;
+    log(server_id, "Forge server files installed").await.ok();
+    Ok(())
+}
+
+async fn log(server_id: &str, line: &str) -> Result<()> {
+    emit_server(
+        server_id,
+        ServerPayloadType::Log {
+            line: line.to_string(),
+        },
+    )
+    .await
+}

packages/app-lib/src/api/servers/lifecycle.rs

@@ -0,0 +1,641 @@
+//! Server process control: starting, stopping, and monitoring the JVM.
+
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::sync::atomic::{AtomicBool, Ordering};
+
+use base64::Engine;
+use chrono::Utc;
+use dashmap::{DashMap, DashSet};
+use portable_pty::{CommandBuilder, MasterPty, PtySize, native_pty_system};
+use std::sync::LazyLock;
+use tokio::io::AsyncWriteExt;
+use tokio::process::{Child, ChildStdin, Command};
+
+use crate::event::ServerPayloadType;
+use crate::event::emit::emit_server;
+use crate::state::{clear_log_buffer, get_log_buffer, push_log_line};
+use crate::util::io::IOError;
+use crate::{ErrorKind, Result};
+
+use super::logs::{
+    analyze_exit_reason, stream_server_output, stream_server_pty_output,
+    tail_server_log_file,
+};
+use super::manifest::{
+    read_manifest, resolve_jar_name, server_path, write_manifest,
+};
+
+const DEFAULT_MEMORY_MB: u32 = 2048;
+const STOP_TIMEOUT_SECS: u64 = 60;
+const MAX_CONSOLE_ROWS: u16 = 8192;
+
+struct ServerProcess {
+    child: tokio::sync::Mutex<ServerChild>,
+    input: tokio::sync::Mutex<ServerInput>,
+    pty_master: Option<tokio::sync::Mutex<Box<dyn MasterPty + Send>>>,
+    stop_requested: AtomicBool,
+}
+
+enum ServerChild {
+    Piped(Child),
+    Pty(Box<dyn portable_pty::Child + Send + Sync>),
+}
+
+enum ServerInput {
+    Piped(ChildStdin),
+    Pty(Box<dyn std::io::Write + Send>),
+}
+
+impl ServerInput {
+    async fn write_all(&mut self, data: &[u8]) -> std::io::Result<()> {
+        match self {
+            Self::Piped(stdin) => {
+                stdin.write_all(data).await?;
+                stdin.flush().await
+            }
+            Self::Pty(writer) => {
+                writer.write_all(data)?;
+                writer.flush()
+            }
+        }
+    }
+}
+
+impl ServerChild {
+    fn try_wait(&mut self) -> std::io::Result<Option<bool>> {
+        match self {
+            Self::Piped(child) => {
+                child.try_wait().map(|status| status.map(|s| s.success()))
+            }
+            Self::Pty(child) => {
+                child.try_wait().map(|status| status.map(|s| s.success()))
+            }
+        }
+    }
+
+    async fn kill(&mut self) -> std::io::Result<()> {
+        match self {
+            Self::Piped(child) => child.kill().await,
+            Self::Pty(child) => child.kill(),
+        }
+    }
+}
+
+static SERVER_PROCESSES: LazyLock<DashMap<String, Arc<ServerProcess>>> =
+    LazyLock::new(DashMap::new);
+
+/// Synchronous start-in-flight guard. Reserving the slot before the first
+/// `.await` prevents concurrent `start` calls (e.g. double-clicks) from both
+/// passing the running check and spawning two JVMs on the same directory.
+static SERVER_STARTING: LazyLock<DashSet<String>> = LazyLock::new(DashSet::new);
+
+pub(super) fn is_running(server_id: &str) -> bool {
+    SERVER_PROCESSES.contains_key(server_id)
+}
+
+/// Whether a server process is currently tracked. Used by the log-file tailer
+/// to stop following once the server has exited.
+pub(super) fn is_server_running(server_id: &str) -> bool {
+    SERVER_PROCESSES.contains_key(server_id)
+}
+
+pub async fn start(
+    server_id: &str,
+    java_path: Option<String>,
+    memory_mb: Option<u32>,
+    jvm_args: Option<Vec<String>>,
+) -> Result<()> {
+    if SERVER_PROCESSES.contains_key(server_id)
+        || !SERVER_STARTING.insert(server_id.to_string())
+    {
+        return Err(ErrorKind::InputError(
+            "Server is already running".to_string(),
+        )
+        .as_error());
+    }
+    let result = start_inner(server_id, java_path, memory_mb, jvm_args).await;
+    SERVER_STARTING.remove(server_id);
+    result
+}
+
+async fn start_inner(
+    server_id: &str,
+    java_path: Option<String>,
+    memory_mb: Option<u32>,
+    jvm_args: Option<Vec<String>>,
+) -> Result<()> {
+    let dir = server_path(server_id).await?;
+    let mut manifest = read_manifest(&dir).await?;
+    let launch_args = if uses_pty_transport(&manifest.server_type) {
+        forge_launch_args(&dir)?
+    } else {
+        let jar_name = resolve_jar_name(&manifest);
+        let jar_path = dir.join(&jar_name);
+        if !jar_path.exists() {
+            return Err(ErrorKind::LauncherError(format!(
+                "Server jar not found: {jar_name}. Download the server files first."
+            ))
+            .as_error());
+        }
+        vec!["-jar".to_string(), jar_name, "nogui".to_string()]
+    };
+
+    let java = java_path
+        .or_else(|| manifest.java_path.clone())
+        .unwrap_or_else(|| "java".to_string());
+    let memory = memory_mb
+        .or(manifest.memory_mb)
+        .unwrap_or(DEFAULT_MEMORY_MB);
+
+    // Ensure eula.txt exists (create with eula=false if missing)
+    let eula_path = dir.join("eula.txt");
+    let eula_created = !eula_path.exists();
+    if eula_created {
+        tokio::fs::write(&eula_path, "eula=false\n")
+            .await
+            .map_err(|e| IOError::with_path(e, &eula_path))?;
+    }
+
+    let mut args = vec![format!("-Xmx{memory}M")];
+    if uses_pty_transport(&manifest.server_type) {
+        args.push("-Dorg.jline.reader.props.list-max=0".to_string());
+    }
+    args.extend(jvm_args.unwrap_or_else(|| manifest.jvm_args.clone()));
+    args.extend(launch_args);
+    let removed_environment = [
+        "DYLD_LIBRARY_PATH",
+        "DYLD_FALLBACK_LIBRARY_PATH",
+        "DYLD_FRAMEWORK_PATH",
+        "DYLD_FALLBACK_FRAMEWORK_PATH",
+        "DYLD_INSERT_LIBRARIES",
+    ];
+
+    let (mut child, input, pty_master, stdout, stderr, pty_reader) =
+        if uses_pty_transport(&manifest.server_type) {
+            let pair = native_pty_system()
+                .openpty(PtySize {
+                    rows: 12,
+                    cols: 80,
+                    pixel_width: 0,
+                    pixel_height: 0,
+                })
+                .map_err(|e| {
+                    ErrorKind::LauncherError(format!(
+                        "Failed to create Forge console PTY: {e}"
+                    ))
+                    .as_error()
+                })?;
+            let reader = pair.master.try_clone_reader().map_err(|e| {
+                ErrorKind::LauncherError(format!(
+                    "Failed to capture Forge console output: {e}"
+                ))
+                .as_error()
+            })?;
+            let writer = pair.master.take_writer().map_err(|e| {
+                ErrorKind::LauncherError(format!(
+                    "Failed to capture Forge console input: {e}"
+                ))
+                .as_error()
+            })?;
+            let mut command = CommandBuilder::new(&java);
+            command.args(&args);
+            command.cwd(&dir);
+            command.env("TERM", "xterm-256color");
+            for variable in removed_environment {
+                command.env_remove(variable);
+            }
+            let child = pair.slave.spawn_command(command).map_err(|e| {
+                ErrorKind::LauncherError(format!(
+                    "Failed to start Forge server process: {e}"
+                ))
+                .as_error()
+            })?;
+            (
+                ServerChild::Pty(child),
+                ServerInput::Pty(writer),
+                Some(tokio::sync::Mutex::new(pair.master)),
+                None,
+                None,
+                Some(reader),
+            )
+        } else {
+            let mut command = Command::new(&java);
+            command.args(&args);
+            command.current_dir(&dir);
+            for variable in removed_environment {
+                command.env_remove(variable);
+            }
+            command.stdout(std::process::Stdio::piped());
+            command.stderr(std::process::Stdio::piped());
+            command.stdin(std::process::Stdio::piped());
+            command.kill_on_drop(true);
+
+            let mut child = command.spawn().map_err(|e| {
+                ErrorKind::LauncherError(format!(
+                    "Failed to start server process: {e}"
+                ))
+                .as_error()
+            })?;
+            let stdout = child.stdout.take();
+            let stderr = child.stderr.take();
+            let stdin = child.stdin.take().ok_or_else(|| {
+                ErrorKind::LauncherError(
+                    "Server stdin could not be captured".to_string(),
+                )
+                .as_error()
+            })?;
+            (
+                ServerChild::Piped(child),
+                ServerInput::Piped(stdin),
+                None,
+                stdout,
+                stderr,
+                None,
+            )
+        };
+
+    manifest.last_started_at = Some(Utc::now());
+    manifest.last_exit_crashed = false;
+    if let Err(error) = write_manifest(&dir, &manifest).await {
+        let _ = child.kill().await;
+        return Err(error);
+    }
+
+    clear_log_buffer(server_id);
+
+    // Start each run from a clean log file. Minecraft's log4j appender appends
+    // to logs/latest.log across launches, so without truncating it the file
+    // tailer would replay the previous run's history into the fresh buffer on
+    // every restart.
+    let _ = std::fs::remove_file(dir.join("logs").join("latest.log"));
+
+    // Surface every startup step in the console. A loader's first launch (e.g.
+    // Fabric downloading the Minecraft server) can stay silent for a long time,
+    // so these lines stop the console from looking frozen.
+    let loader_first_run =
+        matches!(manifest.server_type.as_str(), "fabric" | "quilt")
+            && !dir
+                .join(format!("{}-server-launch.jar", manifest.server_type))
+                .exists();
+
+    log_server_step(
+        server_id,
+        &format!(
+            "Starting server '{}' ({} · Minecraft {})",
+            manifest.name, manifest.server_type, manifest.game_version,
+        ),
+    )
+    .await;
+    log_server_step(server_id, &format!("Java: {java}")).await;
+    log_server_step(server_id, &format!("Memory: {memory} MB")).await;
+    if eula_created {
+        log_server_step(
+            server_id,
+            "eula.txt not found — created with eula=false. Accept the EULA to start the server.",
+        )
+        .await;
+    }
+    log_server_step(
+        server_id,
+        &format!(
+            "Launching {} server ({} · nogui)",
+            manifest.server_type,
+            resolve_jar_name(&manifest),
+        ),
+    )
+    .await;
+    if loader_first_run {
+        log_server_step(
+            server_id,
+            "First launch: downloading Minecraft server files. This may take a few minutes — the console will keep updating as it progresses.",
+        )
+        .await;
+    }
+
+    let process = Arc::new(ServerProcess {
+        child: tokio::sync::Mutex::new(child),
+        input: tokio::sync::Mutex::new(input),
+        pty_master,
+        stop_requested: AtomicBool::new(false),
+    });
+    SERVER_PROCESSES.insert(server_id.to_string(), process.clone());
+
+    if let Some(stdout) = stdout {
+        tokio::spawn(stream_server_output(server_id.to_string(), stdout));
+    }
+    if let Some(stderr) = stderr {
+        tokio::spawn(stream_server_output(server_id.to_string(), stderr));
+    }
+    if let Some(reader) = pty_reader {
+        tokio::spawn(stream_server_pty_output(server_id.to_string(), reader));
+    }
+    // The process pipes (above) capture JVM/installer output, but the server's
+    // own log4j console output is normally written to logs/latest.log rather
+    // than the stdout pipe. Tail that file so the console always shows the
+    // complete, lossless server log (matching what's on disk).
+    tokio::spawn(tail_server_log_file(server_id.to_string(), dir.clone()));
+    tokio::spawn(monitor_server_process(server_id.to_string(), dir, process));
+
+    emit_server(server_id, ServerPayloadType::Started)
+        .await
+        .ok();
+    Ok(())
+}
+
+pub async fn send_command(server_id: &str, command: &str) -> Result<()> {
+    let process = SERVER_PROCESSES
+        .get(server_id)
+        .map(|entry| entry.value().clone())
+        .ok_or_else(|| {
+            ErrorKind::InputError("Server is not running".to_string())
+                .as_error()
+        })?;
+    let mut input = process.input.lock().await;
+    input
+        .write_all(&command_bytes(command))
+        .await
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!("Failed to send command: {e}"))
+                .as_error()
+        })?;
+    Ok(())
+}
+
+fn uses_pty_transport(server_type: &str) -> bool {
+    server_type == "forge"
+}
+
+fn command_bytes(command: &str) -> Vec<u8> {
+    format!("{command}\n").into_bytes()
+}
+
+pub async fn send_console_input(server_id: &str, data: &str) -> Result<()> {
+    let process = SERVER_PROCESSES
+        .get(server_id)
+        .map(|entry| entry.value().clone())
+        .ok_or_else(|| {
+            ErrorKind::InputError("Server is not running".to_string())
+                .as_error()
+        })?;
+    if process.pty_master.is_none() {
+        return Err(ErrorKind::InputError(
+            "Raw console input is only available for Forge servers".to_string(),
+        )
+        .as_error());
+    }
+    let bytes = base64::engine::general_purpose::STANDARD
+        .decode(data)
+        .map_err(|e| {
+            ErrorKind::InputError(format!("Invalid console input: {e}"))
+                .as_error()
+        })?;
+    if bytes.len() > 64 * 1024 {
+        return Err(ErrorKind::InputError(
+            "Console input exceeds 64 KiB".to_string(),
+        )
+        .as_error());
+    }
+    let mut input = process.input.lock().await;
+    input.write_all(&bytes).await.map_err(|e| {
+        ErrorKind::LauncherError(format!("Failed to send command: {e}"))
+            .as_error()
+    })?;
+    Ok(())
+}
+
+pub async fn resize_console(
+    server_id: &str,
+    cols: u16,
+    rows: u16,
+) -> Result<()> {
+    let process = SERVER_PROCESSES
+        .get(server_id)
+        .map(|entry| entry.value().clone())
+        .ok_or_else(|| {
+            ErrorKind::InputError("Server is not running".to_string())
+                .as_error()
+        })?;
+    let master = process.pty_master.as_ref().ok_or_else(|| {
+        ErrorKind::InputError(
+            "Console resizing is only available for Forge servers".to_string(),
+        )
+        .as_error()
+    })?;
+    master
+        .lock()
+        .await
+        .resize(PtySize {
+            rows: rows.clamp(4, MAX_CONSOLE_ROWS),
+            cols: cols.clamp(20, 500),
+            pixel_width: 0,
+            pixel_height: 0,
+        })
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!(
+                "Failed to resize Forge console: {e}"
+            ))
+            .as_error()
+        })?;
+    Ok(())
+}
+
+pub async fn stop(server_id: &str) -> Result<()> {
+    let process = SERVER_PROCESSES
+        .get(server_id)
+        .map(|entry| entry.value().clone())
+        .ok_or_else(|| {
+            ErrorKind::InputError("Server is not running".to_string())
+                .as_error()
+        })?;
+    process.stop_requested.store(true, Ordering::SeqCst);
+    let mut input = process.input.lock().await;
+    let _ = input.write_all(b"stop\n").await;
+
+    let watchdog = process.clone();
+    let server_id = server_id.to_string();
+    tokio::spawn(async move {
+        tokio::time::sleep(std::time::Duration::from_secs(STOP_TIMEOUT_SECS))
+            .await;
+        if let Some(current) = SERVER_PROCESSES.get(&server_id)
+            && current.stop_requested.load(Ordering::SeqCst)
+        {
+            let _ = watchdog.child.lock().await.kill().await;
+        }
+    });
+    Ok(())
+}
+
+pub async fn kill(server_id: &str) -> Result<()> {
+    let process = SERVER_PROCESSES
+        .get(server_id)
+        .map(|entry| entry.value().clone())
+        .ok_or_else(|| {
+            ErrorKind::InputError("Server is not running".to_string())
+                .as_error()
+        })?;
+    process.stop_requested.store(true, Ordering::SeqCst);
+    let mut child = process.child.lock().await;
+    child.kill().await?;
+    Ok(())
+}
+
+async fn monitor_server_process(
+    server_id: String,
+    dir: PathBuf,
+    process: Arc<ServerProcess>,
+) {
+    loop {
+        tokio::time::sleep(std::time::Duration::from_millis(250)).await;
+        let exit_status = {
+            let mut child = process.child.lock().await;
+            match child.try_wait() {
+                Ok(Some(success)) => Some(success),
+                Ok(None) => continue,
+                Err(_) => None,
+            }
+        };
+
+        SERVER_PROCESSES.remove(&server_id);
+        let stop_requested = process.stop_requested.load(Ordering::SeqCst);
+        let eula_accepted = read_eula_accepted(&dir).await;
+        let crashed = exit_status
+            .map(|success| !success && !stop_requested && eula_accepted)
+            .unwrap_or(false);
+
+        // Classify self-exits from the tail of the console output so the UI
+        // can react (e.g. offer the EULA dialog). User-requested stops and
+        // unmatched exits stay unclassified. The brief settle wait lets the
+        // output-stream tasks flush their final lines into the buffer first.
+        let reason = if stop_requested {
+            None
+        } else {
+            tokio::time::sleep(std::time::Duration::from_millis(100)).await;
+            analyze_exit_reason(&get_log_buffer(&server_id))
+        };
+
+        if let Ok(mut manifest) = read_manifest(&dir).await {
+            manifest.last_exit_crashed = crashed;
+            let _ = write_manifest(&dir, &manifest).await;
+        }
+
+        emit_server(&server_id, ServerPayloadType::Stopped { crashed, reason })
+            .await
+            .ok();
+        return;
+    }
+}
+
+/// Builds the JVM launch arguments for a Forge server. Modern Forge (1.17+)
+/// ships `@args` files that enumerate the classpath and main class; legacy Forge
+/// (<=1.16) produces a single runnable `forge-*.jar`.
+fn forge_launch_args(dir: &Path) -> Result<Vec<String>> {
+    let forge_dir = dir
+        .join("libraries")
+        .join("net")
+        .join("minecraftforge")
+        .join("forge");
+    if let Ok(entries) = std::fs::read_dir(&forge_dir) {
+        let args_file = if cfg!(windows) {
+            "win_args.txt"
+        } else {
+            "unix_args.txt"
+        };
+        for entry in entries.flatten() {
+            let candidate = entry.path().join(args_file);
+            if candidate.is_file() {
+                let mut args = Vec::new();
+                if dir.join("user_jvm_args.txt").exists() {
+                    args.push("@user_jvm_args.txt".to_string());
+                }
+                args.push(format!("@{}", candidate.to_string_lossy()));
+                args.push("nogui".to_string());
+                return Ok(args);
+            }
+        }
+    }
+    if let Some(jar) = find_forge_jar(dir) {
+        return Ok(vec!["-jar".to_string(), jar, "nogui".to_string()]);
+    }
+    Err(ErrorKind::LauncherError(
+        "Forge server files are missing. Reinstall the server.".to_string(),
+    )
+    .as_error())
+}
+
+fn find_forge_jar(dir: &Path) -> Option<String> {
+    let entry = std::fs::read_dir(dir).ok()?.flatten().find(|e| {
+        e.file_name().to_string_lossy().starts_with("forge-")
+            && e.path().extension().is_some_and(|ext| ext == "jar")
+    })?;
+    Some(entry.file_name().to_string_lossy().into_owned())
+}
+
+async fn read_eula_accepted(dir: &Path) -> bool {
+    match tokio::fs::read_to_string(dir.join("eula.txt")).await {
+        Ok(text) => text
+            .lines()
+            .find_map(|line| line.split_once('='))
+            .filter(|(key, _)| key.trim() == "eula")
+            .is_some_and(|(_, value)| {
+                value.trim().eq_ignore_ascii_case("true")
+            }),
+        Err(_) => false,
+    }
+}
+
+/// Emits a timestamped, info-level line to the server console: it is both
+/// persisted to the log buffer and pushed as a live `Log` event, so startup
+/// progress is visible even before the JVM produces any output of its own.
+async fn log_server_step(server_id: &str, message: &str) {
+    let line = format!(
+        "{} [Axolotl/INFO]: {}",
+        chrono::Local::now().format("%H:%M:%S"),
+        message,
+    );
+    push_log_line(server_id, line.clone());
+    emit_server(server_id, ServerPayloadType::Log { line })
+        .await
+        .ok();
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[derive(Clone)]
+    struct SharedWriter(Arc<std::sync::Mutex<Vec<u8>>>);
+
+    impl std::io::Write for SharedWriter {
+        fn write(&mut self, buffer: &[u8]) -> std::io::Result<usize> {
+            self.0.lock().unwrap().extend_from_slice(buffer);
+            Ok(buffer.len())
+        }
+
+        fn flush(&mut self) -> std::io::Result<()> {
+            Ok(())
+        }
+    }
+
+    #[test]
+    fn selects_pty_only_for_forge() {
+        assert!(uses_pty_transport("forge"));
+        assert!(!uses_pty_transport("vanilla"));
+        assert!(!uses_pty_transport("fabric"));
+        assert!(!uses_pty_transport("neoforge"));
+    }
+
+    #[test]
+    fn whole_line_commands_end_with_one_newline() {
+        assert_eq!(command_bytes("say hello"), b"say hello\n");
+    }
+
+    #[tokio::test]
+    async fn pty_input_preserves_raw_bytes() {
+        let captured = Arc::new(std::sync::Mutex::new(Vec::new()));
+        let mut input =
+            ServerInput::Pty(Box::new(SharedWriter(captured.clone())));
+        input.write_all(b"\x1b[D\t\x7f").await.unwrap();
+        assert_eq!(*captured.lock().unwrap(), b"\x1b[D\t\x7f");
+    }
+}

packages/app-lib/src/api/servers/logs.rs

@@ -0,0 +1,484 @@
+//! Console output buffering and streaming for servers.
+
+use base64::Engine;
+use std::path::PathBuf;
+use tokio::fs::File;
+use tokio::io::{AsyncBufRead, AsyncBufReadExt, AsyncSeekExt, BufReader};
+
+use crate::Result;
+use crate::api::servers::lifecycle::is_server_running;
+use crate::event::emit::emit_server;
+use crate::event::{ExitReason, ServerPayloadType};
+use crate::state::{clear_log_buffer, push_log_line};
+
+const MAX_PTY_LINE_BYTES: usize = 256 * 1024;
+const MAX_SERVER_LOG_LINE_BYTES: usize = 64 * 1024;
+const SERVER_LOG_TRUNCATION_MARKER: &str =
+    " … [log output truncated by Axolotl] … ";
+
+async fn read_bounded_server_log_line<R>(
+    reader: &mut R,
+) -> std::io::Result<Option<String>>
+where
+    R: AsyncBufRead + Unpin,
+{
+    let mut line = Vec::new();
+    let mut saw_bytes = false;
+    let mut truncated = false;
+
+    loop {
+        let (consumed, reached_line_end) = {
+            let available = reader.fill_buf().await?;
+            if available.is_empty() {
+                if !saw_bytes {
+                    return Ok(None);
+                }
+                break;
+            }
+
+            saw_bytes = true;
+            let consumed = available
+                .iter()
+                .position(|byte| *byte == b'\n')
+                .map_or(available.len(), |index| index + 1);
+            let maximum_content_bytes = MAX_SERVER_LOG_LINE_BYTES
+                .saturating_sub(SERVER_LOG_TRUNCATION_MARKER.len() + 1);
+            let remaining = maximum_content_bytes.saturating_sub(line.len());
+            let copied = remaining.min(consumed);
+            line.extend_from_slice(&available[..copied]);
+            truncated |= copied < consumed;
+            (consumed, available[consumed - 1] == b'\n')
+        };
+        reader.consume(consumed);
+        if reached_line_end {
+            break;
+        }
+    }
+
+    if truncated {
+        while matches!(line.last(), Some(b'\r' | b'\n')) {
+            line.pop();
+        }
+        line.extend_from_slice(SERVER_LOG_TRUNCATION_MARKER.as_bytes());
+        line.push(b'\n');
+    }
+
+    Ok(Some(String::from_utf8_lossy(&line).into_owned()))
+}
+
+pub async fn get_log_buffer(server_id: &str) -> Result<Vec<String>> {
+    Ok(crate::state::get_log_buffer(server_id))
+}
+
+pub async fn clear_log(server_id: &str) -> Result<()> {
+    clear_log_buffer(server_id);
+    Ok(())
+}
+
+pub(super) async fn stream_server_output(
+    server_id: String,
+    reader: impl tokio::io::AsyncRead + Unpin,
+) {
+    let mut buf_reader = BufReader::new(reader);
+    let mut jna_hint_emitted = false;
+    while let Ok(Some(line)) =
+        read_bounded_server_log_line(&mut buf_reader).await
+    {
+        process_server_output_line(
+            &server_id,
+            line.trim_end_matches(['\r', '\n']),
+            &mut jna_hint_emitted,
+        )
+        .await;
+    }
+}
+
+pub(super) async fn stream_server_pty_output(
+    server_id: String,
+    mut reader: Box<dyn std::io::Read + Send>,
+) {
+    let (sender, mut receiver) = tokio::sync::mpsc::channel::<Vec<u8>>(32);
+    tokio::task::spawn_blocking(move || {
+        let mut buffer = vec![0_u8; 8192];
+        loop {
+            match reader.read(&mut buffer) {
+                Ok(0) | Err(_) => break,
+                Ok(read) => {
+                    if sender.blocking_send(buffer[..read].to_vec()).is_err() {
+                        break;
+                    }
+                }
+            }
+        }
+    });
+
+    let mut pending_line = Vec::new();
+    let mut jna_hint_emitted = false;
+    while let Some(bytes) = receiver.recv().await {
+        emit_server(
+            &server_id,
+            ServerPayloadType::ConsoleOutput {
+                data: base64::engine::general_purpose::STANDARD.encode(&bytes),
+            },
+        )
+        .await
+        .ok();
+
+        for line in take_complete_pty_lines(&mut pending_line, &bytes) {
+            let text = String::from_utf8_lossy(&line);
+            process_server_output_line(
+                &server_id,
+                text.trim_end_matches(['\r', '\n']),
+                &mut jna_hint_emitted,
+            )
+            .await;
+        }
+    }
+    if !pending_line.is_empty() {
+        process_server_output_line(
+            &server_id,
+            &String::from_utf8_lossy(&pending_line),
+            &mut jna_hint_emitted,
+        )
+        .await;
+    }
+}
+
+fn take_complete_pty_lines(
+    pending: &mut Vec<u8>,
+    bytes: &[u8],
+) -> Vec<Vec<u8>> {
+    pending.extend_from_slice(bytes);
+    let Some(last_newline) = pending.iter().rposition(|byte| *byte == b'\n')
+    else {
+        if pending.len() > MAX_PTY_LINE_BYTES {
+            pending.clear();
+        }
+        return Vec::new();
+    };
+
+    let remainder = pending.split_off(last_newline + 1);
+    let completed = std::mem::replace(pending, remainder);
+    let mut lines = Vec::new();
+    for line in completed.split_inclusive(|byte| *byte == b'\n') {
+        if line.len() <= MAX_PTY_LINE_BYTES {
+            lines.push(line.to_vec());
+        }
+    }
+    lines
+}
+
+async fn process_server_output_line(
+    server_id: &str,
+    raw_line: &str,
+    jna_hint_emitted: &mut bool,
+) {
+    let cleaned = strip_ansi(raw_line);
+    if cleaned.is_empty()
+        || is_timestamped_log_line(&cleaned)
+        || cleaned.starts_with("> ")
+    {
+        return;
+    }
+    push_log_line(server_id, cleaned.clone());
+    emit_server(server_id, ServerPayloadType::Log { line: cleaned })
+        .await
+        .ok();
+    if !*jna_hint_emitted && is_jna_macos_assertion(raw_line) {
+        *jna_hint_emitted = true;
+        for hint in JNA_CRASH_HINT_LINES {
+            push_log_line(server_id, hint.to_string());
+            emit_server(
+                server_id,
+                ServerPayloadType::Log {
+                    line: hint.to_string(),
+                },
+            )
+            .await
+            .ok();
+        }
+    }
+}
+
+/// Streams the server's `logs/latest.log` file into the console buffer. The
+/// Minecraft/Fabric log4j console output is frequently not delivered through
+/// the process stdout pipe (it goes to the log file instead), so tailing this
+/// file is the authoritative, lossless source of the server's own logs. Lines
+/// already present in the buffer (e.g. delivered via the stdout/stderr pipes)
+/// are skipped to avoid duplicates.
+pub(super) async fn tail_server_log_file(server_id: String, dir: PathBuf) {
+    let log_path = dir.join("logs").join("latest.log");
+    let mut reader = loop {
+        if !is_server_running(&server_id) {
+            return;
+        }
+        match File::open(&log_path).await {
+            Ok(file) => break BufReader::new(file),
+            // The file only appears once the server starts logging; poll until then.
+            Err(_) => {
+                tokio::time::sleep(std::time::Duration::from_millis(250)).await;
+            }
+        }
+    };
+
+    loop {
+        if !is_server_running(&server_id) {
+            return;
+        }
+        match read_bounded_server_log_line(&mut reader).await {
+            Ok(None) => {
+                // Caught up. Detect log rotation (file replaced/truncated) and
+                // otherwise wait for more output to be appended.
+                if let Ok(meta) = tokio::fs::metadata(&log_path).await
+                    && let Ok(pos) = reader.stream_position().await
+                    && meta.len() < pos
+                    && let Ok(file) = File::open(&log_path).await
+                {
+                    reader = BufReader::new(file);
+                }
+                tokio::time::sleep(std::time::Duration::from_millis(200)).await;
+            }
+            Ok(Some(line)) => {
+                let trimmed = line.trim_end_matches(['\r', '\n']);
+                let cleaned = strip_ansi(trimmed);
+                let already_present =
+                    crate::state::get_log_buffer(&server_id).contains(&cleaned);
+                if !cleaned.is_empty() && !already_present {
+                    push_log_line(&server_id, cleaned.clone());
+                    emit_server(
+                        &server_id,
+                        ServerPayloadType::Log { line: cleaned },
+                    )
+                    .await
+                    .ok();
+                }
+            }
+            Err(_) => break,
+        }
+    }
+}
+
+/// Matches the native abort of the known JNA (< 5.13.0) macOS bug (JNA issue
+/// #1452): a failed library load overflows JNA's fixed error buffer and the
+/// JVM dies with SIGABRT before any Java-level exception can be reported.
+fn is_jna_macos_assertion(line: &str) -> bool {
+    line.contains("Assertion failed:")
+        && line.contains("snprintf() output has been truncated")
+        && line.contains("dispatch.c")
+}
+
+/// Detects a server log4j line by its leading `[HH:MM:SS]` timestamp, covering
+/// both console (`[HH:MM:SS INFO]:`) and file (`[HH:MM:SS] [Thread/INFO]:`)
+/// formats. Used to suppress the process-pipe echo of server logs so they are
+/// not duplicated by `tail_server_log_file`.
+fn is_timestamped_log_line(line: &str) -> bool {
+    let b = line.as_bytes();
+    b.first() == Some(&b'[')
+        && b.get(1).is_some_and(|c| c.is_ascii_digit())
+        && b.get(2).is_some_and(|c| c.is_ascii_digit())
+        && b.get(3) == Some(&b':')
+        && b.get(4).is_some_and(|c| c.is_ascii_digit())
+        && b.get(5).is_some_and(|c| c.is_ascii_digit())
+        && b.get(6) == Some(&b':')
+        && b.get(7).is_some_and(|c| c.is_ascii_digit())
+        && b.get(8).is_some_and(|c| c.is_ascii_digit())
+}
+
+/// How many lines at the end of a server's output are inspected when
+/// classifying why it exited.
+const EXIT_ANALYSIS_TAIL_LINES: usize = 50;
+
+/// Classifies why a server exited on its own by scanning the tail of its
+/// console output, newest lines first. Returns `None` when nothing matches:
+/// no guess is better than a wrong one, and unmatched exits simply behave as
+/// before.
+pub(super) fn analyze_exit_reason(lines: &[String]) -> Option<ExitReason> {
+    lines
+        .iter()
+        .rev()
+        .take(EXIT_ANALYSIS_TAIL_LINES)
+        .find_map(|line| is_eula_refusal(line).then_some(ExitReason::Eula))
+}
+
+/// Matches the vanilla server's refusal to boot before the EULA has been
+/// accepted; the process then writes `eula.txt` and exits immediately.
+fn is_eula_refusal(line: &str) -> bool {
+    line.contains("need to agree to the EULA")
+}
+
+const JNA_CRASH_HINT_LINES: [&str; 3] = [
+    "[Axolotl] This crash matches a known JNA bug on macOS (java-native-access#1452):",
+    "[Axolotl] mods bundling JNA below 5.13.0 abort when a native library fails to load.",
+    "[Axolotl] Update or remove the affected mod, or ask the modpack author to bump JNA to 5.13.0+.",
+];
+
+/// Removes ANSI escape sequences (SGR colors, cursor control, OSC titles) that
+/// servers emit when they assume an interactive terminal is attached.
+fn strip_ansi(input: &str) -> String {
+    let mut output = String::with_capacity(input.len());
+    let mut chars = input.char_indices().peekable();
+    while let Some((_, character)) = chars.next() {
+        if character != '\u{1b}' {
+            output.push(character);
+            continue;
+        }
+        match chars.peek().map(|&(_, c)| c) {
+            // CSI sequence: parameter bytes, then a final byte in @..~
+            Some('[') => {
+                chars.next();
+                for (_, c) in chars.by_ref() {
+                    if ('\u{40}'..='\u{7e}').contains(&c) {
+                        break;
+                    }
+                }
+            }
+            // OSC sequence: terminated by BEL or ST (ESC \)
+            Some(']') => {
+                chars.next();
+                let mut saw_escape = false;
+                for (_, c) in chars.by_ref() {
+                    if c == '\u{7}' || (saw_escape && c == '\\') {
+                        break;
+                    }
+                    saw_escape = c == '\u{1b}';
+                }
+            }
+            // Stray escape byte without a recognized sequence
+            _ => {}
+        }
+    }
+    output
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn strips_ansi_escape_sequences_from_server_output() {
+        let line = "[16:02:30 INFO]: \u{1b}[38;2;255;170;0m/mspt: \u{1b}[38;2;255;255;255mView server tick times\u{1b}[0m";
+        assert_eq!(
+            strip_ansi(line),
+            "[16:02:30 INFO]: /mspt: View server tick times"
+        );
+
+        assert_eq!(strip_ansi("\u{1b}]0;Server console\u{7}ready"), "ready");
+        assert_eq!(strip_ansi("\u{1b}]0;Server console\u{1b}\\done"), "done");
+        assert_eq!(strip_ansi("plain text stays"), "plain text stays");
+        assert_eq!(strip_ansi("h\u{e9}llo \u{1b}[31mred"), "h\u{e9}llo red");
+    }
+
+    #[test]
+    fn splits_pty_output_without_losing_partial_or_raw_bytes() {
+        let mut pending = Vec::new();
+        assert_eq!(
+            take_complete_pty_lines(&mut pending, b"first\r\nsecond"),
+            vec![b"first\r\n".to_vec()]
+        );
+        assert_eq!(pending, b"second");
+        assert_eq!(
+            take_complete_pty_lines(&mut pending, b"\nthird\n"),
+            vec![b"second\n".to_vec(), b"third\n".to_vec()]
+        );
+        assert!(pending.is_empty());
+    }
+
+    #[test]
+    fn bounds_unterminated_pty_output() {
+        let mut pending = vec![b'x'; MAX_PTY_LINE_BYTES];
+        assert!(take_complete_pty_lines(&mut pending, b"x").is_empty());
+        assert!(pending.is_empty());
+
+        let oversized = vec![b'x'; MAX_PTY_LINE_BYTES + 1];
+        assert!(take_complete_pty_lines(&mut pending, &oversized).is_empty());
+        assert!(pending.is_empty());
+    }
+
+    #[tokio::test]
+    async fn bounded_server_log_reader_consumes_oversized_line() {
+        let input =
+            format!("{}\nnext\n", "x".repeat(MAX_SERVER_LOG_LINE_BYTES * 2));
+        let mut reader = BufReader::new(std::io::Cursor::new(input));
+
+        let first = read_bounded_server_log_line(&mut reader)
+            .await
+            .unwrap()
+            .unwrap();
+        let second = read_bounded_server_log_line(&mut reader)
+            .await
+            .unwrap()
+            .unwrap();
+
+        assert!(first.contains("truncated by Axolotl"));
+        assert!(first.len() <= MAX_SERVER_LOG_LINE_BYTES);
+        assert_eq!(second, "next\n");
+    }
+
+    #[test]
+    fn detects_timestamped_log_lines() {
+        // Console format (no thread) — duplicated by Paper's stdout echo.
+        assert!(is_timestamped_log_line(
+            "[11:13:49 INFO]: [bootstrap] Running Java 25"
+        ));
+        // File format (with thread) — authoritative source from latest.log.
+        assert!(is_timestamped_log_line(
+            "[11:13:49] [ServerMain/INFO]: [bootstrap] Running"
+        ));
+        assert!(is_timestamped_log_line(
+            "[11:13:49] [Server thread/INFO]: Stopped IO worker!"
+        ));
+        // Non-logged process output must NOT be suppressed.
+        assert!(!is_timestamped_log_line("Downloading mojang_26.2.jar"));
+        assert!(!is_timestamped_log_line("Applying patches"));
+        assert!(!is_timestamped_log_line(
+            "Starting org.bukkit.craftbukkit.Main"
+        ));
+        assert!(!is_timestamped_log_line(
+            "WARNING: A terminally deprecated method in sun.misc.Unsafe"
+        ));
+        assert!(!is_timestamped_log_line(
+            "2026-08-29T03:13:49.279070900Z ServerMain WARN Advanced terminal features",
+        ));
+    }
+
+    #[test]
+    fn detects_jna_macos_assertion() {
+        let line = "Assertion failed: (count <= len && \"snprintf() output has been truncated\"), function LOAD_ERROR, file dispatch.c, line 74.";
+        assert!(is_jna_macos_assertion(line));
+        assert!(!is_jna_macos_assertion(
+            "Assertion failed: something else, file other.c, line 1."
+        ));
+        assert!(!is_jna_macos_assertion("regular log output"));
+    }
+
+    #[test]
+    fn classifies_eula_refusal_from_output_tail() {
+        let eula_line = "[15:26:09] [main/INFO]: You need to agree to the EULA in order to run the server. Go to eula.txt for more info.".to_string();
+        let mut lines = vec![
+            "[15:26:09] [main/INFO]: Starting minecraft server version 26.2"
+                .to_string(),
+            eula_line.clone(),
+        ];
+        assert_eq!(analyze_exit_reason(&lines), Some(ExitReason::Eula));
+
+        // Detected even when buried under later shutdown chatter.
+        lines.push(
+            "[16:44:23] [Server thread/INFO]: Stopped IO worker!".to_string(),
+        );
+        assert_eq!(analyze_exit_reason(&lines), Some(ExitReason::Eula));
+
+        // A normal shutdown matches nothing and stays unclassified.
+        let normal = vec![
+            "[16:44:18] [Server thread/INFO]: Stopping the server".to_string(),
+            "[16:44:23] [Server thread/INFO]: Stopped IO worker!".to_string(),
+        ];
+        assert_eq!(analyze_exit_reason(&normal), None);
+        assert_eq!(analyze_exit_reason(&[]), None);
+
+        // Only the tail is inspected; ancient history does not classify a
+        // much-later exit.
+        let mut old = vec![eula_line];
+        old.resize(EXIT_ANALYSIS_TAIL_LINES + 10, "noise".to_string());
+        assert_eq!(analyze_exit_reason(&old), None);
+    }
+}

packages/app-lib/src/api/servers/manage.rs

@@ -0,0 +1,161 @@
+//! Listing, creation, and settings management for servers.
+
+use chrono::Utc;
+use uuid::Uuid;
+
+use crate::state::remove_log_buffer;
+use crate::util::io::{self, IOError};
+use crate::{ErrorKind, Result, State};
+
+use super::lifecycle::is_running;
+use super::manifest::{
+    ServerInfo, ServerManifest, build_server_info, read_manifest,
+    sanitize_folder_name, server_path, type_default_jar_name, write_manifest,
+};
+
+pub async fn list() -> Result<Vec<ServerInfo>> {
+    let state = State::get().await?;
+    let servers_dir = state.directories.servers_dir();
+    if !servers_dir.exists() {
+        return Ok(Vec::new());
+    }
+
+    let mut servers = Vec::new();
+    let mut entries = tokio::fs::read_dir(&servers_dir)
+        .await
+        .map_err(|e| IOError::with_path(e, &servers_dir))?;
+    while let Some(entry) = entries
+        .next_entry()
+        .await
+        .map_err(|e| IOError::with_path(e, &servers_dir))?
+    {
+        let path = entry.path();
+        if !path.is_dir() {
+            continue;
+        }
+        let Ok(manifest) = read_manifest(&path).await else {
+            continue;
+        };
+        servers.push(build_server_info(&manifest, &path).await);
+    }
+    servers.sort_by(|a, b| {
+        a.manifest
+            .name
+            .to_lowercase()
+            .cmp(&b.manifest.name.to_lowercase())
+    });
+    Ok(servers)
+}
+
+pub async fn get(server_id: &str) -> Result<ServerInfo> {
+    let path = server_path(server_id).await?;
+    let manifest = read_manifest(&path).await?;
+    Ok(build_server_info(&manifest, &path).await)
+}
+
+pub async fn create(
+    name: &str,
+    server_type: &str,
+    game_version: &str,
+    loader_version: Option<String>,
+    java_path: Option<String>,
+    memory_mb: Option<u32>,
+) -> Result<ServerManifest> {
+    let name = name.trim();
+    if name.is_empty() {
+        return Err(ErrorKind::InputError(
+            "Server name cannot be empty".to_string(),
+        )
+        .as_error());
+    }
+
+    let state = State::get().await?;
+    let id = Uuid::new_v4().to_string();
+    let dir_name = format!("{}-{}", sanitize_folder_name(name), &id[..8]);
+    let dir = state.directories.servers_dir().join(&dir_name);
+    io::create_dir_all(&dir).await?;
+
+    let manifest = ServerManifest {
+        id: dir_name,
+        name: name.to_string(),
+        server_type: server_type.to_string(),
+        game_version: game_version.to_string(),
+        loader_version,
+        jar_name: type_default_jar_name(server_type),
+        java_path,
+        memory_mb,
+        icon_path: None,
+        modpack: None,
+        install_state: None,
+        install_error: None,
+        jvm_args: Vec::new(),
+        created_at: Utc::now(),
+        last_started_at: None,
+        last_exit_crashed: false,
+    };
+    write_manifest(&dir, &manifest).await?;
+    Ok(manifest)
+}
+
+/// Sets or clears the server icon. `None` resets to the default icon.
+pub async fn set_icon(
+    server_id: &str,
+    icon_path: Option<String>,
+) -> Result<ServerManifest> {
+    let path = server_path(server_id).await?;
+    let mut manifest = read_manifest(&path).await?;
+    manifest.icon_path = icon_path;
+    write_manifest(&path, &manifest).await?;
+    Ok(manifest)
+}
+
+pub async fn update_settings(
+    server_id: &str,
+    name: Option<String>,
+    java_path: Option<String>,
+    memory_mb: Option<u32>,
+    jvm_args: Option<Vec<String>>,
+) -> Result<ServerManifest> {
+    let path = server_path(server_id).await?;
+    let mut manifest = read_manifest(&path).await?;
+    if let Some(name) = name {
+        let name = name.trim().to_string();
+        if name.is_empty() {
+            return Err(ErrorKind::InputError(
+                "Server name cannot be empty".to_string(),
+            )
+            .as_error());
+        }
+        manifest.name = name;
+    }
+    if let Some(java_path) = java_path {
+        manifest.java_path = if java_path.is_empty() {
+            None
+        } else {
+            Some(java_path)
+        };
+    }
+    if let Some(memory_mb) = memory_mb {
+        manifest.memory_mb = Some(memory_mb);
+    }
+    if let Some(jvm_args) = jvm_args {
+        manifest.jvm_args = jvm_args;
+    }
+    write_manifest(&path, &manifest).await?;
+    Ok(manifest)
+}
+
+pub async fn delete(server_id: &str) -> Result<()> {
+    if is_running(server_id) {
+        return Err(ErrorKind::InputError(
+            "Stop the server before deleting it".to_string(),
+        )
+        .as_error());
+    }
+    let path = server_path(server_id).await?;
+    remove_log_buffer(server_id);
+    tokio::fs::remove_dir_all(&path)
+        .await
+        .map_err(|e| IOError::with_path(e, &path))?;
+    Ok(())
+}

packages/app-lib/src/api/servers/manifest.rs

@@ -0,0 +1,268 @@
+//! Server manifests and per-server metadata: the `axolotl-server.json`
+//! document, derived display info, and path helpers shared by the other
+//! `servers` submodules.
+
+use std::path::{Path, PathBuf};
+
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+
+use crate::state::State;
+use crate::util::io;
+use crate::{ErrorKind, Result};
+
+use super::lifecycle::is_running;
+
+const MANIFEST_FILE: &str = "axolotl-server.json";
+const DEFAULT_JAR_NAME: &str = "server.jar";
+/// Executable launcher jar downloaded from Fabric Meta; must match the
+/// filename used by the frontend's `resolveServerJar('fabric')`.
+const FABRIC_SERVER_JAR_NAME: &str = "fabric-server.jar";
+/// Executable launcher jar downloaded from Quilt Meta; must match the
+/// filename used by the frontend's `resolveServerJar('quilt')`.
+const QUILT_SERVER_JAR_NAME: &str = "quilt-server.jar";
+
+pub(super) fn type_default_jar_name(server_type: &str) -> Option<String> {
+    match server_type {
+        "fabric" => Some(FABRIC_SERVER_JAR_NAME.to_string()),
+        "quilt" => Some(QUILT_SERVER_JAR_NAME.to_string()),
+        _ => None,
+    }
+}
+
+/// Resolves the jar a server launches with: the manifest override, then the
+/// server type default, then the generic default.
+pub(super) fn resolve_jar_name(manifest: &ServerManifest) -> String {
+    manifest
+        .jar_name
+        .clone()
+        .or_else(|| type_default_jar_name(&manifest.server_type))
+        .unwrap_or_else(|| DEFAULT_JAR_NAME.to_string())
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ServerManifest {
+    pub id: String,
+    pub name: String,
+    pub server_type: String,
+    pub game_version: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub loader_version: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub jar_name: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub java_path: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub memory_mb: Option<u32>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub icon_path: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub modpack: Option<ModpackInfo>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub install_state: Option<InstallState>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub install_error: Option<String>,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub jvm_args: Vec<String>,
+    pub created_at: DateTime<Utc>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub last_started_at: Option<DateTime<Utc>>,
+    #[serde(default)]
+    pub last_exit_crashed: bool,
+}
+
+/// Tracks whether a modpack server has finished materializing. `Incomplete`
+/// is written when an install starts (and left behind if the app exits
+/// mid-download); `Failed` records an install error so the UI can offer a
+/// retry. Both clear once the install succeeds.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum InstallState {
+    Incomplete,
+    Failed,
+}
+
+/// Identifies a modpack a server was created from. Populated by
+/// [`super::modpack::install_modpack`] so the UI can badge and link servers
+/// back to their source project.
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct ModpackInfo {
+    pub project_id: String,
+    pub version_id: String,
+    pub title: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub icon_url: Option<String>,
+}
+
+#[derive(Serialize, Debug, Clone)]
+pub struct ServerInfo {
+    #[serde(flatten)]
+    pub manifest: ServerManifest,
+    pub path: String,
+    pub running: bool,
+    pub eula_exists: bool,
+    pub eula_accepted: bool,
+    pub port: Option<u16>,
+}
+
+pub(super) async fn server_path(server_id: &str) -> Result<PathBuf> {
+    if server_id.contains(['/', '\\'])
+        || server_id.contains("..")
+        || server_id.is_empty()
+    {
+        return Err(ErrorKind::InputError(format!(
+            "Invalid server id: {server_id}"
+        ))
+        .as_error());
+    }
+    let state = State::get().await?;
+    let path = state.directories.server_dir(server_id);
+    if !path.is_dir() {
+        return Err(ErrorKind::InputError(format!(
+            "Unknown server: {server_id}"
+        ))
+        .as_error());
+    }
+    Ok(path)
+}
+
+pub(super) async fn read_manifest(dir: &Path) -> Result<ServerManifest> {
+    let bytes = io::read(dir.join(MANIFEST_FILE)).await?;
+    serde_json::from_slice(&bytes).map_err(|e| {
+        ErrorKind::FSError(format!("Failed to parse server manifest: {e}"))
+            .as_error()
+    })
+}
+
+pub(super) async fn write_manifest(
+    dir: &Path,
+    manifest: &ServerManifest,
+) -> Result<()> {
+    let contents = serde_json::to_string_pretty(manifest)?;
+    io::write(dir.join(MANIFEST_FILE), contents).await?;
+    Ok(())
+}
+
+pub(super) fn sanitize_folder_name(name: &str) -> String {
+    let sanitized: String = name
+        .chars()
+        .map(|c| {
+            if c.is_alphanumeric() || c == '-' || c == '_' {
+                c
+            } else {
+                '-'
+            }
+        })
+        .collect();
+    let trimmed = sanitized.trim_matches('-');
+    if trimmed.is_empty() {
+        "server".to_string()
+    } else {
+        trimmed.chars().take(32).collect()
+    }
+}
+
+pub(super) async fn build_server_info(
+    manifest: &ServerManifest,
+    path: &Path,
+) -> ServerInfo {
+    let eula_text = tokio::fs::read_to_string(path.join("eula.txt"))
+        .await
+        .unwrap_or_default();
+    let eula_exists = !eula_text.is_empty();
+    let eula_accepted = eula_text
+        .lines()
+        .find_map(|line| line.split_once('='))
+        .filter(|(key, _)| key.trim() == "eula")
+        .is_some_and(|(_, value)| value.trim().eq_ignore_ascii_case("true"));
+    let port = tokio::fs::read_to_string(path.join("server.properties"))
+        .await
+        .ok()
+        .and_then(|text| {
+            text.lines().find_map(|line| {
+                let (key, value) = line.split_once('=')?;
+                (key.trim() == "server-port")
+                    .then(|| value.trim().parse::<u16>().ok())?
+            })
+        });
+    ServerInfo {
+        manifest: manifest.clone(),
+        path: path.to_string_lossy().into_owned(),
+        running: is_running(&manifest.id),
+        eula_exists,
+        eula_accepted,
+        port,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn sanitize_folder_name_replaces_unsafe_characters() {
+        assert_eq!(sanitize_folder_name("My Server!"), "My-Server");
+        assert_eq!(sanitize_folder_name("../etc"), "etc");
+        assert_eq!(sanitize_folder_name("///"), "server");
+    }
+
+    #[test]
+    fn server_manifest_round_trips() {
+        let manifest = ServerManifest {
+            id: "test-12345678".to_string(),
+            name: "Test".to_string(),
+            server_type: "vanilla".to_string(),
+            game_version: "1.21.4".to_string(),
+            loader_version: None,
+            jar_name: None,
+            java_path: None,
+            memory_mb: Some(2048),
+            icon_path: None,
+            modpack: None,
+            install_state: None,
+            install_error: None,
+            jvm_args: Vec::new(),
+            created_at: Utc::now(),
+            last_started_at: None,
+            last_exit_crashed: false,
+        };
+        let json = serde_json::to_string(&manifest).unwrap();
+        let parsed: ServerManifest = serde_json::from_str(&json).unwrap();
+        assert_eq!(parsed.id, manifest.id);
+        assert_eq!(parsed.name, manifest.name);
+    }
+
+    #[test]
+    fn resolves_jar_name_from_type_then_manifest() {
+        let mut manifest = ServerManifest {
+            id: "test-12345678".to_string(),
+            name: "Test".to_string(),
+            server_type: "fabric".to_string(),
+            game_version: "26.2".to_string(),
+            loader_version: Some("0.19.3".to_string()),
+            jar_name: None,
+            java_path: None,
+            memory_mb: None,
+            icon_path: None,
+            modpack: None,
+            install_state: None,
+            install_error: None,
+            jvm_args: Vec::new(),
+            created_at: Utc::now(),
+            last_started_at: None,
+            last_exit_crashed: false,
+        };
+        assert_eq!(resolve_jar_name(&manifest), FABRIC_SERVER_JAR_NAME);
+
+        manifest.server_type = "quilt".to_string();
+        assert_eq!(resolve_jar_name(&manifest), QUILT_SERVER_JAR_NAME);
+
+        manifest.server_type = "vanilla".to_string();
+        assert_eq!(resolve_jar_name(&manifest), DEFAULT_JAR_NAME);
+
+        manifest.jar_name = Some("custom.jar".to_string());
+        assert_eq!(resolve_jar_name(&manifest), "custom.jar");
+    }
+}

packages/app-lib/src/api/servers/ports.rs

@@ -0,0 +1,170 @@
+//! Platform utilities for inspecting and terminating processes that hold a
+//! TCP port, used to resolve "port already in use" conflicts.
+
+use serde::Serialize;
+use tokio::process::Command;
+
+use crate::{ErrorKind, Result};
+
+pub async fn kill_port_process(port: u16) -> Result<()> {
+    let pids = port_listener_pids(port).await?;
+    if pids.is_empty() {
+        return Err(ErrorKind::InputError(format!(
+            "No process found listening on port {port}"
+        ))
+        .as_error());
+    }
+    for pid in pids {
+        force_terminate_pid(pid).await?;
+    }
+    Ok(())
+}
+
+#[derive(Serialize, Debug, Clone)]
+pub struct PortProcessInfo {
+    pub pid: u32,
+    pub name: Option<String>,
+}
+
+/// Returns the first process listening on the given TCP port, if any.
+pub async fn port_process(port: u16) -> Result<Option<PortProcessInfo>> {
+    let pids = port_listener_pids(port).await?;
+    let Some(&pid) = pids.first() else {
+        return Ok(None);
+    };
+    Ok(Some(PortProcessInfo {
+        pid,
+        name: process_name(pid).await,
+    }))
+}
+
+#[cfg(not(target_os = "windows"))]
+async fn port_listener_pids(port: u16) -> Result<Vec<u32>> {
+    let output = Command::new("lsof")
+        .args(["-t", "-i", &format!("tcp:{port}"), "-s", "tcp:listen"])
+        .output()
+        .await
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!(
+                "Failed to look up processes listening on port {port}: {e}"
+            ))
+            .as_error()
+        })?;
+    let mut pids: Vec<u32> = String::from_utf8_lossy(&output.stdout)
+        .lines()
+        .filter_map(|line| line.trim().parse::<u32>().ok())
+        .collect();
+    pids.sort_unstable();
+    pids.dedup();
+    Ok(pids)
+}
+
+#[cfg(not(target_os = "windows"))]
+async fn force_terminate_pid(pid: u32) -> Result<()> {
+    let output = Command::new("kill")
+        .args(["-9", &pid.to_string()])
+        .output()
+        .await
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!(
+                "Failed to terminate process {pid}: {e}"
+            ))
+            .as_error()
+        })?;
+    if !output.status.success() {
+        return Err(ErrorKind::LauncherError(format!(
+            "Failed to terminate process {pid}"
+        ))
+        .as_error());
+    }
+    Ok(())
+}
+
+#[cfg(not(target_os = "windows"))]
+async fn process_name(pid: u32) -> Option<String> {
+    let output = Command::new("ps")
+        .args(["-p", &pid.to_string(), "-o", "comm="])
+        .output()
+        .await
+        .ok()?;
+    if !output.status.success() {
+        return None;
+    }
+    let name = String::from_utf8_lossy(&output.stdout).trim().to_string();
+    (!name.is_empty()).then_some(name)
+}
+
+#[cfg(target_os = "windows")]
+const CREATE_NO_WINDOW: u32 = 0x0800_0000;
+
+#[cfg(target_os = "windows")]
+async fn port_listener_pids(port: u16) -> Result<Vec<u32>> {
+    let output = Command::new("netstat")
+        .args(["-ano", "-p", "tcp"])
+        .creation_flags(CREATE_NO_WINDOW)
+        .output()
+        .await
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!(
+                "Failed to look up processes listening on port {port}: {e}"
+            ))
+            .as_error()
+        })?;
+    let mut pids: Vec<u32> = String::from_utf8_lossy(&output.stdout)
+        .lines()
+        .filter_map(|line| {
+            let columns: Vec<&str> = line.split_whitespace().collect();
+            if columns.len() < 5
+                || !columns[3].eq_ignore_ascii_case("LISTENING")
+            {
+                return None;
+            }
+            let local_address = columns[1];
+            let local_port = local_address.rsplit(':').next()?;
+            (local_port == port.to_string())
+                .then(|| columns[4].parse::<u32>().ok())?
+        })
+        .collect();
+    pids.sort_unstable();
+    pids.dedup();
+    Ok(pids)
+}
+
+#[cfg(target_os = "windows")]
+async fn force_terminate_pid(pid: u32) -> Result<()> {
+    let output = Command::new("taskkill")
+        .args(["/F", "/PID", &pid.to_string()])
+        .creation_flags(CREATE_NO_WINDOW)
+        .output()
+        .await
+        .map_err(|e| {
+            ErrorKind::LauncherError(format!(
+                "Failed to terminate process {pid}: {e}"
+            ))
+            .as_error()
+        })?;
+    if !output.status.success() {
+        return Err(ErrorKind::LauncherError(format!(
+            "Failed to terminate process {pid}"
+        ))
+        .as_error());
+    }
+    Ok(())
+}
+
+#[cfg(target_os = "windows")]
+async fn process_name(pid: u32) -> Option<String> {
+    let output = Command::new("tasklist")
+        .args(["/FI", &format!("PID eq {pid}"), "/FO", "CSV", "/NH"])
+        .creation_flags(CREATE_NO_WINDOW)
+        .output()
+        .await
+        .ok()?;
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    let line = stdout.lines().next()?;
+    if line.starts_with("INFO") {
+        return None;
+    }
+    let name = line.split(',').next()?.trim_matches('"').to_string();
+    (!name.is_empty()).then_some(name)
+}

packages/app-lib/src/api/settings.rs

@@ -0,0 +1,138 @@
+//! Theseus settings management interface
+
+pub use crate::util::download::DownloadEngine;
+pub use crate::{
+    State,
+    state::{
+        DownloadSourceMode, Hooks, MemorySettings, PrivacySettings, Settings,
+        WindowSize,
+    },
+};
+
+/// Gets entire settings
+#[tracing::instrument]
+pub async fn get() -> crate::Result<Settings> {
+    let state = State::get().await?;
+    let settings = Settings::get(&state.pool).await?;
+    Ok(settings)
+}
+
+/// Sets entire settings
+#[tracing::instrument]
+pub async fn set(mut settings: Settings) -> crate::Result<()> {
+    let state = State::get().await?;
+    let current = Settings::get(&state.pool).await?;
+    settings.telemetry = current.telemetry;
+    settings.telemetry_consent_version = current.telemetry_consent_version;
+    settings.discord_rpc = current.discord_rpc;
+    super::terracotta::validate_public_nodes(
+        &settings.terracotta_public_nodes,
+    )?;
+    settings.apply_legacy_download_source_settings();
+    settings.update(&state.pool).await?;
+    state.update_download_settings(&settings);
+    crate::util::download::set_active_engine(settings.download_engine);
+
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn set_download_engine(engine: DownloadEngine) -> crate::Result<()> {
+    let state = State::get().await?;
+    let mut settings = Settings::get(&state.pool).await?;
+    settings.download_engine = engine;
+    settings.update(&state.pool).await?;
+    crate::util::download::set_active_engine(engine);
+    Ok(())
+}
+
+#[tracing::instrument]
+pub async fn get_privacy() -> crate::Result<PrivacySettings> {
+    let state = State::get().await?;
+    let settings = Settings::get(&state.pool).await?;
+    Ok(PrivacySettings {
+        telemetry: settings.telemetry,
+        discord_rpc: settings.discord_rpc,
+        consent_version: settings.telemetry_consent_version,
+    })
+}
+
+#[tracing::instrument]
+pub async fn set_privacy(
+    privacy: PrivacySettings,
+) -> crate::Result<PrivacySettings> {
+    let state = State::get().await?;
+    let mut transaction = state.pool.begin().await?;
+    sqlx::query(
+		"UPDATE settings SET telemetry = ?, discord_rpc = ?, telemetry_consent_version = ? WHERE id = 0",
+	)
+	.bind(privacy.telemetry)
+	.bind(privacy.discord_rpc)
+	.bind(privacy.consent_version)
+	.execute(&mut *transaction)
+	.await?;
+    sqlx::query("DELETE FROM telemetry_outbox")
+        .execute(&mut *transaction)
+        .await?;
+    transaction.commit().await?;
+
+    if let Err(error) =
+        crate::telemetry::set_enabled(&state, privacy.telemetry).await
+    {
+        tracing::debug!(target: "theseus::telemetry", %error, "Failed to apply telemetry state");
+    }
+    if let Err(error) = state.discord_rpc.clear_to_default(true).await {
+        tracing::debug!(target: "theseus::telemetry", %error, "Failed to apply Discord RPC state");
+    }
+    get_privacy().await
+}
+
+#[tracing::instrument]
+pub async fn set_telemetry(enabled: bool) -> crate::Result<PrivacySettings> {
+    let state = State::get().await?;
+    let mut transaction = state.pool.begin().await?;
+    sqlx::query("UPDATE settings SET telemetry = ? WHERE id = 0")
+        .bind(enabled)
+        .execute(&mut *transaction)
+        .await?;
+    sqlx::query("DELETE FROM telemetry_outbox")
+        .execute(&mut *transaction)
+        .await?;
+    transaction.commit().await?;
+    if let Err(error) = crate::telemetry::set_enabled(&state, enabled).await {
+        tracing::debug!(target: "theseus::telemetry", %error, "Failed to apply telemetry state");
+    }
+    get_privacy().await
+}
+
+#[tracing::instrument]
+pub async fn set_discord_rpc(enabled: bool) -> crate::Result<PrivacySettings> {
+    let state = State::get().await?;
+    sqlx::query("UPDATE settings SET discord_rpc = ? WHERE id = 0")
+        .bind(enabled)
+        .execute(&state.pool)
+        .await?;
+    if let Err(error) = state.discord_rpc.clear_to_default(true).await {
+        tracing::debug!(target: "theseus::telemetry", %error, "Failed to apply Discord RPC state");
+    }
+    get_privacy().await
+}
+
+#[tracing::instrument]
+pub async fn cancel_directory_change(
+    app_identifier: &str,
+) -> crate::Result<()> {
+    // This is called to handle state initialization errors due to folder migrations
+    // failing, so fetching a DB connection pool from `State::get` is not reliable here
+    let pool = crate::state::db::connect(app_identifier).await?;
+    let mut settings = Settings::get(&pool).await?;
+
+    if let Some(prev_custom_dir) = settings.prev_custom_dir {
+        settings.prev_custom_dir = None;
+        settings.custom_dir = Some(prev_custom_dir);
+    }
+
+    settings.update(&pool).await?;
+
+    Ok(())
+}

packages/app-lib/src/api/symlink.rs

@@ -0,0 +1,14 @@
+use crate::util::symlink::SymlinkCapability;
+
+#[tracing::instrument]
+pub async fn check_symlink_capability() -> crate::Result<SymlinkCapability> {
+    Ok(crate::util::symlink::check_symlink_capability().await)
+}
+
+/// Entry point for the elevated link-creation helper process. Exits with 0 on
+/// success and 1 on failure, after writing the outcome to the request's
+/// result file.
+#[cfg(target_os = "windows")]
+pub fn create_link_elevated_helper(payload: &str) -> i32 {
+    crate::util::symlink::create_link_elevated_helper(payload)
+}

packages/app-lib/src/api/tags.rs

@@ -0,0 +1,80 @@
+//! Theseus tag management interface
+use crate::state::CachedEntry;
+pub use crate::{
+    State,
+    state::{Category, DonationPlatform, GameVersion, Loader},
+};
+
+/// Get category tags
+#[tracing::instrument]
+pub async fn get_category_tags() -> crate::Result<Vec<Category>> {
+    let state = State::get().await?;
+    let categories =
+        CachedEntry::get_categories(None, &state.pool, &state.api_semaphore)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::NoValueFor("category tags".to_string())
+            })?;
+
+    Ok(categories)
+}
+
+/// Get report type tags
+#[tracing::instrument]
+pub async fn get_report_type_tags() -> crate::Result<Vec<String>> {
+    let state = State::get().await?;
+    let report_types =
+        CachedEntry::get_report_types(None, &state.pool, &state.api_semaphore)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::NoValueFor("report type tags".to_string())
+            })?;
+
+    Ok(report_types)
+}
+
+/// Get loader tags
+#[tracing::instrument]
+pub async fn get_loader_tags() -> crate::Result<Vec<Loader>> {
+    let state = State::get().await?;
+    let loaders =
+        CachedEntry::get_loaders(None, &state.pool, &state.api_semaphore)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::NoValueFor("loader tags".to_string())
+            })?;
+
+    Ok(loaders)
+}
+
+/// Get game version tags
+#[tracing::instrument]
+pub async fn get_game_version_tags() -> crate::Result<Vec<GameVersion>> {
+    let state = State::get().await?;
+    let game_versions =
+        CachedEntry::get_game_versions(None, &state.pool, &state.api_semaphore)
+            .await?
+            .ok_or_else(|| {
+                crate::ErrorKind::NoValueFor("game version tags".to_string())
+            })?;
+
+    Ok(game_versions)
+}
+
+/// Get donation platform tags
+#[tracing::instrument]
+pub async fn get_donation_platform_tags() -> crate::Result<Vec<DonationPlatform>>
+{
+    let state = State::get().await?;
+    let donation_platforms = CachedEntry::get_donation_platforms(
+        None,
+        &state.pool,
+        &state.api_semaphore,
+    )
+    .await?
+    .ok_or_else(|| {
+        crate::ErrorKind::NoValueFor("donation platform tags".to_string())
+    })?;
+
+    Ok(donation_platforms)
+}

packages/app-lib/src/api/terracotta/binary.rs

@@ -0,0 +1,327 @@
+use eyre::{Context, bail};
+use std::io::Read;
+use std::path::{Path, PathBuf};
+use tracing::info;
+
+pub fn terracotta_platform_key() -> &'static str {
+    match (std::env::consts::OS, std::env::consts::ARCH) {
+        ("linux", "x86_64") => "linux-x86_64",
+        ("linux", "aarch64") => "linux-arm64",
+        ("linux", "riscv64") => "linux-riscv64",
+        ("linux", "loongarch64") => "linux-loongarch64",
+        ("macos", "x86_64") => "macos-x86_64",
+        ("macos", "aarch64") => "macos-arm64",
+        ("windows", "x86_64") => "windows-x86_64",
+        ("windows", "aarch64") => "windows-arm64",
+        ("freebsd", "x86_64") => "freebsd-x86_64",
+        _ => "unsupported",
+    }
+}
+
+pub(super) fn terracotta_binary_name() -> &'static str {
+    if cfg!(target_os = "windows") {
+        "terracotta.exe"
+    } else {
+        "terracotta"
+    }
+}
+
+pub(super) fn versioned_terracotta_binary_name(
+    version: &str,
+    platform: &str,
+) -> String {
+    let extension = if cfg!(target_os = "windows") {
+        ".exe"
+    } else {
+        ""
+    };
+    format!("terracotta-{version}-{platform}{extension}")
+}
+
+pub(super) fn validate_terracotta_version(version: &str) -> eyre::Result<()> {
+    if version.is_empty()
+        || version.len() > 64
+        || version.contains("..")
+        || !version.chars().all(|character| {
+            character.is_ascii_alphanumeric()
+                || matches!(character, '.' | '-' | '_')
+        })
+    {
+        bail!("invalid terracotta version: {version}");
+    }
+    Ok(())
+}
+
+pub(super) fn is_terracotta_executable(path: &Path) -> bool {
+    let Ok(metadata) = std::fs::symlink_metadata(path) else {
+        return false;
+    };
+    if !metadata.file_type().is_file() {
+        return false;
+    }
+
+    let mut magic = [0_u8; 4];
+    if std::fs::File::open(path)
+        .and_then(|mut file| file.read_exact(&mut magic))
+        .is_err()
+    {
+        return false;
+    }
+
+    #[cfg(target_os = "macos")]
+    {
+        matches!(
+            magic,
+            [0xce, 0xfa, 0xed, 0xfe]
+                | [0xcf, 0xfa, 0xed, 0xfe]
+                | [0xfe, 0xed, 0xfa, 0xce]
+                | [0xfe, 0xed, 0xfa, 0xcf]
+                | [0xca, 0xfe, 0xba, 0xbe]
+                | [0xbe, 0xba, 0xfe, 0xca]
+                | [0xca, 0xfe, 0xba, 0xbf]
+                | [0xbf, 0xba, 0xfe, 0xca]
+        )
+    }
+
+    #[cfg(any(target_os = "linux", target_os = "freebsd"))]
+    {
+        magic == [0x7f, b'E', b'L', b'F']
+    }
+
+    #[cfg(target_os = "windows")]
+    {
+        magic[0..2] == [b'M', b'Z']
+    }
+
+    #[cfg(not(any(
+        target_os = "macos",
+        target_os = "linux",
+        target_os = "freebsd",
+        target_os = "windows"
+    )))]
+    {
+        false
+    }
+}
+
+pub(super) fn find_terracotta_executable(
+    dir: &Path,
+    preferred_name: Option<&str>,
+) -> Option<PathBuf> {
+    let mut pending = vec![dir.to_path_buf()];
+    let mut candidates = Vec::new();
+
+    while let Some(current) = pending.pop() {
+        let entries = match std::fs::read_dir(current) {
+            Ok(entries) => entries,
+            Err(_) => continue,
+        };
+
+        for entry in entries.flatten() {
+            let path = entry.path();
+            let file_type = match entry.file_type() {
+                Ok(file_type) => file_type,
+                Err(_) => continue,
+            };
+            if file_type.is_dir() {
+                pending.push(path);
+                continue;
+            }
+
+            let Some(name) = path.file_name().and_then(|name| name.to_str())
+            else {
+                continue;
+            };
+            if (name == terracotta_binary_name()
+                || name.starts_with("terracotta-"))
+                && is_terracotta_executable(&path)
+            {
+                candidates.push(path);
+            }
+        }
+    }
+
+    candidates.sort();
+    preferred_name
+        .and_then(|preferred| {
+            candidates
+                .iter()
+                .find(|path| {
+                    path.file_name().and_then(|name| name.to_str())
+                        == Some(preferred)
+                })
+                .cloned()
+        })
+        .or_else(|| candidates.into_iter().next())
+}
+
+pub(super) fn terracotta_binary_path() -> PathBuf {
+    let base_dir = crate::state::DirectoryInfo::global_handle_if_ready()
+        .map(|directories| directories.config_dir.clone())
+        .or_else(|| {
+            crate::state::DirectoryInfo::initial_settings_dir_path(
+                crate::brand::BUNDLE_IDENTIFIER,
+            )
+        })
+        .unwrap_or_else(|| PathBuf::from("."));
+
+    terracotta_binary_path_in(&base_dir)
+}
+
+pub(super) fn terracotta_binary_path_in(base_dir: &Path) -> PathBuf {
+    base_dir.join("terracotta").join(terracotta_binary_name())
+}
+
+fn legacy_terracotta_binary_path() -> PathBuf {
+    std::env::current_exe()
+        .ok()
+        .and_then(|path| path.parent().map(Path::to_path_buf))
+        .unwrap_or_else(|| PathBuf::from("."))
+        .join("terracotta")
+        .join(terracotta_binary_name())
+}
+
+pub fn terracotta_download_urls(version: &str, platform: &str) -> Vec<String> {
+    let artifact = format!("terracotta-{version}-{platform}-pkg.tar.gz");
+    vec![
+        format!(
+            "https://gitee.com/burningtnt/Terracotta/releases/download/v{version}/{artifact}"
+        ),
+        format!(
+            "https://github.com/burningtnt/Terracotta/releases/download/v{version}/{artifact}"
+        ),
+    ]
+}
+
+pub(super) fn resolve_terracotta_binary_path(bin_path: &Path) -> PathBuf {
+    let resolved_path = if bin_path.is_absolute() {
+        bin_path.to_path_buf()
+    } else {
+        std::env::current_dir()
+            .unwrap_or_else(|_| PathBuf::from("."))
+            .join(bin_path)
+    };
+
+    let preferred_path = if resolved_path.is_dir() {
+        resolved_path.join(terracotta_binary_name())
+    } else if resolved_path.is_file() {
+        resolved_path
+    } else {
+        resolved_path.with_file_name(terracotta_binary_name())
+    };
+
+    if is_terracotta_executable(&preferred_path) {
+        return preferred_path;
+    }
+
+    preferred_path
+        .parent()
+        .and_then(|parent| find_terracotta_executable(parent, None))
+        .unwrap_or(preferred_path)
+}
+
+pub(super) fn resolve_installed_terracotta_binary_path() -> PathBuf {
+    resolve_installed_terracotta_binary_path_from(
+        &terracotta_binary_path(),
+        &legacy_terracotta_binary_path(),
+    )
+}
+
+pub(super) fn resolve_installed_terracotta_binary_path_from(
+    installed_path: &Path,
+    legacy_path: &Path,
+) -> PathBuf {
+    let installed_path = resolve_terracotta_binary_path(installed_path);
+    if is_terracotta_executable(&installed_path) {
+        return installed_path;
+    }
+
+    let legacy_path = resolve_terracotta_binary_path(legacy_path);
+    if is_terracotta_executable(&legacy_path) {
+        legacy_path
+    } else {
+        installed_path
+    }
+}
+
+pub(super) async fn install_terracotta_binary(
+    candidate: &Path,
+    destination: &Path,
+) -> eyre::Result<()> {
+    let file_name = destination
+        .file_name()
+        .and_then(|name| name.to_str())
+        .ok_or_else(|| eyre::eyre!("invalid terracotta destination path"))?;
+    let backup = destination.with_file_name(format!("{file_name}.old"));
+
+    if backup.exists() {
+        tokio::fs::remove_file(&backup)
+            .await
+            .wrap_err("failed to remove stale terracotta backup")?;
+    }
+    if destination.exists() {
+        tokio::fs::rename(destination, &backup)
+            .await
+            .wrap_err("failed to back up the existing terracotta binary")?;
+    }
+
+    if let Err(error) = tokio::fs::rename(candidate, destination).await {
+        if backup.exists() {
+            let _ = tokio::fs::rename(&backup, destination).await;
+        }
+        return Err(error).wrap_err("failed to install terracotta binary");
+    }
+
+    if backup.exists() {
+        tokio::fs::remove_file(&backup).await.wrap_err(
+            "failed to remove terracotta backup after installation",
+        )?;
+    }
+    Ok(())
+}
+
+pub(super) async fn cleanup_legacy_versions(
+    new_version: &str,
+) -> eyre::Result<()> {
+    let target_dir = terracotta_binary_path()
+        .parent()
+        .map(Path::to_path_buf)
+        .unwrap_or_else(|| PathBuf::from("terracotta"));
+
+    if !target_dir.exists() {
+        return Ok(());
+    }
+
+    let mut entries = tokio::fs::read_dir(&target_dir).await?;
+    while let Some(entry) = entries.next_entry().await? {
+        let file_type = entry.file_type().await?;
+        let name = entry.file_name();
+        let name = name.to_string_lossy();
+
+        if file_type.is_file()
+            && (should_cleanup_terracotta_file(&name)
+                || name.ends_with(".tar.gz")
+                || name.ends_with(".old"))
+        {
+            tokio::fs::remove_file(entry.path()).await?;
+            info!(
+                "removed extracted terracotta artifact after installing {new_version}: {name}"
+            );
+        }
+
+        if file_type.is_dir() && name.starts_with("terracotta-") {
+            tokio::fs::remove_dir_all(entry.path()).await?;
+            info!(
+                "removed extracted terracotta directory after installing {new_version}: {name}"
+            );
+        }
+    }
+
+    Ok(())
+}
+
+pub(super) fn should_cleanup_terracotta_file(name: &str) -> bool {
+    name.starts_with("terracotta-")
+        && name != "terracotta-version.json"
+        && name != "terracotta-version.json.tmp"
+}

packages/app-lib/src/api/terracotta/lan.rs

@@ -0,0 +1,124 @@
+use socket2::{Domain, Protocol, SockAddr, Socket, Type};
+use std::net::{IpAddr, Ipv4Addr, SocketAddrV4};
+use tokio::task::JoinHandle;
+use tracing::warn;
+
+#[derive(Default)]
+pub(super) struct MinecraftLanAnnouncer {
+    active: Option<ActiveAnnouncement>,
+}
+
+struct ActiveAnnouncement {
+    port: u16,
+    task: JoinHandle<()>,
+}
+
+impl MinecraftLanAnnouncer {
+    pub(super) fn sync(&mut self, port: Option<u16>) {
+        if self.active.as_ref().is_some_and(|active| {
+            Some(active.port) == port && !active.task.is_finished()
+        }) {
+            return;
+        }
+
+        if let Some(active) = self.active.take() {
+            active.task.abort();
+        }
+        if let Some(port) = port {
+            self.active = Some(ActiveAnnouncement {
+                port,
+                task: tokio::spawn(run(port)),
+            });
+        }
+    }
+}
+
+impl Drop for MinecraftLanAnnouncer {
+    fn drop(&mut self) {
+        if let Some(active) = self.active.take() {
+            active.task.abort();
+        }
+    }
+}
+
+fn sockets() -> Vec<(Ipv4Addr, Socket)> {
+    let mut addresses = local_ip_address::list_afinet_netifas()
+        .unwrap_or_default()
+        .into_iter()
+        .filter_map(|(_, address)| match address {
+            IpAddr::V4(address) if !address.is_unspecified() => Some(address),
+            _ => None,
+        })
+        .collect::<Vec<_>>();
+    addresses.sort_unstable();
+    addresses.dedup();
+
+    addresses
+		.into_iter()
+		.filter_map(|address| {
+			let socket = (|| -> std::io::Result<Socket> {
+				let socket = Socket::new(
+					Domain::IPV4,
+					Type::DGRAM,
+					Some(Protocol::UDP),
+				)?;
+				socket.set_multicast_if_v4(&address)?;
+				socket.set_multicast_loop_v4(true)?;
+				socket.set_multicast_ttl_v4(4)?;
+				socket.bind(&SockAddr::from(SocketAddrV4::new(
+					Ipv4Addr::UNSPECIFIED,
+					0,
+				)))?;
+				Ok(socket)
+			})();
+
+			match socket {
+				Ok(socket) => Some((address, socket)),
+				Err(error) => {
+					warn!(
+						"failed to create Minecraft LAN announcer for {address}: {error}"
+					);
+					None
+				}
+			}
+		})
+		.collect()
+}
+
+async fn run(port: u16) {
+    let sockets = sockets();
+    if sockets.is_empty() {
+        warn!("no IPv4 interfaces available for Minecraft LAN announcements");
+        return;
+    }
+
+    let target =
+        SockAddr::from(SocketAddrV4::new(Ipv4Addr::new(224, 0, 2, 60), 4445));
+    let message =
+        format!("[MOTD]Terracotta | Axolotl Multiplayer[/MOTD][AD]{port}[/AD]");
+    let mut interval =
+        tokio::time::interval(std::time::Duration::from_millis(1500));
+    interval.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
+
+    loop {
+        interval.tick().await;
+        let mut sent = 0;
+        for (address, socket) in &sockets {
+            match socket.send_to(message.as_bytes(), &target) {
+                Ok(_) => sent += 1,
+                Err(error) => tracing::debug!(
+                    target: "terracotta",
+                    interface = %address,
+                    "failed to send Minecraft LAN announcement: {error}"
+                ),
+            }
+        }
+
+        if sent == 0 {
+            warn!(
+                "failed to send Minecraft LAN announcement on every interface"
+            );
+            return;
+        }
+    }
+}

packages/app-lib/src/api/worlds/datapacks.rs

@@ -0,0 +1,566 @@
+use base64::Engine;
+use chrono::{DateTime, Utc};
+use either::Either;
+use quartz_nbt::{NbtCompound, NbtList, NbtTag};
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+use std::io::{Cursor, Read};
+use std::path::{Path, PathBuf};
+use std::sync::{LazyLock, Mutex};
+use std::time::SystemTime;
+use tokio::task::JoinSet;
+use url::Url;
+
+use crate::instance::get_full_path;
+use crate::util::io;
+use crate::{ErrorKind, Result};
+
+use super::{
+    World, WorldDetails, get_singleplayer_worlds_in_instance,
+    read_world_datapack_state,
+};
+
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum DatapackKind {
+    Folder,
+    Zip,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct WorldDatapack {
+    pub file_name: String,
+    pub display_name: String,
+    pub kind: DatapackKind,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub pack_format: Option<i32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub supported_formats: Option<Vec<i32>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub description: Option<serde_json::Value>,
+    #[serde(
+        skip_serializing_if = "Option::is_none",
+        with = "either::serde_untagged_optional"
+    )]
+    pub icon: Option<Either<PathBuf, Url>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub enabled: Option<bool>,
+    pub size: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub modified: Option<DateTime<Utc>>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone)]
+pub struct WorldWithDatapacks {
+    #[serde(flatten)]
+    pub world: World,
+    pub datapacks: Vec<WorldDatapack>,
+}
+
+struct CachedZipDatapackMeta {
+    len: u64,
+    modified: Option<SystemTime>,
+    pack_format: Option<i32>,
+    supported_formats: Option<Vec<i32>>,
+    description: Option<serde_json::Value>,
+    icon: Option<Vec<u8>>,
+}
+
+static ZIP_DATAPACK_META_CACHE: LazyLock<
+    Mutex<HashMap<PathBuf, CachedZipDatapackMeta>>,
+> = LazyLock::new(|| Mutex::new(HashMap::new()));
+
+/// Lists every singleplayer save in the instance together with the datapacks
+/// found in each save's `datapacks` folder.
+pub async fn list_world_datapacks(
+    instance_id: &str,
+) -> Result<Vec<WorldWithDatapacks>> {
+    let instance_dir = get_full_path(instance_id).await?;
+    let mut worlds = Vec::new();
+    get_singleplayer_worlds_in_instance(&instance_dir, &mut worlds).await?;
+
+    let saves_dir = instance_dir.join("saves");
+    let mut tasks = JoinSet::new();
+    for world in worlds {
+        let world_path = match &world.details {
+            WorldDetails::Singleplayer { path, .. } => saves_dir.join(path),
+            WorldDetails::Server { .. } => continue,
+        };
+        tasks.spawn(read_world_datapacks(world_path, world));
+    }
+
+    let mut result = Vec::new();
+    while let Some(joined) = tasks.join_next().await {
+        match joined {
+            Ok(Ok(item)) => result.push(item),
+            Ok(Err(error)) => {
+                tracing::warn!("Skipping unreadable world datapacks: {error}");
+            }
+            Err(error) => {
+                tracing::warn!("World datapack read task panicked: {error}");
+            }
+        }
+    }
+    Ok(result)
+}
+
+/// Deletes a datapack (folder or zip) inside a save's `datapacks` folder.
+pub async fn delete_world_datapack(
+    instance_id: &str,
+    world_path: &str,
+    file_name: &str,
+) -> Result<()> {
+    let instance_dir = get_full_path(instance_id).await?;
+    let world_path = Path::new(world_path);
+    if world_path.components().count() != 1 {
+        return Err(
+            ErrorKind::InputError("Invalid world path".into()).as_error()
+        );
+    }
+    let file_name = Path::new(file_name);
+    if file_name.components().count() != 1 || file_name.as_os_str().is_empty() {
+        return Err(ErrorKind::InputError("Invalid datapack file name".into())
+            .as_error());
+    }
+
+    let datapacks_dir = instance_dir
+        .join("saves")
+        .join(world_path)
+        .join("datapacks");
+    let target = datapacks_dir.join(file_name);
+    if target.parent() != Some(datapacks_dir.as_path()) {
+        return Err(ErrorKind::InputError("Invalid datapack file name".into())
+            .as_error());
+    }
+
+    let meta = io::metadata(&target).await?;
+    if meta.is_dir() {
+        io::remove_dir_all(&target).await?;
+    } else {
+        io::remove_file(&target).await?;
+    }
+    Ok(())
+}
+
+/// Enables or disables a datapack by updating the `DataPacks` tag in the
+/// world's `level.dat`.
+pub async fn set_world_datapack_enabled(
+    instance_id: &str,
+    world_path: &str,
+    file_name: &str,
+    enabled: bool,
+) -> Result<()> {
+    let instance_dir = get_full_path(instance_id).await?;
+    let world_path = Path::new(world_path);
+    if world_path.components().count() != 1 {
+        return Err(
+            ErrorKind::InputError("Invalid world path".into()).as_error()
+        );
+    }
+    let file_name = Path::new(file_name);
+    if file_name.components().count() != 1 || file_name.as_os_str().is_empty() {
+        return Err(ErrorKind::InputError("Invalid datapack file name".into())
+            .as_error());
+    }
+
+    let world_dir = instance_dir.join("saves").join(world_path);
+    let datapacks_dir = world_dir.join("datapacks");
+    let target = datapacks_dir.join(file_name);
+    if target.parent() != Some(datapacks_dir.as_path()) {
+        return Err(ErrorKind::InputError("Invalid datapack file name".into())
+            .as_error());
+    }
+    if !target.exists() {
+        return Err(
+            ErrorKind::InputError("Datapack does not exist".into()).as_error()
+        );
+    }
+
+    let file_id = if target.is_dir() {
+        format!("file/{}", file_name.to_string_lossy())
+    } else {
+        let stem = file_name.file_stem().unwrap_or_default().to_string_lossy();
+        format!("file/{stem}")
+    };
+
+    let level_dat_path = world_dir.join("level.dat");
+    let raw = io::read(&level_dat_path).await?;
+    let updated = tokio::task::spawn_blocking(move || {
+        let (mut root, _) = quartz_nbt::io::read_nbt(
+            &mut Cursor::new(raw),
+            quartz_nbt::io::Flavor::GzCompressed,
+        )?;
+        let data = root.get_mut::<_, &mut NbtCompound>("Data")?;
+
+        if data.get::<_, &NbtCompound>("DataPacks").is_err() {
+            data.insert("DataPacks", NbtTag::Compound(NbtCompound::new()));
+        }
+        let data_packs = data.get_mut::<_, &mut NbtCompound>("DataPacks")?;
+
+        for key in ["Enabled", "Disabled"] {
+            if let Ok(list) = data_packs.get_mut::<_, &mut NbtList>(key) {
+                list.inner_mut().retain(|tag| {
+                    !matches!(tag, NbtTag::String(value) if value == &file_id)
+                });
+            }
+        }
+
+        let key = if enabled { "Enabled" } else { "Disabled" };
+        if let Ok(list) = data_packs.get_mut::<_, &mut NbtList>(key) {
+            list.push(NbtTag::String(file_id.clone()));
+        } else {
+            let mut list = NbtList::new();
+            list.push(NbtTag::String(file_id));
+            data_packs.insert(key, list);
+        }
+
+        let mut level_data = vec![];
+        quartz_nbt::io::write_nbt(
+            &mut level_data,
+            None,
+            &root,
+            quartz_nbt::io::Flavor::GzCompressed,
+        )?;
+        Ok::<_, crate::Error>(level_data)
+    })
+    .await
+    .map_err(|error| {
+        ErrorKind::InputError(format!(
+            "Datapack state write task failed: {error}"
+        ))
+        .as_error()
+    })??;
+
+    io::write(level_dat_path, updated).await?;
+    Ok(())
+}
+
+async fn read_world_datapacks(
+    world_path: PathBuf,
+    world: World,
+) -> Result<WorldWithDatapacks> {
+    let datapacks_dir = world_path.join("datapacks");
+    let mut datapacks = Vec::new();
+    if datapacks_dir.exists() {
+        // Only read the world's level.dat for the enabled/disabled state when it
+        // actually has a datapacks folder, and tolerate a missing/corrupt file.
+        let (enabled, disabled) =
+            match read_world_datapack_state(&world_path).await {
+                Ok(state) => state,
+                Err(error) => {
+                    tracing::debug!(
+                        "Could not read datapack state for world {}: {error}",
+                        world.name
+                    );
+                    (Vec::new(), Vec::new())
+                }
+            };
+
+        let mut entries = io::read_dir(&datapacks_dir).await?;
+        let mut tasks = JoinSet::new();
+        while let Some(entry) = entries.next_entry().await? {
+            let path = entry.path();
+            if entry.file_type().await?.is_dir() {
+                tasks.spawn(read_folder_datapack(
+                    path,
+                    enabled.clone(),
+                    disabled.clone(),
+                ));
+            } else if is_zip_path(&path) {
+                tasks.spawn(read_zip_datapack(
+                    path,
+                    enabled.clone(),
+                    disabled.clone(),
+                ));
+            }
+        }
+        while let Some(joined) = tasks.join_next().await {
+            match joined {
+                Ok(Ok(datapack)) => datapacks.push(datapack),
+                Ok(Err(error)) => {
+                    tracing::warn!("Skipping unreadable datapack: {error}");
+                }
+                Err(error) => {
+                    tracing::warn!("Datapack read task panicked: {error}");
+                }
+            }
+        }
+    }
+
+    Ok(WorldWithDatapacks { world, datapacks })
+}
+
+async fn read_folder_datapack(
+    dir: PathBuf,
+    enabled: Vec<String>,
+    disabled: Vec<String>,
+) -> Result<WorldDatapack> {
+    let name = dir
+        .file_name()
+        .unwrap_or_default()
+        .to_string_lossy()
+        .to_string();
+
+    let (pack_format, supported_formats, description) =
+        read_folder_pack_meta(&dir).await;
+
+    let icon = if dir.join("pack.png").exists() {
+        Some(Either::Left(dir.join("pack.png")))
+    } else {
+        None
+    };
+
+    let size = folder_size(&dir).await.unwrap_or(0);
+    let modified = io::metadata(&dir)
+        .await
+        .ok()
+        .and_then(|meta| meta.modified().ok().map(DateTime::<Utc>::from));
+
+    Ok(WorldDatapack {
+        file_name: name.clone(),
+        display_name: name.clone(),
+        kind: DatapackKind::Folder,
+        pack_format,
+        supported_formats,
+        description,
+        icon,
+        enabled: match_datapack_state(&name, &enabled, &disabled),
+        size,
+        modified,
+    })
+}
+
+async fn read_zip_datapack(
+    path: PathBuf,
+    enabled: Vec<String>,
+    disabled: Vec<String>,
+) -> Result<WorldDatapack> {
+    let file_name = path
+        .file_name()
+        .unwrap_or_default()
+        .to_string_lossy()
+        .to_string();
+    let stem = path
+        .file_stem()
+        .unwrap_or_default()
+        .to_string_lossy()
+        .to_string();
+
+    let zip_path = path.clone();
+    let (pack_format, supported_formats, description, icon_bytes) =
+        tokio::task::spawn_blocking(move || read_zip_pack_meta(&zip_path))
+            .await
+            .map_err(|error| {
+                ErrorKind::InputError(format!(
+                    "Datapack zip read task failed: {error}"
+                ))
+                .as_error()
+            })??;
+
+    let icon = icon_bytes
+        .map(|bytes| {
+            Url::parse(&format!(
+                "data:image/png;base64,{}",
+                base64::engine::general_purpose::STANDARD.encode(bytes)
+            ))
+        })
+        .transpose()
+        .ok()
+        .flatten();
+
+    let size = io::metadata(&path)
+        .await
+        .ok()
+        .map(|meta| meta.len())
+        .unwrap_or(0);
+    let modified = io::metadata(&path)
+        .await
+        .ok()
+        .and_then(|meta| meta.modified().ok().map(DateTime::<Utc>::from));
+
+    Ok(WorldDatapack {
+        file_name,
+        display_name: stem.clone(),
+        kind: DatapackKind::Zip,
+        pack_format,
+        supported_formats,
+        description,
+        icon: icon.map(Either::Right),
+        enabled: match_datapack_state(&stem, &enabled, &disabled),
+        size,
+        modified,
+    })
+}
+
+async fn read_folder_pack_meta(
+    dir: &Path,
+) -> (Option<i32>, Option<Vec<i32>>, Option<serde_json::Value>) {
+    let Ok(bytes) = io::read(dir.join("pack.mcmeta")).await else {
+        return (None, None, None);
+    };
+    parse_pack_mcmeta(&bytes)
+}
+
+fn parse_pack_mcmeta(
+    bytes: &[u8],
+) -> (Option<i32>, Option<Vec<i32>>, Option<serde_json::Value>) {
+    let Ok(value) = serde_json::from_slice::<serde_json::Value>(bytes) else {
+        return (None, None, None);
+    };
+    let Some(pack) = value.get("pack") else {
+        return (None, None, None);
+    };
+    let pack_format = pack
+        .get("pack_format")
+        .and_then(serde_json::Value::as_i64)
+        .map(|format| format as i32);
+    let supported_formats = pack
+        .get("supported_formats")
+        .and_then(parse_supported_formats);
+    let description = pack.get("description").cloned();
+    (pack_format, supported_formats, description)
+}
+
+fn parse_supported_formats(value: &serde_json::Value) -> Option<Vec<i32>> {
+    value.as_array().map(|formats| {
+        formats
+            .iter()
+            .filter_map(serde_json::Value::as_i64)
+            .map(|format| format as i32)
+            .collect()
+    })
+}
+
+fn read_zip_pack_meta(
+    path: &Path,
+) -> std::io::Result<(
+    Option<i32>,
+    Option<Vec<i32>>,
+    Option<serde_json::Value>,
+    Option<Vec<u8>>,
+)> {
+    let metadata = std::fs::metadata(path)?;
+    let signature = (metadata.len(), metadata.modified().ok());
+    let cache_key = path.to_path_buf();
+
+    {
+        let cache = ZIP_DATAPACK_META_CACHE.lock().unwrap();
+        if let Some(cached) = cache.get(&cache_key) {
+            if cached.len == signature.0 && cached.modified == signature.1 {
+                return Ok((
+                    cached.pack_format.clone(),
+                    cached.supported_formats.clone(),
+                    cached.description.clone(),
+                    cached.icon.clone(),
+                ));
+            }
+        }
+    }
+
+    let parsed = read_zip_pack_meta_uncached(path)?;
+
+    let mut cache = ZIP_DATAPACK_META_CACHE.lock().unwrap();
+    if cache.len() >= 1024 {
+        cache.clear();
+    }
+    cache.insert(
+        cache_key,
+        CachedZipDatapackMeta {
+            len: signature.0,
+            modified: signature.1,
+            pack_format: parsed.0.clone(),
+            supported_formats: parsed.1.clone(),
+            description: parsed.2.clone(),
+            icon: parsed.3.clone(),
+        },
+    );
+
+    Ok(parsed)
+}
+
+fn read_zip_pack_meta_uncached(
+    path: &Path,
+) -> std::io::Result<(
+    Option<i32>,
+    Option<Vec<i32>>,
+    Option<serde_json::Value>,
+    Option<Vec<u8>>,
+)> {
+    let file = std::fs::File::open(path)?;
+    let mut archive = zip::ZipArchive::new(file)?;
+
+    let (pack_format, supported_formats, description) =
+        read_zip_entry(&mut archive, "pack.mcmeta")?
+            .as_deref()
+            .map(parse_pack_mcmeta)
+            .unwrap_or((None, None, None));
+    let icon = read_zip_entry(&mut archive, "pack.png")?;
+
+    Ok((pack_format, supported_formats, description, icon))
+}
+
+fn read_zip_entry(
+    archive: &mut zip::ZipArchive<std::fs::File>,
+    name: &str,
+) -> std::io::Result<Option<Vec<u8>>> {
+    if let Ok(mut entry) = archive.by_name(name) {
+        let mut bytes = Vec::new();
+        entry.read_to_end(&mut bytes)?;
+        return Ok(Some(bytes));
+    }
+    let matching = archive
+        .file_names()
+        .map(str::to_string)
+        .find(|file_name| file_name.ends_with(&format!("/{name}")));
+    if let Some(matching) = matching {
+        let mut entry = archive.by_name(&matching)?;
+        let mut bytes = Vec::new();
+        entry.read_to_end(&mut bytes)?;
+        return Ok(Some(bytes));
+    }
+    Ok(None)
+}
+
+fn match_datapack_state(
+    name: &str,
+    enabled: &[String],
+    disabled: &[String],
+) -> Option<bool> {
+    let file_id = format!("file/{name}");
+    if enabled.iter().any(|value| value == &file_id) {
+        return Some(true);
+    }
+    if disabled.iter().any(|value| value == &file_id) {
+        return Some(false);
+    }
+    None
+}
+
+const MAX_SIZE_SCAN_ENTRIES: usize = 50_000;
+
+async fn folder_size(dir: &Path) -> std::io::Result<u64> {
+    let mut total = 0u64;
+    let mut stack = vec![dir.to_path_buf()];
+    let mut scanned = 0usize;
+    while let Some(current) = stack.pop() {
+        let mut entries = tokio::fs::read_dir(&current).await?;
+        while let Some(entry) = entries.next_entry().await? {
+            scanned += 1;
+            if scanned > MAX_SIZE_SCAN_ENTRIES {
+                return Ok(total);
+            }
+            if entry.file_type().await?.is_dir() {
+                stack.push(entry.path());
+            } else {
+                total +=
+                    entry.metadata().await.map(|meta| meta.len()).unwrap_or(0);
+            }
+        }
+    }
+    Ok(total)
+}
+
+fn is_zip_path(path: &Path) -> bool {
+    path.extension()
+        .is_some_and(|extension| extension.eq_ignore_ascii_case("zip"))
+}

packages/app-lib/src/api/worlds/level_data.rs

@@ -0,0 +1,751 @@
+use std::io::Cursor;
+use std::path::{Path, PathBuf};
+
+use chrono::{DateTime, TimeZone, Utc};
+use either::Either;
+use quartz_nbt::{NbtCompound, NbtTag};
+use serde::{Deserialize, Serialize};
+use url::Url;
+
+use super::{
+    SingleplayerGameMode, get_world_dir, get_world_session_lock,
+    resolve_instance_data_dir, resolve_instance_identity,
+    try_get_world_session_lock,
+};
+use crate::util::io;
+use crate::{Error, ErrorKind, Result, State};
+
+#[derive(Deserialize, Serialize, Debug, Copy, Clone, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum WorldDifficulty {
+    Peaceful,
+    Easy,
+    Normal,
+    Hard,
+}
+
+impl WorldDifficulty {
+    fn from_byte(value: i8) -> Self {
+        match value {
+            0 => Self::Peaceful,
+            1 => Self::Easy,
+            3 => Self::Hard,
+            _ => Self::Normal,
+        }
+    }
+
+    fn as_byte(self) -> i8 {
+        match self {
+            Self::Peaceful => 0,
+            Self::Easy => 1,
+            Self::Normal => 2,
+            Self::Hard => 3,
+        }
+    }
+
+    fn from_name(name: &str) -> Option<Self> {
+        match name {
+            "peaceful" => Some(Self::Peaceful),
+            "easy" => Some(Self::Easy),
+            "normal" => Some(Self::Normal),
+            "hard" => Some(Self::Hard),
+            _ => None,
+        }
+    }
+
+    fn as_name(self) -> &'static str {
+        match self {
+            Self::Peaceful => "peaceful",
+            Self::Easy => "easy",
+            Self::Normal => "normal",
+            Self::Hard => "hard",
+        }
+    }
+}
+
+#[derive(Deserialize, Serialize, Debug, Clone)]
+pub struct GameRuleEntry {
+    pub key: String,
+    pub value: String,
+}
+
+#[derive(Deserialize, Serialize, Debug, Clone)]
+pub struct WorldLevelData {
+    pub name: String,
+    #[serde(
+        skip_serializing_if = "Option::is_none",
+        with = "either::serde_untagged_optional"
+    )]
+    pub icon: Option<Either<PathBuf, Url>>,
+    pub game_mode: SingleplayerGameMode,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub difficulty: Option<WorldDifficulty>,
+    pub difficulty_locked: bool,
+    pub hardcore: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub allow_commands: Option<bool>,
+    /// The world seed as a string, to avoid precision loss for the full
+    /// i64 range when crossing the IPC boundary into JavaScript.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub seed: Option<String>,
+    pub game_rules: Vec<GameRuleEntry>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub version_name: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub last_played: Option<DateTime<Utc>>,
+    pub modded: bool,
+    pub locked: bool,
+}
+
+#[derive(Deserialize, Serialize, Debug, Clone, Default)]
+#[serde(default)]
+pub struct WorldSettingsPatch {
+    pub name: Option<String>,
+    pub game_mode: Option<SingleplayerGameMode>,
+    pub difficulty: Option<WorldDifficulty>,
+    pub allow_commands: Option<bool>,
+    /// The new world seed, as a base-10 string within the i64 range.
+    pub seed: Option<String>,
+    /// Values for existing game rules. Keys not present in the world's
+    /// game rule storage are ignored rather than added.
+    pub game_rules: Option<Vec<GameRuleEntry>>,
+}
+
+/// Where each editable aspect of a world is stored. Modern worlds
+/// (roughly 26.x and later) split game rules, world generation settings
+/// and player data out of level.dat into sibling files, while older
+/// worlds keep everything inline. Detection is based purely on what is
+/// present in the world's files, never on version numbers, so reads and
+/// writes always target the location the data actually came from.
+struct WorldDataSources {
+    game_rules: Option<GameRulesSource>,
+    seed: Option<SeedSource>,
+    difficulty: Option<DifficultyFormat>,
+    player_game_type: Option<PlayerGameTypeTarget>,
+}
+
+enum GameRulesSource {
+    LevelDat,
+    Savedata(PathBuf),
+}
+
+enum SeedSource {
+    LevelDatWorldGenSettings,
+    LevelDatRandomSeed,
+    Savedata(PathBuf),
+}
+
+enum DifficultyFormat {
+    LegacyByte,
+    SettingsCompound,
+}
+
+enum PlayerGameTypeTarget {
+    LevelDatPlayer,
+    PlayerFile(PathBuf),
+}
+
+fn savedata_path(world_dir: &Path, file_name: &str) -> PathBuf {
+    world_dir.join("data").join("minecraft").join(file_name)
+}
+
+async fn existing_savedata_path(
+    world_dir: &Path,
+    file_name: &str,
+) -> Option<PathBuf> {
+    let path = savedata_path(world_dir, file_name);
+    tokio::fs::try_exists(&path)
+        .await
+        .unwrap_or(false)
+        .then_some(path)
+}
+
+async fn probe_world_data_sources(
+    world_dir: &Path,
+    data: &NbtCompound,
+) -> WorldDataSources {
+    let game_rules = if data.get::<_, &NbtCompound>("GameRules").is_ok() {
+        Some(GameRulesSource::LevelDat)
+    } else {
+        existing_savedata_path(world_dir, "game_rules.dat")
+            .await
+            .map(GameRulesSource::Savedata)
+    };
+
+    let has_world_gen_settings_seed = data
+        .get::<_, &NbtCompound>("WorldGenSettings")
+        .ok()
+        .and_then(|settings| settings.get::<_, &NbtTag>("seed").ok())
+        .and_then(numeric_nbt_value)
+        .is_some();
+    let seed = if has_world_gen_settings_seed {
+        Some(SeedSource::LevelDatWorldGenSettings)
+    } else if data
+        .get::<_, &NbtTag>("RandomSeed")
+        .ok()
+        .and_then(numeric_nbt_value)
+        .is_some()
+    {
+        Some(SeedSource::LevelDatRandomSeed)
+    } else {
+        existing_savedata_path(world_dir, "world_gen_settings.dat")
+            .await
+            .map(SeedSource::Savedata)
+    };
+
+    let difficulty = if data.get::<_, i8>("Difficulty").is_ok() {
+        Some(DifficultyFormat::LegacyByte)
+    } else if data.get::<_, &NbtCompound>("difficulty_settings").is_ok() {
+        Some(DifficultyFormat::SettingsCompound)
+    } else {
+        None
+    };
+
+    let player_game_type = if data.get::<_, &NbtCompound>("Player").is_ok() {
+        Some(PlayerGameTypeTarget::LevelDatPlayer)
+    } else {
+        match data.get::<_, &NbtTag>("singleplayer_uuid") {
+            Ok(NbtTag::IntArray(parts)) => {
+                uuid_string_from_parts(parts).map(|uuid| {
+                    PlayerGameTypeTarget::PlayerFile(
+                        world_dir
+                            .join("players")
+                            .join("data")
+                            .join(format!("{uuid}.dat")),
+                    )
+                })
+            }
+            _ => None,
+        }
+    };
+
+    WorldDataSources {
+        game_rules,
+        seed,
+        difficulty,
+        player_game_type,
+    }
+}
+
+fn uuid_string_from_parts(parts: &[i32]) -> Option<String> {
+    if parts.len() != 4 {
+        return None;
+    }
+    let hex: String = parts
+        .iter()
+        .map(|part| format!("{:08x}", *part as u32))
+        .collect();
+    Some(format!(
+        "{}-{}-{}-{}-{}",
+        &hex[0..8],
+        &hex[8..12],
+        &hex[12..16],
+        &hex[16..20],
+        &hex[20..32]
+    ))
+}
+
+fn game_type_of(mode: SingleplayerGameMode) -> i32 {
+    match mode {
+        SingleplayerGameMode::Survival => 0,
+        SingleplayerGameMode::Creative => 1,
+        SingleplayerGameMode::Adventure => 2,
+        SingleplayerGameMode::Spectator => 3,
+    }
+}
+
+fn numeric_nbt_value(tag: &NbtTag) -> Option<i64> {
+    match tag {
+        NbtTag::Byte(value) => Some(i64::from(*value)),
+        NbtTag::Short(value) => Some(i64::from(*value)),
+        NbtTag::Int(value) => Some(i64::from(*value)),
+        NbtTag::Long(value) => Some(*value),
+        _ => None,
+    }
+}
+
+fn extract_level_seed(data: &NbtCompound) -> Option<i64> {
+    if let Ok(settings) = data.get::<_, &NbtCompound>("WorldGenSettings")
+        && let Ok(tag) = settings.get::<_, &NbtTag>("seed")
+        && let Some(seed) = numeric_nbt_value(tag)
+    {
+        return Some(seed);
+    }
+    data.get::<_, &NbtTag>("RandomSeed")
+        .ok()
+        .and_then(numeric_nbt_value)
+}
+
+/// Rewrites every numeric tag named `seed` in the compound, covering the
+/// modern `WorldGenSettings.seed` field, the per-dimension generator and
+/// biome source seeds used by the 1.16 and 1.17 world formats, and the
+/// `data.seed` field of split world_gen_settings.dat files.
+fn set_seed_tags_recursively(compound: &mut NbtCompound, seed: i64) {
+    for (name, tag) in compound.inner_mut() {
+        if name.eq_ignore_ascii_case("seed") && numeric_nbt_value(tag).is_some()
+        {
+            *tag = NbtTag::Long(seed);
+            continue;
+        }
+        set_seed_in_tag(tag, seed);
+    }
+}
+
+fn set_seed_in_tag(tag: &mut NbtTag, seed: i64) {
+    match tag {
+        NbtTag::Compound(child) => set_seed_tags_recursively(child, seed),
+        NbtTag::List(list) => {
+            for item in list.iter_mut() {
+                set_seed_in_tag(item, seed);
+            }
+        }
+        _ => {}
+    }
+}
+
+/// Renders a stored game rule value as the string form used across the
+/// IPC boundary. Legacy worlds store every rule as a string; split
+/// game_rules.dat files store native types, where a Byte of 0 or 1 is a
+/// boolean and other numeric tags are plain numbers.
+fn rule_tag_to_value(tag: &NbtTag) -> Option<String> {
+    match tag {
+        NbtTag::String(value) => Some(value.clone()),
+        NbtTag::Byte(0) => Some("false".to_string()),
+        NbtTag::Byte(1) => Some("true".to_string()),
+        NbtTag::Byte(value) => Some(value.to_string()),
+        NbtTag::Short(value) => Some(value.to_string()),
+        NbtTag::Int(value) => Some(value.to_string()),
+        NbtTag::Long(value) => Some(value.to_string()),
+        _ => None,
+    }
+}
+
+/// Converts a string value back into the tag type the rule already has
+/// in the file, so the file's own schema decides the written type and a
+/// value that cannot be represented is rejected instead of guessed at.
+fn rule_value_to_tag(existing: &NbtTag, value: &str) -> Result<NbtTag> {
+    let invalid = || {
+        Error::from(ErrorKind::InputError(format!(
+            "Invalid game rule value: {value}"
+        )))
+    };
+    Ok(match existing {
+        NbtTag::String(_) => NbtTag::String(value.to_string()),
+        NbtTag::Byte(_) => match value {
+            "true" => NbtTag::Byte(1),
+            "false" => NbtTag::Byte(0),
+            other => NbtTag::Byte(other.trim().parse().map_err(|_| invalid())?),
+        },
+        NbtTag::Short(_) => {
+            NbtTag::Short(value.trim().parse().map_err(|_| invalid())?)
+        }
+        NbtTag::Int(_) => {
+            NbtTag::Int(value.trim().parse().map_err(|_| invalid())?)
+        }
+        NbtTag::Long(_) => {
+            NbtTag::Long(value.trim().parse().map_err(|_| invalid())?)
+        }
+        _ => return Err(invalid()),
+    })
+}
+
+fn collect_game_rules(rules: &NbtCompound) -> Vec<GameRuleEntry> {
+    let mut entries: Vec<GameRuleEntry> = rules
+        .inner()
+        .iter()
+        .filter_map(|(key, tag)| {
+            rule_tag_to_value(tag).map(|value| GameRuleEntry {
+                key: key.clone(),
+                value,
+            })
+        })
+        .collect();
+    entries.sort_by(|a, b| {
+        a.key.to_ascii_lowercase().cmp(&b.key.to_ascii_lowercase())
+    });
+    entries
+}
+
+fn apply_game_rule_patch(
+    target: &mut NbtCompound,
+    rules: &[GameRuleEntry],
+) -> Result<()> {
+    for rule in rules {
+        let Ok(existing) = target.get::<_, &NbtTag>(&*rule.key) else {
+            continue;
+        };
+        let new_tag = rule_value_to_tag(existing, &rule.value)?;
+        target.insert(rule.key.clone(), new_tag);
+    }
+    Ok(())
+}
+
+fn read_nbt_root(raw: &[u8]) -> Result<(NbtCompound, String)> {
+    Ok(quartz_nbt::io::read_nbt(
+        &mut Cursor::new(raw),
+        quartz_nbt::io::Flavor::GzCompressed,
+    )?)
+}
+
+fn write_nbt_root(root: &NbtCompound, root_name: &str) -> Result<Vec<u8>> {
+    let mut out = vec![];
+    quartz_nbt::io::write_nbt(
+        &mut out,
+        Some(root_name),
+        root,
+        quartz_nbt::io::Flavor::GzCompressed,
+    )?;
+    Ok(out)
+}
+
+/// Replaces a world file safely: the previous bytes are kept as a
+/// sibling `<name>_old` backup (matching the vanilla level.dat_old
+/// convention) and the new bytes land via a temp file and atomic rename.
+async fn backup_and_replace(
+    path: &Path,
+    original: &[u8],
+    updated: &[u8],
+) -> Result<()> {
+    let mut backup = path.as_os_str().to_owned();
+    backup.push("_old");
+    io::write(PathBuf::from(backup), original).await?;
+
+    let mut temp = path.as_os_str().to_owned();
+    temp.push(".axolotl-tmp");
+    let temp = PathBuf::from(temp);
+    io::write(&temp, updated).await?;
+    io::rename_or_move(&temp, path).await?;
+    Ok(())
+}
+
+async fn read_savedata_data_compound(path: &Path) -> Result<NbtCompound> {
+    let raw = io::read(path).await?;
+    let (mut root, _) = read_nbt_root(&raw)?;
+    match root.inner_mut().remove("data") {
+        Some(NbtTag::Compound(data)) => Ok(data),
+        _ => Err(ErrorKind::InputError(format!(
+            "Missing data tag in {}",
+            path.display()
+        ))
+        .into()),
+    }
+}
+
+/// Applies an in-place mutation to the `data` compound of a savedata
+/// file, leaving every other tag (including DataVersion) untouched.
+async fn modify_savedata_file<F>(path: &Path, mutate: F) -> Result<()>
+where
+    F: FnOnce(&mut NbtCompound) -> Result<()>,
+{
+    let original = io::read(path).await?;
+    let (mut root, root_name) = read_nbt_root(&original)?;
+    let data = root.get_mut::<_, &mut NbtCompound>("data").map_err(|_| {
+        Error::from(ErrorKind::InputError(format!(
+            "Missing data tag in {}",
+            path.display()
+        )))
+    })?;
+    mutate(data)?;
+    let updated = write_nbt_root(&root, &root_name)?;
+    backup_and_replace(path, &original, &updated).await
+}
+
+async fn update_player_game_type(path: &Path, game_type: i32) -> Result<()> {
+    if !tokio::fs::try_exists(path).await.unwrap_or(false) {
+        return Ok(());
+    }
+    let original = io::read(path).await?;
+    let (mut root, root_name) = read_nbt_root(&original)?;
+    root.insert("playerGameType", NbtTag::Int(game_type));
+    let updated = write_nbt_root(&root, &root_name)?;
+    backup_and_replace(path, &original, &updated).await
+}
+
+pub async fn get_world_level_data(
+    instance: &str,
+    world: &str,
+) -> Result<WorldLevelData> {
+    let state = State::get().await?;
+    let (instance_id, instance_path, game_dir_override) =
+        resolve_instance_identity(instance, &state).await?;
+    let instance_dir = resolve_instance_data_dir(
+        &instance_id,
+        &instance_path,
+        game_dir_override.as_deref(),
+        &state,
+    )
+    .await?;
+    let world_dir = get_world_dir(&instance_dir, world);
+
+    let locked = try_get_world_session_lock(&world_dir).await?.is_none();
+
+    let raw = io::read(world_dir.join("level.dat")).await?;
+    let (root, _) = read_nbt_root(&raw)?;
+    let data = root.get::<_, &NbtCompound>("Data").map_err(|_| {
+        Error::from(ErrorKind::InputError(
+            "Missing Data tag in level.dat".into(),
+        ))
+    })?;
+
+    let sources = probe_world_data_sources(&world_dir, data).await;
+
+    let game_rules = match &sources.game_rules {
+        Some(GameRulesSource::LevelDat) => data
+            .get::<_, &NbtCompound>("GameRules")
+            .map(collect_game_rules)
+            .unwrap_or_default(),
+        Some(GameRulesSource::Savedata(path)) => {
+            match read_savedata_data_compound(path).await {
+                Ok(rules) => collect_game_rules(&rules),
+                Err(e) => {
+                    tracing::warn!(
+                        "Failed to read game rules from {}: {e}",
+                        path.display()
+                    );
+                    vec![]
+                }
+            }
+        }
+        None => vec![],
+    };
+
+    let seed = match &sources.seed {
+        Some(
+            SeedSource::LevelDatWorldGenSettings
+            | SeedSource::LevelDatRandomSeed,
+        ) => extract_level_seed(data),
+        Some(SeedSource::Savedata(path)) => {
+            match read_savedata_data_compound(path).await {
+                Ok(settings) => settings
+                    .get::<_, &NbtTag>("seed")
+                    .ok()
+                    .and_then(numeric_nbt_value),
+                Err(e) => {
+                    tracing::warn!(
+                        "Failed to read world gen settings from {}: {e}",
+                        path.display()
+                    );
+                    None
+                }
+            }
+        }
+        None => None,
+    };
+
+    let (difficulty, difficulty_locked, hardcore) = match &sources.difficulty {
+        Some(DifficultyFormat::LegacyByte) | None => (
+            data.get::<_, i8>("Difficulty")
+                .ok()
+                .map(WorldDifficulty::from_byte),
+            data.get::<_, i8>("DifficultyLocked").unwrap_or(0) != 0,
+            data.get::<_, i8>("hardcore").unwrap_or(0) != 0,
+        ),
+        Some(DifficultyFormat::SettingsCompound) => {
+            let settings =
+                data.get::<_, &NbtCompound>("difficulty_settings").ok();
+            (
+                settings
+                    .and_then(|s| s.get::<_, &str>("difficulty").ok())
+                    .and_then(WorldDifficulty::from_name),
+                settings
+                    .map(|s| s.get::<_, i8>("locked").unwrap_or(0) != 0)
+                    .unwrap_or(false),
+                settings
+                    .map(|s| s.get::<_, i8>("hardcore").unwrap_or(0) != 0)
+                    .unwrap_or(false),
+            )
+        }
+    };
+
+    let game_mode = match data.get::<_, i32>("GameType").unwrap_or(0) {
+        1 => SingleplayerGameMode::Creative,
+        2 => SingleplayerGameMode::Adventure,
+        3 => SingleplayerGameMode::Spectator,
+        _ => SingleplayerGameMode::Survival,
+    };
+
+    let icon_path = world_dir.join("icon.png");
+    let icon = tokio::fs::try_exists(&icon_path)
+        .await
+        .unwrap_or(false)
+        .then_some(Either::Left(icon_path));
+
+    Ok(WorldLevelData {
+        name: data
+            .get::<_, &str>("LevelName")
+            .unwrap_or_default()
+            .to_string(),
+        icon,
+        game_mode,
+        difficulty,
+        difficulty_locked,
+        hardcore,
+        allow_commands: data
+            .get::<_, i8>("allowCommands")
+            .ok()
+            .map(|allow| allow != 0),
+        seed: seed.map(|seed| seed.to_string()),
+        game_rules,
+        version_name: data
+            .get::<_, &NbtCompound>("Version")
+            .ok()
+            .and_then(|version| version.get::<_, &str>("Name").ok())
+            .map(str::to_string),
+        last_played: data
+            .get::<_, i64>("LastPlayed")
+            .ok()
+            .and_then(|millis| Utc.timestamp_millis_opt(millis).single()),
+        modded: data.get::<_, i8>("WasModded").unwrap_or(0) != 0,
+        locked,
+    })
+}
+
+pub async fn update_world_settings(
+    instance: &Path,
+    world: &str,
+    patch: WorldSettingsPatch,
+) -> Result<()> {
+    let world_dir = get_world_dir(instance, world);
+    let level_dat_path = world_dir.join("level.dat");
+    if !level_dat_path.exists() {
+        return Err(ErrorKind::InputError(
+            "The world does not contain a level.dat file".into(),
+        )
+        .into());
+    }
+    let _lock = get_world_session_lock(&world_dir).await?;
+
+    let original = io::read(&level_dat_path).await?;
+    let (mut root, root_name) = read_nbt_root(&original)?;
+    let sources = {
+        let data = root.get::<_, &NbtCompound>("Data").map_err(|_| {
+            Error::from(ErrorKind::InputError(
+                "Missing Data tag in level.dat".into(),
+            ))
+        })?;
+        probe_world_data_sources(&world_dir, data).await
+    };
+    let data = root.get_mut::<_, &mut NbtCompound>("Data").map_err(|_| {
+        Error::from(ErrorKind::InputError(
+            "Missing Data tag in level.dat".into(),
+        ))
+    })?;
+
+    let mut level_dirty = false;
+
+    if let Some(name) = &patch.name {
+        data.insert("LevelName", NbtTag::String(name.trim_ascii().to_string()));
+        level_dirty = true;
+    }
+
+    if let Some(mode) = patch.game_mode {
+        let game_type = game_type_of(mode);
+        data.insert("GameType", NbtTag::Int(game_type));
+        level_dirty = true;
+        match &sources.player_game_type {
+            Some(PlayerGameTypeTarget::LevelDatPlayer) => {
+                if let Ok(player) =
+                    data.get_mut::<_, &mut NbtCompound>("Player")
+                {
+                    player.insert("playerGameType", NbtTag::Int(game_type));
+                }
+            }
+            Some(PlayerGameTypeTarget::PlayerFile(path)) => {
+                update_player_game_type(path, game_type).await?;
+            }
+            None => {}
+        }
+    }
+
+    if let Some(difficulty) = patch.difficulty {
+        match &sources.difficulty {
+            Some(DifficultyFormat::SettingsCompound) => {
+                if let Ok(settings) =
+                    data.get_mut::<_, &mut NbtCompound>("difficulty_settings")
+                {
+                    settings.insert(
+                        "difficulty",
+                        NbtTag::String(difficulty.as_name().to_string()),
+                    );
+                }
+            }
+            Some(DifficultyFormat::LegacyByte) | None => {
+                data.insert("Difficulty", NbtTag::Byte(difficulty.as_byte()));
+            }
+        }
+        level_dirty = true;
+    }
+
+    if let Some(allow_commands) = patch.allow_commands {
+        data.insert("allowCommands", NbtTag::Byte(allow_commands as i8));
+        level_dirty = true;
+    }
+
+    if let Some(seed) = &patch.seed {
+        let seed = seed.trim().parse::<i64>().map_err(|_| {
+            Error::from(ErrorKind::InputError(
+                "The world seed must be a whole number".into(),
+            ))
+        })?;
+        match &sources.seed {
+            Some(SeedSource::LevelDatWorldGenSettings) => {
+                if let Ok(settings) =
+                    data.get_mut::<_, &mut NbtCompound>("WorldGenSettings")
+                {
+                    set_seed_tags_recursively(settings, seed);
+                }
+                level_dirty = true;
+            }
+            Some(SeedSource::LevelDatRandomSeed) => {
+                data.insert("RandomSeed", NbtTag::Long(seed));
+                level_dirty = true;
+            }
+            Some(SeedSource::Savedata(path)) => {
+                modify_savedata_file(path, |settings| {
+                    set_seed_tags_recursively(settings, seed);
+                    Ok(())
+                })
+                .await?;
+            }
+            None => {
+                return Err(ErrorKind::InputError(
+                    "The world does not store an editable seed".into(),
+                )
+                .into());
+            }
+        }
+    }
+
+    if let Some(rules) = &patch.game_rules
+        && !rules.is_empty()
+    {
+        match &sources.game_rules {
+            Some(GameRulesSource::LevelDat) => {
+                if let Ok(game_rules) =
+                    data.get_mut::<_, &mut NbtCompound>("GameRules")
+                {
+                    apply_game_rule_patch(game_rules, rules)?;
+                    level_dirty = true;
+                }
+            }
+            Some(GameRulesSource::Savedata(path)) => {
+                modify_savedata_file(path, |data| {
+                    apply_game_rule_patch(data, rules)
+                })
+                .await?;
+            }
+            None => {
+                return Err(ErrorKind::InputError(
+                    "The world does not store editable game rules".into(),
+                )
+                .into());
+            }
+        }
+    }
+
+    if level_dirty {
+        let updated = write_nbt_root(&root, &root_name)?;
+        backup_and_replace(&level_dat_path, &original, &updated).await?;
+    }
+    Ok(())
+}

packages/app-lib/src/brand.rs

@@ -0,0 +1,24 @@
+pub const PRODUCT_NAME: &str = "Axolotl Launcher";
+pub const SHORT_PRODUCT_NAME: &str = "Axolotl";
+pub const WEBSITE: &str = "https://www.ghs.red";
+pub const BUNDLE_IDENTIFIER: &str = "red.ghs.axolotl";
+pub const DEEP_LINK_SCHEME: &str = "axolotl";
+
+pub fn user_agent(version: &str, os: &str) -> String {
+    format!("garbage-human-studio/axolotl/{version} ({os})")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn user_agent_is_unique_and_contains_no_contact_information() {
+        let user_agent = user_agent("1.2.3", "windows");
+
+        assert_eq!(user_agent, "garbage-human-studio/axolotl/1.2.3 (windows)");
+        assert!(!user_agent.contains("ghs.red"));
+        assert!(!user_agent.contains("http"));
+        assert!(!user_agent.contains('@'));
+    }
+}

packages/app-lib/src/error.rs

@@ -0,0 +1,309 @@
+//! Theseus error type
+use std::sync::Arc;
+
+use crate::util;
+use data_url::DataUrlError;
+use derive_more::Display;
+use serde::{Deserialize, Serialize};
+use tracing_error::InstrumentError;
+
+#[derive(Serialize, Deserialize, Debug, Display)]
+#[display("{description}")]
+pub struct LabrinthError {
+    pub error: String,
+    pub description: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub status: Option<u16>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub method: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub url: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub route: Option<String>,
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum ErrorKind {
+    #[error("{0:?}")]
+    Any(eyre::Report),
+
+    #[error("Filesystem error: {0}")]
+    FSError(String),
+
+    #[error("Serialization error (INI): {0}")]
+    INIError(#[from] serde_ini::de::Error),
+
+    #[error("Serialization error (JSON): {0}")]
+    JSONError(#[from] serde_json::Error),
+
+    #[error("Serialization error (NBT): {0}")]
+    NBTError(#[from] quartz_nbt::io::NbtIoError),
+
+    #[error("NBT data structure error: {0}")]
+    NBTReprError(#[from] quartz_nbt::NbtReprError),
+
+    #[error("Serialization error (websocket): {0}")]
+    WebsocketSerializationError(
+        #[from] ariadne::networking::serialization::SerializationError,
+    ),
+
+    #[error("Error parsing UUID: {0}")]
+    UUIDError(#[from] uuid::Error),
+
+    #[error("Error parsing URL: {0}")]
+    URLError(#[from] url::ParseError),
+
+    #[error("Unable to read {0} from any source")]
+    NoValueFor(String),
+
+    #[error("Metadata error: {0}")]
+    MetadataError(#[from] daedalus::Error),
+
+    #[error("Minecraft authentication error: {0}")]
+    MinecraftAuthenticationError(
+        #[from] crate::state::MinecraftAuthenticationError,
+    ),
+
+    #[error("I/O error: {0}")]
+    IOError(#[from] util::io::IOError),
+
+    #[error("I/O (std) error: {0}")]
+    StdIOError(#[from] std::io::Error),
+
+    #[error("Error launching Minecraft: {0}")]
+    LauncherError(String),
+
+    #[error("Error fetching URL: {0}")]
+    FetchError(#[from] reqwest::Error),
+
+    #[error("Network download error: {0}")]
+    NetworkError(String),
+
+    #[error("HTTP {status} for {method} {url}")]
+    HttpError {
+        status: u16,
+        method: String,
+        url: String,
+    },
+
+    #[error("Too many API errors, try again in {0} minutes")]
+    ApiIsDownError(u32),
+
+    #[error("{0}")]
+    LabrinthError(LabrinthError),
+
+    #[error("Websocket error: {0}")]
+    WSError(#[from] async_tungstenite::tungstenite::Error),
+
+    #[error("Websocket closed before {0} could be received!")]
+    WSClosedError(String),
+
+    #[error("Incorrect Sha1 hash for download: {0} != {1}")]
+    HashError(String, String),
+
+    #[error("Regex error: {0}")]
+    RegexError(#[from] regex::Error),
+
+    #[error("Paths stored in the database need to be valid UTF-8: {0}")]
+    UTFError(std::path::PathBuf),
+
+    #[error("Invalid input: {0}")]
+    InputError(String),
+
+    #[error(
+        "The instance upgrade plan is stale (planned revision {planned_revision}, current revision {current_revision})"
+    )]
+    StaleInstanceUpgradePlan {
+        planned_revision: u64,
+        current_revision: u64,
+    },
+
+    #[error(
+        "The instance upgrade plan filesystem source is stale for instance {instance_id}"
+    )]
+    StaleInstanceUpgradePlanSource { instance_id: String },
+
+    #[error("Join handle error: {0}")]
+    JoinError(#[from] tokio::task::JoinError),
+
+    #[error("Recv error: {0}")]
+    RecvError(#[from] tokio::sync::oneshot::error::RecvError),
+
+    #[error("Error acquiring semaphore: {0}")]
+    AcquireError(#[from] tokio::sync::AcquireError),
+
+    #[error("Instance {0} is not managed by the app!")]
+    UnmanagedInstanceError(String),
+
+    #[error(
+        "Instance {instance_id} is not ready while install stage is {stage}"
+    )]
+    InstanceNotReady { instance_id: String, stage: String },
+
+    #[error("User is not logged in, no credentials available!")]
+    NoCredentialsError,
+
+    #[error("JRE error: {0}")]
+    JREError(#[from] crate::util::jre::JREError),
+
+    #[error("Error parsing date: {0}")]
+    ChronoParseError(#[from] chrono::ParseError),
+
+    #[error("Event error: {0}")]
+    EventError(#[from] crate::event::EventError),
+
+    #[error("Zip error: {0}")]
+    ZipError(#[from] async_zip::error::ZipError),
+
+    #[error("File watching error: {0}")]
+    NotifyError(#[from] notify::Error),
+
+    #[error("Error stripping prefix: {0}")]
+    StripPrefixError(#[from] std::path::StripPrefixError),
+
+    #[error("Error: {0}")]
+    OtherError(String),
+
+    #[cfg(feature = "tauri")]
+    #[error("Tauri error: {0}")]
+    TauriError(#[from] tauri::Error),
+
+    #[error("Error interacting with database: {0}")]
+    Sqlx(#[from] sqlx::Error),
+
+    #[error("Unable to read {cache_type} cache: {message}")]
+    CacheReadError {
+        cache_type: String,
+        message: String,
+        sqlite_code: Option<String>,
+    },
+
+    #[error("Error while applying migrations: {0}")]
+    SqlxMigrate(#[from] sqlx::migrate::MigrateError),
+
+    #[error("Move directory error: {0}")]
+    DirectoryMoveError(String),
+
+    #[error("Error resolving DNS: {0}")]
+    DNSError(#[from] hickory_resolver::ResolveError),
+
+    #[error("An online profile for {user_name} is not available")]
+    OnlineMinecraftProfileUnavailable { user_name: String },
+
+    #[error("Invalid data URL: {0}")]
+    InvalidDataUrl(#[from] DataUrlError),
+
+    #[error("Invalid data URL: {0}")]
+    InvalidDataUrlBase64(#[from] data_url::forgiving_base64::InvalidBase64),
+
+    #[error("Invalid PNG")]
+    InvalidPng,
+
+    #[error("Invalid PNG: {0}")]
+    PngDecodingError(#[from] png::DecodingError),
+
+    #[error("PNG encoding error: {0}")]
+    PngEncodingError(#[from] png::EncodingError),
+
+    #[error(
+        "A skin texture must have a dimension of either 64x64 or 64x32 pixels"
+    )]
+    InvalidSkinTexture,
+
+    #[error("RPC error: {0}")]
+    RpcError(String),
+
+    #[cfg(windows)]
+    #[error("Windows error: {0}")]
+    WindowsError(#[from] windows_core::Error),
+
+    #[error("zbus error: {0}")]
+    ZbusError(#[from] zbus::Error),
+
+    #[error("Deserialization error: {0}")]
+    DeserializationError(#[from] serde::de::value::Error),
+
+    #[error("Discord IPC error: {0}")]
+    DiscordRichPresenceError(#[from] discord_rich_presence::error::Error),
+}
+
+#[derive(Debug)]
+pub struct Error {
+    pub raw: Arc<ErrorKind>,
+    pub source: tracing_error::TracedError<Arc<ErrorKind>>,
+    context: Option<String>,
+}
+
+impl std::error::Error for Error {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        self.source.source()
+    }
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(fmt, "{}", self.source)?;
+        if let Some(context) = &self.context {
+            write!(fmt, "\n{context}")?;
+        }
+        Ok(())
+    }
+}
+
+impl Error {
+    pub(crate) fn with_context(mut self, context: impl Into<String>) -> Self {
+        self.context = Some(context.into());
+        self
+    }
+
+    /// Returns a user-facing message for this error, replacing raw database
+    /// errors that are meaningless to end users with an actionable hint.
+    ///
+    /// SQLite foreign-key violation (code 787) surfaces when an instance is
+    /// deleted while a content write is still in flight; the write-path
+    /// validation already reports most of these cleanly, this is the final
+    /// fallback at the Tauri boundary.
+    pub fn user_facing_message(&self) -> String {
+        if let ErrorKind::Sqlx(sqlx::Error::Database(db_error)) =
+            self.raw.as_ref()
+            && db_error.code().as_deref() == Some("787")
+        {
+            return "This instance was deleted or is being modified; refresh the instance list and try again."
+                .to_string();
+        }
+        self.to_string()
+    }
+}
+
+impl<E: Into<ErrorKind>> From<E> for Error {
+    fn from(source: E) -> Self {
+        let error = Into::<ErrorKind>::into(source);
+        let boxed_error = Arc::new(error);
+
+        Self {
+            raw: boxed_error.clone(),
+            source: boxed_error.in_current_span(),
+            context: None,
+        }
+    }
+}
+
+impl From<eyre::Report> for Error {
+    fn from(value: eyre::Report) -> Self {
+        let error = Arc::new(ErrorKind::Any(value));
+
+        Self {
+            raw: error.clone(),
+            source: error.in_current_span(),
+            context: None,
+        }
+    }
+}
+
+impl ErrorKind {
+    pub fn as_error(self) -> Error {
+        self.into()
+    }
+}
+
+pub type Result<T> = core::result::Result<T, Error>;

packages/app-lib/src/event/emit.rs

@@ -0,0 +1,517 @@
+use super::{FriendPayload, LoadingBarId};
+use crate::event::{
+    CommandPayload, EventError, InstanceBulkUpdateProgressPayload,
+    InstancePayloadType, LoadingBar, LoadingBarType, ProcessPayloadType,
+    ServerPayloadType,
+};
+#[cfg(feature = "tauri")]
+use crate::event::{
+    InstancePayload, JavaDiscoveryPayload, JavaDownloadConfirmationPayload,
+    LoadingPayload, ProcessPayload, ServerPayload, WarningPayload,
+};
+use futures::prelude::*;
+use serde_json::Value;
+#[cfg(feature = "tauri")]
+use std::sync::LazyLock;
+#[cfg(feature = "tauri")]
+use tauri::{Emitter, Manager};
+#[cfg(feature = "tauri")]
+use tokio::sync::oneshot;
+use uuid::Uuid;
+
+#[cfg(feature = "cli")]
+const CLI_PROGRESS_BAR_TOTAL: u64 = 1000;
+
+#[cfg(feature = "tauri")]
+static JAVA_DOWNLOAD_CONFIRMATIONS: LazyLock<
+    dashmap::DashMap<Uuid, oneshot::Sender<bool>>,
+> = LazyLock::new(dashmap::DashMap::new);
+
+#[cfg(feature = "tauri")]
+struct PendingJavaDownloadConfirmation(Uuid);
+
+#[cfg(feature = "tauri")]
+impl Drop for PendingJavaDownloadConfirmation {
+    fn drop(&mut self) {
+        JAVA_DOWNLOAD_CONFIRMATIONS.remove(&self.0);
+    }
+}
+
+/*
+   Events are a way we can communicate with the Tauri frontend from the Rust backend.
+   We include a feature flag for Tauri, so that we can compile this code without Tauri.
+
+   To use events, we need to do the following:
+    1) Make sure we are using the tauri feature flag
+    2) Initialize the EventState with EventState::init() *before* initializing the theseus State
+    3) Call emit_x functions to send events to the frontend
+   For emit_loading() specifically, we need to initialize the loading bar with init_loading() first and pass the received loader in
+
+   For example:
+   pub async fn loading_function() -> crate::Result<()> {
+        loading_function()).await;
+   }
+
+   pub async fn loading_function() -> crate::Result<()> {
+       let loading_bar = init_loading(LoadingBarType::StateInit, 100.0, "Loading something long...").await;
+       for i in 0..100 {
+           emit_loading(&loading_bar, 1.0, None)?;
+           tokio::time::sleep(Duration::from_millis(100)).await;
+       }
+   }
+*/
+
+/// Initialize a loading bar for use in emit_loading
+/// This will generate a LoadingBarId, which is used to refer to the loading bar uniquely.
+/// total is the total amount of work to be done- all emissions will be considered a fraction of this value (should be 1 or 100 for simplicity)
+/// title is the title of the loading bar
+/// The app will wait for this loading bar to finish before exiting, as it is considered safe.
+pub async fn init_loading(
+    bar_type: LoadingBarType,
+    total: f64,
+    title: &str,
+) -> crate::Result<LoadingBarId> {
+    let key = init_loading_unsafe(bar_type, total, title).await?;
+    Ok(key)
+}
+
+/// An unsafe loading bar can be created without adding it to the SafeProcesses list,
+/// meaning that the app won't ask to wait for it to finish before exiting.
+pub async fn init_loading_unsafe(
+    bar_type: LoadingBarType,
+    total: f64,
+    title: &str,
+) -> crate::Result<LoadingBarId> {
+    let event_state = crate::EventState::get()?;
+    let key = LoadingBarId(Uuid::new_v4());
+
+    event_state.loading_bars.insert(
+        key.0,
+        LoadingBar {
+            loading_bar_uuid: key.0,
+            message: title.to_string(),
+            total,
+            current: 0.0,
+            last_sent: 0.0,
+            bar_type,
+            #[cfg(feature = "cli")]
+            cli_progress_bar: {
+                let pb = indicatif::ProgressBar::new(CLI_PROGRESS_BAR_TOTAL);
+
+                pb.set_position(0);
+                pb.set_style(
+                    indicatif::ProgressStyle::default_bar()
+                        .template(
+                            "{spinner:.green} [{elapsed_precise}] [{bar:.lime/green}] {pos}/{len} {msg}",
+                        ).unwrap()
+                        .progress_chars("#>-"),
+                );
+                pb
+            },
+        },
+    );
+    // attempt an initial loading_emit event to the frontend
+    emit_loading(&key, 0.0, None)?;
+    Ok(key)
+}
+
+// emit_loading emits a loading event to the frontend
+// key refers to the loading bar to update
+// increment refers to by what relative increment to the loading struct's total to update
+// message is the message to display on the loading bar- if None, use the loading bar's default one
+// By convention, fraction is the fraction of the progress bar that is filled
+#[tracing::instrument(level = "debug")]
+pub fn emit_loading(
+    key: &LoadingBarId,
+    increment_frac: f64,
+    message: Option<&str>,
+) -> crate::Result<()> {
+    let event_state = crate::EventState::get()?;
+
+    let Some(mut loading_bar) = event_state.loading_bars.get_mut(&key.0) else {
+        return Err(EventError::NoLoadingBar(key.0).into());
+    };
+
+    // Tick up loading bar
+    loading_bar.current += increment_frac;
+    let display_frac = loading_bar.current / loading_bar.total;
+
+    if f64::abs(display_frac - loading_bar.last_sent) > 0.005 {
+        // Emit event to indicatif progress bar
+        #[cfg(feature = "cli")]
+        {
+            loading_bar.cli_progress_bar.set_message(
+                message
+                    .map(|x| x.to_string())
+                    .unwrap_or(loading_bar.message.clone()),
+            );
+            loading_bar.cli_progress_bar.set_position(
+                (display_frac * CLI_PROGRESS_BAR_TOTAL as f64).round() as u64,
+            );
+        }
+
+        //Emit event to tauri
+        #[cfg(feature = "tauri")]
+        event_state
+            .app
+            .emit(
+                "loading",
+                LoadingPayload {
+                    fraction: if display_frac >= 1.0 {
+                        None // by convention, when its done, we submit None
+                    // any further updates will be ignored (also sending None)
+                    } else {
+                        Some(display_frac)
+                    },
+                    message: message
+                        .unwrap_or(&loading_bar.message)
+                        .to_string(),
+                    event: loading_bar.bar_type.clone(),
+                    loader_uuid: loading_bar.loading_bar_uuid,
+                },
+            )
+            .map_err(EventError::from)?;
+
+        #[cfg(not(any(feature = "cli", feature = "tauri")))]
+        let _ = message;
+
+        loading_bar.last_sent = display_frac;
+    }
+
+    Ok(())
+}
+
+// emit_warning(message)
+pub async fn emit_warning(message: &str) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit(
+                "warning",
+                WarningPayload {
+                    message: message.to_string(),
+                    kind: None,
+                    instance_id: None,
+                    instance_name: None,
+                },
+            )
+            .map_err(EventError::from)?;
+    }
+    tracing::warn!("{}", message);
+    Ok(())
+}
+
+pub async fn emit_minecraft_crash_warning(
+    instance_id: &str,
+    instance_name: &str,
+) -> crate::Result<()> {
+    let message = format!("Instance {instance_name} has crashed");
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit(
+                "warning",
+                WarningPayload {
+                    message: message.clone(),
+                    kind: Some("minecraft_crash".to_string()),
+                    instance_id: Some(instance_id.to_string()),
+                    instance_name: Some(instance_name.to_string()),
+                },
+            )
+            .map_err(EventError::from)?;
+    }
+    tracing::warn!(instance_id = instance_id, "{}", message);
+    Ok(())
+}
+
+// emit_java_discovery_update(count)
+// Fired when a Java rescan changed the set of discovered installations
+#[allow(unused_variables)]
+pub async fn emit_java_discovery_update(count: usize) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit("java_discovery_update", JavaDiscoveryPayload { count })
+            .map_err(EventError::from)?;
+    }
+    tracing::debug!("Java discovery updated: {count} installations");
+    Ok(())
+}
+
+#[allow(unused_variables)]
+pub async fn request_java_download_confirmation(
+    version: u32,
+) -> crate::Result<bool> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        let request_id = Uuid::new_v4();
+        let (sender, receiver) = oneshot::channel();
+        JAVA_DOWNLOAD_CONFIRMATIONS.insert(request_id, sender);
+        let _pending = PendingJavaDownloadConfirmation(request_id);
+
+        event_state
+            .app
+            .emit(
+                "java_download_confirmation",
+                JavaDownloadConfirmationPayload {
+                    request_id,
+                    version,
+                },
+            )
+            .map_err(EventError::from)?;
+
+        Ok(receiver.await.unwrap_or(false))
+    }
+
+    #[cfg(not(feature = "tauri"))]
+    Ok(true)
+}
+
+#[cfg(feature = "tauri")]
+pub fn respond_to_java_download_confirmation(
+    request_id: Uuid,
+    approved: bool,
+) -> bool {
+    JAVA_DOWNLOAD_CONFIRMATIONS
+        .remove(&request_id)
+        .is_some_and(|(_, sender)| sender.send(approved).is_ok())
+}
+
+#[allow(unused_variables)]
+pub async fn emit_instance_bulk_update_progress(
+    payload: InstanceBulkUpdateProgressPayload,
+) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit("instance_bulk_update_progress", payload)
+            .map_err(EventError::from)?;
+    }
+    Ok(())
+}
+
+// emit_command(CommandPayload::Something { something })
+// ie: installing a pack, opening an .mrpack, etc
+// Generally used for url deep links and file opens that we want to handle in the frontend
+pub async fn emit_command(command: CommandPayload) -> crate::Result<()> {
+    tracing::debug!("Command: {}", serde_json::to_string(&command)?);
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit("command", command)
+            .map_err(EventError::from)?;
+
+        if let Some(window) = event_state.app.get_window("main") {
+            let _ = window.set_focus();
+        }
+    }
+    Ok(())
+}
+
+// emit_process(instance_id, uuid, event, message, crashed)
+#[allow(unused_variables)]
+pub async fn emit_process(
+    instance_id: &str,
+    uuid: Uuid,
+    pid: u32,
+    maximize_window: bool,
+    event: ProcessPayloadType,
+    message: &str,
+    crashed: Option<bool>,
+) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit(
+                "process",
+                ProcessPayload {
+                    instance_id: instance_id.to_string(),
+                    uuid,
+                    pid,
+                    maximize_window,
+                    event,
+                    message: message.to_string(),
+                    crashed,
+                },
+            )
+            .map_err(EventError::from)?;
+    }
+    Ok(())
+}
+
+// emit_instance(path, event)
+#[allow(unused_variables)]
+pub async fn emit_instance(
+    instance_id: &str,
+    event: InstancePayloadType,
+) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit(
+                "instance",
+                InstancePayload {
+                    instance_id: instance_id.to_string(),
+                    event,
+                },
+            )
+            .map_err(EventError::from)?;
+    }
+    Ok(())
+}
+
+// emit_server(server_id, event)
+#[allow(unused_variables)]
+pub async fn emit_server(
+    server_id: &str,
+    event: ServerPayloadType,
+) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit(
+                "server",
+                ServerPayload {
+                    server_id: server_id.to_string(),
+                    event,
+                },
+            )
+            .map_err(EventError::from)?;
+    }
+    Ok(())
+}
+
+#[allow(unused_variables)]
+pub async fn emit_friend(payload: FriendPayload) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit("friend", payload)
+            .map_err(EventError::from)?;
+    }
+
+    Ok(())
+}
+
+#[allow(unused_variables)]
+pub async fn emit_notification(payload: Value) -> crate::Result<()> {
+    #[cfg(feature = "tauri")]
+    {
+        let event_state = crate::EventState::get()?;
+        event_state
+            .app
+            .emit("notification", payload)
+            .map_err(EventError::from)?;
+    }
+
+    Ok(())
+}
+
+// loading_join! macro
+// loading_join!(key: Option<&LoadingBarId>, total: f64, message: Option<&str>; task1, task2, task3...)
+// This will submit a loading event with the given message for each task as they complete
+// task1, task2, task3 are async tasks that you want to to join on await on
+// Key is the key to use for which loading bar to submit these results to- a LoadingBarId. If None, it does nothing
+// Total is the total amount of progress that the loading bar should take up by all futures in this (will be split evenly amongst them).
+// If message is Some(t) you will overwrite this loading bar's message with a custom one
+// For example, if you want the tasks to range as 0.1, 0.2, 0.3 (of the progress bar), you would do:
+// loading_join!(loading_bar, 0.1; task1, task2, task3)
+// This will await on each of the tasks, and as each completes, it will emit a loading event for 0.033, 0.066, 0.099, etc
+// This should function as a drop-in replacement for tokio::try_join_all! in most cases- except the function *itself* calls ? rather than needing it.
+#[macro_export]
+macro_rules! count {
+    () => (0usize);
+    ( $x:tt $($xs:tt)* ) => (1usize + $crate::count!($($xs)*));
+}
+#[macro_export]
+macro_rules! loading_join {
+    ($key:expr, $total:expr, $message:expr; $($task:expr $(,)?)+) => {
+        {
+            let key = $key;
+            let message : Option<&str> = $message;
+
+            let num_futures = $crate::count!($($task)*);
+            let increment = $total / num_futures as f64;
+
+
+            paste::paste! {
+                $( let [ <unique_name $task>] = {
+                    {
+                        let key = key.clone();
+                        let message = message.clone();
+                        async move {
+                            let res = $task.await;
+                            if let Some(key) = key {
+                                $crate::event::emit::emit_loading(key, increment, message)?;
+                            }
+                            res
+                        }
+                    }
+                };)+
+            }
+
+            paste::paste! {
+                tokio::try_join! (
+                    $( [ <unique_name $task>] ),+
+                )
+            }
+        }
+    };
+
+}
+
+// A drop in replacement to try_for_each_concurrent that emits loading events as it goes
+// Key is the key to use for which loading bar- a LoadingBarId. If None, does nothing
+// Total is the total amount of progress that the loading bar should take up by all futures in this (will be split evenly amongst them).
+// If message is Some(t) you will overwrite this loading bar's message with a custom one
+// num_futs is the number of futures that will be run, which is needed as we allow Iterator to be passed in, which doesn't have a size
+#[tracing::instrument(skip(stream, f))]
+
+pub async fn loading_try_for_each_concurrent<I, F, Fut, T>(
+    stream: I,
+    limit: Option<usize>,
+    key: Option<&LoadingBarId>,
+    total: f64,
+    num_futs: usize, // num is in here as we allow Iterator to be passed in, which doesn't have a size
+    message: Option<&str>,
+    f: F,
+) -> crate::Result<()>
+where
+    I: futures::TryStreamExt<Error = crate::Error> + TryStream<Ok = T>,
+    F: FnMut(T) -> Fut + Send,
+    Fut: Future<Output = crate::Result<()>> + Send,
+    T: Send,
+{
+    let mut f = f;
+    stream
+        .try_for_each_concurrent(limit, |item| {
+            let f = f(item);
+            async move {
+                f.await?;
+                if let Some(key) = key {
+                    emit_loading(key, total / (num_futs as f64), message)?;
+                }
+                Ok(())
+            }
+        })
+        .await
+}

packages/app-lib/src/event/mod.rs

@@ -0,0 +1,414 @@
+//! Theseus state management system
+use ariadne::ids::UserId;
+use ariadne::users::UserStatus;
+use chrono::{DateTime, Utc};
+use dashmap::DashMap;
+use serde::{Deserialize, Serialize};
+use std::{path::PathBuf, sync::Arc};
+#[cfg(feature = "tauri")]
+use tauri::Emitter;
+use tokio::sync::OnceCell;
+use uuid::Uuid;
+
+pub mod emit;
+
+// Global event state
+// Stores the Tauri app handle and other event-related state variables
+static EVENT_STATE: OnceCell<Arc<EventState>> = OnceCell::const_new();
+pub struct EventState {
+    /// Tauri app
+    #[cfg(feature = "tauri")]
+    pub app: tauri::AppHandle,
+    pub loading_bars: DashMap<Uuid, LoadingBar>,
+}
+
+impl EventState {
+    #[cfg(feature = "tauri")]
+    pub async fn init(app: tauri::AppHandle) -> crate::Result<Arc<Self>> {
+        EVENT_STATE
+            .get_or_try_init(|| async {
+                Ok(Arc::new(Self {
+                    app,
+                    loading_bars: DashMap::new(),
+                }))
+            })
+            .await
+            .cloned()
+    }
+
+    #[cfg(not(feature = "tauri"))]
+    pub async fn init() -> crate::Result<Arc<Self>> {
+        EVENT_STATE
+            .get_or_try_init(|| async {
+                Ok(Arc::new(Self {
+                    loading_bars: DashMap::new(),
+                }))
+            })
+            .await
+            .cloned()
+    }
+
+    pub fn get() -> crate::Result<Arc<Self>> {
+        Ok(EVENT_STATE.get().ok_or(EventError::NotInitialized)?.clone())
+    }
+
+    // Values provided should not be used directly, as they are clones and are not guaranteed to be up-to-date
+    pub async fn list_progress_bars() -> crate::Result<DashMap<Uuid, LoadingBar>>
+    {
+        let value = Self::get()?;
+        Ok(value.loading_bars.clone())
+    }
+
+    #[cfg(feature = "tauri")]
+    pub async fn get_main_window() -> crate::Result<Option<tauri::WebviewWindow>>
+    {
+        use tauri::Manager;
+        let value = Self::get()?;
+        Ok(value.app.get_webview_window("main"))
+    }
+}
+
+#[derive(Serialize, Debug, Clone)]
+pub struct LoadingBar {
+    // loading_bar_uuid not be used directly by external functions as it may not reflect the current state of the loading bar/hashmap
+    pub loading_bar_uuid: Uuid,
+    pub message: String,
+    pub total: f64,
+    pub current: f64,
+    #[serde(skip)]
+    pub last_sent: f64,
+    pub bar_type: LoadingBarType,
+    #[cfg(feature = "cli")]
+    #[serde(skip)]
+    pub cli_progress_bar: indicatif::ProgressBar,
+}
+
+#[derive(Serialize, Debug, Clone)]
+pub struct LoadingBarId(Uuid);
+
+// When Loading bar id is dropped, we should remove it from the hashmap
+impl Drop for LoadingBarId {
+    fn drop(&mut self) {
+        let loader_uuid = self.0;
+        tokio::spawn(async move {
+            if let Ok(event_state) = EventState::get() {
+                #[cfg(any(feature = "tauri", feature = "cli"))]
+                if let Some((_, bar)) =
+                    event_state.loading_bars.remove(&loader_uuid)
+                {
+                    #[cfg(feature = "tauri")]
+                    {
+                        let loader_uuid = bar.loading_bar_uuid;
+                        let event = bar.bar_type.clone();
+                        let fraction = bar.current / bar.total;
+
+                        let _ = event_state.app.emit(
+                            "loading",
+                            LoadingPayload {
+                                fraction: None,
+                                message: "Completed".to_string(),
+                                event,
+                                loader_uuid,
+                            },
+                        );
+                        tracing::trace!(
+                            "Exited at {fraction} for loading bar: {:?}",
+                            loader_uuid
+                        );
+                    }
+
+                    // Emit event to indicatif progress bar arc
+                    #[cfg(feature = "cli")]
+                    {
+                        let cli_progress_bar = bar.cli_progress_bar;
+                        cli_progress_bar.finish();
+                    }
+                }
+
+                #[cfg(not(any(feature = "tauri", feature = "cli")))]
+                event_state.loading_bars.remove(&loader_uuid);
+            }
+        });
+    }
+}
+
+#[derive(Serialize, Deserialize, Clone, Debug, Hash, PartialEq, Eq)]
+#[serde(tag = "type")]
+#[serde(rename_all = "snake_case")]
+pub enum LoadingBarType {
+    LegacyDataMigration,
+    DirectoryMove {
+        old: PathBuf,
+        new: PathBuf,
+    },
+    JavaDownload {
+        version: u32,
+    },
+    PackFileDownload {
+        instance_id: String,
+        pack_name: String,
+        icon: Option<String>,
+        pack_version: String,
+    },
+    PackDownload {
+        instance_id: String,
+        pack_name: String,
+        icon: Option<PathBuf>,
+        pack_id: Option<String>,
+        pack_version: Option<String>,
+    },
+    MinecraftDownload {
+        instance_id: String,
+        instance_name: String,
+    },
+    InstanceUpdate {
+        instance_id: String,
+        instance_name: String,
+    },
+    ZipExtract {
+        instance_id: String,
+        instance_name: String,
+    },
+    ConfigChange {
+        new_path: PathBuf,
+    },
+    CopyInstance {
+        import_location: PathBuf,
+        instance_name: String,
+    },
+    LauncherUpdate {
+        version: String,
+        current_version: String,
+    },
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+pub struct LoadingPayload {
+    pub event: LoadingBarType,
+    pub loader_uuid: Uuid,
+    pub fraction: Option<f64>, // by convention, if optional, it means the loading is done
+    pub message: String,
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+pub struct WarningPayload {
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub kind: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub instance_id: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub instance_name: Option<String>,
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+pub struct JavaDiscoveryPayload {
+    pub count: usize,
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+#[serde(rename_all = "camelCase")]
+pub struct JavaDownloadConfirmationPayload {
+    pub request_id: Uuid,
+    pub version: u32,
+}
+
+#[derive(Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct InstanceBulkUpdateProgressPayload {
+    pub instance_id: String,
+    pub stage: InstanceBulkUpdateProgressStage,
+    pub current: usize,
+    pub total: usize,
+}
+
+#[derive(Serialize, Clone)]
+#[serde(rename_all = "snake_case")]
+pub enum InstanceBulkUpdateProgressStage {
+    ResolvingVersions,
+    Downloading,
+    Finishing,
+}
+
+#[derive(Serialize, Deserialize, Clone)]
+#[serde(tag = "event")]
+pub enum CommandPayload {
+    InstallMod {
+        id: String,
+    },
+    InstallVersion {
+        id: String,
+    },
+    InstallModpack {
+        id: String,
+    },
+    InstallServer {
+        id: String,
+    },
+    LaunchInstance {
+        id: String,
+        server: Option<String>,
+        singleplayer_world: Option<String>,
+    },
+    RunMRPack {
+        // run or install .mrpack
+        path: PathBuf,
+    },
+    OpenSeedMap {
+        // URL query string describing the shared seed-map state
+        query: String,
+    },
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+pub struct ProcessPayload {
+    pub instance_id: String,
+    pub uuid: Uuid,
+    pub pid: u32,
+    pub maximize_window: bool,
+    pub event: ProcessPayloadType,
+    pub message: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub crashed: Option<bool>,
+}
+
+#[derive(Serialize, Clone, Debug)]
+#[serde(rename_all = "snake_case")]
+pub enum ProcessPayloadType {
+    Launched,
+    Finished,
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+pub struct ServerPayload {
+    #[serde(rename = "serverId")]
+    pub server_id: String,
+    #[serde(flatten)]
+    pub event: ServerPayloadType,
+}
+
+/// Classifies why a server process exited on its own, derived from the tail
+/// of its console output so the UI can react (e.g. offer the EULA dialog)
+/// instead of just reporting a dead process.
+#[derive(Serialize, Clone, Debug, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum ExitReason {
+    Eula,
+}
+
+#[derive(Serialize, Clone, Debug)]
+#[serde(tag = "event", rename_all = "snake_case")]
+pub enum ServerPayloadType {
+    Log {
+        line: String,
+    },
+    ConsoleOutput {
+        data: String,
+    },
+    DownloadProgress {
+        downloaded: u64,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        total: Option<u64>,
+    },
+    Started,
+    Stopped {
+        crashed: bool,
+        #[serde(skip_serializing_if = "Option::is_none")]
+        reason: Option<ExitReason>,
+    },
+    #[allow(dead_code)]
+    EulaRequired {
+        server_id: String,
+        eula_text: String,
+    },
+}
+
+#[derive(Serialize, Clone)]
+#[cfg(feature = "tauri")]
+pub struct InstancePayload {
+    pub instance_id: String,
+    #[serde(flatten)]
+    pub event: InstancePayloadType,
+}
+
+#[derive(Serialize, Clone)]
+#[serde(tag = "event", rename_all = "snake_case")]
+pub enum InstancePayloadType {
+    Created,
+    Synced,
+    ContentChanged {
+        revision: u64,
+    },
+    ServersUpdated,
+    WorldUpdated {
+        world: String,
+    },
+    ServerJoined {
+        host: String,
+        port: u16,
+        timestamp: DateTime<Utc>,
+    },
+    Edited,
+    ContentInstallFinished {
+        project_ids: Vec<String>,
+        #[serde(default)]
+        dependency_project_ids: Vec<String>,
+    },
+    ContentInstallFailed {
+        project_ids: Vec<String>,
+        message: String,
+    },
+    Removed,
+}
+
+#[derive(Serialize, Clone)]
+#[serde(rename_all = "snake_case")]
+#[serde(tag = "event")]
+pub enum FriendPayload {
+    FriendRequest { from: UserId },
+    UserOffline { id: UserId },
+    StatusUpdate { user_status: UserStatus },
+    StatusSync,
+}
+
+#[cfg(feature = "tauri")]
+pub use self::log_types::*;
+
+#[cfg(feature = "tauri")]
+mod log_types {
+    use crate::state::Log4jEvent;
+    use serde::Serialize;
+
+    #[derive(Serialize, Clone)]
+    #[serde(tag = "type", rename_all = "snake_case")]
+    pub enum LogEvent {
+        Log4j(Log4jEvent),
+        Legacy { message: String },
+    }
+
+    #[derive(Serialize, Clone)]
+    pub struct LogPayload {
+        pub instance_id: String,
+        #[serde(flatten)]
+        pub event: LogEvent,
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum EventError {
+    #[error("Event state was not properly initialized")]
+    NotInitialized,
+
+    #[error("Non-existent loading bar of key: {0}")]
+    NoLoadingBar(Uuid),
+
+    #[cfg(feature = "tauri")]
+    #[error("Tauri error: {0}")]
+    TauriError(#[from] tauri::Error),
+}