fix: 修复未登录皮肤站时启动卡住且不再弹玩家选择

未登录皮肤站时启动游戏会弹窗要求选择/登录玩家。若点击“登录皮肤站”
跳转后不登录直接返回，再次启动不会重新弹窗，而是卡在“正在启动”。

原因：InstancePlayerModal 的 signInSkinSite 跳转登录时只隐藏弹窗，
没有 settle 玩家选择的 Promise，因此 prepareInstancePlayer 在
preparing 表中留下的任务永不结束。再次启动时复用了这个悬空任务，
既不再弹窗也无法继续启动。

修复：
- instance-player 新增哨兵错误 PlayerSelectionNavigatedAwayError。
- signInSkinSite 跳转登录前以该错误 reject 当前选择，使
  prepareInstancePlayer 的任务正常结束、清理 in-flight 记录，下次
  启动会重新弹出玩家选择。
- App.vue 的启动错误处理识别该哨兵：跳转登录是用户主动操作而非启动
  失败，静默中止启动，不弹错误提示。

apps/app-frontend/src/App.vue

@@ -113,6 +113,7 @@ import {
 } from '@/helpers/events.js'
 import { install_create_modpack_instance, install_get_modpack_preview } from '@/helpers/install'
 import { type DirectLinkSyncReport, get as getInstance, run } from '@/helpers/instance'
+import { PlayerSelectionNavigatedAwayError } from '@/helpers/instance-player'
 import { reconcileMojangAuthSourceAtStartup } from '@/helpers/mojang-auth'
 import { cancelLogin, get as getCreds, login, logout } from '@/helpers/mr_auth.ts'
 import { mergeUrlQuery, parseModrinthLink } from '@/helpers/project-links.ts'
@@ -1757,6 +1758,10 @@ async function handleCommand(e) {
 	} else if (e.event === 'LaunchInstance') {
 		const instance = await getInstance(e.id).catch(() => null)
 		const handleLaunchCommandError = async (launchError) => {
+			// Navigating to the skin-site login to pick a player is a deliberate
+			// user action, not a launch failure: stay silent and let the user
+			// re-trigger the launch after signing in.
+			if (launchError instanceof PlayerSelectionNavigatedAwayError) return
 			const handled =
 				(await minecraftCrashModal.value?.handleLaunchError(launchError, {
 					instance_id: e.id,

apps/app-frontend/src/components/instance/InstancePlayerModal.vue

@@ -14,6 +14,7 @@ import {
 import { users } from '@/helpers/auth'
 import { getInstanceMode } from '@/helpers/hosted-packs'
 import {
+	PlayerSelectionNavigatedAwayError,
 	registerInstancePlayerPicker,
 	saveInstancePlayer,
 	waitForSkinSiteSession,
@@ -127,6 +128,14 @@ async function select(player: PlayerChoice) {
 function signInSkinSite() {
 	awaitingSkinLogin.value = true
 	hideForLogin = true
+	active.value = false
+	generation++
+	// Settle the pending selection so `prepareInstancePlayer` releases its
+	// in-flight entry; otherwise a later launch would await this forever and
+	// never re-prompt. The caller treats this sentinel as a silent abort.
+	rejectSelection?.(new PlayerSelectionNavigatedAwayError())
+	resolveSelection = undefined
+	rejectSelection = undefined
 	openSkinSiteLogin()
 	modal.value?.hide()
 	void router.push('/starlight-skin')

apps/app-frontend/src/components/ui/AccountsCard.vue

@@ -291,6 +291,7 @@ import {
 	users,
 } from '@/helpers/auth'
 import { process_listener } from '@/helpers/events'
+import { registerSkinSitePlayers } from '@/helpers/instance-player'
 import { getPlayerHeadUrl } from '@/helpers/rendering/batch-skin-renderer.ts'
 import type { Skin } from '@/helpers/skins'
 import { get_available_skins } from '@/helpers/skins'
@@ -630,11 +631,22 @@ async function setAccount(account: MinecraftCredential) {
 }
 
 watch(
-	[skinSitePlayers, defaultUser],
-	([availablePlayers, selectedLocalUser]) => {
+	[skinSitePlayers, defaultUser, skinSiteUser],
+	([availablePlayers, selectedLocalUser, siteUser]) => {
 		if (!selectedLocalUser && !selectedSkinSitePlayerId.value && availablePlayers.length > 0) {
 			selectSkinSitePlayer(availablePlayers[0].uuid)
 		}
+		// Register skin-site players as launcher accounts as soon as they are
+		// available, so the account picker shows them without requiring a first
+		// launch. `registerSkinSitePlayers` is idempotent and best-effort.
+		if (siteUser?.uuid && availablePlayers.length > 0) {
+			const pendingIds = availablePlayers.map((player) => player.uuid)
+			void registerSkinSitePlayers(pendingIds, siteUser.uuid)
+				.then(() => refreshValues())
+				.catch((error) => {
+					console.warn('Failed to register skin site players:', error)
+				})
+		}
 	},
 	{ immediate: true },
 )

apps/app-frontend/src/helpers/instance-player.ts

@@ -17,6 +17,18 @@ export type InstancePlayer = {
 	skin_site_user?: string | null
 }
 export type PlayerChoice = InstancePlayer & { head?: string }
+
+/**
+ * Thrown when the player picker is dismissed because the user navigated to the
+ * skin-site login page. Callers should treat this as a silent launch abort
+ * (the user will pick a player next time), not as a real failure.
+ */
+export class PlayerSelectionNavigatedAwayError extends Error {
+	constructor() {
+		super('已跳转至皮肤站登录，请登录后重新启动。')
+		this.name = 'PlayerSelectionNavigatedAwayError'
+	}
+}
 type Picker = (instanceId: string, locked: InstancePlayer | null) => Promise<InstancePlayer>
 let picker: Picker | undefined
 const preparing = new Map<string, Promise<void>>()
@@ -56,6 +68,52 @@ export async function authenticateInstancePlayer(player: InstancePlayer) {
 	}
 }
 
+/**
+ * Registers every skin-site player as a launcher account so they show up in the
+ * account picker immediately after signing in to the skin site, instead of only
+ * after a first launch. Idempotent: players that already exist in the account
+ * list (matched by profile UUID) are skipped, and already-signed-in players are
+ * not re-requested. Best-effort: a single player failing does not abort the rest.
+ */
+export async function registerSkinSitePlayers(
+	playerIds: string[],
+	userUuid: string,
+): Promise<void> {
+	if (playerIds.length === 0) return
+	if (skinSiteStatus.value !== 'signed-in' || skinSiteUser.value?.uuid !== userUuid) return
+
+	let known = new Set<string>()
+	try {
+		const existing = await users()
+		known = new Set(
+			(existing as Array<{ profile?: { id?: string } }>)
+				.map((account) => account?.profile?.id)
+				.filter((id): id is string => typeof id === 'string'),
+		)
+	} catch {
+		// If the account list cannot be read, still attempt to register; the
+		// backend upsert is idempotent.
+	}
+
+	for (const playerId of playerIds) {
+		if (known.has(playerId)) continue
+		if (skinSiteStatus.value !== 'signed-in' || skinSiteUser.value?.uuid !== userUuid) return
+		try {
+			// Request a fresh download token per player: the skin site login
+			// endpoint may bind a token to a single player id.
+			const token = await requestSkinSiteDownloadToken()
+			await invoke('plugin:auth|login_skin_site_player', {
+				token,
+				playerId,
+				userId: userUuid,
+			})
+			known.add(playerId)
+		} catch (error) {
+			console.warn(`Failed to register skin site player ${playerId}:`, error)
+		}
+	}
+}
+
 export async function saveInstancePlayer(instanceId: string, player: InstancePlayer) {
 	await authenticateInstancePlayer(player)
 	await invoke('plugin:auth|set_instance_player', { instanceId, player })

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

@@ -436,16 +436,23 @@ pub async fn create(
     // e.g. `<root>/<pack name>`. Avoid a `versions/<name>` layout: that shape
     // is reserved for externally linked launcher instances and would make the
     // launcher expect a Minecraft version JSON beside the pack.
-    let game_dir_override = game_dir_root
+    let game_dir_override = match game_dir_root
         .as_deref()
         .map(str::trim)
         .filter(|root| !root.is_empty())
-        .map(|root| {
-            Path::new(root)
-                .join(&publication.manifest.name)
-                .to_string_lossy()
-                .into_owned()
-        });
+    {
+        Some(root) => {
+            // The pack's game files live in their own folder under the chosen
+            // root, e.g. `<root>/<pack name>`. If that folder already exists
+            // (a previous install of the same pack, or a name clash), pick a
+            // suffixed sibling instead of sharing the folder with another
+            // instance.
+            let base = Path::new(root).join(&publication.manifest.name);
+            let resolved = unique_game_dir(&base);
+            Some(resolved.to_string_lossy().into_owned())
+        }
+        None => None,
+    };
     let instance = crate::state::create_instance(
         crate::state::CreateInstance {
             name: publication.manifest.name.clone(),
@@ -480,6 +487,29 @@ pub async fn create(
     Ok(instance.id)
 }
 
+/// Returns `base` when its directory does not exist yet; otherwise returns the
+/// first `base (n)` (n = 1, 2, …) whose directory is still free. Mirrors the
+/// instance-folder de-duplication in `create_instance::resolve_instance_path`,
+/// so re-installing the same hosted pack no longer makes two instances share a
+/// single game folder.
+fn unique_game_dir(base: &Path) -> PathBuf {
+    if !base.exists() {
+        return base.to_path_buf();
+    }
+    let parent = base.parent().unwrap_or_else(|| Path::new(""));
+    let name = base
+        .file_name()
+        .map(|n| n.to_string_lossy().into_owned())
+        .unwrap_or_else(|| "instance".to_string());
+    let mut which = 1u32;
+    loop {
+        let candidate = parent.join(format!("{name} ({which})"));
+        if !candidate.exists() {
+            return candidate;
+        }
+        which += 1;
+    }
+}
 pub async fn binding(instance_id: &str) -> crate::Result<Option<Binding>> {
     read_json(&crate::instance::get_full_path(instance_id).await?, BINDING)
         .await

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

@@ -266,7 +266,9 @@ async fn import_atlauncher_unmanaged(
     let state = State::get().await?;
     finish_import(
         instance_id,
-        minecraft_folder,
+        Some(minecraft_folder),
+        None,
+        false,
         &state.io_semaphore,
         reporter,
         details,

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

@@ -170,7 +170,9 @@ pub(crate) async fn import_axolotl(
 
     finish_import(
         instance_id,
-        source_path,
+        Some(source_path),
+        None,
+        false,
         &state.io_semaphore,
         reporter,
         details,

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

@@ -221,7 +221,9 @@ pub async fn import_curseforge(
     let state = State::get().await?;
     finish_import(
         instance_id,
-        curseforge_instance_folder,
+        Some(curseforge_instance_folder),
+        None,
+        false,
         &state.io_semaphore,
         reporter,
         details,

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

@@ -118,7 +118,9 @@ pub async fn import_gdlauncher(
     let state = State::get().await?;
     finish_import(
         instance_id,
-        gdlauncher_instance_folder,
+        Some(gdlauncher_instance_folder),
+        None,
+        false,
         &state.io_semaphore,
         reporter,
         details,

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

@@ -3,7 +3,7 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use super::{ImportOverrides, instance_json};
+use super::{ImportOverrides, instance_json, resolve_import_game_root};
 use crate::{
     State,
     install::{InstallPhaseDetails, InstallProgressReporter},
@@ -29,29 +29,129 @@ pub async fn import_generic(
     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
+    // Resolve the source layout. Three inputs describe the same import from
+    // different angles and must be reconciled consistently:
+    //
+    // - `instance_folder`: the game root chosen by the caller (normally the
+    //   `.minecraft` root for a PCL/HMCL install, or the folder itself).
+    // - `instance_path`: when present, the specific `versions/<name>` folder
+    //   the user selected. A `.minecraft` root can hold many versions; only
+    //   this one belongs to the instance being imported.
+    // - `overrides.game_dir_override`: the user's explicit version-isolation
+    //   choice.
+    //
+    // The old behaviour copied/symlinked the whole `.minecraft` root and let
+    // the version folder dangle, which produced vanilla-only copies (mods
+    // stayed in versions/<name>) and cloned every sibling version too.
+    let layout = resolve_import_layout(
+        &instance_folder,
+        instance_path.as_deref(),
+        overrides.game_dir_override.as_deref(),
+    );
+
+    let info = detect_instance_info(&layout.json_source, overrides).await?;
+    register_instance(instance_id, &layout.name, &info).await?;
+    copy_instance_files(instance_id, &layout, reporter, details, symlink)
+        .await
+}
+
+/// The resolved source layout for a generic import.
+///
+/// `content_source` holds the shared game content (mods/saves/config) that
+/// belongs to the instance; `version_dir` is the selected `versions/<name>`
+/// folder. Both are merged into the instance directory by the copy/symlink
+/// stage, so a version-isolated import keeps the root-level mods it used to
+/// leave behind.
+struct ImportLayout {
+    /// Display name for the instance (the version folder name when isolated,
+    /// otherwise the game root folder name).
+    name: String,
+    /// Directory the version JSON is detected from.
+    json_source: PathBuf,
+    /// Directory whose game content (mods/saves/config) belongs to the
+    /// instance. For a shared root this is the root itself; for the "move the
+    /// root content into versions/<name>" isolation strategy this is still the
+    /// root, but its content is copied *into* the instance (which then becomes
+    /// the game dir).
+    content_source: Option<PathBuf>,
+    /// Selected `versions/<name>` folder, when the source is a shared root.
+    version_dir: Option<PathBuf>,
+    /// Whether the instance uses version isolation.
+    isolated: bool,
+}
+
+/// Reconciles the three import inputs into one layout.
+///
+/// Rules:
+/// - When `instance_path` is given it is the authoritative version folder; the
+///   instance is version-isolated unless the user explicitly asked to share.
+/// - When the user asked to share, the `.minecraft` root is the game dir.
+/// - Without a selected version folder, fall back to the old auto-detection so
+///   direct folder imports keep working.
+fn resolve_import_layout(
+    instance_folder: &Path,
+    selected_version: Option<&Path>,
+    game_dir_override: Option<&str>,
+) -> ImportLayout {
+    let root_name = instance_folder
+        .file_name()
+        .map(|n| n.to_string_lossy().to_string())
+        .unwrap_or_else(|| "imported".to_string());
+
+    // Explicit "version shared" choice: copy the whole `.minecraft` root.
+    let shared_forced = game_dir_override
+        .map(|dir| {
+            let normalized = dir.trim_end_matches(['/', '\\']);
+            normalized.eq_ignore_ascii_case(
+                instance_folder
+                    .to_string_lossy()
+                    .trim_end_matches(['/', '\\']),
+            )
+        })
+        .unwrap_or(false);
+
+    if let Some(version_dir) = selected_version {
+        let version_name = version_dir
             .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)
-    };
+            .unwrap_or_else(|| root_name.clone());
 
-    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
+        if shared_forced {
+            // User explicitly chose to share the `.minecraft` root even though
+            // a version folder was selected.
+            return ImportLayout {
+                name: root_name,
+                json_source: version_dir.to_path_buf(),
+                content_source: Some(instance_folder.to_path_buf()),
+                version_dir: Some(version_dir.to_path_buf()),
+                isolated: false,
+            };
+        }
+
+        // Version-isolated strategy (甲): the instance becomes the game dir.
+        // The version files (`versions/<name>`) and the shared root content
+        // (mods/saves/config) are both merged into the instance, so mods that
+        // live at the `.minecraft` root survive the import instead of being
+        // left behind.
+        return ImportLayout {
+            name: version_name,
+            json_source: version_dir.to_path_buf(),
+            content_source: Some(instance_folder.to_path_buf()),
+            version_dir: Some(version_dir.to_path_buf()),
+            isolated: true,
+        };
+    }
+
+    // No explicit version folder: fall back to auto-detection.
+    let (name, dotminecraft) = resolve_dotminecraft(instance_folder);
+    let game_root = resolve_import_game_root(&dotminecraft);
+    ImportLayout {
+        name,
+        json_source: dotminecraft.clone(),
+        content_source: Some(game_root.clone()),
+        version_dir: None,
+        isolated: game_root != dotminecraft,
+    }
 }
 
 /// Stage 1 — resolve the name and the `.minecraft` directory of an imported
@@ -325,21 +425,30 @@ async fn resolve_loader_version(
 }
 
 /// Stage 4 — copy (or symlink) the source files into the instance profile.
+///
+/// Uses the reconciled [`ImportLayout`]: the shared content root (mods/saves/
+/// config) and the selected `versions/<name>` folder are both merged into the
+/// instance directory, so a version-isolated import keeps root-level content.
 async fn copy_instance_files(
     instance_id: &str,
-    dotminecraft: &Path,
+    layout: &ImportLayout,
     reporter: InstallProgressReporter,
     details: InstallPhaseDetails,
     symlink: bool,
 ) -> crate::Result<()> {
     let state = State::get().await?;
     tracing::debug!(
-        "import_generic: finishing import for instance_id={}",
-        instance_id
+        "import_generic: finishing import for instance_id={} content_source={:?} version_dir={:?} isolated={}",
+        instance_id,
+        layout.content_source,
+        layout.version_dir,
+        layout.isolated
     );
     finish_import(
         instance_id,
-        dotminecraft.to_path_buf(),
+        layout.content_source.clone(),
+        layout.version_dir.clone(),
+        layout.isolated,
         &state.io_semaphore,
         reporter,
         details,
@@ -399,6 +508,7 @@ mod tests {
             game_version: Some("1.20.1".to_string()),
             loader: Some(ModLoader::Fabric),
             loader_version: Some("0.15.11".to_string()),
+            ..Default::default()
         };
 
         let info = detect_instance_info(directory.path(), &overrides)
@@ -418,6 +528,7 @@ mod tests {
                 game_version: Some("1.20.1".to_string()),
                 loader: Some(ModLoader::Fabric),
                 loader_version: Some(loader_version.to_string()),
+                ..Default::default()
             };
 
             let info = detect_instance_info(directory.path(), &overrides)

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

@@ -196,7 +196,8 @@ pub(crate) fn normalize_imported_loader_version(
     game_version: &str,
     detected_version: &str,
 ) -> String {
-    let detected_version = detected_version.trim();
+    let detected_version = sanitize_loader_version(detected_version);
+    let detected_version = detected_version.as_str();
     let without_family = match loader {
         "fabric" | "legacy_fabric" => detected_version
             .strip_prefix("fabric-loader-")
@@ -212,7 +213,7 @@ pub(crate) fn normalize_imported_loader_version(
     }
     .unwrap_or(detected_version);
 
-    match loader {
+    let normalized = match loader {
         "fabric" | "legacy_fabric" | "quilt" => without_family
             .strip_suffix(&format!("-{game_version}"))
             .unwrap_or(without_family)
@@ -232,7 +233,8 @@ pub(crate) fn normalize_imported_loader_version(
                 .to_string()
         }
         _ => without_family.to_string(),
-    }
+    };
+    sanitize_loader_version(&normalized)
 }
 
 fn extract_version(
@@ -575,6 +577,11 @@ fn detect_adjuncts(
 
 /// Extracts the loader version string from JSON content by finding a needle
 /// and reading until a terminator character.
+///
+/// The terminator set includes `:` `]` `[` and whitespace because non-standard
+/// launcher JSONs (notably PCL) may embed the loader coordinate in a composite
+/// string such as `net.neoforged:neoforge:21.1.250:client]`, where the real
+/// version ends at the first extra `:` rather than at the closing quote.
 fn try_extract_version_from_needle(
     content: &str,
     needle: &str,
@@ -582,17 +589,32 @@ fn try_extract_version_from_needle(
 ) -> Option<String> {
     let pos = content.find(needle)?;
     let after = &content[pos + needle.len()..];
-    let end = after.find(&['"', ',', '\n', '}'] as &[char])?;
+    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())
+        Some(sanitize_loader_version(&ver[pos + 1..]))
     } else {
-        Some(ver.to_string())
+        Some(sanitize_loader_version(ver))
     }
 }
 
+/// Trims junk that non-standard launcher JSONs append to a loader coordinate
+/// (e.g. `21.1.250:client]`, `44.0.3 ` or `0.15.11\n`). Keeps only the leading
+/// version token so the metadata resolver receives a clean id.
+fn sanitize_loader_version(raw: &str) -> String {
+    let trimmed = raw.trim();
+    // Cut at the first character that cannot appear in a loader version id.
+    let end = trimmed
+        .find(|ch: char| {
+            !(ch.is_ascii_alphanumeric() || ch == '.' || ch == '-' || ch == '_' || ch == '+')
+        })
+        .unwrap_or(trimmed.len());
+    trimmed[..end].trim().to_string()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -837,4 +859,35 @@ mod tests {
         assert_eq!(info.loader.as_deref(), Some("fabric"));
         assert_eq!(info.loader_version.as_deref(), Some("0.15.11"));
     }
+
+    #[test]
+    fn sanitizes_loader_version_with_launcher_suffix() {
+        // PCL and other launchers may embed composite coordinates such as
+        // `net.neoforged:neoforge:21.1.250:client]`; the extracted version must
+        // stop at the first extra `:` instead of swallowing `:client]`.
+        assert_eq!(sanitize_loader_version("21.1.250:client]"), "21.1.250");
+        assert_eq!(sanitize_loader_version("44.0.3 "), "44.0.3");
+        assert_eq!(sanitize_loader_version("0.15.11\n"), "0.15.11");
+        assert_eq!(sanitize_loader_version("1.21.1-52.0.0"), "1.21.1-52.0.0");
+        assert_eq!(
+            sanitize_loader_version("1.7.10-10.13.4.1614-1.7.10"),
+            "1.7.10-10.13.4.1614-1.7.10"
+        );
+    }
+
+    #[test]
+    fn detect_loader_version_stops_at_extra_colon() {
+        assert_loader(
+            r#"{
+                "id": "1.21.1-neoforge-21.1.250",
+                "libraries": [
+                    {
+                        "name": "net.neoforged:neoforge:21.1.250:client]"
+                    }
+                ]
+            }"#,
+            "neoforge",
+            Some("21.1.250"),
+        );
+    }
 }

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

@@ -303,7 +303,9 @@ async fn import_mmc_unmanaged(
     let state = State::get().await?;
     finish_import(
         instance_id,
-        minecraft_folder,
+        Some(minecraft_folder),
+        None,
+        false,
         &state.io_semaphore,
         reporter,
         details,

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

@@ -661,6 +661,10 @@ pub(crate) struct ImportOverrides {
     pub game_version: Option<String>,
     pub loader: Option<ModLoader>,
     pub loader_version: Option<String>,
+    /// The user's explicit game directory (version isolation choice). When set,
+    /// it is the absolute path the instance should use as its working
+    /// directory; when `None`, the layout is auto-detected.
+    pub game_dir_override: Option<String>,
 }
 
 pub(crate) async fn import_instance_with_reporter(
@@ -1045,7 +1049,9 @@ pub async fn recache_icon(
 
 pub(crate) async fn copy_dotminecraft_with_reporter(
     instance_id: &str,
-    dotminecraft: PathBuf,
+    content_source: Option<PathBuf>,
+    version_dir: Option<PathBuf>,
+    isolated: bool,
     io_semaphore: &IoSemaphore,
     reporter: InstallProgressReporter,
     details: InstallPhaseDetails,
@@ -1053,7 +1059,36 @@ pub(crate) async fn copy_dotminecraft_with_reporter(
     let instance_path =
         crate::api::instance::get_full_path(instance_id).await?;
 
-    let files = collect_dotminecraft_files(&dotminecraft).await?;
+    let mut files: Vec<(PathBuf, PathBuf)> = Vec::new();
+
+    if let Some(content_root) = &content_source {
+        // Copy the shared content (mods/saves/config/…). When a specific
+        // version folder is in play, every sibling under `versions/` belongs to
+        // a different instance and must not be cloned here.
+        //
+        // - shared import: keep the selected version, drop the rest;
+        // - isolated import (甲): drop the whole `versions/` tree here — the
+        //   selected version is copied separately below and merged into the
+        //   instance root.
+        let keep_version = if isolated {
+            None
+        } else {
+            version_dir.as_deref()
+        };
+        let mut content_files =
+            collect_dotminecraft_files(content_root, keep_version, isolated)
+                .await?;
+        files.append(&mut content_files);
+    }
+
+    if isolated && let Some(version) = &version_dir {
+        // Merge the selected version files (`<name>.json`, `<name>.jar`, and any
+        // nested `mods/`, `config/`, … that live inside the version folder)
+        // directly into the instance root so the instance directory becomes a
+        // self-contained game dir.
+        let mut version_files = collect_version_files(version).await?;
+        files.append(&mut version_files);
+    }
 
     let total = files.len() as u64;
     if total == 0 {
@@ -1085,6 +1120,8 @@ pub(crate) async fn copy_dotminecraft_with_reporter(
 /// at the source root (`<dirname>.json` and `<dirname>.jar`).
 async fn collect_dotminecraft_files(
     dotminecraft: &Path,
+    keep_version: Option<&Path>,
+    isolated: bool,
 ) -> crate::Result<Vec<(PathBuf, PathBuf)>> {
     // Collect all files recursively
     let files = get_all_subfiles(dotminecraft, false).await?;
@@ -1098,6 +1135,14 @@ async fn collect_dotminecraft_files(
     let skip_json = format!("{dirname}.json");
     let skip_jar = format!("{dirname}.jar");
 
+    // When a specific version folder is requested from a shared `.minecraft`
+    // root, every other entry under `versions/` belongs to a different
+    // instance. Resolve the relative keep-path once so the loop can compare
+    // cheaply (e.g. `versions/1.21.1-NeoForge_21.1.250`).
+    let keep_relative = keep_version
+        .and_then(|version| version.strip_prefix(dotminecraft).ok())
+        .map(|rel| rel.to_path_buf());
+
     let mut collected = Vec::new();
     for abs_path in files {
         let metadata = tokio::fs::symlink_metadata(&abs_path)
@@ -1117,6 +1162,23 @@ async fn collect_dotminecraft_files(
         else {
             continue;
         };
+
+        // In the isolated strategy the whole `versions/` tree is handled
+        // separately (only the selected version is copied, and it is merged
+        // into the instance root), so skip it entirely here to avoid cloning
+        // sibling versions.
+        if isolated {
+            if rel.components().next().map(|c| c.as_os_str())
+                == Some("versions".as_ref())
+            {
+                continue;
+            }
+        } else if let Some(keep) = &keep_relative
+            && is_other_version_entry(&rel, keep)
+        {
+            continue;
+        }
+
         if rel
             .parent()
             .is_some_and(|path| !path.as_os_str().is_empty())
@@ -1132,6 +1194,70 @@ async fn collect_dotminecraft_files(
     Ok(collected)
 }
 
+/// Collects every file inside a selected `versions/<name>` folder, mapping each
+/// path relative to that folder so the contents merge directly into the
+/// instance root (the instance becomes a self-contained, version-isolated game
+/// dir).
+async fn collect_version_files(
+    version_dir: &Path,
+) -> crate::Result<Vec<(PathBuf, PathBuf)>> {
+    let files = get_all_subfiles(version_dir, false).await?;
+    let mut collected = Vec::new();
+    for abs_path in files {
+        let metadata = tokio::fs::symlink_metadata(&abs_path)
+            .await
+            .map_err(|error| IOError::with_path(error, &abs_path))?;
+        if crate::util::io::is_symlink_or_reparse(&metadata) {
+            tracing::warn!(
+                path = %abs_path.display(),
+                "Skipping nested symlink or reparse point while copying a version folder"
+            );
+            continue;
+        }
+        if let Ok(rel) = abs_path.strip_prefix(version_dir) {
+            collected.push((abs_path, rel.to_path_buf()));
+        }
+    }
+    Ok(collected)
+}
+
+/// True if `rel` lives under `versions/` but does not belong to the selected
+/// version folder `keep` (which is itself relative to the `.minecraft` root,
+/// e.g. `versions/1.21.1-NeoForge_21.1.250`).
+///
+/// `rel` may be the version directory itself, a file directly inside it, or a
+/// path nested deeper. Anything sharing the first two path components with
+/// `keep` is kept; every other `versions/<other>` entry is excluded.
+fn is_other_version_entry(rel: &Path, keep: &Path) -> bool {
+    let mut rel_components = rel.components();
+    let mut keep_components = keep.components();
+
+    // Both must start with the literal `versions` component.
+    if rel_components.next().map(|c| c.as_os_str()) != Some("versions".as_ref()) {
+        return false;
+    }
+    if keep_components.next().map(|c| c.as_os_str()) != Some("versions".as_ref()) {
+        return false;
+    }
+
+    let rel_version = rel_components.next().map(|c| c.as_os_str());
+    let keep_version = keep_components.next().map(|c| c.as_os_str());
+
+    // `rel` is always a *file* path relative to the `.minecraft` root. A file
+    // that sits directly under `versions/` (e.g. `versions/version_manifest.json`)
+    // has exactly two components and is shared metadata, not a version folder:
+    // leave it alone. Only when there is at least a third component
+    // (`versions/<name>/<file>`) can the second component be treated as a
+    // version directory name.
+    let rel_is_inside_version_dir = rel_components.next().is_some();
+
+    match (rel_version, keep_version) {
+        (Some(rel_v), Some(keep_v)) if rel_is_inside_version_dir => rel_v != keep_v,
+        // A file directly under `versions/`, shared metadata: keep it.
+        _ => false,
+    }
+}
+
 /// Copies the collected files into the instance profile concurrently, bounded
 /// by the I/O semaphore, reporting progress after every completed file.
 async fn copy_files_with_progress(
@@ -1225,7 +1351,7 @@ async fn copy_files_with_progress(
 /// back to the source folder itself: the game creates the content folders
 /// there on first run, and for imports the user's explicit game-dir choice
 /// (or no override, i.e. the managed symlink) decides the rest.
-fn resolve_import_game_root(source: &Path) -> PathBuf {
+pub(crate) fn resolve_import_game_root(source: &Path) -> PathBuf {
     // The source is itself the game root: either a whole Minecraft folder that
     // carries a game body, or any folder that already holds game content
     // (a version-isolated `versions/<name>` with mods/saves/config inside).
@@ -1300,19 +1426,27 @@ fn dir_has_game_content(root: &Path) -> bool {
 
 pub(crate) async fn finish_import(
     instance_id: &str,
-    dotminecraft: PathBuf,
+    content_source: Option<PathBuf>,
+    version_dir: Option<PathBuf>,
+    isolated: bool,
     io_semaphore: &IoSemaphore,
     reporter: InstallProgressReporter,
     details: InstallPhaseDetails,
     symlink: bool,
 ) -> crate::Result<()> {
-    let local_source = LocalRuntimeSource::discover(&dotminecraft);
+    // The directory the game body / version JSON lives in, used to discover the
+    // local runtime source. Prefer the selected version folder, else the
+    // content root.
+    let primary_source = version_dir
+        .clone()
+        .or_else(|| content_source.clone())
+        .ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "Import has no content source".to_string(),
+            )
+        })?;
+    let local_source = LocalRuntimeSource::discover(&primary_source);
 
-    // Respect an explicitly chosen game-dir override (the user's isolated /
-    // not-isolated selection, already stored on the instance row at creation).
-    // Only fall back to auto-detection for symlink imports that did not carry
-    // an explicit override, so copy imports always stay built-in (no override)
-    // and the frontend's choice is never clobbered.
     let state = crate::state::State::get().await?;
     let pool = &state.pool;
     let existing_override =
@@ -1324,17 +1458,15 @@ pub(crate) async fn finish_import(
         .map(|(_, override_dir)| override_dir)
         .unwrap_or(None);
     if existing_override.is_none() && symlink {
-        // For a non-version-isolated import the game content (mods, saves, config)
-        // lives in the `.minecraft` root, not in the detected `versions/<name>`
-        // subfolder. Detect that and record the override so the instance uses the
-        // real game root directly instead of an empty version subfolder.
-        let game_root = resolve_import_game_root(&dotminecraft);
-        if game_root != dotminecraft {
+        // For a symlinked import the game dir is the referenced source root,
+        // not the empty managed instance folder. Record it so the instance
+        // launches from the real location.
+        if let Some(content_root) = &content_source {
             crate::state::edit_instance(
                 instance_id,
                 crate::state::EditInstance {
                     game_dir_override: Some(Some(
-                        game_root.to_string_lossy().to_string(),
+                        content_root.to_string_lossy().to_string(),
                     )),
                     ..Default::default()
                 },
@@ -1345,6 +1477,11 @@ pub(crate) async fn finish_import(
     }
 
     if symlink {
+        let source_root = content_source.clone().ok_or_else(|| {
+            crate::ErrorKind::InputError(
+                "Symlink import requires a content source".to_string(),
+            )
+        })?;
         let state = State::get().await?;
         let relative_path =
             instance_rows::get_instance_path_by_id(instance_id, &state.pool)
@@ -1354,7 +1491,7 @@ pub(crate) async fn finish_import(
                 })?;
         // The instance's managed folder lives at instances_dir/<path>. This is
         // where the symlink is created; it must NOT go through the game-dir
-        // override (which points at the external .minecraft root).
+        // override (which points at the external source root).
         let instance_path =
             state.directories.instances_dir().join(&relative_path);
 
@@ -1402,7 +1539,7 @@ pub(crate) async fn finish_import(
                 return Err(error.into());
             }
             if let Err(error) =
-                io::create_symlink(&dotminecraft, &instance_path).await
+                io::create_symlink(&source_root, &instance_path).await
             {
                 let _ = io::rename_or_move(&backup_path, &instance_path).await;
                 watch_instance_folder(
@@ -1423,14 +1560,14 @@ pub(crate) async fn finish_import(
             )
             .await;
         } else {
-            io::create_symlink(&dotminecraft, &instance_path).await?;
+            io::create_symlink(&source_root, &instance_path).await?;
         }
 
         crate::state::edit_instance(
             instance_id,
             crate::state::EditInstance {
                 symlink_target: Some(Some(
-                    dotminecraft.to_string_lossy().to_string(),
+                    source_root.to_string_lossy().to_string(),
                 )),
                 ..Default::default()
             },
@@ -1440,7 +1577,9 @@ pub(crate) async fn finish_import(
     } else {
         copy_dotminecraft_with_reporter(
             instance_id,
-            dotminecraft,
+            content_source,
+            version_dir,
+            isolated,
             io_semaphore,
             reporter.clone(),
             details,

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

@@ -210,7 +210,9 @@ pub async fn import_instance(
     let state = State::get().await?;
     finish_import(
         instance_id,
-        source,
+        Some(source),
+        None,
+        false,
         &state.io_semaphore,
         reporter,
         details,

packages/app-lib/src/install/runner.rs

@@ -1529,10 +1529,10 @@ async fn run_request(
             game_version,
             loader,
             loader_version,
-            game_dir_override: _,
+            game_dir_override,
         } => {
             tracing::debug!(
-                "InstallRequest::ImportInstance: launcher_type={launcher_type} base_path={} instance_folder={instance_folder} symlink={symlink}",
+                "InstallRequest::ImportInstance: launcher_type={launcher_type} base_path={} instance_folder={instance_folder} symlink={symlink} game_dir_override={game_dir_override:?}",
                 base_path.display()
             );
             let Some(instance_id) = current_instance_id(job_state) else {
@@ -1562,6 +1562,7 @@ async fn run_request(
                     game_version,
                     loader,
                     loader_version,
+                    game_dir_override,
                 },
                 // TODO(B2): apply overrides to launcher-specific importers
                 // (MultiMC/Prism/ATLauncher/GDLauncher/Curseforge/ModrinthApp);
@@ -1590,8 +1591,12 @@ async fn run_request(
             let state = State::get().await?;
             crate::api::pack::import::copy_dotminecraft_with_reporter(
                 &instance_id,
-                crate::api::instance::get_full_path(&source_instance_id)
-                    .await?,
+                Some(
+                    crate::api::instance::get_full_path(&source_instance_id)
+                        .await?,
+                ),
+                None,
+                false,
                 &state.io_semaphore,
                 InstallProgressReporter::new(job_id, job_state.clone()),
                 InstallPhaseDetails::Empty,
@@ -2526,7 +2531,9 @@ async fn copy_physical_instance_contents(
     )?;
     crate::api::pack::import::copy_dotminecraft_with_reporter(
         target_instance_id,
-        source_path,
+        Some(source_path),
+        None,
+        false,
         &state.io_semaphore,
         InstallProgressReporter::new(job_id, job_state.clone()),
         InstallPhaseDetails::Empty,

packages/app-lib/src/state/instances/commands/remove_instance.rs

@@ -32,12 +32,17 @@ pub(crate) async fn remove_instance(
         .game_dir_override
         .as_deref()
         .map(PathBuf::from)
-        .filter(|path| is_version_isolated_game_dir(path))
+        .filter(|path| {
+            // Delete the external game directory when the instance owns it.
+            // A version-isolated `versions/<name>` folder is obviously
+            // exclusive; a plain `<root>/<pack name>` folder is also owned by
+            // this instance. A shared `.minecraft` root, however, holds the
+            // game's libraries/assets and must never be deleted with one
+            // instance.
+            is_version_isolated_game_dir(path)
+                || !is_shared_minecraft_root(path)
+        })
     {
-        // New instances created against a configured `.minecraft` root use
-        // a private `versions/<name>` directory. Remove that external
-        // directory when the instance is deleted, while preserving shared
-        // (non-isolated) overrides for backwards compatibility.
         game_dir_override
     } else {
         state.directories.instances_dir().join(&instance.path)
@@ -69,3 +74,12 @@ fn is_version_isolated_game_dir(path: &Path) -> bool {
         .and_then(|name| name.to_str())
         == Some("versions")
 }
+
+/// Heuristic: a shared `.minecraft` root holds the game's libraries and
+/// assets, which must survive the removal of any single instance that points
+/// at it. Instance-owned external folders (e.g. a hosted modpack's
+/// `<root>/<pack name>` directory) contain only mods/saves/config and no such
+/// shared game body.
+fn is_shared_minecraft_root(path: &Path) -> bool {
+    path.join("libraries").is_dir() || path.join("assets").is_dir()
+}

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

@@ -616,220 +616,62 @@ impl Process {
         let mut buf_reader = BufReader::new(reader);
 
         if xml_logging {
-            let mut reader = Reader::from_reader(buf_reader);
-            reader.config_mut().enable_all_checks(false);
-
-            let mut buf = Vec::new();
-            let mut current_event = Log4jEvent::default();
-            let mut in_event = false;
-            let mut in_message = false;
-            let mut in_throwable = false;
-            let mut current_content = String::new();
+            // NOTE: we deliberately do NOT use quick-xml's streaming async reader
+            // here. Its parser marks itself `ParseState::Done` permanently after
+            // any I/O/parse error or a transient `Eof` (see quick-xml #513), so a
+            // single split XML frame on the live pipe would silently kill all
+            // further log forwarding — which is exactly the "logs stop after the
+            // client finished starting" bug.
+            //
+            // Instead we accumulate raw bytes into a buffer and cut out complete
+            // `<log4j:Event ...>…</log4j:Event>` frames, parsing each frame in one
+            // synchronous pass. Malformed or partial frames are skipped without
+            // poisoning the stream, so forwarding always continues.
+            let mut pending = String::new();
+            let mut chunk = [0u8; 8192];
 
             loop {
-                match reader.read_event_into_async(&mut buf).await {
+                let read = match tokio::io::AsyncReadExt::read(&mut buf_reader, &mut chunk).await {
+                    Ok(0) => break,
+                    Ok(n) => n,
                     Err(e) => {
-                        tracing::error!(
-                            "Error at position {}: {:?}",
-                            reader.buffer_position(),
-                            e
-                        );
+                        tracing::warn!("Live log read error: {e}");
                         break;
                     }
-                    // exits the loop when reaching end of file
-                    Ok(Event::Eof) => break,
+                };
 
-                    Ok(Event::Start(e)) => {
-                        match e.name().as_ref() {
-                            b"log4j:Event" => {
-                                // Reset for new event
-                                current_event = Log4jEvent::default();
-                                in_event = true;
+                pending.push_str(&String::from_utf8_lossy(&chunk[..read]));
 
-                                // Extract attributes
-                                for attr in e.attributes().flatten() {
-                                    let key = String::from_utf8_lossy(
-                                        attr.key.into_inner(),
-                                    )
-                                    .to_string();
-                                    let value =
-                                        String::from_utf8_lossy(&attr.value)
-                                            .to_string();
-
-                                    match key.as_str() {
-                                        "logger" => {
-                                            current_event.logger_name =
-                                                Some(value)
-                                        }
-                                        "level" => {
-                                            current_event.level = Some(value)
-                                        }
-                                        "thread" => {
-                                            current_event.thread_name =
-                                                Some(value)
-                                        }
-                                        "timestamp" => {
-                                            current_event.timestamp_millis =
-                                                value.parse::<i64>().ok()
-                                        }
-                                        _ => {}
-                                    }
-                                }
-                            }
-                            b"log4j:Message" => {
-                                in_message = true;
-                                current_content = String::new();
-                            }
-                            b"log4j:Throwable" => {
-                                in_throwable = true;
-                                current_content = String::new();
-                            }
-                            _ => {}
-                        }
-                    }
-                    Ok(Event::End(e)) => {
-                        match e.name().as_ref() {
-                            b"log4j:Message" => {
-                                in_message = false;
-                                current_event.message =
-                                    Some(current_content.clone());
-                            }
-                            b"log4j:Throwable" => {
-                                in_throwable = false;
-                                current_event.throwable =
-                                    if current_content.is_empty() {
-                                        None
-                                    } else {
-                                        Some(current_content.clone())
-                                    };
-
-                                // Write log entry + throwable to file
-                                if let Some(formatted_log) =
-                                    Self::format_log4j_entry(&current_event)
-                                {
-                                    if let Err(e) = Process::append_to_log_file(
-                                        &log_path,
-                                        &formatted_log,
-                                    ) {
-                                        tracing::error!(
-                                            "Failed to write to log file: {}",
-                                            e
-                                        );
-                                    }
-
-                                    if let Some(ref throwable) =
-                                        current_event.throwable
-                                        && let Err(e) =
-                                            Process::append_to_log_file(
-                                                &log_path, throwable,
-                                            )
-                                    {
-                                        tracing::error!(
-                                            "Failed to write throwable to log file: {}",
-                                            e
-                                        );
-                                    }
-                                }
-
-                                Self::emit_log4j_event(
-                                    instance_id,
-                                    &current_event,
-                                );
-                            }
-                            b"log4j:Event" => {
-                                in_event = false;
-                                // If no throwable was present, write the log entry at the end of the event
-                                if current_event.message.is_some()
-                                    && current_event.throwable.is_none()
-                                {
-                                    if let Some(formatted_log) =
-                                        Self::format_log4j_entry(&current_event)
-                                        && let Err(e) =
-                                            Process::append_to_log_file(
-                                                &log_path,
-                                                &formatted_log,
-                                            )
-                                    {
-                                        tracing::error!(
-                                            "Failed to write to log file: {}",
-                                            e
-                                        );
-                                    }
-
-                                    if let Some(timestamp_millis) =
-                                        current_event.timestamp_millis
-                                    {
-                                        let timestamp =
-                                            timestamp_millis.to_string();
-                                        let message = current_event
-                                            .message
-                                            .as_deref()
-                                            .unwrap_or("")
-                                            .trim();
-                                        crate::api::multiplayer::observe_minecraft_log(
-                                        instance_id,
-                                        instance_name,
-                                        process_id,
-                                        message,
-                                    )
-                                    .await;
-                                        if let Err(e) = Self::maybe_handle_server_join_logging(
-											instance_id,
-											&timestamp,
-											message,
-                                        ).await {
-                                            tracing::error!("Failed to handle server join logging: {e}");
-                                        }
-                                    }
-
-                                    Self::emit_log4j_event(
-                                        instance_id,
-                                        &current_event,
-                                    );
-                                }
-                            }
-                            _ => {}
-                        }
-                    }
-                    Ok(Event::Text(mut e)) => {
-                        if in_message || in_throwable {
-                            if let Ok(text) = e.xml_content() {
-                                append_bounded_log4j_content(
-                                    &mut current_content,
-                                    &text,
-                                );
-                            }
-                        } else if !in_event
-                            && !e.inplace_trim_end()
-                            && !e.inplace_trim_start()
-                            && let Ok(text) = e.xml_content()
-                        {
-                            if let Err(e) = Process::append_to_log_file(
-                                &log_path,
-                                &format!("{text}\n"),
-                            ) {
-                                tracing::error!(
-                                    "Failed to write to log file: {}",
-                                    e
-                                );
-                            }
-                            Self::emit_legacy_log(instance_id, &text);
-                        }
-                    }
-                    Ok(Event::CData(e)) => {
-                        if (in_message || in_throwable)
-                            && let Ok(text) = e.xml_content()
-                        {
-                            append_bounded_log4j_content(
-                                &mut current_content,
-                                &text,
-                            );
-                        }
-                    }
-                    _ => (),
+                // Drain every complete frame currently buffered.
+                while let Some(frame) = take_next_log4j_frame(&mut pending) {
+                    Self::handle_log4j_frame(
+                        instance_id,
+                        instance_name,
+                        process_id,
+                        &log_path,
+                        &frame,
+                    )
+                    .await;
                 }
 
-                buf.clear();
+                // Guard against a runaway buffer if no frame delimiters ever
+                // appear (e.g. raw non-XML output on a logging-configured
+                // instance). Flush it as legacy text so it is not lost.
+                if pending.len() > MAX_PERSISTED_LOG_LINE_BYTES {
+                    let text = std::mem::take(&mut pending);
+                    if let Err(e) = Self::append_to_log_file(&log_path, &text) {
+                        tracing::warn!("Failed to write to log file: {e}");
+                    }
+                    Self::emit_legacy_log(instance_id, text.trim_end());
+                }
+            }
+
+            // Flush any trailing partial content on stream end.
+            if !pending.trim().is_empty() {
+                if let Err(e) = Self::append_to_log_file(&log_path, &pending) {
+                    tracing::warn!("Failed to write to log file: {e}");
+                }
+                Self::emit_legacy_log(instance_id, pending.trim_end());
             }
         } else {
             while let Ok(Some(line)) =
@@ -862,6 +704,164 @@ impl Process {
         }
     }
 
+    /// Parses one complete `<log4j:Event …>…</log4j:Event>` frame and forwards
+    /// its content to the log file / frontend. A frame that fails to parse is
+    /// logged and dropped; it never stops the reader loop.
+    async fn handle_log4j_frame(
+        instance_id: &str,
+        instance_name: &str,
+        process_id: &str,
+        log_path: &Path,
+        frame: &str,
+    ) {
+        let mut reader = Reader::from_str(frame);
+        reader.config_mut().enable_all_checks(false);
+
+        let mut current_event = Log4jEvent::default();
+        let mut in_message = false;
+        let mut in_throwable = false;
+        let mut current_content = String::new();
+
+        let mut buf = Vec::new();
+        loop {
+            match reader.read_event_into(&mut buf) {
+                Err(e) => {
+                    tracing::warn!("Malformed live log frame: {e}");
+                    break;
+                }
+                Ok(Event::Eof) => break,
+                Ok(Event::Start(e)) => match e.name().as_ref() {
+                    b"log4j:Event" => {
+                        current_event = Log4jEvent::default();
+                        for attr in e.attributes().flatten() {
+                            let key =
+                                String::from_utf8_lossy(attr.key.into_inner())
+                                    .to_string();
+                            let value = String::from_utf8_lossy(&attr.value)
+                                .to_string();
+                            match key.as_str() {
+                                "logger" => {
+                                    current_event.logger_name = Some(value)
+                                }
+                                "level" => current_event.level = Some(value),
+                                "thread" => {
+                                    current_event.thread_name = Some(value)
+                                }
+                                "timestamp" => {
+                                    current_event.timestamp_millis =
+                                        value.parse::<i64>().ok()
+                                }
+                                _ => {}
+                            }
+                        }
+                    }
+                    b"log4j:Message" => {
+                        in_message = true;
+                        current_content = String::new();
+                    }
+                    b"log4j:Throwable" => {
+                        in_throwable = true;
+                        current_content = String::new();
+                    }
+                    _ => {}
+                },
+                Ok(Event::End(e)) => match e.name().as_ref() {
+                    b"log4j:Message" => {
+                        in_message = false;
+                        current_event.message = Some(current_content.clone());
+                    }
+                    b"log4j:Throwable" => {
+                        in_throwable = false;
+                        current_event.throwable =
+                            if current_content.is_empty() {
+                                None
+                            } else {
+                                Some(current_content.clone())
+                            };
+                    }
+                    b"log4j:Event" => {
+                        if let Some(formatted) =
+                            Self::format_log4j_entry(&current_event)
+                        {
+                            if let Err(e) =
+                                Self::append_to_log_file(log_path, &formatted)
+                            {
+                                tracing::error!(
+                                    "Failed to write to log file: {e}"
+                                );
+                            }
+                            if let Some(ref throwable) = current_event.throwable
+                                && let Err(e) = Self::append_to_log_file(
+                                    log_path,
+                                    throwable,
+                                )
+                            {
+                                tracing::error!(
+                                    "Failed to write throwable to log file: {e}"
+                                );
+                            }
+
+                            if let Some(timestamp_millis) =
+                                current_event.timestamp_millis
+                            {
+                                let timestamp = timestamp_millis.to_string();
+                                let message = current_event
+                                    .message
+                                    .as_deref()
+                                    .unwrap_or("")
+                                    .trim();
+                                crate::api::multiplayer::observe_minecraft_log(
+                                    instance_id,
+                                    instance_name,
+                                    process_id,
+                                    message,
+                                )
+                                .await;
+                                if let Err(e) =
+                                    Self::maybe_handle_server_join_logging(
+                                        instance_id,
+                                        &timestamp,
+                                        message,
+                                    )
+                                    .await
+                                {
+                                    tracing::error!(
+                                        "Failed to handle server join logging: {e}"
+                                    );
+                                }
+                            }
+
+                            Self::emit_log4j_event(instance_id, &current_event);
+                        }
+                    }
+                    _ => {}
+                },
+                Ok(Event::Text(e)) => {
+                    if (in_message || in_throwable)
+                        && let Ok(text) = e.xml_content()
+                    {
+                        append_bounded_log4j_content(
+                            &mut current_content,
+                            &text,
+                        );
+                    }
+                }
+                Ok(Event::CData(e)) => {
+                    if (in_message || in_throwable)
+                        && let Ok(text) = e.xml_content()
+                    {
+                        append_bounded_log4j_content(
+                            &mut current_content,
+                            &text,
+                        );
+                    }
+                }
+                _ => (),
+            }
+            buf.clear();
+        }
+    }
+
     fn format_timestamp(timestamp_millis: Option<i64>) -> String {
         if let Some(timestamp_val) = timestamp_millis {
             let datetime_utc = if timestamp_val > i32::MAX as i64 {
@@ -1267,7 +1267,28 @@ impl Process {
         Ok(())
     }
 }
+/// Cuts the next complete `<log4j:Event …>…</log4j:Event>` frame out of the
+/// live buffer and returns it as an owned string, leaving any trailing partial
+/// frame in place.
+///
+/// Returns `None` when the buffer does not yet contain a full frame. This is a
+/// plain string operation on purpose: it never poisons any parser state, so a
+/// split or malformed frame on the live pipe cannot stop log forwarding.
+fn take_next_log4j_frame(buffer: &mut String) -> Option<String> {
+    const OPEN: &str = "<log4j:Event";
+    const CLOSE: &str = "</log4j:Event>";
 
+    let start = buffer.find(OPEN)?;
+    // Discard anything before the frame (raw text, XML prolog, …).
+    if start > 0 {
+        buffer.drain(..start);
+    }
+    let close = buffer.find(CLOSE)?;
+    let end = close + CLOSE.len();
+    let frame = buffer[..end].to_string();
+    buffer.drain(..end);
+    Some(frame)
+}
 #[cfg(test)]
 mod post_upgrade_tests {
     use super::*;

packages/ui/src/layouts/shared/console/components/LogViewport.vue

@@ -19,32 +19,30 @@
 			/>
 		</div>
 
-		<div
-			v-else
-			class="log-viewport-spacer relative w-full min-w-max"
-			:style="{ height: totalHeight + 'px' }"
-		>
+		<!--
+			Native virtualization: every line is rendered, but `content-visibility:
+			auto` lets the browser skip layout/paint for off-screen lines, while
+			`contain-intrinsic-size` gives the skipped elements a placeholder size
+			so the scrollbar stays stable. This avoids the manual height estimation
+			that used to make tall (wrapped / highlighted) lines overlap.
+		-->
+		<div v-else class="log-viewport-spacer relative w-full min-w-max">
 			<div
-				class="absolute inset-x-0 top-0"
-				:style="{ transform: 'translateY(' + topOffset + 'px)' }"
+				v-for="item in lines"
+				:key="item.originalIndex"
+				:data-line="item.originalIndex + 1"
+				class="log-line log-line-cv flex items-stretch whitespace-pre"
+				:class="entryClass(item.line)"
+				:style="lineStyle"
 			>
-				<div
-					v-for="item in windowItems"
-					:key="item.originalIndex"
-					:data-line="item.originalIndex + 1"
-					class="log-line flex items-stretch whitespace-pre"
-					:class="entryClass(item.line)"
-					:style="{ height: estimateHeight(item) + 'px' }"
+				<span
+					class="flex shrink-0 w-[52px] items-center justify-end leading-none text-right text-secondary bg-surface-3 border-r border-solid border-surface-3 select-none overflow-hidden"
+					>{{ item.originalIndex + 1 }}</span
 				>
-					<span
-						class="flex shrink-0 w-[52px] items-center justify-end leading-none text-right text-secondary bg-surface-3 border-r border-solid border-surface-3 select-none overflow-hidden"
-						>{{ item.originalIndex + 1 }}</span
-					>
-					<span
-						class="log-line-content flex-1 px-2 break-all [overflow-wrap:anywhere]"
-						v-html="renderLine(item)"
-					></span>
-				</div>
+				<span
+					class="log-line-content flex-1 px-2 break-all [overflow-wrap:anywhere]"
+					v-html="renderLine(item)"
+				></span>
 			</div>
 		</div>
 
@@ -99,114 +97,21 @@ const props = withDefaults(
 )
 
 const viewportRef = ref<HTMLElement | null>(null)
-const scrollTop = ref(0)
-const viewportHeight = ref(0)
 const stickToBottom = ref(true)
 
-// 行高：单行 = 字号 × 1.4（与等宽字体匹配），wrap 时按估算折行数放大
-const lineHeightPx = computed(() => Math.round(props.fontSize * 1.4))
-// wrap 折行估算：0.6em 为等宽字符平均宽，乘 0.9 留保守余量（行高宁高勿矮，避免内容溢出重叠）
-const charsPerLine = computed(() => {
-	const vp = viewportRef.value
-	if (!vp) return 120
-	return Math.max(20, Math.floor((vp.clientWidth / (props.fontSize * 0.6)) * 0.9))
+// Placeholder row height for `contain-intrinsic-size`. Native
+// `content-visibility: auto` replaces this with the real measured height once a
+// line enters the viewport, so it only needs to be a reasonable estimate to
+// keep the scrollbar from jumping. Wrapped lines can be taller, so bias higher.
+const intrinsicLineHeight = computed(() => {
+	const single = Math.round(props.fontSize * 1.4)
+	return props.wrap ? single * 2 : single
 })
 
-function estimateHeight(item: ViewportLine): number {
-	if (!props.wrap) return lineHeightPx.value
-	const lines = Math.max(1, Math.ceil(item.line.text.length / charsPerLine.value))
-	return lines * lineHeightPx.value
-}
-
-// 高度前缀和缓存：lines/wrap/fontSize 变化时重建（O(n)），滚动时二分查找（O(log n)）
-// 总高度必须是响应式的：普通变量 + 无依赖 computed 会缓存过期值，
-// 清空控制台后模板不再读取它，重启后 spacer 会以旧高度渲染（底部空白）。
-let heightPrefix: number[] | null = null
-const heightTotal = ref(0)
-
-function rebuildHeights() {
-	const n = props.lines.length
-	if (!props.wrap) {
-		heightPrefix = null
-		heightTotal.value = n * lineHeightPx.value
-		return
-	}
-	const prefix = new Array<number>(n)
-	let acc = 0
-	for (let i = 0; i < n; i++) {
-		prefix[i] = acc
-		acc += estimateHeight(props.lines[i]!)
-	}
-	heightPrefix = prefix
-	heightTotal.value = acc
-}
-
-watch(
-	() => [props.lines, props.wrap, props.fontSize] as const,
-	([lines], previous) => {
-		rebuildHeights()
-		// A fresh stream after an empty console (clear, restart, initial
-		// hydration) always resumes bottom-following.
-		if (previous && previous[0].length === 0 && lines.length > 0) {
-			stickToBottom.value = true
-		}
-		if (lines.length === 0) {
-			// Reset the virtual window state along with the DOM scroll position;
-			// browsers may clamp silently without firing a scroll event.
-			scrollTop.value = 0
-			if (viewportRef.value) viewportRef.value.scrollTop = 0
-		}
-		if (stickToBottom.value) {
-			nextTick(scrollToBottom)
-		}
-	},
-	{ immediate: true },
-)
-
-const totalHeight = computed(() => heightTotal.value)
-
-// 虚拟窗口：可见行 + 上下缓冲
-const WINDOW_BUFFER = 15
-
-function computeWindow(): { items: ViewportLine[]; startIndex: number } {
-	const n = props.lines.length
-	if (n === 0) return { items: [], startIndex: 0 }
-
-	let start = 0
-	let end = n - 1
-
-	if (n > WINDOW_BUFFER * 2) {
-		if (props.wrap && heightPrefix) {
-			let lo = 0
-			let hi = n - 1
-			while (lo < hi) {
-				const mid = (lo + hi + 1) >> 1
-				if (heightPrefix[mid]! <= scrollTop.value) lo = mid
-				else hi = mid - 1
-			}
-			start = Math.max(0, lo - WINDOW_BUFFER)
-		} else {
-			const first = Math.floor(scrollTop.value / lineHeightPx.value)
-			start = Math.max(0, first - WINDOW_BUFFER)
-		}
-		end = Math.min(
-			n - 1,
-			start + Math.ceil(viewportHeight.value / lineHeightPx.value) + WINDOW_BUFFER * 2,
-		)
-	}
-
-	return { items: props.lines.slice(start, end + 1), startIndex: start }
-}
-
-const windowState = computed(computeWindow)
-const windowItems = computed(() => windowState.value.items)
-
-const topOffset = computed(() => {
-	const { startIndex } = windowState.value
-	if (startIndex === 0) return 0
-	if (props.wrap && heightPrefix) return heightPrefix[startIndex]!
-	return startIndex * lineHeightPx.value
-})
+const lineStyle = computed(() => ({
+	'content-visibility': 'auto',
+	'contain-intrinsic-size': `auto ${intrinsicLineHeight.value}px`,
+}))
 
 function entryClass(line: LogLine): string {
 	if (line.level === 'error') return 'entry-error'
@@ -235,43 +140,47 @@ function renderLine(item: ViewportLine): string {
 function handleScroll() {
 	const vp = viewportRef.value
 	if (!vp) return
-	scrollTop.value = vp.scrollTop
-	viewportHeight.value = vp.clientHeight
-	stickToBottom.value = vp.scrollTop + vp.clientHeight >= vp.scrollHeight - lineHeightPx.value * 2
+	stickToBottom.value = vp.scrollTop + vp.clientHeight >= vp.scrollHeight - 32
 }
 
 function scrollToBottom() {
 	const vp = viewportRef.value
 	if (!vp) return
 	vp.scrollTop = vp.scrollHeight
-	scrollTop.value = vp.scrollTop
 	stickToBottom.value = true
 }
 
-function syncViewportSize() {
-	const vp = viewportRef.value
-	if (!vp) return
-	viewportHeight.value = vp.clientHeight
-	// 窗口宽度影响 wrap 折行估算，resize 时重建高度缓存
-	if (props.wrap) rebuildHeights()
-}
-
 let resizeObserver: ResizeObserver | null = null
 
 onMounted(() => {
-	syncViewportSize()
 	if (stickToBottom.value) nextTick(scrollToBottom)
-	resizeObserver = new ResizeObserver(syncViewportSize)
+	resizeObserver = new ResizeObserver(() => {
+		if (stickToBottom.value) scrollToBottom()
+	})
 	if (viewportRef.value) resizeObserver.observe(viewportRef.value)
-	window.addEventListener('resize', syncViewportSize)
 })
 
 onBeforeUnmount(() => {
 	resizeObserver?.disconnect()
 	resizeObserver = null
-	window.removeEventListener('resize', syncViewportSize)
 })
 
+// Follow the tail while new lines stream in, but only when the user has not
+// scrolled up. A fresh stream after an empty console (clear, restart, initial
+// hydration) always resumes bottom-following.
+watch(
+	() => props.lines,
+	(lines, previous) => {
+		if (previous && previous.length === 0 && lines.length > 0) {
+			stickToBottom.value = true
+		}
+		if (stickToBottom.value) {
+			nextTick(scrollToBottom)
+		}
+	},
+	{ immediate: true },
+)
+
 defineExpose({
 	scrollToBottom,
 })