diff --git a/src/main/java/com/moepus/serverwarashi/common/core/ticket/CrossModLocks.java b/src/main/java/com/moepus/serverwarashi/common/core/ticket/CrossModLocks.java
new file mode 100644
index 0000000..3ed51b4
--- /dev/null
+++ b/src/main/java/com/moepus/serverwarashi/common/core/ticket/CrossModLocks.java
@@ -0,0 +1,60 @@
+package com.moepus.serverwarashi.common.core.ticket;
+
+import java.lang.reflect.Field;
+import java.util.concurrent.locks.ReentrantLock;
+
+/**
+ * 跨 mod 共享锁访问器。
+ * <p>
+ * DimensionalRipper 让维度 tick 跑在独立线程后，会并发修改 {@code DistanceManager.tickets}
+ * （{@code Long2ObjectOpenHashMap}，非线程安全）。DR 用
+ * {@code dev.modzuozhi.core.compat.DistanceManagerLock.LOCK} 串行化所有 ticket 写路径。
+ * <p>
+ * warashi 的性能采样在主线程遍历同一张 ticket 表（{@link TicketScanService}），必须持同一把锁，
+ * 否则遍历会与维度线程的写并发 → fastutil fail-fast 迭代器 NPE（已实测）。
+ * <p>
+ * <b>软依赖</b>：通过反射获取 DR 的锁；DR 未加载则 {@link #distanceManagerLock()} 返回 null，
+ * 调用方退化为无锁（原行为不变）。获取一次后缓存。
+ */
+public final class CrossModLocks {
+    private static final String DR_LOCK_CLASS =
+            "dev.modzuozhi.core.compat.DistanceManagerLock";
+    private static final String DR_LOCK_FIELD = "LOCK";
+
+    private static volatile ReentrantLock distanceManagerLock;
+    private static volatile boolean resolved;
+
+    private CrossModLocks() {
+    }
+
+    /**
+     * DR 的 DistanceManager 共享锁；DR 未加载时返回 null。
+     * 首次调用解析后缓存（含「解析失败」结果，避免反复抛异常）。
+     */
+    public static ReentrantLock distanceManagerLock() {
+        if (!resolved) {
+            synchronized (CrossModLocks.class) {
+                if (!resolved) {
+                    distanceManagerLock = resolve();
+                    resolved = true;
+                }
+            }
+        }
+        return distanceManagerLock;
+    }
+
+    private static ReentrantLock resolve() {
+        try {
+            Class<?> lockClass = Class.forName(DR_LOCK_CLASS, false,
+                    Thread.currentThread().getContextClassLoader());
+            Field field = lockClass.getField(DR_LOCK_FIELD);
+            Object value = field.get(null);
+            if (value instanceof ReentrantLock lock) {
+                return lock;
+            }
+        } catch (Throwable ignored) {
+            // DR 未加载 / 字段缺失：退化为无锁。
+        }
+        return null;
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/com/moepus/serverwarashi/common/core/ticket/TicketScanService.java b/src/main/java/com/moepus/serverwarashi/common/core/ticket/TicketScanService.java
index eba4c35..e265fc6 100644
--- a/src/main/java/com/moepus/serverwarashi/common/core/ticket/TicketScanService.java
+++ b/src/main/java/com/moepus/serverwarashi/common/core/ticket/TicketScanService.java
@@ -6,8 +6,18 @@ import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.Ticket;
 import net.minecraft.util.SortedArraySet;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.locks.ReentrantLock;
+
 /**
  * 低分配遍历 DistanceManager 当前 ticket 表的访问器。
+ * <p>
+ * <b>并发安全</b>：{@code DistanceManager.tickets} 是非线程安全的
+ * {@code Long2ObjectOpenHashMap}。DimensionalRipper 维度线程会在 tick 中并发增删 ticket，
+ * 与主线程此处的遍历冲突 → fastutil fail-fast 迭代器 NPE（已实测）。
+ * 故遍历时持 DR 的共享锁（{@link CrossModLocks}），并在锁内把 entry 快照到局部 List 再遍历，
+ * 避免持锁期间执行 visitor（可能较慢）。DR 未加载时锁为 null，退化为原无锁行为。
  */
 public final class TicketScanService {
     private TicketScanService() {
@@ -19,15 +29,40 @@ public final class TicketScanService {
     }
 
     public static void visitTicketChunks(DistanceManagerAccessor distanceManager, TicketChunkVisitor visitor) {
-        for (Long2ObjectMap.Entry<SortedArraySet<Ticket<?>>> entry :
-                distanceManager.getTickets().long2ObjectEntrySet()) {
-            long chunkPos = entry.getLongKey();
-            SortedArraySet<Ticket<?>> tickets = entry.getValue();
-            if (tickets.isEmpty()) {
-                continue;
+        ReentrantLock lock = CrossModLocks.distanceManagerLock();
+        if (lock == null) {
+            // DR 未加载：原行为，直接遍历。
+            for (Long2ObjectMap.Entry<SortedArraySet<Ticket<?>>> entry :
+                    distanceManager.getTickets().long2ObjectEntrySet()) {
+                visitEntry(entry, visitor);
             }
-            visitor.visitChunk(chunkPos, tickets);
+            return;
         }
+        // DR 共存：锁内快照 entry，锁外遍历，与维度线程的 ticket 写互斥。
+        List<Long2ObjectMap.Entry<SortedArraySet<Ticket<?>>>> snapshot;
+        lock.lock();
+        try {
+            snapshot = new ArrayList<>();
+            for (Long2ObjectMap.Entry<SortedArraySet<Ticket<?>>> entry :
+                    distanceManager.getTickets().long2ObjectEntrySet()) {
+                snapshot.add(entry);
+            }
+        } finally {
+            lock.unlock();
+        }
+        for (Long2ObjectMap.Entry<SortedArraySet<Ticket<?>>> entry : snapshot) {
+            visitEntry(entry, visitor);
+        }
+    }
+
+    private static void visitEntry(Long2ObjectMap.Entry<SortedArraySet<Ticket<?>>> entry,
+                                   TicketChunkVisitor visitor) {
+        long chunkPos = entry.getLongKey();
+        SortedArraySet<Ticket<?>> tickets = entry.getValue();
+        if (tickets.isEmpty()) {
+            return;
+        }
+        visitor.visitChunk(chunkPos, tickets);
     }
 
     @FunctionalInterface