diff --git a/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.test.ts b/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.test.ts
index a0b25e2e2..58a236cc5 100644
--- a/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.test.ts
+++ b/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.test.ts
@@ -1,10 +1,11 @@
 /** @vitest-environment jsdom */
-import { afterEach, describe, expect, it } from 'vitest';
+import { afterEach, describe, expect, it, vi } from 'vitest';
 
 import {
   collectTurnBlocks,
   type ConversationTurnAnchor,
   findTurnBlock,
+  invalidateTurnBlocks,
   readTopVisibleTurnAnchor,
   restoreTurnAnchor,
 } from './conversationScrollAnchor';
@@ -52,6 +53,32 @@ describe('collectTurnBlocks', () => {
     const { list } = buildList(['t1', 't2']);
     expect(collectTurnBlocks(list)).toHaveLength(2);
   });
+
+  it('同一列表连续收集只查一次 DOM', () => {
+    const { list } = buildList(['t1', 't2']);
+    collectTurnBlocks(list);
+    const query = vi.spyOn(list, 'querySelectorAll');
+
+    // 一次滚动帧里读锚点、还原锚点会各查一遍：没失效就不该再碰 DOM。
+    collectTurnBlocks(list);
+
+    expect(query).not.toHaveBeenCalled();
+    query.mockRestore();
+  });
+
+  it('子元素变化并失效后重新收集', () => {
+    const { list } = buildList(['t1']);
+    const before = collectTurnBlocks(list);
+    const extra = document.createElement('div');
+    extra.dataset.turnKey = 't2';
+    list.appendChild(extra);
+
+    invalidateTurnBlocks(list);
+
+    const after = collectTurnBlocks(list);
+    expect(after).toHaveLength(2);
+    expect(after).not.toBe(before);
+  });
 });
 
 describe('readTopVisibleTurnAnchor', () => {
diff --git a/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.ts b/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.ts
index 077b41d31..4511247e6 100644
--- a/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.ts
+++ b/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/conversationScrollAnchor.ts
@@ -26,9 +26,27 @@ function turnKeyOf(element: Element): string | null {
     : null;
 }
 
-/** 列表里所有带回合身份的块，按文档顺序。 */
+/**
+ * 块集合缓存：一次滚动或一次补偿里读锚点、还原锚点会各查一遍整个列表，长会话下就是每个滚动
+ * 帧的 O(块数) DOM 查询。失效信号是列表子元素增删——只有子元素变化才可能改变「哪些块带回合
+ * 身份」，而 `useConversationScroll` 的 `MutationObserver` 已经在听同一个信号。
+ */
+const turnBlockCache = new WeakMap<HTMLElement, HTMLElement[]>();
+
+/** 列表里所有带回合身份的块，按文档顺序；子元素没变时复用上一次的结果。 */
 export function collectTurnBlocks(list: HTMLElement): HTMLElement[] {
-  return Array.from(list.querySelectorAll<HTMLElement>(TURN_BLOCK_SELECTOR));
+  const cached = turnBlockCache.get(list);
+  if (cached) return cached;
+  const blocks = Array.from(
+    list.querySelectorAll<HTMLElement>(TURN_BLOCK_SELECTOR),
+  );
+  turnBlockCache.set(list, blocks);
+  return blocks;
+}
+
+/** 列表子元素变了（回合追加、历史前插、加载行挂卸）：丢掉缓存，下次重新收集。 */
+export function invalidateTurnBlocks(list: HTMLElement): void {
+  turnBlockCache.delete(list);
 }
 
 /** 按「回合 key + 块序号」定位具体块；找不到返回 null。 */
diff --git a/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/useConversationScroll.ts b/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/useConversationScroll.ts
index bf8c55c03..f71dc4216 100644
--- a/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/useConversationScroll.ts
+++ b/apps/ai-game-creator-shell/src/view/project-development/chat/components/DirectProjectConversation/useConversationScroll.ts
@@ -11,6 +11,7 @@ import {
 import type { DirectChatTurn } from '../../conversation/directTurnPresentation';
 import {
   type ConversationTurnAnchor,
+  invalidateTurnBlocks,
   readTopVisibleTurnAnchor,
   restoreTurnAnchor,
 } from './conversationScrollAnchor';
@@ -210,13 +211,15 @@ export function useConversationScroll({
   }, [turns]);
 
   // 观察列表的直接子元素：展开 / 收起、流式正文增长、图片撑高、历史前插都只有这一个入口。
-  // 子元素增删（回合追加、加载行挂卸）由 MutationObserver 触发重订阅。
+  // 子元素增删（回合追加、加载行挂卸）由 MutationObserver 触发重订阅，同时让锚点的块集合缓存失效。
   useEffect(() => {
     const list = listRef.current;
     if (!list || typeof ResizeObserver === 'undefined') return undefined;
 
     let observer: ResizeObserver | null = null;
     const subscribe = () => {
+      // 同一份子元素信号同时喂给两处：块集合缓存（锚点定位）与 ResizeObserver 的观察名单。
+      invalidateTurnBlocks(list);
       observer?.disconnect();
       observer = new ResizeObserver(() => compensateLayout());
       for (const child of Array.from(list.children)) {