App 聊天历史分页改走连拉循环

首屏与「显示更早」共用 readDirectHistoryPages，不再各自单发一页
首屏基线取空并在守卫后一次性并入聊天 reducer，失败仍按原有语义抛出
「显示更早」按当前视图条目判断新回合，取到多页一次性并入并推进锚点
连拉中途失败保留已取到的页，报错统一走同一个出口

apps/ai-game-creator-shell/src/App.tsx

@@ -232,17 +232,19 @@ import {
 } from './features/project-workspace/chatComposerQueue';
 import { DeveloperProjectPanels } from './features/project-workspace/DeveloperProjectPanels';
 import { DeveloperRuntimePanels } from './features/project-workspace/DeveloperRuntimePanels';
+import { readDirectHistoryPages } from './features/project-workspace/directHistoryPaging';
 import {
   applyDirectThreadConsumeResult,
   type DirectThreadChatState,
   emptyDirectThreadChatState,
-  mergeDirectThreadHistorySlice,
+  mergeDirectHistoryItems,
   resolveDirectThreadBootstrap,
   selectDirectChatEntries,
 } from './features/project-workspace/directThreadChat';
 import {
   type DirectThreadConsumeResult,
   type DirectThreadHistorySlice,
+  type DirectThreadItem,
   type DirectThreadSubscriptionBootstrap,
 } from './features/project-workspace/directThreadEvents';
 import type { DirectCodexUserContentPart } from './features/project-workspace/generated';
@@ -3491,21 +3493,38 @@ export function App({
       let runtimeError = '';
       let loadedDirectHistoryHasMore = false;
       let loadedDirectHistoryFirstItemId: string | null = null;
-      // 首屏切片先暂存，待下方 staleness 守卫通过后再并入聊天 reducer：
+      // 首屏连拉到的条目先暂存，待下方 staleness 守卫通过后再并入聊天 reducer：
       // 迟到的切片属于已经切走的项目，不能在守卫之前就写进全局聊天状态。
-      let loadedDirectHistorySlice: DirectThreadHistorySlice | null = null;
+      let loadedDirectHistoryItems: DirectThreadItem[] = [];
       const projectConversation = directCodexProductRuntime
         ? (() => {
-            return invoke<DirectThreadHistorySlice>(
-              'read_direct_project_history_slice',
-              {
-                projectPath: nextProjectPath,
-                limit: CONVERSATION_INITIAL_VISIBLE_COUNT,
-              },
-            ).then((slice) => {
-              loadedDirectHistoryHasMore = slice.hasMore;
-              loadedDirectHistoryFirstItemId = slice.firstItemId;
-              loadedDirectHistorySlice = slice;
+            // 首屏铺的就是这份视图的基线，"新回合"比较没有意义：判据退化为"这一页得有能渲染
+            // 的条目"，所以基线取空，免得拿上一份对话的残留状态去比。首屏失败仍按原有语义
+            // 抛出，交给调用方的 catch 处理。
+            return readDirectHistoryPages({
+              existingEntries: [],
+              beforeItemId: null,
+              readSlice: (beforeItemId) =>
+                invoke<DirectThreadHistorySlice>(
+                  'read_direct_project_history_slice',
+                  beforeItemId
+                    ? {
+                        projectPath: nextProjectPath,
+                        beforeItemId,
+                        limit: CONVERSATION_INITIAL_VISIBLE_COUNT,
+                      }
+                    : {
+                        projectPath: nextProjectPath,
+                        limit: CONVERSATION_INITIAL_VISIBLE_COUNT,
+                      },
+                ),
+            }).then((pages) => {
+              if (pages.error) {
+                throw pages.error;
+              }
+              loadedDirectHistoryHasMore = pages.hasMore;
+              loadedDirectHistoryFirstItemId = pages.firstItemId;
+              loadedDirectHistoryItems = pages.items;
               return {
                 path: nextProjectPath,
                 agentId: null,
@@ -3579,12 +3598,10 @@ export function App({
       if (directCodexProductRuntime) {
         setDirectHistoryHasMore(loadedDirectHistoryHasMore);
         directHistoryOldestItemIdRef.current = loadedDirectHistoryFirstItemId;
-        if (loadedDirectHistorySlice) {
-          const slice = loadedDirectHistorySlice;
+        if (loadedDirectHistoryItems.length > 0) {
+          const items = loadedDirectHistoryItems;
           // 首屏历史进聊天 reducer；`messages` 在 DirectProject 下只剩运行期本地消息。
-          setDirectThreadChat((state) =>
-            mergeDirectThreadHistorySlice(state, slice),
-          );
+          setDirectThreadChat((state) => mergeDirectHistoryItems(state, items));
         }
       }
       setMessages((current) => {
@@ -11807,24 +11824,37 @@ export function App({
       if (invoke && projectPath && !directHistoryLoadingRef.current) {
         directHistoryLoadingRef.current = true;
         try {
-          const slice = await invoke<DirectThreadHistorySlice>(
-            'read_direct_project_history_slice',
-            {
-              projectPath,
-              beforeItemId: directHistoryOldestItemIdRef.current,
-              limit: CONVERSATION_VISIBLE_STEP,
-            },
-          );
+          // 一次点击连拉，直到出现新回合或取不动为止：一屏全是工具卡片 / 思考文本时，
+          // 单发一页会让用户点了"显示更早"却看不到任何变化。
+          const pages = await readDirectHistoryPages({
+            existingEntries: selectDirectChatEntries(directThreadChat),
+            beforeItemId: directHistoryOldestItemIdRef.current,
+            readSlice: (beforeItemId) =>
+              invoke<DirectThreadHistorySlice>(
+                'read_direct_project_history_slice',
+                beforeItemId
+                  ? {
+                      projectPath,
+                      beforeItemId,
+                      limit: CONVERSATION_VISIBLE_STEP,
+                    }
+                  : { projectPath, limit: CONVERSATION_VISIBLE_STEP },
+              ),
+          });
           if (localProjectPathRef.current !== projectPath) {
             return;
           }
-          // 更早的一屏历史进聊天 reducer：与运行态同形、同身份，重复读取只补不重。
+          // 连拉到的页一次性进聊天 reducer：与运行态同形、同身份，重复读取只补不重。
           setDirectThreadChat((state) =>
-            mergeDirectThreadHistorySlice(state, slice),
+            mergeDirectHistoryItems(state, pages.items),
           );
-          setDirectHistoryHasMore(slice.hasMore);
+          setDirectHistoryHasMore(pages.hasMore);
           directHistoryOldestItemIdRef.current =
-            slice.firstItemId ?? directHistoryOldestItemIdRef.current;
+            pages.firstItemId ?? directHistoryOldestItemIdRef.current;
+          if (pages.error) {
+            // 已经取到的页照常进视图，失败只走下面同一个报错出口。
+            throw pages.error;
+          }
         } catch (error) {
           setWorkspaceStatus(
             `读取更早的对话历史失败：${error instanceof Error ? error.message : String(error)}`,