diff --git a/apps/ai-game-creator-shell/src/App.tsx b/apps/ai-game-creator-shell/src/App.tsx
index 72285aa78..2abc16df0 100644
--- a/apps/ai-game-creator-shell/src/App.tsx
+++ b/apps/ai-game-creator-shell/src/App.tsx
@@ -3491,6 +3491,9 @@ 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：
+      // 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;
       const projectConversation = directCodexProductRuntime
         ? (() => {
             return invoke<DirectThreadHistorySlice>(
@@ -3502,10 +3505,7 @@ export function App({
             ).then((slice) => {
               loadedDirectHistoryHasMore = slice.hasMore;
               loadedDirectHistoryFirstItemId = slice.firstItemId;
-              // 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),
-              );
+              loadedDirectHistorySlice = slice;
               return {
                 path: nextProjectPath,
                 agentId: null,
@@ -3579,6 +3579,13 @@ export function App({
       if (directCodexProductRuntime) {
         setDirectHistoryHasMore(loadedDirectHistoryHasMore);
         directHistoryOldestItemIdRef.current = loadedDirectHistoryFirstItemId;
+        if (loadedDirectHistorySlice) {
+          const slice = loadedDirectHistorySlice;
+          // 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),
+          );
+        }
       }
       setMessages((current) => {
         // replace 分支同样不能丢掉尚未落盘的运行时消息（初始需求）。