修复更早历史读取失败消息为空时挂起态与错误行一起消失

- 失败消息统一收口成非空兜底文案，空 message 不再让 historyError 变 falsy
- 新增控制器回归用例：宿主抛 new Error() 时挂起态仍成立

Co-authored-by: Junie <junie@jetbrains.com>

apps/ai-game-creator-shell/src/view/project-development/chat/controller/useDirectProjectChatController.test.tsx

@@ -10,6 +10,7 @@ type SliceRequest = {
   projectPath: string;
   beforeItemId: string | undefined;
   resolve: (slice: HistorySlice) => void;
+  reject: (error: unknown) => void;
 };
 
 function userItem(itemId: string): ThreadItem {
@@ -25,7 +26,7 @@ function slice(
 }
 
 /**
- * 装一个可控的 Tauri invoke：历史切片读取全部挂起，用例自己决定哪一页何时落地。
+ * 装一个可控的 Tauri invoke：历史切片读取全部挂起，用例自己决定哪一页何时落地 / 落空。
  *
  * `resolveTauriInvoke` 只读 `window.__TAURI__.core.invoke`，这里就是控制器唯一的外部接缝。
  */
@@ -34,11 +35,12 @@ function installDeferredHistoryInvoke() {
   const invoke = vi.fn(
     async (command: string, args?: Record<string, unknown>) => {
       if (command !== 'read_direct_project_history_slice') return undefined;
-      return new Promise<HistorySlice>((resolve) => {
+      return new Promise<HistorySlice>((resolve, reject) => {
         requests.push({
           projectPath: String(args?.projectPath ?? ''),
           beforeItemId: args?.beforeItemId as string | undefined,
           resolve,
+          reject,
         });
       });
     },
@@ -64,6 +66,23 @@ function installDeferredHistoryInvoke() {
   };
 }
 
+function renderChatController(initialProjectPath: string) {
+  const allowed = async () => true;
+  return renderHook(
+    ({ projectPath }: { projectPath: string }) =>
+      useDirectProjectChatController({
+        enabled: true,
+        ensureConversationReadAllowed: allowed,
+        ensureConversationWriteAllowed: allowed,
+        onRuntimeError: () => undefined,
+        projectId: 'project-1',
+        projectPath,
+        refreshManifest: () => undefined,
+      }),
+    { initialProps: { projectPath: initialProjectPath } },
+  );
+}
+
 afterEach(() => {
   cleanup();
   delete window.__TAURI__;
@@ -72,20 +91,7 @@ afterEach(() => {
 describe('更早历史加载态的项目归属', () => {
   it('切项目后旧项目在飞的读取才落地，不能清掉新项目正在进行的加载态', async () => {
     const tauri = installDeferredHistoryInvoke();
-    const allowed = async () => true;
-    const { result, rerender } = renderHook(
-      ({ projectPath }: { projectPath: string }) =>
-        useDirectProjectChatController({
-          enabled: true,
-          ensureConversationReadAllowed: allowed,
-          ensureConversationWriteAllowed: allowed,
-          onRuntimeError: () => undefined,
-          projectId: 'project-1',
-          projectPath,
-          refreshManifest: () => undefined,
-        }),
-      { initialProps: { projectPath: '/projects/a' } },
-    );
+    const { result, rerender } = renderChatController('/projects/a');
 
     // 首屏：/a 的第一页落地，拿到「还有更早」。
     const firstScreenA = await tauri.take('/projects/a');
@@ -129,3 +135,29 @@ describe('更早历史加载态的项目归属', () => {
     expect(result.current.historyLoading).toBe(false);
   });
 });
+
+describe('更早历史失败的挂起态', () => {
+  it('宿主没给出失败消息时，挂起态仍是可判定的非空值', async () => {
+    const tauri = installDeferredHistoryInvoke();
+    const { result } = renderChatController('/projects/a');
+
+    const firstScreen = await tauri.take('/projects/a');
+    await act(async () => {
+      firstScreen.resolve(slice([userItem('a2')], true, 'a2'));
+    });
+    await waitFor(() => expect(result.current.historyHasMore).toBe(true));
+
+    await act(async () => {
+      void result.current.loadEarlierHistory();
+    });
+    const failing = await tauri.take('/projects/a', 'a2');
+    await act(async () => {
+      failing.reject(new Error(''));
+    });
+
+    // `historyError` 同时是「挂起自动加载」的闸门与内联错误行的显隐开关：空串是 falsy，
+    // 两者会一起消失，滚到顶就变成反复重试同一个失败读取。
+    expect(result.current.historyError).toBeTruthy();
+    expect(result.current.historyLoading).toBe(false);
+  });
+});

apps/ai-game-creator-shell/src/view/project-development/chat/controller/useDirectProjectChatController.ts

@@ -44,6 +44,15 @@ import { useDirectThreadChatSubscription } from './useDirectThreadChatSubscripti
 export const MAX_CHAT_COMPOSER_ATTACHMENTS = 8;
 export const DIRECT_HISTORY_PAGE_SIZE = CONVERSATION_VISIBLE_STEP;
 
+/**
+ * 更早历史读取失败时的兜底文案。
+ *
+ * 宿主可能抛出空 message 的错误（裸 `new Error()`、宿主侧空串）。空串是 falsy，而
+ * `historyError` 同时是「挂起自动加载」的闸门与内联错误行的显隐开关——空串会让两者一起
+ * 消失，滚到顶就变成反复重试同一个失败读取。这里在源头收口成一句稳定文案。
+ */
+const DIRECT_HISTORY_LOAD_ERROR_FALLBACK = '读取更早的对话历史失败';
+
 /**
  * 工作台壳注入的项目对话读权限门。返回 `false` 表示已入队确认：读取由 `onConfirmed`
  * 触发，壳自己负责取消时的状态文案。
@@ -707,7 +716,9 @@ export function useDirectProjectChatController({
     } catch (error) {
       // 与加载成功路径同样按项目守卫：切项目后在飞的读取失败不能算到新项目头上。
       if (projectPathRef.current !== nextProjectPath) return;
-      const message = error instanceof Error ? error.message : String(error);
+      const message =
+        (error instanceof Error ? error.message : String(error)) ||
+        DIRECT_HISTORY_LOAD_ERROR_FALLBACK;
       historyErrorRef.current = message;
       setHistoryError(message);
     } finally {