测试骨架的历史切片按 limit 与锚点分页

- harness.ts 的 read_direct_project_history_slice 按生产口径从队尾取一屏、锚点条目不进窗口
- 按本屏最老一条算 firstItemId，收满一屏后再有条目才算 hasMore
- project-development.suite.ts 补一条用例：26 条历史只显示尾部 20 条，点「显示更早的对话」按锚点取回前 6 条后按钮消失

apps/ai-game-creator-shell/tests/appSurface/harness.ts

@@ -1023,10 +1023,33 @@ function createProjectSupervisorRuntimeHarness({
         return { events };
       }
       if (command === 'read_direct_project_history_slice') {
+        // 生产口径：从文件尾反向取一屏可显示条目，锚点条目本身不进窗口；收满一屏之后
+        // 再见一条才算 `hasMore`，`firstItemId` 是本屏最老一条的 itemId。
+        const requestedLimit = Number(args?.limit ?? 20);
+        const limit = Math.min(
+          Math.max(Number.isFinite(requestedLimit) ? requestedLimit : 20, 1),
+          200,
+        );
+        const beforeItemId =
+          typeof args?.beforeItemId === 'string' && args.beforeItemId
+            ? args.beforeItemId
+            : null;
+        let end = directThreadHistoryItems.length;
+        if (beforeItemId) {
+          const anchorIndex = directThreadHistoryItems.findIndex(
+            (item) => String(item.itemId ?? '') === beforeItemId,
+          );
+          end =
+            anchorIndex >= 0 ? anchorIndex : directThreadHistoryItems.length;
+        }
+        const start = Math.max(0, end - limit);
+        const window = directThreadHistoryItems.slice(start, end);
+        const oldest = window[0];
         return {
-          items: [...directThreadHistoryItems],
-          hasMore: false,
-          firstItemId: null,
+          items: [...window],
+          hasMore: start > 0,
+          firstItemId:
+            oldest && typeof oldest.itemId === 'string' ? oldest.itemId : null,
         };
       }
       if (command === 'start_game_creator_supervisor_runtime_task') {

apps/ai-game-creator-shell/tests/appSurface/project-development.suite.ts

@@ -8342,6 +8342,87 @@ export function registerProjectSupervisorSurfaceTests() {
     ).toHaveLength(2);
   });
 
+  it('loads the earlier direct history page from the first-item anchor', async () => {
+    // 分页锚点走的是首屏切片给出的 `firstItemId`：切片本身从队尾取，老的一屏靠锚点继续向前。
+    const projectPath = '/tmp/launcher-direct-history-pagination-game';
+    const manifest = createGameCreationAppManifest(
+      'local-project-draft',
+      'launcher-direct-history-pagination-game',
+    );
+    const supervisorHarness = createProjectSupervisorRuntimeHarness({
+      projectPath,
+    });
+    // 26 条 > 首屏 20 条：首屏只显示最后 20 条，前面 6 条要靠"显示更早"翻页取回。
+    supervisorHarness.setDirectThreadHistory(
+      Array.from({ length: 26 }, (_, index) => {
+        const label = `历史对话 ${String(index + 1).padStart(2, '0')}`;
+        return {
+          itemType: 'message',
+          itemId: `direct-codex:turn-${label}:user`,
+          role: 'user',
+          text: label,
+          at: 1000 + index,
+        };
+      }),
+    );
+    const invoke = vi.fn(
+      async (command: string, args?: Record<string, unknown>) => {
+        if (command === 'get_design_agent_runtime_mode') return null;
+        if (command === 'inspect_local_project_directory') {
+          return {
+            projectPath,
+            exists: true,
+            isDirectory: true,
+            isGameCreatorProject: true,
+            projectName: 'launcher-direct-history-pagination-game',
+            recentRunStatus: null,
+            recentRunStopReason: null,
+          };
+        }
+        if (command === 'get_local_game_manifest') {
+          return manifest;
+        }
+        if (command === 'get_local_game_preview_status') {
+          return { status: 'stopped', url: null, port: null, root: null };
+        }
+        return supervisorHarness.invoke(command, args);
+      },
+    );
+    window.__TAURI__ = {
+      core: { invoke },
+      event: { listen: supervisorHarness.listen },
+    };
+    renderLauncherProjectsAt('/?launcher');
+
+    pickProjectFromLauncher(projectPath);
+
+    const supervisorSurface = await screen.findByLabelText('陶泥儿项目对话');
+    expect(
+      await within(supervisorSurface).findByText('历史对话 26'),
+    ).not.toBeNull();
+    // 首屏是尾部的 20 条：第 7 条起可见，更早的 6 条还没读进来。
+    expect(within(supervisorSurface).getByText('历史对话 07')).not.toBeNull();
+    expect(within(supervisorSurface).queryByText('历史对话 06')).toBeNull();
+    expect(invoke).toHaveBeenCalledWith('read_direct_project_history_slice', {
+      projectPath,
+      limit: 20,
+    });
+
+    fireEvent.click(screen.getByRole('button', { name: '显示更早的对话' }));
+
+    // 翻页按首屏最老一条的锚点向前取；取到文件头后按钮消失。
+    expect(
+      await within(supervisorSurface).findByText('历史对话 01'),
+    ).not.toBeNull();
+    expect(within(supervisorSurface).getByText('历史对话 06')).not.toBeNull();
+    expect(screen.queryByRole('button', { name: /显示更早/ })).toBeNull();
+    expect(invoke).toHaveBeenCalledWith('read_direct_project_history_slice', {
+      projectPath,
+      beforeItemId: 'direct-codex:turn-历史对话 07:user',
+      limit: 20,
+    });
+  });
+
   it('drains a notify that lands before the subscribe receipt so the running turn is not stranded', async () => {
     // 真实竞态：`subscribe` 在 Rust 侧已经注册好 subscriber 并开始通知，但前端还没拿到
     // subscriptionId。此时的通知不能白丢——拿到回执后必须补一次 consume，否则整个回合会卡在队列里。