fix: 修复 AI 设计任务栏同步与独立滚动

问题：生成任务未及时出现在右侧栏，任务区与会话区还会共享外层滚动。

实现：补齐 Agent 回合与 Quote 确认后的任务同步，锁定左右滚动容器并增加桌面布局和异步任务回归测试。

tests/unit/image-canvas-page.test.tsx

@@ -220,6 +220,38 @@ describe('ImageCanvas Workspace-first design experience', () => {
     expect(screen.queryByText(/当前 Agent/)).not.toBeInTheDocument();
   });
 
+  it('keeps the task list visible in a 1404px desktop workspace', async () => {
+    const previousWidth = window.innerWidth;
+    Object.defineProperty(window, 'innerWidth', { configurable: true, value: 1404 });
+
+    try {
+      render(<MemoryRouter><ImageCanvas /></MemoryRouter>);
+      await screen.findByTestId('image-workspace-conversation');
+
+      expect(screen.getByTestId('design-task-list')).toBeInTheDocument();
+      expect(screen.getByTestId('design-pane-divider')).toHaveClass('lg:block');
+    } finally {
+      Object.defineProperty(window, 'innerWidth', {
+        configurable: true,
+        value: previousWidth,
+      });
+    }
+  });
+
+  it('keeps conversation and task scrolling isolated', async () => {
+    render(<MemoryRouter><ImageCanvas /></MemoryRouter>);
+    await screen.findByTestId('image-workspace-conversation');
+
+    expect(screen.getByTestId('image-canvas-page'))
+      .toHaveClass('h-full', 'overflow-hidden');
+    expect(screen.getByTestId('image-workspace-conversation'))
+      .toHaveClass('overflow-y-auto', 'overscroll-contain');
+    expect(screen.getByTestId('design-task-list'))
+      .toHaveClass('lg:h-full', 'overflow-hidden');
+    expect(screen.getByTestId('design-task-scroll'))
+      .toHaveClass('lg:h-[calc(100%-57px)]', 'overflow-y-auto', 'overscroll-contain');
+  });
+
   it('explains the project model before the first Workspace is created', async () => {
     fetchImageWorkspaceMock.mockResolvedValueOnce({
       ...bootstrapFixture,
@@ -250,6 +282,35 @@ describe('ImageCanvas Workspace-first design experience', () => {
     expect(confirmImageWorkspaceGenerationMock).not.toHaveBeenCalled();
   });
 
+  it('refreshes tasks after an Agent turn creates a generation task', async () => {
+    const queuedTask = {
+      ...taskFixture,
+      taskId: 'task-two',
+      status: 'queued' as const,
+      resultAssets: [],
+    };
+    fetchImageWorkspaceTasksMock
+      .mockResolvedValueOnce([])
+      .mockResolvedValueOnce([queuedTask]);
+
+    render(<MemoryRouter><ImageCanvas /></MemoryRouter>);
+    await screen.findByTestId('design-quote-quote-one');
+
+    const confirmationReply = workspaceFixture().messages[1].quickReplies[0];
+    fireEvent.change(screen.getByLabelText('设计需求'), {
+      target: { value: confirmationReply },
+    });
+    fireEvent.click(screen.getByRole('button', { name: '发送给设计 Agent' }));
+
+    await waitFor(() => expect(sendImageWorkspaceMessageMock).toHaveBeenCalledWith(
+      'workspace-cloud',
+      1,
+      confirmationReply,
+    ));
+    await waitFor(() => expect(fetchImageWorkspaceTasksMock).toHaveBeenCalledTimes(2));
+    expect(await screen.findByTestId('design-task-task-two')).toBeInTheDocument();
+  });
+
   it('creates a generation task only through explicit Quote confirmation', async () => {
     fetchImageWorkspaceTasksMock
       .mockResolvedValueOnce([taskFixture])
@@ -268,4 +329,28 @@ describe('ImageCanvas Workspace-first design experience', () => {
       .toHaveBeenCalledWith('workspace-cloud', 1, 'quote-one'));
     await waitFor(() => expect(fetchImageWorkspaceTasksMock).toHaveBeenCalledTimes(2));
   });
+
+  it('keeps checking after Quote confirmation until the new task becomes visible', async () => {
+    const queuedTask = {
+      ...taskFixture,
+      taskId: 'task-delayed',
+      status: 'queued' as const,
+      resultAssets: [],
+    };
+    fetchImageWorkspaceTasksMock
+      .mockResolvedValueOnce([])
+      .mockResolvedValueOnce([])
+      .mockResolvedValueOnce([queuedTask]);
+
+    render(<MemoryRouter><ImageCanvas /></MemoryRouter>);
+    await screen.findByTestId('design-quote-quote-one');
+
+    fireEvent.click(screen.getByRole('button', { name: '确认并开始生成' }));
+
+    await waitFor(() => expect(confirmImageWorkspaceGenerationMock)
+      .toHaveBeenCalledWith('workspace-cloud', 1, 'quote-one'));
+    await waitFor(() => expect(fetchImageWorkspaceTasksMock).toHaveBeenCalledTimes(3));
+    expect(await screen.findByTestId('design-task-task-delayed'))
+      .toBeInTheDocument();
+  });
 });