test(FN-4306): complete Step 4 — add capacity banner gating coverage

Fusion-Task-Id: FN-4306
Fusion-Task-Lineage: b0ab9b60-de02-40a7-ad8b-0ca18c98e16c

packages/dashboard/app/components/__tests__/App.test.tsx

@@ -23,10 +23,19 @@ const defaultSettings: Settings = {
   worktreeInitCommand: "",
   testCommand: "",
   buildCommand: "",
+  capacityRiskBannerEnabled: false,
+  capacityRiskTodoThreshold: 20,
   experimentalFeatures: { insights: true, skillsView: true, agentsView: true, memoryView: true, evalsView: true },
 };
 
- 
+const mockAgentStats = {
+  activeCount: 0,
+  busyCount: 0,
+  pausedCount: 0,
+  todoTaskCount: 0,
+  idleNonEphemeralCount: 1,
+};
+
 const mockSubscribeSse = vi.fn((..._args: any[]) => vi.fn());
 
 vi.mock("../../sse-bus", () => ({
@@ -55,6 +64,7 @@ vi.mock("../../api", async (importOriginal) => {
     fetchModels: vi.fn(() => Promise.resolve({ models: [], favoriteProviders: [], favoriteModels: [] })),
     fetchGitRemotes: vi.fn(() => Promise.resolve([])),
     fetchAgents: vi.fn(() => Promise.resolve([])),
+    fetchAgentStats: vi.fn(() => Promise.resolve({ ...mockAgentStats })),
     fetchTaskDetail: vi.fn((id: string) => Promise.resolve({ id, title: `Task ${id}` })),
     fetchUnreadCount: vi.fn(() => Promise.resolve({ unreadCount: 0 })),
     fetchDashboardHealth: vi.fn(() => Promise.resolve({
@@ -660,6 +670,8 @@ beforeEach(() => {
   });
   mockUseViewportMode.mockReset();
   mockUseViewportMode.mockReturnValue("desktop");
+  mockAgentStats.todoTaskCount = 0;
+  mockAgentStats.idleNonEphemeralCount = 1;
 });
 
 describe("FN-4250 FileBrowserProvider coverage", () => {
@@ -685,6 +697,45 @@ describe("FN-4250 FileBrowserProvider coverage", () => {
   });
 });
 
+describe("Capacity risk banner gating", () => {
+  it("does not render banner when capacityRiskBannerEnabled is false", async () => {
+    mockAgentStats.todoTaskCount = 21;
+    mockAgentStats.idleNonEphemeralCount = 0;
+    vi.mocked(fetchSettings).mockResolvedValueOnce({
+      ...defaultSettings,
+      capacityRiskBannerEnabled: false,
+      capacityRiskTodoThreshold: 20,
+    });
+
+    render(<App />);
+    await waitForAppShell();
+
+    expect(screen.queryByText(/Capacity risk:/i)).not.toBeInTheDocument();
+  });
+
+  it("renders and dismisses banner when enabled", async () => {
+    mockAgentStats.todoTaskCount = 21;
+    mockAgentStats.idleNonEphemeralCount = 0;
+    vi.mocked(fetchSettings).mockResolvedValueOnce({
+      ...defaultSettings,
+      capacityRiskBannerEnabled: true,
+      capacityRiskTodoThreshold: 20,
+    });
+
+    render(<App />);
+    await waitFor(() => {
+      expect(screen.getByText(/Capacity risk:/i)).toBeInTheDocument();
+    });
+
+    fireEvent.click(screen.getByRole("button", { name: /dismiss capacity warning/i }));
+
+    expect(localStorage.getItem(scopedKey("kb-capacity-risk-banner-dismissed", DEFAULT_PROJECT_ID))).toBe("true");
+    await waitFor(() => {
+      expect(screen.queryByText(/Capacity risk:/i)).not.toBeInTheDocument();
+    });
+  });
+});
+
 describe("App backend-unreachable first-run flow", () => {
   it("renders backend connection error page instead of setup wizard when projects fetch fails during first-run", async () => {
     mockProjectsState.projects = [];

packages/dashboard/app/hooks/__tests__/useAppSettings.test.ts

@@ -30,6 +30,7 @@ describe("useAppSettings", () => {
       taskStuckTimeoutMs: 600000,
       staleHighFanoutBlockerAgeThresholdMs: 7200000,
       showQuickChatFAB: false,
+      capacityRiskBannerEnabled: false,
     } as never);
 
     mockUpdateSettings.mockResolvedValue({} as never);
@@ -49,6 +50,8 @@ describe("useAppSettings", () => {
       expect(result.current.taskStuckTimeoutMs).toBe(600000);
       expect(result.current.staleHighFanoutBlockerAgeThresholdMs).toBe(7200000);
       expect(result.current.showQuickChatFAB).toBe(false);
+      expect(result.current.capacityRiskBannerEnabled).toBe(false);
+      expect(result.current.capacityRiskTodoThreshold).toBe(20);
     });
 
     expect(mockFetchConfig).toHaveBeenCalledWith("proj_123");
@@ -117,6 +120,26 @@ describe("useAppSettings", () => {
     );
   });
 
+  it("propagates capacity risk settings from fetchSettings", async () => {
+    mockFetchSettings.mockResolvedValueOnce({
+      autoMerge: false,
+      globalPause: true,
+      enginePaused: false,
+      prAuthAvailable: true,
+      taskStuckTimeoutMs: 600000,
+      showQuickChatFAB: false,
+      capacityRiskBannerEnabled: true,
+      capacityRiskTodoThreshold: 30,
+    } as never);
+
+    const { result } = renderHook(() => useAppSettings("proj_123"));
+
+    await waitFor(() => {
+      expect(result.current.capacityRiskBannerEnabled).toBe(true);
+      expect(result.current.capacityRiskTodoThreshold).toBe(30);
+    });
+  });
+
   it("refresh() re-fetches and updates state", async () => {
     const { result } = renderHook(() => useAppSettings("proj_123"));
 

packages/dashboard/app/utils/projectStorage.ts

@@ -31,6 +31,7 @@ export const PROJECT_STORAGE_KEYS: string[] = [
   "kb-chat-active-session",
   "kb-dashboard-working-branch-filter",
   "kb-dashboard-base-branch-filter",
+  "kb-capacity-risk-banner-dismissed",
   "kb-files-line-numbers",
   "fusion-plugin-dependency-graph:positions",
 ];