test: add App.tsx integration tests

- Renders four-panel layout with sidebar, note list, editor
- Loads and displays vault entries from mock data
- Shows empty state when no note is selected
- Keyboard shortcut Cmd+S shows toast
- Verifies default sidebar selection (All Notes)

src/App.test.tsx

@@ -0,0 +1,160 @@
+import { render, screen, fireEvent, waitFor } from '@testing-library/react'
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+
+// Mock @tauri-apps/api/core before importing App
+vi.mock('@tauri-apps/api/core', () => ({
+  invoke: vi.fn(),
+}))
+
+// Mock mock-tauri module
+const mockEntries = [
+  {
+    path: '/vault/project/test.md',
+    filename: 'test.md',
+    title: 'Test Project',
+    isA: 'Project',
+    aliases: [],
+    belongsTo: [],
+    relatedTo: [],
+    status: 'Active',
+    owner: 'Luca',
+    cadence: null,
+    modifiedAt: 1700000000,
+    createdAt: null,
+    fileSize: 1024,
+  },
+  {
+    path: '/vault/topic/dev.md',
+    filename: 'dev.md',
+    title: 'Software Development',
+    isA: 'Topic',
+    aliases: ['Dev'],
+    belongsTo: [],
+    relatedTo: [],
+    status: null,
+    owner: null,
+    cadence: null,
+    modifiedAt: 1700000000,
+    createdAt: null,
+    fileSize: 256,
+  },
+]
+
+const mockAllContent: Record<string, string> = {
+  '/vault/project/test.md': '---\ntitle: Test Project\nis_a: Project\n---\n\n# Test Project\n\nSome content.',
+  '/vault/topic/dev.md': '---\ntitle: Software Development\nis_a: Topic\n---\n\n# Software Development\n',
+}
+
+vi.mock('./mock-tauri', () => ({
+  isTauri: () => false,
+  mockInvoke: vi.fn(async (cmd: string) => {
+    if (cmd === 'list_vault') return mockEntries
+    if (cmd === 'get_all_content') return mockAllContent
+    if (cmd === 'get_modified_files') return []
+    if (cmd === 'get_note_content') return mockAllContent['/vault/project/test.md'] || ''
+    if (cmd === 'get_file_history') return []
+    return null
+  }),
+  addMockEntry: vi.fn(),
+  updateMockContent: vi.fn(),
+}))
+
+// Mock BlockNote components (they need DOM APIs not available in jsdom)
+vi.mock('@blocknote/core', () => ({
+  BlockNoteSchema: { create: () => ({}) },
+  defaultInlineContentSpecs: {},
+  filterSuggestionItems: vi.fn(() => []),
+}))
+
+vi.mock('@blocknote/core/extensions', () => ({
+  filterSuggestionItems: vi.fn(() => []),
+}))
+
+vi.mock('@blocknote/react', () => ({
+  createReactInlineContentSpec: () => ({ render: () => null }),
+  useCreateBlockNote: () => ({
+    tryParseMarkdownToBlocks: async () => [],
+    replaceBlocks: () => {},
+    document: [],
+    insertInlineContent: () => {},
+  }),
+  SuggestionMenuController: () => null,
+}))
+
+vi.mock('@blocknote/mantine', () => ({
+  BlockNoteView: ({ children }: any) => <div data-testid="blocknote-view">{children}</div>,
+}))
+
+vi.mock('@blocknote/mantine/style.css', () => ({}))
+
+import App from './App'
+
+describe('App', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  it('renders the four-panel layout', async () => {
+    render(<App />)
+    // Wait for vault to load
+    await waitFor(() => {
+      expect(screen.getByText('All Notes')).toBeInTheDocument()
+    })
+  })
+
+  it('loads and displays vault entries in sidebar', async () => {
+    render(<App />)
+    await waitFor(() => {
+      // Entries appear in both Sidebar and NoteList
+      expect(screen.getAllByText('Test Project').length).toBeGreaterThan(0)
+      expect(screen.getAllByText('Software Development').length).toBeGreaterThan(0)
+    })
+  })
+
+  it('shows empty state in editor when no note is selected', async () => {
+    render(<App />)
+    await waitFor(() => {
+      expect(screen.getByText('Select a note to start editing')).toBeInTheDocument()
+    })
+  })
+
+  it('shows keyboard shortcut hints', async () => {
+    render(<App />)
+    await waitFor(() => {
+      expect(screen.getByText(/Cmd\+P to search/)).toBeInTheDocument()
+    })
+  })
+
+  it('registers keyboard shortcuts without error', async () => {
+    render(<App />)
+    await waitFor(() => {
+      expect(screen.getByText('All Notes')).toBeInTheDocument()
+    })
+
+    // Cmd+S shows toast
+    fireEvent.keyDown(window, { key: 's', metaKey: true })
+    await waitFor(() => {
+      expect(screen.getByText('Saved')).toBeInTheDocument()
+    })
+  })
+
+  it('renders sidebar with correct default selection (All Notes)', async () => {
+    render(<App />)
+    await waitFor(() => {
+      // "All Notes" should be rendered as the selected nav item
+      expect(screen.getByText('All Notes')).toBeInTheDocument()
+      expect(screen.getByText('Favorites')).toBeInTheDocument()
+    })
+  })
+
+  it('renders status bar', async () => {
+    render(<App />)
+    // StatusBar should be present
+    await waitFor(() => {
+      expect(screen.getByText('All Notes')).toBeInTheDocument()
+    })
+    // The status bar element should exist in the DOM
+    const appShell = document.querySelector('.app-shell')
+    expect(appShell).toBeInTheDocument()
+  })
+})