diff --git a/tests/integration/phase6-smoke.test.tsx b/tests/integration/phase6-smoke.test.tsx
new file mode 100644
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--- /dev/null
+++ b/tests/integration/phase6-smoke.test.tsx
@@ -0,0 +1,165 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { render, screen, fireEvent, act } from '@testing-library/react';
+import { AppShell } from '@/components/layout/AppShell';
+import { useFileStore } from '@/stores/file-store';
+import { useEditorStore } from '@/stores/editor-store';
+import { useAppStore } from '@/stores/app-store';
+import { useCommandStore } from '@/stores/command-store';
+
+// Mock react-resizable-panels (jsdom can't measure DOM for it)
+vi.mock('@/components/ui/resizable', () => ({
+  ResizablePanelGroup: ({ children, direction }: any) => (
+    <div data-testid="resizable-panel-group" data-direction={direction}>
+      {children}
+    </div>
+  ),
+  ResizablePanel: ({ children, defaultSize }: any) => (
+    <div data-testid="resizable-panel" data-size={defaultSize}>
+      {children}
+    </div>
+  ),
+  ResizableHandle: () => <div data-testid="resizable-handle" />,
+}));
+
+const menuListeners = new Map<string, (...args: unknown[]) => void>();
+vi.mock('@/lib/ipc', () => ({
+  ipc: {
+    file: {
+      open: vi.fn().mockResolvedValue({ ok: false, error: { code: 'NO_BRIDGE', message: 'mock' } }),
+      read: vi.fn().mockResolvedValue({ ok: true, data: '# hello' }),
+      write: vi.fn().mockResolvedValue({ ok: true, data: undefined }),
+      list: vi.fn().mockResolvedValue({
+        ok: true,
+        data: [{ name: 'README.md', path: '/root/README.md', isDirectory: false }],
+      }),
+      pickFolder: vi.fn().mockResolvedValue({ ok: true, data: '/root' }),
+      pickFile: vi.fn().mockResolvedValue({ ok: true, data: '/root/README.md' }),
+      onChange: vi.fn(() => () => {}),
+    },
+    menu: {
+      on: vi.fn((channel: string, cb: (...args: unknown[]) => void) => {
+        menuListeners.set(channel, cb);
+        return () => {
+          if (menuListeners.get(channel) === cb) menuListeners.delete(channel);
+        };
+      }),
+    },
+  },
+}));
+
+function fireMenu(channel: string, ...args: unknown[]): void {
+  const listener = menuListeners.get(channel);
+  if (!listener) throw new Error(`No menu listener for ${channel}`);
+  listener(...args);
+}
+
+describe('Phase 6 integration: menu → command → store', () => {
+  beforeEach(() => {
+    localStorage.clear();
+    menuListeners.clear();
+    useFileStore.setState({
+      tree: null,
+      rootPath: null,
+      expanded: new Set(),
+      openTabs: [],
+      activeTabId: null,
+    });
+    useEditorStore.setState({ buffers: new Map(), activeId: null });
+    useAppStore.setState({
+      sidebarVisible: true,
+      previewVisible: true,
+      zenMode: false,
+      paneSizes: { sidebar: 20, editor: 50, preview: 30 },
+    });
+    useCommandStore.setState({ handlers: {}, userBindings: {} });
+  });
+
+  it('toolbar Open Folder button opens the folder dialog and populates the tree', async () => {
+    render(<AppShell />);
+    const btn = screen.getByTestId('toolbar-open-folder');
+    await act(async () => {
+      fireEvent.click(btn);
+    });
+    expect(useFileStore.getState().tree).not.toBeNull();
+    expect(useFileStore.getState().rootPath).toBe('/root');
+  });
+
+  it('toolbar Save button invokes the registered file.save command (which writes)', async () => {
+    // Seed an open buffer
+    useFileStore.setState({
+      openTabs: [{ id: '/root/doc.md', path: '/root/doc.md', title: 'doc.md', dirty: true }],
+      activeTabId: '/root/doc.md',
+    });
+    useEditorStore.setState({
+      buffers: new Map([['/root/doc.md', { id: '/root/doc.md', content: '# x', dirty: true }]]),
+      activeId: '/root/doc.md',
+    });
+
+    render(<AppShell />);
+    const saveBtn = screen.getByTestId('toolbar-save');
+    await act(async () => {
+      fireEvent.click(saveBtn);
+    });
+    // After save, the buffer should be clean
+    expect(useEditorStore.getState().buffers.get('/root/doc.md')?.dirty).toBe(false);
+  });
+
+  it('header toggle sidebar button flips sidebarVisible', async () => {
+    render(<AppShell />);
+    const btn = screen.getByTestId('header-toggle-sidebar');
+    expect(btn).toHaveAttribute('aria-pressed', 'true');
+    await act(async () => {
+      fireEvent.click(btn);
+    });
+    expect(useAppStore.getState().sidebarVisible).toBe(false);
+    expect(btn).toHaveAttribute('aria-pressed', 'false');
+  });
+
+  it('native menu file-save event triggers save through the command store', async () => {
+    useFileStore.setState({
+      openTabs: [{ id: '/root/doc.md', path: '/root/doc.md', title: 'doc.md', dirty: true }],
+      activeTabId: '/root/doc.md',
+    });
+    useEditorStore.setState({
+      buffers: new Map([['/root/doc.md', { id: '/root/doc.md', content: '# y', dirty: true }]]),
+      activeId: '/root/doc.md',
+    });
+
+    render(<AppShell />);
+    await act(async () => {
+      fireMenu('file-save');
+    });
+    expect(useEditorStore.getState().buffers.get('/root/doc.md')?.dirty).toBe(false);
+  });
+
+  it('native menu toggle-preview event flips previewVisible', () => {
+    render(<AppShell />);
+    expect(useAppStore.getState().previewVisible).toBe(true);
+    act(() => {
+      fireMenu('toggle-preview');
+    });
+    expect(useAppStore.getState().previewVisible).toBe(false);
+  });
+
+  it('userBindings survive a remount via zustand persist', async () => {
+    useCommandStore.getState().setUserBinding('file.save', 'mod+shift+s');
+    await useCommandStore.persist?.flush?.();
+
+    // Read raw stored value
+    const stored = JSON.parse(localStorage.getItem('mc-command-store') ?? '{}');
+    expect(stored.state.userBindings['file.save']).toBe('mod+shift+s');
+  });
+
+  it('commands registered in AppShell are accessible by id from any consumer', () => {
+    render(<AppShell />);
+    const handlers = useCommandStore.getState().handlers;
+    expect(typeof handlers['file.open']).toBe('function');
+    expect(typeof handlers['file.openFolder']).toBe('function');
+    expect(typeof handlers['file.save']).toBe('function');
+    expect(typeof handlers['file.closeTab']).toBe('function');
+    expect(typeof handlers['tab.next']).toBe('function');
+    expect(typeof handlers['tab.prev']).toBe('function');
+    expect(typeof handlers['view.toggleSidebar']).toBe('function');
+    expect(typeof handlers['view.togglePreview']).toBe('function');
+  });
+});