diff --git a/frontend/src/components/panels/__tests__/Sidebar.test.tsx b/frontend/src/components/panels/__tests__/Sidebar.test.tsx
new file mode 100644
index 0000000..79ce5eb
--- /dev/null
+++ b/frontend/src/components/panels/__tests__/Sidebar.test.tsx
@@ -0,0 +1,269 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest'
+import { render, screen, fireEvent, waitFor } from '@testing-library/react'
+import { Sidebar } from '../Sidebar'
+import { useCanvasStore } from '@/stores/canvasStore'
+import type { Node } from '@xyflow/react'
+import type { NodeData } from '@/types'
+
+// ── Mocks ────────────────────────────────────────────────────────────────────
+
+vi.mock('@/stores/canvasStore')
+
+vi.mock('@/api/client', () => ({
+  scanApi: {
+    trigger: vi.fn().mockResolvedValue({}),
+    pending: vi.fn().mockResolvedValue({ data: [] }),
+    hidden: vi.fn().mockResolvedValue({ data: [] }),
+    runs: vi.fn().mockResolvedValue({ data: [] }),
+    stop: vi.fn().mockResolvedValue({}),
+  },
+  settingsApi: {
+    get: vi.fn().mockResolvedValue({ data: { interval_seconds: 60 } }),
+    save: vi.fn().mockResolvedValue({ data: { interval_seconds: 60 } }),
+  },
+}))
+
+vi.mock('sonner', () => ({ toast: { success: vi.fn(), error: vi.fn() } }))
+
+vi.mock('@/components/ui/Logo', () => ({
+  Logo: ({ showText }: { showText: boolean }) => (
+    <div data-testid="logo" data-show-text={showText} />
+  ),
+}))
+
+vi.mock('@/components/ui/tooltip', () => ({
+  Tooltip: ({ children }: { children: React.ReactNode }) => <>{children}</>,
+  TooltipTrigger: ({ children }: { children: React.ReactNode }) => <>{children}</>,
+  TooltipContent: () => null,
+}))
+
+vi.mock('@/components/modals/PendingDeviceModal', () => ({
+  PendingDeviceModal: () => null,
+}))
+
+// ── Helpers ───────────────────────────────────────────────────────────────────
+
+const makeNode = (id: string, status: NodeData['status'], type: NodeData['type'] = 'server'): Node<NodeData> => ({
+  id,
+  type,
+  position: { x: 0, y: 0 },
+  data: { label: id, type, status, services: [] },
+})
+
+const mockToggleHideIp = vi.fn()
+
+function mockStore(overrides: Partial<ReturnType<typeof useCanvasStore>> = {}) {
+  vi.mocked(useCanvasStore).mockReturnValue({
+    nodes: [],
+    hasUnsavedChanges: false,
+    hideIp: false,
+    toggleHideIp: mockToggleHideIp,
+    addNode: vi.fn(),
+    scanEventTs: 0,
+    ...overrides,
+  } as ReturnType<typeof useCanvasStore>)
+}
+
+const defaultProps = {
+  onAddNode: vi.fn(),
+  onAddGroupRect: vi.fn(),
+  onScan: vi.fn(),
+  onSave: vi.fn(),
+  onNodeApproved: vi.fn(),
+}
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+describe('Sidebar', () => {
+  beforeEach(() => {
+    mockStore()
+    vi.clearAllMocks()
+  })
+
+  // ── Render ─────────────────────────────────────────────────────────────────
+
+  it('renders logo and nav items', () => {
+    render(<Sidebar {...defaultProps} />)
+    expect(screen.getByTestId('logo')).toBeInTheDocument()
+    expect(screen.getByText('Add Node')).toBeInTheDocument()
+    expect(screen.getByText('Save Canvas')).toBeInTheDocument()
+    expect(screen.getByText('Scan Network')).toBeInTheDocument()
+  })
+
+  it('shows all view nav items', () => {
+    render(<Sidebar {...defaultProps} />)
+    expect(screen.getByText('Canvas')).toBeInTheDocument()
+    expect(screen.getByText('Pending Devices')).toBeInTheDocument()
+    expect(screen.getByText('Hidden Devices')).toBeInTheDocument()
+    expect(screen.getByText('Scan History')).toBeInTheDocument()
+  })
+
+  // ── Stats ──────────────────────────────────────────────────────────────────
+
+  it('displays total / online / offline counts from store', () => {
+    mockStore({
+      nodes: [
+        makeNode('n1', 'online'),
+        makeNode('n2', 'online'),
+        makeNode('n3', 'offline'),
+        makeNode('n4', 'unknown'),
+      ],
+    })
+    render(<Sidebar {...defaultProps} />)
+    // Total (excludes groupRect)
+    expect(screen.getByText('4')).toBeInTheDocument()
+    // Online
+    expect(screen.getByText('2')).toBeInTheDocument()
+    // Offline
+    expect(screen.getByText('1')).toBeInTheDocument()
+  })
+
+  it('excludes groupRect nodes from stats', () => {
+    mockStore({
+      nodes: [
+        makeNode('n1', 'unknown'),  // 1 real node, not online/offline
+        makeNode('zone', 'unknown', 'groupRect'),
+      ],
+    })
+    render(<Sidebar {...defaultProps} />)
+    // Total row shows 1 (groupRect excluded), online/offline both 0
+    const totalRow = screen.getByText('Total').closest('div')!
+    expect(totalRow).toHaveTextContent('1')
+    expect(screen.getAllByText('0')).toHaveLength(2) // online=0, offline=0
+  })
+
+  // ── Collapse ───────────────────────────────────────────────────────────────
+
+  it('collapses sidebar on toggle button click', () => {
+    render(<Sidebar {...defaultProps} />)
+    const aside = screen.getByRole('complementary')
+    expect(aside).toHaveStyle({ width: '220px' })
+
+    const toggle = aside.querySelector('button')!
+    fireEvent.click(toggle)
+    expect(aside).toHaveStyle({ width: '48px' })
+  })
+
+  it('hides label text when collapsed', () => {
+    render(<Sidebar {...defaultProps} />)
+    const aside = screen.getByRole('complementary')
+    const toggle = aside.querySelector('button')!
+    fireEvent.click(toggle)
+    expect(screen.queryByText('Add Node')).not.toBeInTheDocument()
+  })
+
+  it('hides stats footer when collapsed', () => {
+    render(<Sidebar {...defaultProps} />)
+    expect(screen.getByText('Total')).toBeInTheDocument()
+    const toggle = screen.getByRole('complementary').querySelector('button')!
+    fireEvent.click(toggle)
+    expect(screen.queryByText('Total')).not.toBeInTheDocument()
+  })
+
+  it('shows logo with showText=false when collapsed', () => {
+    render(<Sidebar {...defaultProps} />)
+    const logo = screen.getByTestId('logo')
+    expect(logo).toHaveAttribute('data-show-text', 'true')
+    const toggle = screen.getByRole('complementary').querySelector('button')!
+    fireEvent.click(toggle)
+    expect(logo).toHaveAttribute('data-show-text', 'false')
+  })
+
+  // ── Action callbacks ───────────────────────────────────────────────────────
+
+  it('calls onAddNode when Add Node is clicked', () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Add Node'))
+    expect(defaultProps.onAddNode).toHaveBeenCalledOnce()
+  })
+
+  it('calls onAddGroupRect when Add Zone is clicked', () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Add Zone'))
+    expect(defaultProps.onAddGroupRect).toHaveBeenCalledOnce()
+  })
+
+  it('calls onSave when Save Canvas is clicked', () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Save Canvas'))
+    expect(defaultProps.onSave).toHaveBeenCalledOnce()
+  })
+
+  it('calls toggleHideIp when Hide IPs is clicked', () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Hide IPs'))
+    expect(mockToggleHideIp).toHaveBeenCalledOnce()
+  })
+
+  it('shows Show IPs label when hideIp is true', () => {
+    mockStore({ hideIp: true })
+    render(<Sidebar {...defaultProps} />)
+    expect(screen.getByText('Show IPs')).toBeInTheDocument()
+  })
+
+  // ── Unsaved changes badge ──────────────────────────────────────────────────
+
+  it('shows unsaved badge dot on Save Canvas when hasUnsavedChanges', () => {
+    mockStore({ hasUnsavedChanges: true })
+    render(<Sidebar {...defaultProps} />)
+    // The badge is a span sibling of the Save Canvas button icon
+    const saveBtn = screen.getByText('Save Canvas').closest('button')!
+    const badge = saveBtn.querySelector('span.rounded-full')
+    expect(badge).toBeInTheDocument()
+  })
+
+  it('does not show unsaved badge when no changes', () => {
+    mockStore({ hasUnsavedChanges: false })
+    render(<Sidebar {...defaultProps} />)
+    const saveBtn = screen.getByText('Save Canvas').closest('button')!
+    const badge = saveBtn.querySelector('span.rounded-full')
+    expect(badge).not.toBeInTheDocument()
+  })
+
+  // ── Scan action ────────────────────────────────────────────────────────────
+
+  it('calls scanApi.trigger and onScan prop when Scan Network is clicked', async () => {
+    const { scanApi } = await import('@/api/client')
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Scan Network'))
+    await waitFor(() => expect(scanApi.trigger).toHaveBeenCalledOnce())
+    expect(defaultProps.onScan).toHaveBeenCalledOnce()
+  })
+
+  it('switches to Scan History view after scan is triggered', async () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Scan Network'))
+    await waitFor(() => expect(screen.getByText('History')).toBeInTheDocument())
+  })
+
+  // ── Navigation ─────────────────────────────────────────────────────────────
+
+  it('shows Pending panel when Pending Devices nav item is clicked', async () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Pending Devices'))
+    await waitFor(() => expect(screen.getByText('No pending devices')).toBeInTheDocument())
+  })
+
+  it('shows Hidden panel when Hidden Devices nav item is clicked', async () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Hidden Devices'))
+    await waitFor(() => expect(screen.getByText('No hidden devices')).toBeInTheDocument())
+  })
+
+  it('shows History panel when Scan History nav item is clicked', async () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Scan History'))
+    await waitFor(() => expect(screen.getByText('No scans yet')).toBeInTheDocument())
+  })
+
+  it('toggles Settings panel on Settings click', async () => {
+    render(<Sidebar {...defaultProps} />)
+    fireEvent.click(screen.getByText('Settings'))
+    await waitFor(() =>
+      expect(screen.getByText('Status check interval (s)')).toBeInTheDocument(),
+    )
+    // Click the nav button again to close (use role to avoid matching the panel heading)
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    expect(screen.queryByText('Status check interval (s)')).not.toBeInTheDocument()
+  })
+})
diff --git a/frontend/src/hooks/__tests__/useStatusPolling.test.ts b/frontend/src/hooks/__tests__/useStatusPolling.test.ts
new file mode 100644
index 0000000..845c231
--- /dev/null
+++ b/frontend/src/hooks/__tests__/useStatusPolling.test.ts
@@ -0,0 +1,170 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
+import { renderHook } from '@testing-library/react'
+import { useStatusPolling } from '../useStatusPolling'
+import { useCanvasStore } from '@/stores/canvasStore'
+import { useAuthStore } from '@/stores/authStore'
+
+vi.mock('@/stores/canvasStore')
+vi.mock('@/stores/authStore')
+
+const mockUpdateNode = vi.fn()
+const mockNotifyScanDeviceFound = vi.fn()
+
+class MockWebSocket {
+  static instances: MockWebSocket[] = []
+  url: string
+  onopen: (() => void) | null = null
+  onmessage: ((e: { data: string }) => void) | null = null
+  onerror: ((e: unknown) => void) | null = null
+  send = vi.fn()
+  close = vi.fn()
+
+  constructor(url: string) {
+    this.url = url
+    MockWebSocket.instances.push(this)
+  }
+}
+
+describe('useStatusPolling', () => {
+  beforeEach(() => {
+    MockWebSocket.instances = []
+    vi.stubGlobal('WebSocket', MockWebSocket)
+
+    vi.mocked(useCanvasStore).mockReturnValue({
+      updateNode: mockUpdateNode,
+      notifyScanDeviceFound: mockNotifyScanDeviceFound,
+    } as ReturnType<typeof useCanvasStore>)
+
+    vi.mocked(useAuthStore).mockReturnValue({
+      isAuthenticated: true,
+      token: 'test-token',
+    } as ReturnType<typeof useAuthStore>)
+
+    Object.defineProperty(window, 'location', {
+      value: { protocol: 'http:', host: 'localhost:5173' },
+      writable: true,
+    })
+  })
+
+  afterEach(() => {
+    vi.restoreAllMocks()
+    mockUpdateNode.mockClear()
+    mockNotifyScanDeviceFound.mockClear()
+  })
+
+  it('does not open WebSocket when not authenticated', () => {
+    vi.mocked(useAuthStore).mockReturnValue({
+      isAuthenticated: false,
+      token: null,
+    } as ReturnType<typeof useAuthStore>)
+    renderHook(() => useStatusPolling())
+    expect(MockWebSocket.instances).toHaveLength(0)
+  })
+
+  it('does not open WebSocket when token is missing', () => {
+    vi.mocked(useAuthStore).mockReturnValue({
+      isAuthenticated: true,
+      token: null,
+    } as ReturnType<typeof useAuthStore>)
+    renderHook(() => useStatusPolling())
+    expect(MockWebSocket.instances).toHaveLength(0)
+  })
+
+  it('connects to correct ws:// URL', () => {
+    renderHook(() => useStatusPolling())
+    expect(MockWebSocket.instances).toHaveLength(1)
+    expect(MockWebSocket.instances[0].url).toBe('ws://localhost:5173/api/v1/status/ws/status')
+  })
+
+  it('uses wss:// when page is served over https', () => {
+    Object.defineProperty(window, 'location', {
+      value: { protocol: 'https:', host: 'mylab.local' },
+      writable: true,
+    })
+    renderHook(() => useStatusPolling())
+    expect(MockWebSocket.instances[0].url).toMatch(/^wss:\/\//)
+  })
+
+  it('sends token as first message on open', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    ws.onopen?.()
+    expect(ws.send).toHaveBeenCalledWith(JSON.stringify({ token: 'test-token' }))
+  })
+
+  it('calls updateNode with correct data on status message', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    ws.onmessage?.({
+      data: JSON.stringify({
+        node_id: 'node-1',
+        status: 'online',
+        checked_at: '2024-01-01T12:00:00Z',
+        response_time_ms: 42,
+      }),
+    })
+    expect(mockUpdateNode).toHaveBeenCalledWith('node-1', {
+      status: 'online',
+      response_time_ms: 42,
+      last_seen: '2024-01-01T12:00:00Z',
+    })
+  })
+
+  it('sets last_seen to undefined when status is offline', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    ws.onmessage?.({
+      data: JSON.stringify({
+        node_id: 'node-1',
+        status: 'offline',
+        checked_at: '2024-01-01T12:00:00Z',
+      }),
+    })
+    expect(mockUpdateNode).toHaveBeenCalledWith('node-1', {
+      status: 'offline',
+      response_time_ms: undefined,
+      last_seen: undefined,
+    })
+  })
+
+  it('sets response_time_ms to undefined when null in message', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    ws.onmessage?.({
+      data: JSON.stringify({ node_id: 'node-1', status: 'online', response_time_ms: null }),
+    })
+    expect(mockUpdateNode).toHaveBeenCalledWith(
+      'node-1',
+      expect.objectContaining({ response_time_ms: undefined }),
+    )
+  })
+
+  it('calls notifyScanDeviceFound on scan_device_found message', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    ws.onmessage?.({ data: JSON.stringify({ type: 'scan_device_found' }) })
+    expect(mockNotifyScanDeviceFound).toHaveBeenCalledOnce()
+    expect(mockUpdateNode).not.toHaveBeenCalled()
+  })
+
+  it('ignores malformed JSON without throwing', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    expect(() => ws.onmessage?.({ data: 'not-valid-json{{' })).not.toThrow()
+    expect(mockUpdateNode).not.toHaveBeenCalled()
+  })
+
+  it('ignores messages with no node_id or status', () => {
+    renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    ws.onmessage?.({ data: JSON.stringify({ some: 'unknown-field' }) })
+    expect(mockUpdateNode).not.toHaveBeenCalled()
+  })
+
+  it('closes WebSocket on unmount', () => {
+    const { unmount } = renderHook(() => useStatusPolling())
+    const ws = MockWebSocket.instances[0]
+    unmount()
+    expect(ws.close).toHaveBeenCalledOnce()
+  })
+})