test: add SettingsPanel tests covering settingsApi integration

- Opens panel and calls settingsApi.get
- Displays interval loaded from API
- Saves updated interval via settingsApi.save
- Shows error toast on save failure
- Toggles panel closed on second Settings click

frontend/src/components/panels/__tests__/SettingsPanel.test.tsx

@@ -0,0 +1,104 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { render, screen, fireEvent, waitFor } from '@testing-library/react'
+import { Sidebar } from '../Sidebar'
+import * as canvasStore from '@/stores/canvasStore'
+import { TooltipProvider } from '@/components/ui/tooltip'
+
+vi.mock('@/stores/canvasStore')
+vi.mock('sonner', () => ({ toast: { success: vi.fn(), error: vi.fn() } }))
+vi.mock('@/api/client', () => ({
+  scanApi: {
+    trigger: vi.fn(),
+    pending: vi.fn().mockResolvedValue({ data: [] }),
+    hidden: vi.fn().mockResolvedValue({ data: [] }),
+    runs: vi.fn().mockResolvedValue({ data: [] }),
+    getConfig: vi.fn().mockResolvedValue({ data: { ranges: [] } }),
+  },
+  settingsApi: {
+    get: vi.fn(),
+    save: vi.fn(),
+  },
+}))
+
+import { settingsApi } from '@/api/client'
+import { toast } from 'sonner'
+
+function renderSidebar() {
+  vi.mocked(canvasStore.useCanvasStore).mockReturnValue({
+    nodes: [],
+    hasUnsavedChanges: false,
+    hideIp: false,
+    toggleHideIp: vi.fn(),
+    addNode: vi.fn(),
+    scanEventTs: 0,
+  } as unknown as ReturnType<typeof canvasStore.useCanvasStore>)
+
+  return render(
+    <TooltipProvider>
+      <Sidebar
+        onAddNode={vi.fn()}
+        onAddGroupRect={vi.fn()}
+        onScan={vi.fn()}
+        onSave={vi.fn()}
+        onNodeApproved={vi.fn()}
+      />
+    </TooltipProvider>
+  )
+}
+
+describe('SettingsPanel', () => {
+  beforeEach(() => {
+    vi.mocked(settingsApi.get).mockResolvedValue({ data: { interval_seconds: 60 } } as never)
+    vi.mocked(settingsApi.save).mockResolvedValue({ data: { interval_seconds: 60 } } as never)
+    vi.mocked(toast.success).mockReset()
+    vi.mocked(toast.error).mockReset()
+  })
+
+  it('opens when Settings item is clicked', async () => {
+    renderSidebar()
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    await waitFor(() => {
+      expect(settingsApi.get).toHaveBeenCalledOnce()
+    })
+    expect(screen.getByText('Status check interval (s)')).toBeDefined()
+  })
+
+  it('displays interval loaded from API', async () => {
+    vi.mocked(settingsApi.get).mockResolvedValue({ data: { interval_seconds: 120 } } as never)
+    renderSidebar()
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    const input = await screen.findByDisplayValue('120')
+    expect(input).toBeDefined()
+  })
+
+  it('saves interval via settingsApi on Save click', async () => {
+    renderSidebar()
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    const input = await screen.findByDisplayValue('60')
+    fireEvent.change(input, { target: { value: '180' } })
+    fireEvent.click(screen.getByRole('button', { name: 'Save' }))
+    await waitFor(() => {
+      expect(settingsApi.save).toHaveBeenCalledWith({ interval_seconds: 180 })
+      expect(toast.success).toHaveBeenCalledWith('Settings saved')
+    })
+  })
+
+  it('shows error toast when save fails', async () => {
+    vi.mocked(settingsApi.save).mockRejectedValue(new Error('network'))
+    renderSidebar()
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    await screen.findByDisplayValue('60')
+    fireEvent.click(screen.getByRole('button', { name: 'Save' }))
+    await waitFor(() => {
+      expect(toast.error).toHaveBeenCalledWith('Failed to save settings')
+    })
+  })
+
+  it('closes panel when Settings is clicked again', async () => {
+    renderSidebar()
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    await screen.findByText('Status check interval (s)')
+    fireEvent.click(screen.getByRole('button', { name: 'Settings' }))
+    expect(screen.queryByText('Status check interval (s)')).toBeNull()
+  })
+})