feat(frontend): calendar-aware paddock briefing digest (#26)

Reframe Briefing into GP-window sections with driver/team tag chips, a sticky
"since last race" header, and client-side digest helpers (gpWindows, groupByWindow,
tagItems). Overlapping inter-race windows resolve to the latest GP; undated items
land in a Recent bucket. Vitest covers digest lib + page render/filter behaviour.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/test/BriefingPage.test.tsx

@@ -0,0 +1,209 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { render, screen, waitFor, fireEvent, within } from '@testing-library/react'
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import { BriefingPage } from '../pages/BriefingPage'
+import type { ChampHubDriver, ChampHubTeam, ChampionshipHub, Meeting, NewsItem } from '../types'
+
+vi.mock('../api', () => ({
+  fetchNews: vi.fn(),
+  fetchNewsArticle: vi.fn(),
+  markNewsRead: vi.fn(),
+  fetchSeasons: vi.fn(),
+  fetchSeasonMeetings: vi.fn(),
+  fetchChampionshipHub: vi.fn(),
+}))
+
+import {
+  fetchNews,
+  fetchNewsArticle,
+  fetchSeasons,
+  fetchSeasonMeetings,
+  fetchChampionshipHub,
+  markNewsRead,
+} from '../api'
+
+const mockFetchNews = vi.mocked(fetchNews)
+const mockFetchNewsArticle = vi.mocked(fetchNewsArticle)
+const mockFetchSeasons = vi.mocked(fetchSeasons)
+const mockFetchSeasonMeetings = vi.mocked(fetchSeasonMeetings)
+const mockFetchHub = vi.mocked(fetchChampionshipHub)
+const mockMarkNewsRead = vi.mocked(markNewsRead)
+
+const bahrain: Meeting = {
+  meeting_key: 1,
+  meeting_name: 'Bahrain',
+  meeting_official_name: 'Bahrain GP',
+  location: 'Sakhir',
+  country_name: 'Bahrain',
+  country_code: 'BRN',
+  country_flag: '',
+  circuit_short_name: 'Sakhir',
+  date_start: '2025-03-14T00:00:00+00:00',
+  date_end: '2025-03-16T23:59:59+00:00',
+  year: 2025,
+}
+
+const monaco: Meeting = {
+  meeting_key: 2,
+  meeting_name: 'Monaco',
+  meeting_official_name: 'Monaco GP',
+  location: 'Monaco',
+  country_name: 'Monaco',
+  country_code: 'MON',
+  country_flag: '',
+  circuit_short_name: 'Monaco',
+  date_start: '2025-05-23T00:00:00+00:00',
+  date_end: '2025-05-25T23:59:59+00:00',
+  year: 2025,
+}
+
+const drivers: ChampHubDriver[] = [
+  {
+    driver_number: 1,
+    name_acronym: 'VER',
+    full_name: 'Max Verstappen',
+    team_name: 'Red Bull',
+    team_colour: '3671c6',
+    points: 100,
+    position: 1,
+    wins: 3,
+    podiums: 5,
+    poles: 2,
+    form: [25, 18, 25],
+    cumulative: [25, 43, 68, 100],
+    teammate_wins: 4,
+    teammate_losses: 1,
+  },
+  {
+    driver_number: 4,
+    name_acronym: 'NOR',
+    full_name: 'Lando Norris',
+    team_name: 'McLaren',
+    team_colour: 'ff8000',
+    points: 80,
+    position: 2,
+    wins: 1,
+    podiums: 4,
+    poles: 1,
+    form: [18, 25, 18],
+    cumulative: [18, 36, 54, 80],
+    teammate_wins: 3,
+    teammate_losses: 2,
+  },
+]
+
+const teams: ChampHubTeam[] = [
+  { team_name: 'Red Bull', team_colour: '3671c6', points: 150, position: 1, wins: 4 },
+  { team_name: 'McLaren', team_colour: 'ff8000', points: 120, position: 2, wins: 2 },
+]
+
+const hub: ChampionshipHub = {
+  season: 2025,
+  round: 2,
+  total_rounds: 2,
+  rounds_left: 0,
+  last_race: 'Monaco GP',
+  round_labels: ['R1', 'R2'],
+  drivers,
+  teams,
+}
+
+const newsItems: NewsItem[] = [
+  {
+    source: 'autosport-f1',
+    title: 'Verstappen sets the pace in Bahrain',
+    url: 'https://example.com/bahrain-ver',
+    published_at: '2025-03-15T10:00:00Z',
+    fetched_at: '2025-03-15T11:00:00Z',
+    summary: 'Red Bull dominate opening practice',
+  },
+  {
+    source: 'racefans-f1',
+    title: 'Norris targets Monaco upgrade',
+    url: 'https://example.com/monaco-nor',
+    published_at: '2025-04-20T10:00:00Z',
+    fetched_at: '2025-04-20T11:00:00Z',
+    summary: 'McLaren bring new floor',
+  },
+  {
+    source: 'bbc-f1',
+    title: 'Undated paddock rumour',
+    url: 'https://example.com/undated',
+    fetched_at: '2025-04-21T11:00:00Z',
+  },
+]
+
+function renderPage() {
+  const queryClient = new QueryClient({
+    defaultOptions: { queries: { retry: false } },
+  })
+
+  return render(
+    <QueryClientProvider client={queryClient}>
+      <BriefingPage />
+    </QueryClientProvider>,
+  )
+}
+
+describe('BriefingPage digest layout', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    vi.setSystemTime(new Date('2025-04-10T12:00:00Z'))
+    mockFetchSeasons.mockResolvedValue([2025])
+    mockFetchSeasonMeetings.mockResolvedValue([bahrain, monaco])
+    mockFetchHub.mockResolvedValue(hub)
+    mockFetchNews.mockResolvedValue(newsItems)
+    mockFetchNewsArticle.mockResolvedValue({ title: 'Article', content: '<p>Body</p>' })
+    mockMarkNewsRead.mockResolvedValue(undefined)
+  })
+
+  afterEach(() => {
+    vi.useRealTimers()
+  })
+
+  it('renders sticky since-last header, GP sections, and recent bucket', async () => {
+    renderPage()
+
+    await waitFor(() => {
+      expect(screen.getByTestId('digest-sticky-header')).toHaveTextContent('Since Bahrain')
+    })
+
+    expect(screen.getByTestId('digest-window-2')).toHaveTextContent('Monaco')
+    expect(screen.getByTestId('digest-window-1')).toHaveTextContent('Bahrain')
+    expect(screen.getByTestId('digest-recent')).toHaveTextContent('Undated paddock rumour')
+    expect(screen.getByText('Verstappen sets the pace in Bahrain')).toBeInTheDocument()
+    expect(screen.getByText('Norris targets Monaco upgrade')).toBeInTheDocument()
+  })
+
+  it('filters the digest when a tag chip is clicked', async () => {
+    renderPage()
+
+    await waitFor(() => {
+      expect(screen.getByTestId('digest-sticky-header')).toBeInTheDocument()
+    })
+
+    const sticky = screen.getByTestId('digest-sticky-header')
+    const norTag = within(sticky).getByRole('button', { name: /^NOR$/i })
+    fireEvent.click(norTag)
+
+    await waitFor(() => {
+      expect(screen.queryByText('Verstappen sets the pace in Bahrain')).not.toBeInTheDocument()
+    })
+    expect(screen.getByText('Norris targets Monaco upgrade')).toBeInTheDocument()
+    expect(screen.getByTestId('digest-filter-clear')).toBeInTheDocument()
+
+    fireEvent.click(screen.getByTestId('digest-filter-clear'))
+    await waitFor(() => {
+      expect(screen.getByText('Verstappen sets the pace in Bahrain')).toBeInTheDocument()
+    })
+  })
+
+  it('preserves category tabs', async () => {
+    renderPage()
+
+    await waitFor(() => {
+      expect(screen.getByRole('tab', { name: /All/i })).toBeInTheDocument()
+    })
+    expect(screen.getByRole('tab', { name: /News/i })).toBeInTheDocument()
+  })
+})