Implement watch-event feature (017) with bookmark in RsvpBar

Add client-side watch/bookmark functionality: users can save events to
localStorage without RSVPing via a bookmark button next to the "I'm attending"
CTA. Watched events appear in the event list with a "Watching" label.
Bookmark is only visible for visitors (not attendees or organizers).

Includes spec, plan, research, tasks, unit tests, and E2E tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/e2e/watch-event.spec.ts

@@ -0,0 +1,218 @@
+import { http, HttpResponse } from 'msw'
+import { test, expect } from './msw-setup'
+import type { StoredEvent } from '../src/composables/useEventStorage'
+
+const STORAGE_KEY = 'fete:events'
+
+const fullEvent = {
+  eventToken: 'a1b2c3d4-e5f6-7890-abcd-ef1234567890',
+  title: 'Summer BBQ',
+  description: 'Bring your own drinks!',
+  dateTime: '2026-03-15T20:00:00+01:00',
+  timezone: 'Europe/Berlin',
+  location: 'Central Park, NYC',
+  attendeeCount: 12,
+  cancelled: false,
+}
+
+const rsvpToken = 'd4e5f6a7-b8c9-0123-4567-890abcdef012'
+const organizerToken = 'org-token-1234'
+
+function seedEvents(events: StoredEvent[]): string {
+  return `window.localStorage.setItem('${STORAGE_KEY}', ${JSON.stringify(JSON.stringify(events))})`
+}
+
+function watchSeed(): StoredEvent {
+  return {
+    eventToken: fullEvent.eventToken,
+    title: fullEvent.title,
+    dateTime: fullEvent.dateTime,
+  }
+}
+
+function rsvpSeed(): StoredEvent {
+  return {
+    eventToken: fullEvent.eventToken,
+    title: fullEvent.title,
+    dateTime: fullEvent.dateTime,
+    rsvpToken,
+    rsvpName: 'Anna',
+  }
+}
+
+function organizerSeed(): StoredEvent {
+  return {
+    eventToken: fullEvent.eventToken,
+    title: fullEvent.title,
+    dateTime: fullEvent.dateTime,
+    organizerToken,
+  }
+}
+
+test.describe('US1: Watch event from detail page', () => {
+  test('bookmark unfilled by default, tapping watches the event', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+    )
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).toBeVisible()
+    await expect(bookmark).toHaveAttribute('aria-label', 'Watch this event')
+
+    await bookmark.click()
+
+    await expect(bookmark).toHaveAttribute('aria-label', 'Stop watching this event')
+
+    // Navigate to event list via back link
+    await page.locator('.detail__back').click()
+
+    // Event appears with "Watching" label
+    await expect(page.getByText('Summer BBQ')).toBeVisible()
+    await expect(page.getByText('Watching')).toBeVisible()
+  })
+})
+
+test.describe('US2: Un-watch event from detail page', () => {
+  test('tapping filled bookmark un-watches the event', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+    )
+    await page.addInitScript(seedEvents([watchSeed()]))
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).toHaveAttribute('aria-label', 'Stop watching this event')
+
+    await bookmark.click()
+
+    await expect(bookmark).toHaveAttribute('aria-label', 'Watch this event')
+
+    // Navigate to event list via back link (avoid page.goto re-running addInitScript)
+    await page.locator('.detail__back').click()
+
+    // Event is gone
+    await expect(page.getByText('Summer BBQ')).not.toBeVisible()
+  })
+})
+
+test.describe('US3: Bookmark reflects attending status', () => {
+  test('bookmark is not visible when user has RSVPed, list shows Attendee', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+    )
+    await page.addInitScript(seedEvents([rsvpSeed()]))
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    // Bookmark not shown for attendees — RsvpBar shows status state
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).not.toBeVisible()
+
+    // Navigate to list via back link
+    await page.locator('.detail__back').click()
+    await expect(page.getByText('Attendee')).toBeVisible()
+    await expect(page.getByText('Watching')).not.toBeVisible()
+  })
+})
+
+test.describe('US4: RSVP cancellation preserves watch status', () => {
+  test('cancel RSVP → bookmark reappears, list shows Watching', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+      http.delete('*/api/events/:token/rsvps/:rsvpToken', () => {
+        return new HttpResponse(null, { status: 204 })
+      }),
+    )
+    await page.addInitScript(seedEvents([rsvpSeed()]))
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    // Cancel RSVP
+    await page.getByRole('button', { name: /You're attending/ }).click()
+    await page.locator('.rsvp-bar__cancel').click()
+    await page.getByRole('alertdialog').getByRole('button', { name: 'Cancel attendance' }).click()
+
+    // Bookmark reappears in CTA state, filled because event is still stored
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).toBeVisible()
+    await expect(bookmark).toHaveAttribute('aria-label', 'Stop watching this event')
+
+    // Navigate to list via back link
+    await page.locator('.detail__back').click()
+    await expect(page.getByText('Watching')).toBeVisible()
+    await expect(page.getByText('Attendee')).not.toBeVisible()
+  })
+})
+
+test.describe('US5: No bookmark for attendees and organizers', () => {
+  test('attendee does not see bookmark', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+    )
+    await page.addInitScript(seedEvents([rsvpSeed()]))
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).not.toBeVisible()
+  })
+
+  test('organizer does not see bookmark', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+    )
+    await page.addInitScript(seedEvents([organizerSeed()]))
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).not.toBeVisible()
+  })
+})
+
+test.describe('US6: Un-watch from event list', () => {
+  test('deleting a watched event skips confirmation dialog', async ({ page }) => {
+    await page.addInitScript(seedEvents([watchSeed()]))
+    await page.goto('/')
+
+    await expect(page.getByText('Summer BBQ')).toBeVisible()
+
+    await page.getByRole('button', { name: /Remove Summer BBQ/ }).click()
+
+    // No confirmation dialog — event removed immediately
+    await expect(page.getByText('Remove event?')).not.toBeVisible()
+    await expect(page.getByText('Summer BBQ')).not.toBeVisible()
+  })
+})
+
+test.describe('US7: Watcher upgrades to attendee', () => {
+  test('watch → RSVP → bookmark disappears, list shows Attendee', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => HttpResponse.json(fullEvent)),
+      http.post('*/api/events/:token/rsvps', () => {
+        return HttpResponse.json(
+          { rsvpToken: 'new-rsvp-token', name: 'Max' },
+          { status: 201 },
+        )
+      }),
+    )
+    await page.addInitScript(seedEvents([watchSeed()]))
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    // Verify watching state — bookmark visible
+    const bookmark = page.locator('.rsvp-bar__bookmark-inner')
+    await expect(bookmark).toBeVisible()
+    await expect(bookmark).toHaveAttribute('aria-label', 'Stop watching this event')
+
+    // RSVP
+    await page.getByRole('button', { name: "I'm attending" }).click()
+    const dialog = page.getByRole('dialog', { name: 'RSVP' })
+    await dialog.getByLabel('Your name').fill('Max')
+    await dialog.getByRole('button', { name: 'Count me in' }).click()
+
+    // Bookmark gone — status bar shown instead
+    await expect(bookmark).not.toBeVisible()
+
+    // Navigate to list via back link
+    await page.locator('.detail__back').click()
+    await expect(page.getByText('Attendee')).toBeVisible()
+    await expect(page.getByText('Watching')).not.toBeVisible()
+  })
+})