Add RSVP frontend: bottom sheet form, RsvpBar, and localStorage persistence

Introduces BottomSheet and RsvpBar components, integrates the RSVP
submission flow into EventDetailView, extends useEventStorage with
saveRsvp/getRsvp, and adds unit tests plus an E2E spec for the RSVP
workflow.

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

frontend/e2e/event-rsvp.spec.ts

@@ -0,0 +1,185 @@
+import { http, HttpResponse } from 'msw'
+import { test, expect } from './msw-setup'
+
+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,
+  expired: false,
+}
+
+test.describe('US1: RSVP submission flow', () => {
+  test('submits RSVP, updates attendee count, and persists in localStorage', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+      http.post('*/api/events/:token/rsvps', () => {
+        return HttpResponse.json(
+          { rsvpToken: 'd4e5f6a7-b8c9-0123-4567-890abcdef012', name: 'Max Mustermann' },
+          { status: 201 },
+        )
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    // CTA is visible
+    const cta = page.getByRole('button', { name: "I'm attending" })
+    await expect(cta).toBeVisible()
+
+    // Open bottom sheet
+    await cta.click()
+    const dialog = page.getByRole('dialog', { name: 'RSVP' })
+    await expect(dialog).toBeVisible()
+
+    // Fill name and submit
+    await dialog.getByLabel('Your name').fill('Max Mustermann')
+    await dialog.getByRole('button', { name: 'Count me in' }).click()
+
+    // Bottom sheet closes, status bar appears
+    await expect(dialog).not.toBeVisible()
+    await expect(page.getByText("You're attending!")).toBeVisible()
+    await expect(cta).not.toBeVisible()
+
+    // Attendee count incremented
+    await expect(page.getByText('13')).toBeVisible()
+
+    // Verify localStorage
+    const stored = await page.evaluate(() => {
+      const raw = localStorage.getItem('fete:events')
+      return raw ? JSON.parse(raw) : null
+    })
+    expect(stored).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          eventToken: 'a1b2c3d4-e5f6-7890-abcd-ef1234567890',
+          rsvpToken: 'd4e5f6a7-b8c9-0123-4567-890abcdef012',
+          rsvpName: 'Max Mustermann',
+        }),
+      ]),
+    )
+  })
+
+  test('shows validation error when name is empty', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+    await page.getByRole('button', { name: "I'm attending" }).click()
+
+    const dialog = page.getByRole('dialog', { name: 'RSVP' })
+    await dialog.getByRole('button', { name: 'Count me in' }).click()
+
+    await expect(page.getByText('Please enter your name.')).toBeVisible()
+  })
+
+  test('restores RSVP status from localStorage on page load', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+    )
+
+    // Pre-seed localStorage
+    await page.goto('/')
+    await page.evaluate(() => {
+      localStorage.setItem(
+        'fete:events',
+        JSON.stringify([
+          {
+            eventToken: 'a1b2c3d4-e5f6-7890-abcd-ef1234567890',
+            title: 'Summer BBQ',
+            dateTime: '2026-03-15T20:00:00+01:00',
+            expiryDate: '',
+            rsvpToken: 'existing-rsvp-token',
+            rsvpName: 'Anna',
+          },
+        ]),
+      )
+    })
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    // Status bar should show, not CTA
+    await expect(page.getByText("You're attending!")).toBeVisible()
+    await expect(page.getByRole('button', { name: "I'm attending" })).not.toBeVisible()
+  })
+
+  test('shows error when server is unreachable during RSVP', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+      http.post('*/api/events/:token/rsvps', () => {
+        return HttpResponse.json(
+          { type: 'about:blank', title: 'Bad Request', status: 400 },
+          { status: 400, headers: { 'Content-Type': 'application/problem+json' } },
+        )
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+    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()
+
+    await expect(page.getByText('Could not submit RSVP. Please try again.')).toBeVisible()
+  })
+
+  test('does not show RSVP bar for organizer', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json(fullEvent)
+      }),
+    )
+
+    // Pre-seed localStorage with organizer token
+    await page.goto('/')
+    await page.evaluate(() => {
+      localStorage.setItem(
+        'fete:events',
+        JSON.stringify([
+          {
+            eventToken: 'a1b2c3d4-e5f6-7890-abcd-ef1234567890',
+            organizerToken: 'org-token-123',
+            title: 'Summer BBQ',
+            dateTime: '2026-03-15T20:00:00+01:00',
+            expiryDate: '',
+          },
+        ]),
+      )
+    })
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    // Event content should load
+    await expect(page.getByText('Summer BBQ')).toBeVisible()
+
+    // But no RSVP bar
+    await expect(page.getByRole('button', { name: "I'm attending" })).not.toBeVisible()
+    await expect(page.getByText("You're attending!")).not.toBeVisible()
+  })
+
+  test('does not show RSVP bar on expired event', async ({ page, network }) => {
+    network.use(
+      http.get('*/api/events/:token', () => {
+        return HttpResponse.json({ ...fullEvent, expired: true })
+      }),
+    )
+
+    await page.goto(`/events/${fullEvent.eventToken}`)
+
+    await expect(page.getByText('This event has ended.')).toBeVisible()
+    await expect(page.getByRole('button', { name: "I'm attending" })).not.toBeVisible()
+  })
+})

frontend/src/assets/main.css

@@ -192,3 +192,34 @@ textarea.form-field {
   white-space: nowrap;
   border: 0;
 }
+
+/* Bottom sheet form */
+.sheet-title {
+  font-size: 1.2rem;
+  font-weight: 700;
+  color: var(--color-text);
+}
+
+.rsvp-form {
+  display: flex;
+  flex-direction: column;
+  gap: var(--spacing-md);
+}
+
+.rsvp-form__label {
+  font-size: 0.85rem;
+  font-weight: 700;
+  color: var(--color-text);
+  padding-left: 0.25rem;
+}
+
+.rsvp-form__field-error {
+  color: #d32f2f;
+  font-size: 0.875rem;
+  font-weight: 600;
+  padding-left: 0.25rem;
+}
+
+.rsvp-form__error {
+  text-align: center;
+}

frontend/src/components/BottomSheet.vue

@@ -0,0 +1,96 @@
+<template>
+  <Teleport to="body">
+    <Transition name="sheet">
+      <div v-if="open" class="sheet-backdrop" @click.self="$emit('close')" @keydown.escape="$emit('close')">
+        <div class="sheet" role="dialog" aria-modal="true" :aria-label="label" ref="sheetEl" tabindex="-1">
+          <div class="sheet__handle" aria-hidden="true" />
+          <slot />
+        </div>
+      </div>
+    </Transition>
+  </Teleport>
+</template>
+
+<script setup lang="ts">
+import { ref, watch, nextTick } from 'vue'
+
+defineProps<{
+  open: boolean
+  label: string
+}>()
+
+defineEmits<{
+  close: []
+}>()
+
+const sheetEl = ref<HTMLElement | null>(null)
+
+watch(
+  () => sheetEl.value,
+  async (el) => {
+    if (el) {
+      await nextTick()
+      const firstInput = el.querySelector<HTMLElement>('input, textarea, button[type="submit"]')
+      if (firstInput) {
+        firstInput.focus()
+      } else {
+        el.focus()
+      }
+    }
+  },
+)
+</script>
+
+<style scoped>
+.sheet-backdrop {
+  position: fixed;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.4);
+  display: flex;
+  align-items: flex-end;
+  justify-content: center;
+  z-index: 100;
+}
+
+.sheet {
+  background: var(--color-card);
+  border-radius: 20px 20px 0 0;
+  padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-2xl);
+  width: 100%;
+  max-width: var(--content-max-width);
+  display: flex;
+  flex-direction: column;
+  gap: var(--spacing-lg);
+  outline: none;
+}
+
+.sheet__handle {
+  width: 36px;
+  height: 4px;
+  background: #ccc;
+  border-radius: 2px;
+  align-self: center;
+  flex-shrink: 0;
+}
+
+/* Transition */
+.sheet-enter-active,
+.sheet-leave-active {
+  transition: opacity 0.25s ease;
+}
+
+.sheet-enter-active .sheet,
+.sheet-leave-active .sheet {
+  transition: transform 0.25s ease;
+}
+
+.sheet-enter-from,
+.sheet-leave-to {
+  opacity: 0;
+}
+
+.sheet-enter-from .sheet,
+.sheet-leave-to .sheet {
+  transform: translateY(100%);
+}
+</style>

frontend/src/components/RsvpBar.vue

@@ -0,0 +1,75 @@
+<template>
+  <div class="rsvp-bar">
+    <div class="rsvp-bar__inner">
+      <!-- Status state: already RSVPed -->
+      <div v-if="hasRsvp" class="rsvp-bar__status">
+        <span class="rsvp-bar__check" aria-hidden="true">✓</span>
+        <span class="rsvp-bar__text">You're attending!</span>
+      </div>
+
+      <!-- CTA state: no RSVP yet -->
+      <button v-else class="btn-primary rsvp-bar__cta" type="button" @click="$emit('open')">
+        I'm attending
+      </button>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+defineProps<{
+  hasRsvp?: boolean
+}>()
+
+defineEmits<{
+  open: []
+}>()
+</script>
+
+<style scoped>
+.rsvp-bar {
+  position: fixed;
+  bottom: 0;
+  left: 0;
+  right: 0;
+  display: flex;
+  justify-content: center;
+  z-index: 50;
+  padding: var(--spacing-md) var(--content-padding);
+  padding-bottom: calc(var(--spacing-md) + env(safe-area-inset-bottom, 0px));
+}
+
+.rsvp-bar__inner {
+  width: 100%;
+  max-width: var(--content-max-width);
+}
+
+.rsvp-bar__cta {
+  width: 100%;
+}
+
+.rsvp-bar__status {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: var(--spacing-xs);
+  background: var(--color-card);
+  border-radius: var(--radius-card);
+  padding: var(--spacing-md) var(--spacing-lg);
+  box-shadow: var(--shadow-card);
+  font-weight: 600;
+  font-size: 0.95rem;
+  color: var(--color-text);
+}
+
+.rsvp-bar__check {
+  color: #4caf50;
+  font-size: 1.1rem;
+  font-weight: 700;
+}
+
+.rsvp-bar__text {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+</style>

frontend/src/components/__tests__/BottomSheet.spec.ts

@@ -0,0 +1,51 @@
+import { describe, it, expect } from 'vitest'
+import { mount } from '@vue/test-utils'
+import BottomSheet from '../BottomSheet.vue'
+
+function mountSheet(open = true) {
+  return mount(BottomSheet, {
+    props: { open, label: 'Test Sheet' },
+    slots: { default: '<p>Sheet content</p>' },
+    attachTo: document.body,
+  })
+}
+
+describe('BottomSheet', () => {
+  it('renders slot content when open', () => {
+    const wrapper = mountSheet(true)
+    expect(document.body.textContent).toContain('Sheet content')
+    wrapper.unmount()
+  })
+
+  it('does not render content when closed', () => {
+    const wrapper = mountSheet(false)
+    expect(document.body.querySelector('[role="dialog"]')).toBeNull()
+    wrapper.unmount()
+  })
+
+  it('has aria-modal and aria-label on the dialog', () => {
+    const wrapper = mountSheet(true)
+    const dialog = document.body.querySelector('[role="dialog"]')!
+    expect(dialog.getAttribute('aria-modal')).toBe('true')
+    expect(dialog.getAttribute('aria-label')).toBe('Test Sheet')
+    wrapper.unmount()
+  })
+
+  it('emits close when backdrop is clicked', async () => {
+    const wrapper = mountSheet(true)
+    const backdrop = document.body.querySelector('.sheet-backdrop')! as HTMLElement
+    await backdrop.click()
+    // Vue test utils tracks emitted events on the wrapper
+    expect(wrapper.emitted('close')).toBeTruthy()
+    wrapper.unmount()
+  })
+
+  it('emits close on Escape key', async () => {
+    const wrapper = mountSheet(true)
+    const backdrop = document.body.querySelector('.sheet-backdrop')! as HTMLElement
+    backdrop.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }))
+    await wrapper.vm.$nextTick()
+    expect(wrapper.emitted('close')).toBeTruthy()
+    wrapper.unmount()
+  })
+})

frontend/src/components/__tests__/RsvpBar.spec.ts

@@ -0,0 +1,30 @@
+import { describe, it, expect } from 'vitest'
+import { mount } from '@vue/test-utils'
+import RsvpBar from '../RsvpBar.vue'
+
+describe('RsvpBar', () => {
+  it('renders CTA button when hasRsvp is false', () => {
+    const wrapper = mount(RsvpBar)
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(true)
+    expect(wrapper.find('.rsvp-bar__cta').text()).toBe("I'm attending")
+    expect(wrapper.find('.rsvp-bar__status').exists()).toBe(false)
+  })
+
+  it('renders status text when hasRsvp is true', () => {
+    const wrapper = mount(RsvpBar, { props: { hasRsvp: true } })
+    expect(wrapper.find('.rsvp-bar__status').exists()).toBe(true)
+    expect(wrapper.find('.rsvp-bar__text').text()).toBe("You're attending!")
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(false)
+  })
+
+  it('emits open when CTA button is clicked', async () => {
+    const wrapper = mount(RsvpBar)
+    await wrapper.find('.rsvp-bar__cta').trigger('click')
+    expect(wrapper.emitted('open')).toHaveLength(1)
+  })
+
+  it('does not render CTA button when hasRsvp is true', () => {
+    const wrapper = mount(RsvpBar, { props: { hasRsvp: true } })
+    expect(wrapper.find('button').exists()).toBe(false)
+  })
+})

frontend/src/composables/__tests__/useEventStorage.spec.ts

@@ -116,4 +116,52 @@ describe('useEventStorage', () => {
     expect(events).toHaveLength(1)
     expect(events[0]!.title).toBe('New Title')
   })
+
+  it('saves and retrieves RSVP for an existing event', () => {
+    const { saveCreatedEvent, saveRsvp, getRsvp } = useEventStorage()
+
+    saveCreatedEvent({
+      eventToken: 'abc-123',
+      title: 'Birthday',
+      dateTime: '2026-06-15T20:00:00+02:00',
+      expiryDate: '2026-07-15',
+    })
+
+    saveRsvp('abc-123', 'rsvp-token-1', 'Max', 'Birthday', '2026-06-15T20:00:00+02:00')
+
+    const rsvp = getRsvp('abc-123')
+    expect(rsvp).toEqual({ rsvpToken: 'rsvp-token-1', rsvpName: 'Max' })
+  })
+
+  it('saves RSVP for a new event (not previously stored)', () => {
+    const { saveRsvp, getRsvp, getStoredEvents } = useEventStorage()
+
+    saveRsvp('new-event', 'rsvp-token-2', 'Anna', 'Party', '2026-08-01T18:00:00+02:00')
+
+    const rsvp = getRsvp('new-event')
+    expect(rsvp).toEqual({ rsvpToken: 'rsvp-token-2', rsvpName: 'Anna' })
+
+    const events = getStoredEvents()
+    expect(events).toHaveLength(1)
+    expect(events[0]!.eventToken).toBe('new-event')
+    expect(events[0]!.title).toBe('Party')
+  })
+
+  it('returns undefined RSVP for event without RSVP', () => {
+    const { saveCreatedEvent, getRsvp } = useEventStorage()
+
+    saveCreatedEvent({
+      eventToken: 'abc-123',
+      title: 'Test',
+      dateTime: '2026-06-15T20:00:00+02:00',
+      expiryDate: '2026-07-15',
+    })
+
+    expect(getRsvp('abc-123')).toBeUndefined()
+  })
+
+  it('returns undefined RSVP for unknown event', () => {
+    const { getRsvp } = useEventStorage()
+    expect(getRsvp('unknown')).toBeUndefined()
+  })
 })

frontend/src/composables/useEventStorage.ts

@@ -4,6 +4,8 @@ export interface StoredEvent {
   title: string
   dateTime: string
   expiryDate: string
+  rsvpToken?: string
+  rsvpName?: string
 }
 
 const STORAGE_KEY = 'fete:events'
@@ -37,5 +39,25 @@ export function useEventStorage() {
     return event?.organizerToken
   }
 
-  return { saveCreatedEvent, getStoredEvents, getOrganizerToken }
+  function saveRsvp(eventToken: string, rsvpToken: string, rsvpName: string, title: string, dateTime: string): void {
+    const events = readEvents()
+    const existing = events.find((e) => e.eventToken === eventToken)
+    if (existing) {
+      existing.rsvpToken = rsvpToken
+      existing.rsvpName = rsvpName
+    } else {
+      events.push({ eventToken, title, dateTime, expiryDate: '', rsvpToken, rsvpName })
+    }
+    writeEvents(events)
+  }
+
+  function getRsvp(eventToken: string): { rsvpToken: string; rsvpName: string } | undefined {
+    const event = readEvents().find((e) => e.eventToken === eventToken)
+    if (event?.rsvpToken && event?.rsvpName) {
+      return { rsvpToken: event.rsvpToken, rsvpName: event.rsvpName }
+    }
+    return undefined
+  }
+
+  return { saveCreatedEvent, getStoredEvents, getOrganizerToken, saveRsvp, getRsvp }
 }

frontend/src/views/EventDetailView.vue

@@ -54,6 +54,38 @@
       <p class="detail__message">Something went wrong.</p>
       <button class="btn-primary" type="button" @click="fetchEvent">Retry</button>
     </div>
+
+    <!-- RSVP bar (only for loaded, non-expired events) -->
+    <RsvpBar
+      v-if="state === 'loaded' && event && !event.expired && !isOrganizer"
+      :has-rsvp="!!rsvpName"
+      @open="sheetOpen = true"
+    />
+
+    <!-- RSVP bottom sheet -->
+    <BottomSheet :open="sheetOpen" label="RSVP" @close="sheetOpen = false">
+      <h2 class="sheet-title">RSVP</h2>
+      <form class="rsvp-form" @submit.prevent="submitRsvp" novalidate>
+        <div class="form-group">
+          <label class="rsvp-form__label" for="rsvp-name">Your name</label>
+          <input
+            id="rsvp-name"
+            v-model.trim="nameInput"
+            class="form-field"
+            type="text"
+            placeholder="e.g. Max Mustermann"
+            maxlength="100"
+            required
+            @input="nameError = ''"
+          />
+          <span v-if="nameError" class="rsvp-form__field-error" role="alert">{{ nameError }}</span>
+        </div>
+        <button class="btn-primary" type="submit" :disabled="submitting">
+          {{ submitting ? 'Sending…' : "Count me in" }}
+        </button>
+        <p v-if="submitError" class="rsvp-form__field-error rsvp-form__error" role="alert">{{ submitError }}</p>
+      </form>
+    </BottomSheet>
   </main>
 </template>
 
@@ -61,15 +93,29 @@
 import { ref, computed, onMounted } from 'vue'
 import { RouterLink, useRoute } from 'vue-router'
 import { api } from '@/api/client'
+import { useEventStorage } from '@/composables/useEventStorage'
+import BottomSheet from '@/components/BottomSheet.vue'
+import RsvpBar from '@/components/RsvpBar.vue'
 import type { components } from '@/api/schema'
 
 type GetEventResponse = components['schemas']['GetEventResponse']
 type State = 'loading' | 'loaded' | 'not-found' | 'error'
 
 const route = useRoute()
+const { saveRsvp, getRsvp, getOrganizerToken } = useEventStorage()
+
 const state = ref<State>('loading')
 const event = ref<GetEventResponse | null>(null)
 
+// RSVP state
+const sheetOpen = ref(false)
+const nameInput = ref('')
+const nameError = ref('')
+const submitError = ref('')
+const submitting = ref(false)
+const rsvpName = ref<string | undefined>(undefined)
+const isOrganizer = ref(false)
+
 const formattedDateTime = computed(() => {
   if (!event.value) return ''
   const formatted = new Intl.DateTimeFormat(undefined, {
@@ -95,11 +141,68 @@ async function fetchEvent() {
 
     event.value = data!
     state.value = 'loaded'
+
+    // Check if current user is the organizer
+    isOrganizer.value = !!getOrganizerToken(event.value.eventToken)
+
+    // Restore RSVP status from localStorage
+    const stored = getRsvp(event.value.eventToken)
+    if (stored) {
+      rsvpName.value = stored.rsvpName
+    }
   } catch {
     state.value = 'error'
   }
 }
 
+async function submitRsvp() {
+  nameError.value = ''
+  submitError.value = ''
+
+  if (!nameInput.value) {
+    nameError.value = 'Please enter your name.'
+    return
+  }
+
+  if (nameInput.value.length > 100) {
+    nameError.value = 'Name must be 100 characters or fewer.'
+    return
+  }
+
+  submitting.value = true
+
+  try {
+    const { data, error } = await api.POST('/events/{token}/rsvps', {
+      params: { path: { token: route.params.token as string } },
+      body: { name: nameInput.value },
+    })
+
+    if (error) {
+      submitError.value = 'Could not submit RSVP. Please try again.'
+      return
+    }
+
+    // Persist RSVP in localStorage
+    saveRsvp(
+      event.value!.eventToken,
+      data!.rsvpToken,
+      data!.name,
+      event.value!.title,
+      event.value!.dateTime,
+    )
+
+    // Update UI
+    rsvpName.value = data!.name
+    event.value!.attendeeCount += 1
+    sheetOpen.value = false
+    nameInput.value = ''
+  } catch {
+    submitError.value = 'Could not submit RSVP. Please try again.'
+  } finally {
+    submitting.value = false
+  }
+}
+
 onMounted(fetchEvent)
 </script>
 

frontend/src/views/__tests__/EventCreateView.spec.ts

@@ -14,6 +14,8 @@ vi.mock('@/composables/useEventStorage', () => ({
     saveCreatedEvent: vi.fn(),
     getStoredEvents: vi.fn(() => []),
     getOrganizerToken: vi.fn(),
+    saveRsvp: vi.fn(),
+    getRsvp: vi.fn(),
   })),
 }))
 
@@ -165,6 +167,8 @@ describe('EventCreateView', () => {
       saveCreatedEvent: mockSave,
       getStoredEvents: vi.fn(() => []),
       getOrganizerToken: vi.fn(),
+      saveRsvp: vi.fn(),
+      getRsvp: vi.fn(),
     })
 
     vi.mocked(api.POST).mockResolvedValueOnce({

frontend/src/views/__tests__/EventDetailView.spec.ts

@@ -7,9 +7,24 @@ import { api } from '@/api/client'
 vi.mock('@/api/client', () => ({
   api: {
     GET: vi.fn(),
+    POST: vi.fn(),
   },
 }))
 
+const mockSaveRsvp = vi.fn()
+const mockGetRsvp = vi.fn()
+const mockGetOrganizerToken = vi.fn()
+
+vi.mock('@/composables/useEventStorage', () => ({
+  useEventStorage: vi.fn(() => ({
+    saveCreatedEvent: vi.fn(),
+    getStoredEvents: vi.fn(() => []),
+    getOrganizerToken: mockGetOrganizerToken,
+    saveRsvp: mockSaveRsvp,
+    getRsvp: mockGetRsvp,
+  })),
+}))
+
 function createTestRouter(_token?: string) {
   return createRouter({
     history: createMemoryHistory(),
@@ -26,6 +41,7 @@ async function mountWithToken(token = 'test-token') {
   await router.isReady()
   return mount(EventDetailView, {
     global: { plugins: [router] },
+    attachTo: document.body,
   })
 }
 
@@ -40,12 +56,22 @@ const fullEvent = {
   expired: false,
 }
 
+function mockLoadedEvent(eventOverrides = {}) {
+  vi.mocked(api.GET).mockResolvedValue({
+    data: { ...fullEvent, ...eventOverrides },
+    error: undefined,
+    response: new Response(null, { status: 200 }),
+  } as never)
+}
+
 beforeEach(() => {
   vi.restoreAllMocks()
+  mockGetRsvp.mockReturnValue(undefined)
+  mockGetOrganizerToken.mockReturnValue(undefined)
 })
 
 describe('EventDetailView', () => {
-  // T014: Loading state
+  // Loading state
   it('renders skeleton shimmer placeholders while loading', async () => {
     vi.mocked(api.GET).mockReturnValue(new Promise(() => {}))
 
@@ -53,15 +79,12 @@ describe('EventDetailView', () => {
 
     expect(wrapper.find('[aria-busy="true"]').exists()).toBe(true)
     expect(wrapper.findAll('.skeleton').length).toBeGreaterThanOrEqual(3)
+    wrapper.unmount()
   })
 
-  // T013: Loaded state — all fields
+  // Loaded state — all fields
   it('renders all event fields when loaded', async () => {
-    vi.mocked(api.GET).mockResolvedValue({
+    mockLoadedEvent()
-      data: fullEvent,
-      error: undefined,
-      response: new Response(null, { status: 200 }),
-    } as never)
 
     const wrapper = await mountWithToken()
     await flushPromises()
@@ -71,37 +94,25 @@ describe('EventDetailView', () => {
     expect(wrapper.text()).toContain('Central Park, NYC')
     expect(wrapper.text()).toContain('12')
     expect(wrapper.text()).toContain('Europe/Berlin')
+    wrapper.unmount()
   })
 
-  // T013: Loaded state — locale-formatted date/time
+  // Loaded state — locale-formatted date/time
   it('formats date/time with Intl.DateTimeFormat and timezone', async () => {
-    vi.mocked(api.GET).mockResolvedValue({
+    mockLoadedEvent()
-      data: fullEvent,
-      error: undefined,
-      response: new Response(null, { status: 200 }),
-    } as never)
 
     const wrapper = await mountWithToken()
     await flushPromises()
 
     const dateField = wrapper.findAll('.detail__value')[0]!
     expect(dateField.text()).toContain('(Europe/Berlin)')
-    // The formatted date part is locale-dependent but should contain the year
     expect(dateField.text()).toContain('2026')
+    wrapper.unmount()
   })
 
-  // T013: Loaded state — optional fields absent
+  // Loaded state — optional fields absent
   it('does not render description and location when absent', async () => {
-    vi.mocked(api.GET).mockResolvedValue({
+    mockLoadedEvent({ description: undefined, location: undefined, attendeeCount: 0 })
-      data: {
-        ...fullEvent,
-        description: undefined,
-        location: undefined,
-        attendeeCount: 0,
-      },
-      error: undefined,
-      response: new Response(null, { status: 200 }),
-    } as never)
 
     const wrapper = await mountWithToken()
     await flushPromises()
@@ -109,38 +120,33 @@ describe('EventDetailView', () => {
     expect(wrapper.text()).not.toContain('Description')
     expect(wrapper.text()).not.toContain('Location')
     expect(wrapper.text()).toContain('0')
+    wrapper.unmount()
   })
 
-  // T020 (US2): Expired state
+  // Expired state
   it('renders "event has ended" banner when expired', async () => {
-    vi.mocked(api.GET).mockResolvedValue({
+    mockLoadedEvent({ expired: true })
-      data: { ...fullEvent, expired: true },
-      error: undefined,
-      response: new Response(null, { status: 200 }),
-    } as never)
 
     const wrapper = await mountWithToken()
     await flushPromises()
 
     expect(wrapper.text()).toContain('This event has ended.')
     expect(wrapper.find('.detail__banner--expired').exists()).toBe(true)
+    wrapper.unmount()
   })
 
-  // T020 (US2): No expired banner when not expired
+  // No expired banner when not expired
   it('does not render expired banner when event is active', async () => {
-    vi.mocked(api.GET).mockResolvedValue({
+    mockLoadedEvent()
-      data: fullEvent,
-      error: undefined,
-      response: new Response(null, { status: 200 }),
-    } as never)
 
     const wrapper = await mountWithToken()
     await flushPromises()
 
     expect(wrapper.find('.detail__banner--expired').exists()).toBe(false)
+    wrapper.unmount()
   })
 
-  // T023 (US4): Not found state
+  // Not found state
   it('renders "event not found" when API returns 404', async () => {
     vi.mocked(api.GET).mockResolvedValue({
       data: undefined,
@@ -152,11 +158,11 @@ describe('EventDetailView', () => {
     await flushPromises()
 
     expect(wrapper.text()).toContain('Event not found.')
-    // No event data in DOM
     expect(wrapper.find('.detail__title').exists()).toBe(false)
+    wrapper.unmount()
   })
 
-  // T027: Server error + retry
+  // Server error + retry
   it('renders error state with retry button on server error', async () => {
     vi.mocked(api.GET).mockResolvedValue({
       data: undefined,
@@ -169,9 +175,10 @@ describe('EventDetailView', () => {
 
     expect(wrapper.text()).toContain('Something went wrong.')
     expect(wrapper.find('button').text()).toBe('Retry')
+    wrapper.unmount()
   })
 
-  // T027: Retry button re-fetches
+  // Retry button re-fetches
   it('retry button triggers a new fetch', async () => {
     vi.mocked(api.GET)
       .mockResolvedValueOnce({
@@ -194,5 +201,167 @@ describe('EventDetailView', () => {
     await flushPromises()
 
     expect(wrapper.find('.detail__title').text()).toBe('Summer BBQ')
+    wrapper.unmount()
+  })
+
+  // RSVP bar
+  it('shows RSVP CTA bar on active event', async () => {
+    mockLoadedEvent()
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(true)
+    expect(wrapper.find('.rsvp-bar__cta').text()).toBe("I'm attending")
+    wrapper.unmount()
+  })
+
+  it('does not show RSVP bar for organizer', async () => {
+    mockGetOrganizerToken.mockReturnValue('org-token-123')
+    mockLoadedEvent()
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    expect(wrapper.find('.rsvp-bar').exists()).toBe(false)
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(false)
+    wrapper.unmount()
+  })
+
+  it('does not show RSVP bar on expired event', async () => {
+    mockLoadedEvent({ expired: true })
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(false)
+    expect(wrapper.find('.rsvp-bar').exists()).toBe(false)
+    wrapper.unmount()
+  })
+
+  it('shows RSVP status bar when localStorage has RSVP', async () => {
+    mockGetRsvp.mockReturnValue({ rsvpToken: 'rsvp-1', rsvpName: 'Max' })
+    mockLoadedEvent()
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    expect(wrapper.find('.rsvp-bar__status').exists()).toBe(true)
+    expect(wrapper.find('.rsvp-bar__text').text()).toBe("You're attending!")
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(false)
+    wrapper.unmount()
+  })
+
+  // RSVP form submission
+  it('opens bottom sheet when CTA is clicked', async () => {
+    mockLoadedEvent()
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    expect(document.body.querySelector('[role="dialog"]')).toBeNull()
+
+    await wrapper.find('.rsvp-bar__cta').trigger('click')
+    await flushPromises()
+
+    expect(document.body.querySelector('[role="dialog"]')).not.toBeNull()
+    wrapper.unmount()
+  })
+
+  it('shows validation error when submitting empty name', async () => {
+    mockLoadedEvent()
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    await wrapper.find('.rsvp-bar__cta').trigger('click')
+    await flushPromises()
+
+    // Form is inside Teleport — find via document.body
+    const form = document.body.querySelector('.rsvp-form')! as HTMLFormElement
+    form.dispatchEvent(new Event('submit', { bubbles: true }))
+    await flushPromises()
+
+    expect(document.body.querySelector('.rsvp-form__field-error')?.textContent).toBe('Please enter your name.')
+    expect(vi.mocked(api.POST)).not.toHaveBeenCalled()
+    wrapper.unmount()
+  })
+
+  it('submits RSVP, saves to storage, and shows status', async () => {
+    mockLoadedEvent()
+    vi.mocked(api.POST).mockResolvedValue({
+      data: { rsvpToken: 'rsvp-token-1', name: 'Max' },
+      error: undefined,
+      response: new Response(null, { status: 201 }),
+    } as never)
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    // Open sheet
+    await wrapper.find('.rsvp-bar__cta').trigger('click')
+    await flushPromises()
+
+    // Fill name via Teleported input
+    const input = document.body.querySelector('#rsvp-name')! as HTMLInputElement
+    input.value = 'Max'
+    input.dispatchEvent(new Event('input', { bubbles: true }))
+    await flushPromises()
+
+    // Submit form
+    const form = document.body.querySelector('.rsvp-form')! as HTMLFormElement
+    form.dispatchEvent(new Event('submit', { bubbles: true }))
+    await flushPromises()
+
+    // Verify API call
+    expect(vi.mocked(api.POST)).toHaveBeenCalledWith('/events/{token}/rsvps', {
+      params: { path: { token: 'test-token' } },
+      body: { name: 'Max' },
+    })
+
+    // Verify storage
+    expect(mockSaveRsvp).toHaveBeenCalledWith(
+      'abc-123',
+      'rsvp-token-1',
+      'Max',
+      'Summer BBQ',
+      '2026-03-15T20:00:00+01:00',
+    )
+
+    // Verify UI switched to status
+    expect(wrapper.find('.rsvp-bar__text').text()).toBe("You're attending!")
+    expect(wrapper.find('.rsvp-bar__cta').exists()).toBe(false)
+
+    // Verify attendee count incremented
+    expect(wrapper.text()).toContain('13')
+
+    wrapper.unmount()
+  })
+
+  it('shows error when RSVP submission fails', async () => {
+    mockLoadedEvent()
+    vi.mocked(api.POST).mockResolvedValue({
+      data: undefined,
+      error: { type: 'about:blank', title: 'Bad Request', status: 400 },
+      response: new Response(null, { status: 400 }),
+    } as never)
+
+    const wrapper = await mountWithToken()
+    await flushPromises()
+
+    await wrapper.find('.rsvp-bar__cta').trigger('click')
+    await flushPromises()
+
+    const input = document.body.querySelector('#rsvp-name')! as HTMLInputElement
+    input.value = 'Max'
+    input.dispatchEvent(new Event('input', { bubbles: true }))
+    await flushPromises()
+
+    const form = document.body.querySelector('.rsvp-form')! as HTMLFormElement
+    form.dispatchEvent(new Event('submit', { bubbles: true }))
+    await flushPromises()
+
+    expect(document.body.textContent).toContain('Could not submit RSVP. Please try again.')
+    wrapper.unmount()
   })
 })