diff --git a/apps/api/src/routes/events.ts b/apps/api/src/routes/events.ts
index 1e22c32..18f2436 100644
--- a/apps/api/src/routes/events.ts
+++ b/apps/api/src/routes/events.ts
@@ -64,12 +64,19 @@ const eventsQuerySchema = z.object({
   end: z.string().regex(/^\d{4}-\d{2}-\d{2}$/),
 })
 
-/** Shared event field validation (V5 — bounded lengths, T-03-08). */
+/**
+ * Shared event field validation (V5 — bounded lengths, T-03-08).
+ *
+ * Field names match the PWA CreateEventPayload (apps/pwa/src/api/client.ts:119-128)
+ * exactly — title/start/end — so no rename map is needed end-to-end (CR-01).
+ * The stored payload JSON uses these same names; the outbox worker (plan 03-10)
+ * reads title/start/end when building the VEVENT.
+ */
 const eventFieldsSchema = z.object({
-  summary: z.string().min(1).max(255),
+  title: z.string().min(1).max(255),
   allDay: z.boolean(),
-  dtstart: z.string().min(1).max(64), // ISO string or DATE
-  dtend: z.string().min(1).max(64),
+  start: z.string().min(1).max(64), // ISO string or DATE (YYYY-MM-DD for allDay)
+  end: z.string().min(1).max(64),
   location: z.string().max(2000).optional(),
   description: z.string().max(2000).optional(),
   recurrence: z.enum(['none', 'daily', 'weekly', 'monthly', 'yearly']).optional(),
diff --git a/apps/api/tests/routes/events.test.ts b/apps/api/tests/routes/events.test.ts
index 89b7847..67d3c8a 100644
--- a/apps/api/tests/routes/events.test.ts
+++ b/apps/api/tests/routes/events.test.ts
@@ -289,10 +289,10 @@ describe('POST /api/events/create', () => {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({
-        summary: 'New event',
+        title: 'New event',
         allDay: false,
-        dtstart: '2026-06-15T10:00:00Z',
-        dtend: '2026-06-15T11:00:00Z',
+        start: '2026-06-15T10:00:00Z',
+        end: '2026-06-15T11:00:00Z',
         calendarUrl: 'https://caldav.fastmail.com/dav/calendars/user/test@fm.com/Default/',
       }),
     })
@@ -324,10 +324,10 @@ describe('POST /api/events/create', () => {
       method: 'POST',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({
-        summary: 'Unauthorized write',
+        title: 'Unauthorized write',
         allDay: false,
-        dtstart: '2026-06-15T10:00:00Z',
-        dtend: '2026-06-15T11:00:00Z',
+        start: '2026-06-15T10:00:00Z',
+        end: '2026-06-15T11:00:00Z',
         calendarUrl: 'https://caldav.fastmail.com/dav/calendars/user/other@fm.com/Personal/',
       }),
     })
@@ -363,10 +363,10 @@ describe('PATCH /api/events/:uid/edit', () => {
       method: 'PATCH',
       headers: { 'Content-Type': 'application/json' },
       body: JSON.stringify({
-        summary: 'Updated title',
+        title: 'Updated title',
         allDay: false,
-        dtstart: '2026-06-15T10:00:00Z',
-        dtend: '2026-06-15T11:00:00Z',
+        start: '2026-06-15T10:00:00Z',
+        end: '2026-06-15T11:00:00Z',
         calendarUrl: 'https://caldav.fastmail.com/dav/calendars/user/test@fm.com/Default/',
       }),
     })