diff --git a/apps/pwa/src/api/client.ts b/apps/pwa/src/api/client.ts
index 75b7a46..9c2788a 100644
--- a/apps/pwa/src/api/client.ts
+++ b/apps/pwa/src/api/client.ts
@@ -104,7 +104,7 @@ export async function fetchMe(): Promise<MeResponse> {
  * to build the Schedule-X calendarId that keys into buildCalendarConfig().
  */
 export interface CalendarOccurrence {
-  id: string            // `${uid}::${dtstart_iso}` — stable identity
+  id: string            // `ev-<sanitized-uid>-<epochMs>` — stable identity (server: expand.ts makeOccurrenceId)
   uid: string
   calendarId: number    // DB calendar-row id — do NOT use for SX calendarId routing
   calendarName: string