NestJS Notification Architecture

Priority: P0 (Standard)

Implement "Dual-Write" notification system: persist to Database (In-App) and send via FCM (Push).

Workflow: Send Notification

1. Save to database — Persist notification entity with type enum and metadata.
2. Check FCM token — Verify recipient valid fcmToken; skip push if missing.
3. Send push — Call FCM inside try/catch; never let FCM failure block request.
4. Serialize data — Convert Dates to ISO strings; keep FCM data payload flat (IDs only).

Dual-Write Service Example

See implementation examples

Structure

See implementation examples