Unread/Read State Tracking

Without a read-state column, every notification looks identical forever — the bell badge never clears, users learn to ignore it, and push/email digests repeat content the user already saw in-app. A single read_at timestamp unlocks unread counts, mark-all-as-read, per-channel deduplication across web and mobile, and analytics on notification effectiveness. Missing this field means every downstream notification feature is blocked until the schema is backfilled.

Add a nullable readAt DateTime? column to the notification model, expose PATCH endpoints for single-item and bulk mark-as-read, and compute the unread badge from notifications.filter(n => !n.readAt).length. Store the timestamp (not a boolean) so you can audit read latency later. See prisma/schema.prisma and app/api/notifications/[id]/route.ts:

model Notification {
  id String @id
  readAt DateTime?
  userId String
}