Notification Grouping & Batching

One notification per like scales linearly with your viral posts — a post with 500 likes creates 500 bell pings, and the user stops opening the app. Grouping collapses that into 'Alex and 499 others liked your post,' which preserves the signal without the noise. Without batching, push-notification open rates crater, email digests become unreadable, and heavy users disable notifications platform-wide rather than per-type, which you cannot recover from.

On notification creation, upsert into an existing unread row keyed by (userId, type, targetId) — append the new actor to an actorIds array and increment similarCount instead of inserting a new row. Render the grouped form as 'FirstActor and N others your post.' See the notification creation path:

const existing = await db.notification.findFirst({ where: { type, targetId, userId, readAt: null } })
if (existing) return db.notification.update({ where: { id: existing.id }, data: { actorIds: [...new Set([...existing.actorIds, actorId])], similarCount: existing.similarCount + 1 } })