Push Notifications Overview

Instructions

Push notifications are a privileged channel. They drive retention and support real-time features, but every mis-send erodes trust. This skill covers the flow end-to-end and the mistakes that cost engagement.

1. Architecture at 10,000 feet

Server -> FCM (Android, all)  -> Device (system tray) -> App handler
       -> APNs (iOS)          -> Device (system tray) -> App handler

• Android: FCM is the transport. Even if you use Firebase or a third party, the wire is FCM.
• iOS: APNs is the transport. FCM routes to APNs under the hood when you use Firebase.
• Token lifecycle: the device registers, you store {userId, platform, token} on the server, and invalidate on sign-out or token rotation.

2. Notification vs Data Messages