How do you implement push notifications reliably?

Push delivery has three stages: the OS receives the message, the app processes it, and the UI reflects it. Each stage can fail. Tokens rotate, permission can be denied, background execution is limited, and notification taps need a route that works even on a cold start.

Future<void> initPush() async {
  final settings = await FirebaseMessaging.instance.requestPermission();
  if (settings.authorizationStatus == AuthorizationStatus.denied) return;

  final token = await FirebaseMessaging.instance.getToken();
  if (token == null) return;
  await api.registerDeviceToken(token);

  FirebaseMessaging.instance.onTokenRefresh.listen(api.registerDeviceToken);

  FirebaseMessaging.onMessage.listen((message) {
    final route = message.data['route'];
    if (route != null) appRouter.go(route);
  });
}

• Ask for permission at a moment the user understands, not on first launch by default
• Register tokens per user and remove them on logout
• Android notification channels control importance and sound; create them deliberately
• iOS needs APNs configuration and correct entitlements; test on a physical device
• Use data messages for app logic and notification messages for visible alerts, subject to platform behaviour

Tap handling and cold start

A notification tap can launch the app from terminated state. Read the initial message and route after the router is ready, otherwise the navigation is lost. Deduplicate handling if both foreground and background callbacks fire. Deep link payloads should be validated like any external input.