feat(mobile/android): end-to-end push notifications — FCM registration, POST_NOTIFICATIONS, and banner display

[Vaughan-g-aus]

Motivation

Buzz on Android never shows an OS notification. A member who backgrounds the app learns about a DM or an @mention only when they reopen it. #4402 reports the same gap from the user side: the app stops receiving messages in the background and needs a restart.

The iOS half is already in flight — PR #1924 adds .alert/.badge/.sound authorization, registerForRemoteNotifications(), and a NotificationService extension. Android has no equivalent, and no client-side Android issue is filed for it.

Confirmed by reading main on 2026-08-17:

• mobile/pubspec.yaml — no firebase_messaging and no flutter_local_notifications. Android has no push path and no local-notification path.
• mobile/android/app/src/main/AndroidManifest.xml — no POST_NOTIFICATIONS permission (required since Android 13), no FCM service, no receiver.
• Nothing under mobile/lib creates a kind:30350 push lease.
• crates/buzz-push-gateway/src/ ships apns.rs with no FCM transport. That server half is feat(push): add an Android FCM transport profile to the NIP-PL push gateway #3229.

Proposed solution

Android client work, sized to land after #3229:

1. Add an FCM dependency and register the device token at startup.
2. Publish a NIP-PL kind:30350 push lease per installation, mirroring the iOS path in PR Add NIP-PL iOS push notification foundation #1924.
3. Declare POST_NOTIFICATIONS in the manifest and request it at runtime on Android 13+.
4. Create a notification channel and display a banner on wake for DMs, @mentions, and thread replies the user is in — matching the slot rules already used by desktop in desktop/src/features/notifications/.
5. NIP-PL carries a wake signal only, so banner text must come from the events fetched after reconnect, never from the push payload.

Alternatives considered

• UnifiedPush instead of FCM. NIP-PL names it as an optional profile. It removes the Google dependency and suits self-hosted relays (NIP-PL on a self-hosted relay is unreachable by design: the default gateway is push.buzz.xyz and only block can sign APNs for the App Store app #5206), but it requires the user to install a distributor app, so it is a poor default.
• A foreground service holding the WebSocket open. No Google dependency, but Android kills it under memory pressure, it drains battery, and it forces a permanent status-bar notification.
• Local notifications only, no push. The app would show banners while it runs and nothing while backgrounded. That is half the value, but it is a smaller first step and it does not depend on feat(push): add an Android FCM transport profile to the NIP-PL push gateway #3229.

Additional context

Closest existing issue: #4657 — "Mobile client never registers for push". It covers the transport gap for both platforms. This issue is the Android client half plus the display layer, which #4657 does not specify.

Related:

• feat(push): add an Android FCM transport profile to the NIP-PL push gateway #3229 — Android FCM transport profile in the push gateway (server half; blocks steps 1 and 2).
• PR Add NIP-PL iOS push notification foundation #1924 — NIP-PL iOS push foundation. The Android work should mirror its push_bridge.dart / push_models.dart structure.
• Android: app stops receiving new messages in the background, requires restart #4402 — Android: app stops receiving new messages in the background (the user-visible symptom).
• NIP-PL on a self-hosted relay is unreachable by design: the default gateway is push.buzz.xyz and only block can sign APNs for the App Store app #5206 — self-hosted relays cannot reach the default APNs gateway; the same constraint will apply to FCM.
• Spec: docs/nips/NIP-PL.md (status: draft).

[fdagostino]

Adding concrete demand from a self-hosted operator: Android push support in the official Buzz application is blocking our mobile rollout.

We use the official Android application published by Buzz against a self-hosted relay. Messaging works, but the application does not receive OS push notifications.

We are specifically requesting support in the official Play Store application, not a custom Android build.

Could the maintainers confirm:

1. Whether Android push will use FCM through the NIP-PL architecture.
2. Whether official Android applications will support arbitrary self-hosted relays.
3. Whether there is a planned implementation, milestone, or pull request.
4. What server and relay configuration self-hosters will need.

We can beta-test the implementation on physical Android devices and provide sanitized relay and gateway diagnostics.

Related self-hosted push request: #5206

[tommck]

Honestly pretty wild to have a chat style app that doesn't have notifications from day 1