Files
buzz/mobile
Tom Brow f78a32cf03 feat(mobile): hard-block under-18 users on the store age signal (#4665)
### What changed?

Buzz mobile checks the app-store age signal at launch and hard-blocks
the app behind a full-screen 18+ notice when the store says the
signed-in person is under 18.

No age signal (e.g. declined permission, indeterminate value,
unsupported OS versions) results in no block.

The age value is never persisted. It is read, used to compute one
boolean, and discarded. Nothing is written to disk, and neither the age
value nor the range is logged or sent to analytics.

Platform notes:
- **New dependency `com.google.android.play:age-signals:0.0.4`.** This
is the only way to read the Play signal. Its AAR declares `minSdkVersion
23`, below the app's 24, so it forces **no minSdk bump**, and it
self-declares its own consent activity, so **no AndroidManifest change**
is needed.
- **iOS entitlement and linking.** `DeclaredAgeRange` autolinks from the
import. `Runner.entitlements` now declares
`com.apple.developer.declared-age-range`, and the call remains behind
`#available(iOS 26.0, *)`.

### Why?

App stores now expose a declared-age range, and Buzz's Terms require
users to be 18 or older. This wires the store signal to that rule with
the smallest change that is defensible.

Absent signals, declined or undeterminable results, and unsupported OS
versions allow the app through. A transient native request failure does
not become evidence that access is allowed: the app remains gated until
a retry produces a result. Only an affirmative under-18 signal produces
the permanent restriction screen.

### How is it tested?

Added tests:

-
[`age_signal_provider_test`](https://github.com/block/buzz/tree/main/mobile/test/features/age_gate)
covers the 17/18 boundary, open-ended ranges, no-signal, transient
recovery, bounded retry exhaustion, malformed payloads, and request-once
behavior
-
[`age_gate_app_test`](https://github.com/block/buzz/tree/main/mobile/test/features/age_gate)
proves authenticated content remains unmounted while the signal is
pending or retryable, and verifies the retry path
-
[`age_restriction_page_test`](https://github.com/block/buzz/tree/main/mobile/test/features/age_gate)
asserts the block screen offers no bypass affordance
-
[`community_provider_test`](https://github.com/block/buzz/tree/main/mobile/test/shared/community)
verifies age restriction clears push state, persists inactive leases,
and retries a failed tombstone
-
[`AgeSignalPayloadTest`](https://github.com/block/buzz/tree/main/mobile/android/app/src/test/kotlin/xyz/block/buzz/mobile)
pins the Android success payload to exactly `{status, ageUpper}` and
verifies failures return the distinct retryable platform error

### Deployment note

Enable the Declared Age Range capability and regenerate signing profiles
carrying the entitlement. This relops/App Store Connect task is not
performed by this PR.

*🤖 This PR was authored [with an
agent](codex://threads/019e5128-536b-73b3-8348-88651123f6da).*

| Age restriction screen |
| --- |
| <img
src="https://github.com/user-attachments/assets/5b0f48b1-df9b-4a60-9800-80b33f128535"
alt="Age restriction screen" width="320"> |

---------

Signed-off-by: Tom Brow <tomb@block.xyz>
Co-authored-by: npub12wpjffj7q5qjsky5jvk4ldwlxmse5xll3d8gytk4wqd0c5y7jvwspg37n6 <538324a65e0501285894932d5fb5df36e19a1bff8b4e822ed5701afc509e931d@buzz.block.builderlab.xyz>
Co-authored-by: npub1tquskdu6yc4h8l7xxtceculxw600grekeq0xg2ukqfrwl7vrzg3quz3gmp <58390b379a262b73ffc632f19c73e6769ef40f36c81e642b960246eff9831222@buzz.block.builderlab.xyz>
Co-authored-by: Codex <noreply@openai.com>
2026-09-15 05:21:27 -07:00
..

Buzz Mobile

Flutter mobile client for Buzz.

Setup

Use the Flutter SDK pinned by the repository. Activate Hermit from the repo root before resolving packages or running any Flutter command:

cd /path/to/buzz
. ./bin/activate-hermit
./bin/just mobile-install

mobile-build-android intentionally builds with --no-pub. If an IDE or an external Flutter SDK has touched mobile/.dart_tool, rerun mobile-install with the pinned SDK before building so flutter_test, sky_engine, and the engine all come from the same Flutter version.

Run

# From repo root (applies a worktree-isolated debug identity and starts/reuses Simulator):
just mobile-dev

# Direct (uses the app's configured community; apply worktree overrides first):
cd mobile && flutter run

Worktree-aware debug identity

Debug builds produced from a git worktree get a unique app identifier keyed to the worktree directory name (xyz.block.buzz.dogfood.mobile.<slug> on iOS, xyz.block.buzz.mobile.<slug> on Android) plus a display-only branch label in the app name (Buzz (my-branch), or a short SHA when the worktree is detached). Because the identifier follows the directory rather than the branch, one worktree keeps exactly one installed app — and its login state — across branch switches, and builds from multiple worktrees install side by side, mirroring the desktop dev experience. Release and profile builds always keep the production identity and name.

just mobile-dev and just mobile-build-android apply this automatically by running scripts/mobile-worktree-overrides.sh, which writes two gitignored files:

  • mobile/ios/Flutter/WorktreeOverrides.xcconfig (included by Debug builds only; a developer's AppOverrides.xcconfig is included after it, so app-specific overrides like a personal BUNDLE_IDENTIFIER for device signing always win)
  • mobile/android/worktree.properties (read by the debug build type only)

Android developers can keep a stable local test identity that takes precedence over the generated worktree values by creating the gitignored mobile/android/AppOverrides.properties:

appName=Buzz Pairing
applicationIdSuffix=.device_pairing_e2e1

These values are consumed by the debug build type only. The standard just mobile-build-android command can still be used; regenerating worktree.properties does not overwrite AppOverrides.properties. Release and profile builds keep the production Buzz name and application ID.

For direct Xcode / Android Studio / flutter run development, run ./scripts/mobile-worktree-overrides.sh from the repo root once per branch switch to refresh the display label (the install identity never changes); the persisted files are then picked up by any subsequent build. In the main checkout the script is a no-op that removes stale override files, restoring the plain Buzz identity.

For an Android debug build that must remain installed alongside other Buzz worktree builds, set an explicit launcher name and package suffix when invoking the generator or a recipe that invokes it:

BUZZ_ANDROID_DEBUG_APP_NAME="Buzz Huddles" \
BUZZ_ANDROID_DEBUG_ID_SUFFIX=".huddles_829c" \
./bin/just mobile-build-android

This example produces the debug-only package xyz.block.buzz.mobile.huddles_829c with the launcher label Buzz Huddles. The suffix must start with a dot followed by a lowercase letter and may contain only lowercase letters, digits, and underscores. Release and profile builds ignore these overrides and retain the production package and name.

To remove leftover worktree-suffixed installs from booted iOS simulators and connected Android emulators, run just mobile-clean (add --dry-run via ./scripts/mobile-worktree-clean.sh --dry-run to preview). Production installs are never touched.

iOS push capability

Every iOS artifact builds and embeds the Notification Service Extension and native push bridge. Runtime activation is fail-closed and scoped to the current relay. After authenticated connectivity and a fully valid NIP-11 nip-pl push descriptor, Buzz independently requests display permission and registers with APNs. Display denial or request failure does not gate the device token, gateway enrollment, or lease publication, so a later user opt-in can display pushes without rebuilding transport authority. An absent, malformed, or unreachable descriptor leaves push inactive without partial enrollment.

Relay rollout remains an explicit deployment opt-in. Only deployments with BUZZ_PUSH_ENABLED=true advertise the descriptor and process push. See docs/push-gateway-deployment.md for the canonical gateway profile contract, manual physical-device proof, measurements, and rollback procedure.

For local physical-device development, override the identity and sandbox environments in the gitignored mobile/ios/Flutter/AppOverrides.xcconfig:

BUNDLE_IDENTIFIER = xyz.block.buzz.mobile
BUZZ_DEVELOPMENT_TEAM = EYF346PHUG
BUZZ_IOS_PUSH_ENVIRONMENT = development
BUZZ_APP_ATTEST_ENVIRONMENT = development

This exercises the client, extension, relay, and gateway integration without requiring a dogfood development signing identity. It uses the canonical gateway's server-owned App Store profile configured for sandbox in the local development gateway; it does not validate the internally distributed dogfood artifact or enable the App Store profile in production. Validate dogfood APNs end to end by cutting an internal release, waiting for it to reach Mobile Releases/Comp Portal, and installing that signed artifact on a physical device.

Parent app identifiers require Apple's Communication Notifications capability and a regenerated app provisioning profile. The Notification Service Extension profile does not require that capability. Enable it on the personal development App ID for local rich-presentation validation. Enabling it on the Block dogfood and eventual App Store App IDs is a release follow-up and is not performed by this repository change. Without a matching parent profile, source and unit validation still work, but the app cannot be signed for a physical device.

APNs and the gateway continue to carry only the constant opaque wake-up. The extension fetches the message from the scoped relay, verifies message, sender profile, and channel-metadata signatures, and uses a bounded App Group cache for names and app-rendered avatar thumbnails. It never fetches an avatar URL; missing, stale, or invalid enrichment falls back to the verified message with a short sender pubkey, community subtitle, and no image.

Checks

dart format --output=none --set-exit-if-changed .
flutter analyze
flutter test

Or from the repo root: just mobile-check and just mobile-test.

Android release signing

Android release builds fail unless all upload-key inputs are supplied through the environment:

  • BUZZ_ANDROID_UPLOAD_KEYSTORE_PATH: path to a CI-vended keystore file
  • BUZZ_ANDROID_UPLOAD_KEYSTORE_PASSWORD
  • BUZZ_ANDROID_UPLOAD_KEY_ALIAS
  • BUZZ_ANDROID_UPLOAD_KEY_PASSWORD

The keystore path must be absolute, and the keystore must remain outside the repository. Development and debug builds do not require these variables.

Release pipelines that sign through the central APK Signer service instead of a local upload keystore must set BUZZ_ANDROID_RELEASE_SIGNING=external. That mode produces an unsigned release bundle and refuses to run if any BUZZ_ANDROID_UPLOAD_* value is also set.

Architecture

lib/
├── main.dart              # Entry point, Riverpod bootstrap
├── app.dart               # MaterialApp with theme
├── shared/
│   └── theme/             # Catppuccin light/dark, spacing tokens, extensions
└── features/
    └── home/              # Placeholder home surface
  • State management: Riverpod + Hooks (HookConsumerWidget)
  • Theme: Catppuccin Latte (light) / Macchiato (dark) — matches desktop
  • Spacing: Grid tokens for consistent spacing
  • Linting: flutter_lints + riverpod_lint via custom_lint
  • Feature isolation: No cross-feature imports except shared/