hapi/android

HAPI Android Companion

Native Android client (Kotlin + Jetpack Compose) for the HAPI hub. Fully independent from the web app; shares only the protocol contract (docs/api/) and the golden fixtures (shared/fixtures/).

• applicationId: run.hapi.companion · minSdk 26 · target/compileSdk 36
• Toolchain: Gradle 8.14.2 (wrapper) · AGP 8.11.1 · Kotlin 2.1.21 · Compose BOM 2025.05.00 · JDK 17+ (CI uses 21)

Modules

Module	Type	Responsibility
:core:protocol	pure Kotlin/JVM (no Android)	Hub wire types (kotlinx.serialization), chat pipeline port (normalize → reduce → tool groups), message-window/pagination logic, versioned patch application, modes catalog, git output parsers, BindLink pairing-link parsing. M1a landed: wire/ (HapiJson, Session/SessionPatch/SessionSummary, DecryptedMessage, AgentState, Machine, 13-type SyncEvent union via SyncEvents.parse, MessagesResponse), catalog/ (flavors + permission/collaboration modes), patch/SessionPatching.kt (exact port of web/src/lib/sessionPatch.ts), all fixture-verified.
:core:data	Android library	Transport + persistence. M1b landed — auth/ (JwtPeek, CredentialStore interface + EncryptedPrefsCredentialStore/in-memory, HubUrls origin normalization, HubRegistry roster behind a storage seam, AuthInterceptor + single-flight TokenAuthenticator with ensureFreshToken() and terminal AuthEvents), api/ (HapiApi — plain OkHttp + kotlinx.serialization, one suspend fun per v1 endpoint incl. generated-image bytes via a 256 MB OkHttp cache and the multipart transcription helper; ApiError with (status, code)), HubSession per-hub factory; MockWebServer-tested. M1c landed — sse/: SseEngine (per-key global/session:<id> loops, connection-changed handshake gate with ok/gap resume verdict, per-key Last-Event-ID cursors advanced only after downstream hand-off (at-least-once), 10 s connect deadline, 90 s watchdog, 1 s→30 s→300 s backoff + jitter, background retry deferral + 45 s foreground stale check, one silent 401 re-auth per cycle), OkHttpSseTransport (dedicated client, readTimeout=0, incremental gzip decoding pinned by test, acceptEncodingIdentity fallback), SyncEventRouter → SyncTargets seam; virtual-time tested. Still to come: StateFlow stores + AtomicFile JSON snapshots (M2), FCM registration + WorkManager workers (M4).
:app	Android application	Compose UI, navigation, deep links (hapicompanion://bind), FCM service (M4), hand-rolled DI (AppGraph, no Hilt). M1d landed — di/ (AppGraph process singletons: Preferences DataStore-backed HubRegistryStorage, EncryptedPrefsCredentialStore, HubRegistry, auth-terminal fan-out; HubGraph per active hub: HubSession + SseEngine wired to ensureFreshToken, recreated on hub switch; LocalAppGraph CompositionLocal + viewModelFactory helper), feature/pairing/ (landing / zxing ScanContract QR scan / manual entry sharing one PairingViewModel: health + protocol check → POST /api/auth → persist + activate), feature/home/ placeholder (hub switcher + sign-out), Navigation.kt (pairing ⇄ home, auth-terminal → pairing with banner), bind deep-link handling in MainActivity.

Dependency direction: :app → :core:data → :core:protocol.

Protocol conformance fixtures

:core:protocol is the porting target for web/src/chat/ and is verified against golden fixtures generated from the web implementation (track K). The test task already passes the fixtures location as a system property:

// core/protocol/build.gradle.kts
tasks.test {
    systemProperty("hapi.fixtures.dir", rootDir.parentFile.resolve("shared/fixtures").absolutePath)
}

Fixture-driven tests (M2) read System.getProperty("hapi.fixtures.dir") — no further build changes are needed when shared/fixtures/** lands. CI re-runs this suite whenever android/** or shared/fixtures/** change.

Building

Requires an Android SDK for :app/:core:data (set ANDROID_HOME or android/local.properties with sdk.dir=...). :core:protocol alone needs only a JDK.

cd android
./gradlew :core:protocol:test        # pure JVM protocol tests (fast)
./gradlew :app:assembleDebug         # debug APK
./gradlew :app:installDebug          # install on a connected device

Without an Android SDK you can still run the protocol suite by configuring only the needed projects:

./gradlew --no-configuration-cache --configure-on-demand :core:protocol:test

CI (.github/workflows/android.yml) runs the protocol tests and :app:assembleDebug on every PR touching android/** or shared/fixtures/**.

Pairing

HAPI is self-hosted: the app talks to a hub you run. Pairing = giving the app a hub URL plus that hub's access token; the app verifies the hub (GET /health, protocol version), exchanges the token for a JWT (POST /api/auth), stores the credentials in EncryptedSharedPreferences (keyed per hub — multiple hubs can be paired, one active at a time), and lands on the session UI. Three entry points:

1. QR scan — the hub prints two QR codes when started with --relay (also under web Settings → Companion pairing). The in-app scanner accepts both: the companion deeplink (hapicompanion://bind?hub=…&code=…) and the web direct-access URL (…?hub=…&token=…).
2. Deep link — scanning the companion QR with the system camera opens the app directly with a confirm screen (hapicompanion://bind intent filter).
3. Manual entry — hub URL + access token, for hubs started without --relay.

Pairing against a local dev hub

# repo root: start the hub (prints the access token + QR codes)
bun run dev

# emulator: the host machine is 10.0.2.2
#   Hub URL:       http://10.0.2.2:3006
#   Access token:  from the hub terminal / hub settings.json (CLI_API_TOKEN)
# physical device: use the machine's LAN IP, e.g. http://192.168.1.10:3006
adb shell am start -a android.intent.action.VIEW \
  -d "hapicompanion://bind?hub=http%3A%2F%2F10.0.2.2%3A3006&code=<accessToken>"  # optional: exercises the deep link

Plain-http LAN/emulator hubs work in all build types: the manifest opts in to cleartext traffic (android:usesCleartextTraffic="true"), because self-hosted LAN hubs are the primary pairing target and Android cannot scope the exemption to local addresses only. Sign-out (home → Sign out) deletes the stored credentials for that hub and drops it from the roster.

Milestones (track B of the native-clients plan)

• M0 — this scaffold: modules, version catalog, CI, placeholder screen.
• M1 — foundations: wire types + modes catalog; auth + HapiApi (MockWebServer-tested); SseEngine reconnect state machine + versioned patches (gzip streaming verified); pairing UI + hapicompanion://bind deep link.
• M2 — read-only chat: chat pipeline port gated on fixtures all-green; session list; MessageWindowStore port; Markdown renderer; read-only chat screen (LazyColumn(reverseLayout = true)).
• M3 — interaction: composer (optimistic send/queue/steer/drafts), permission approvals UX, session controls (mode/model/abort/resume/rename/archive), new session, dictation.
  • B-M3ce landed — voice dictation: mic button in the composer (RECORD_AUDIO requested at first use), MediaRecorder → m4a/AAC, provider discovery via GET /api/voice/transcription/providers (first standard-capable provider; a hub without one shows a notice), upload through the multipart POST /api/voice/transcription, transcript appended at the composer text with a space separator; DictationController is a plain seam over recorder + API, JVM-tested with fakes. Slash commands: typing a lone /token opens a dropdown merging the session's metadata.slashCommands names with the GET /slash-commands RPC list (RPC entries win dedupe; exact → prefix → contains filtering), tap inserts /name (the skills $ trigger is deferred). Session ops: list long-press sheet and chat top-bar overflow gain Rename (PATCH /sessions/:id, optimistic name with roll-forward on failure), Delete (confirm; 409-while-active surfaced), and Reopen for inactive sessions (POST /reopen; a superseding id reuses the supersede path — window seed + draft move + navigate-replace; 422 missing-metadata formatted); chat shows an inactive-session bar ("send to resume, or Reopen").
• M4 — FCM push (register → notification actions via expedited WorkManager) + files/git viewer, Scratchlist, usage/storage stats.
  • B-M4a landed — FCM push + notification actions. :core:data push/: PushPayload (data-only contract v1 decoding: type/severity/notifySummary parsing, channel routing, type-<sessionId> coalescing tags, unknown type/contractVersion degrade to plain title/body), DeviceRegistrar (registers the FCM token with every paired hub on start/pairing/onNewToken, DataStore-persisted deviceId UUID, WorkManager retry seam, best-effort unregister on sign-out before credentials are wiped), PushHubAccess + PushActionRunner (workers build a HubSession on demand from stored credentials — no HubGraph needed in background — and resolve the owning hub: active hub first, other paired hubs on 404 session-miss). :app: push/PushBinding (Firebase availability gate — no google-services.json → all push paths no-op), fcm/ (HapiFirebaseMessagingService, NotificationChannels — permission_requests HIGH / ready / task_notifications, PushNotifications builder with severity accents + suppress-when-open rule, NotificationActionReceiver → expedited PermissionActionWorker (Allow/Deny → approve/deny {}) and SendMessageWorker (RemoteInput reply → {text, localId}) with pending → done/"Already handled"/failed notification states), WorkManager on-demand init + HapiWorkerFactory, notification tap → internal MainActivity intent route → chat.
• M5 — polish: zh-CN i18n, OLED/Material You theming, predictive back, LeakCanary pass, Play listing + self-build docs.
  • B-M5a landed — zh-CN localization + in-app language switching (see "Internationalization" below).

Internationalization (B-M5a)

The app ships English (default) and Simplified Chinese (app/src/main/res/values-zh-rCN/strings.xml). Every user-visible string lives in resources; both files carry the same key set (lint MissingTranslation is the gate).

Adding a string

1. Add it to app/src/main/res/values/strings.xml with a feature-prefixed key matching the existing convention (chat_, sessions_, files_, scratchlist_, pairing_, settings_, new_session_, notif_, tool_ for tool-card titles). Dynamic values use positional format args (%1$s, %2$d); count-dependent copy uses explicit _one/_many keys (the deliberate house style — no <plurals>).
2. Add the zh-CN twin to values-zh-rCN/strings.xml. Terminology source of truth is the web corpus web/src/lib/locales/zh-CN.ts — reuse its product terms (会话 session, 机器 machine, 权限模式 permission mode, 工作树 worktree, 草稿夹 scratchlist, 语音输入 dictation, 用量 usage, 智能体/代理 agent). Technical identifiers (model ids, flavor names like Claude/Codex, permission-mode catalog labels, CLI flags) stay untranslated, matching the web's choices.
3. Reference it: composables via stringResource(R.string...). ViewModels stay string-free — transient notices are semantic sealed types (ChatNotice, ScratchlistNotice, PairingError, DictationErrorKind) resolved at the UI layer; where a ViewModel genuinely composes display text it takes a small Strings seam (FilesStrings, FileViewerStrings, NewSessionStrings) whose defaults are the English values (JVM tests construct without arguments) and whose production instance is resource-resolved in the Navigation holders. Server-provided error text passes through verbatim.

Language switching

Settings → App language offers Follow system (default) / English / 简体中文. The choice persists in LanguagePrefs (DataStore) and applies immediately via AppCompatDelegate.setApplicationLocales:

• MainActivity extends AppCompatActivity (theme parent Theme.AppCompat.DayNight.NoActionBar) so per-app locales work back to API 26; on API 33+ the framework LocaleManager takes over (the app also declares android:localeConfig for the system App-languages screen).
• The manifest opts into appcompat's autoStoreLocales (AppLocalesMetadataHolderService meta-data), which re-applies the stored choice synchronously on cold start.
• Surfaces that resolve strings from the application context — FCM notifications, WorkManager result updates, notification-action receivers — wrap their context with localizedForAppLanguage(AppGraph.appLanguage) (di/LocaleContexts.kt), since per-app locales only retarget activity contexts below API 33.

Out of scope on purpose: :core:protocol presentation strings (getEventPresentation, tool-group activity titles) stay English — the web does not translate them either, and terminology parity with the web wins.

Firebase / push

FCM needs a Firebase project binding, which is deliberately optional: the com.google.gms.google-services plugin is applied conditionally (only when app/google-services.json exists — see app/build.gradle.kts), so the repo always builds green without any Firebase config. Without one, FirebaseApp never initializes, PushBinding.isAvailable reports false, and every push code path (registration, FCM service, workers, the notification-permission prompt) no-ops — the app behaves like pre-M4a.

To enable push:

1. Official builds: CI injects the default Firebase project's google-services.json before assembling (the file is gitignored; app/google-services.json.example documents the expected shape).
2. Self-builds: create your own Firebase project, add an Android app with your applicationId (default run.hapi.companion), download google-services.json into android/app/, and rebuild.
3. Hub side: point the hub at the same Firebase project — FCM_SERVICE_ACCOUNT_PATH + FCM_PROJECT_ID (docs/api/native-companion-contract.md). The device registers itself with every paired hub (POST /api/devices/register) on pairing, app start, and token rotation, and unregisters on sign-out.

Multi-hub note: the FCM payload does not name the sending hub (contract v1), so notification actions resolve it — the workers try the active hub first, then the other paired hubs when a hub answers 404 for the session. Single-hub setups always hit on the first try. Tapping a notification opens the session against the active hub.

Planned for v1.x: runtime FirebaseOptions handed out by the hub, so self-builds get push without baking a config into the APK. That lands entirely behind the existing app/.../push/PushBinding.kt seam.