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.
`:core:data`	Android library	Transport + persistence: `HapiApi` (OkHttp REST, single-flight 401 re-auth), `SseEngine` (okhttp-sse, resume/backoff state machine), StateFlow stores + AtomicFile JSON snapshots, credential store, FCM registration, WorkManager workers. Placeholder in M0 — see `DataModule.kt`.
`:app`	Android application	Compose UI, navigation, deep links (`hapicompanion://bind`), FCM service (M4), hand-rolled DI (`AppGraph`, no Hilt).

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/**.

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.
M4 — FCM push (register → notification actions via expedited WorkManager) + files/git viewer, Scratchlist, usage/storage stats.
M5 — polish: zh-CN i18n, OLED/Material You theming, predictive back, LeakCanary pass, Play listing + self-build docs.

Firebase / push (self-build note)

M0 deliberately does not apply the com.google.gms.google-services plugin and has no Firebase dependency, so the project builds without any google-services.json. In M4a the plugin lands together with the FCM service: official builds inject the default Firebase project config in CI, while self-builders drop in their own app/google-services.json (docs will accompany M4a; a PushBinding seam for hub-provided FirebaseOptions is planned for v1.x).