# WebTerm — Android client

A native Android client for the WebTerm browser-terminal server, targeting functional
parity with the shipped **iOS** client. See the full design in
[`docs/ANDROID_CLIENT_PLAN.md`](../docs/ANDROID_CLIENT_PLAN.md) (stack §2, module
architecture §3, server contract §4, task waves §5).

This directory is a **Gradle multi-module** project. The module set mirrors the iOS
SPM package set and inherits its rule: *dependencies only flow down; nothing points
upward* (ARCHITECTURE §1).

## Build environment (SDK installed — all modules build)

The Android SDK **is installed** and every module — pure Kotlin/JVM and Android-framework
alike — builds and unit-tests here. AGP 9.2.1 (built-in Kotlin) + Gradle 9.6.1 build
against SDK 35/36.

- **Pure Kotlin/JVM (`./gradlew test`):** `:wire-protocol`, `:session-core`, `:api-client`,
  `:client-tls`, `:test-support`, `:transport-okhttp`.
- **Android-framework (online in [`settings.gradle.kts`](settings.gradle.kts)):**
  `:app`, `:terminal-view`, `:host-registry`, `:client-tls-android`.

Setup: `local.properties` → `sdk.dir=/usr/local/share/android-commandlinetools`;
`google()` is in `pluginManagement`/`dependencyResolutionManagement`. Green gate:
`./gradlew test :app:assembleDebug koverVerify`.

## Module map (mirror of the iOS SPM packages — plan §3)

| iOS SPM package        | Android module         | Kind                          | Status |
|------------------------|------------------------|-------------------------------|--------|
| WireProtocol           | `:wire-protocol`       | pure Kotlin/JVM               | ✅ built |
| SessionCore (reducers) | `:session-core`        | pure Kotlin/JVM               | ✅ built |
| APIClient              | `:api-client`          | pure Kotlin/JVM               | ✅ built |
| ClientTLS (pure half)  | `:client-tls`          | pure Kotlin/JVM               | ✅ built |
| TestSupport            | `:test-support`        | pure Kotlin/JVM (fakes)       | ✅ built |
| ClientTLS (fwk half)   | `:client-tls-android`  | Android (AndroidKeyStore/Tink)| ✅ built |
| HostRegistry           | `:host-registry`       | Android (DataStore)           | ✅ built |
| SwiftTerm host view    | `:terminal-view`       | Android (Termux wrap)         | ✅ built |
| App/WebTerm            | `:app`                 | Android app (Compose/Hilt/FCM)| ✅ built |
| `URLSession*Transport` | `:transport-okhttp`    | pure Kotlin/JVM (OkHttp)      | ✅ built |

> `:transport-okhttp` (A7) holds the OkHttp `TermTransport`/`HttpTransport`
> implementations that the two iOS `URLSession*Transport`s consolidate into
> (plan §3 framing note). OkHttp is a plain JVM library, so the module builds and
> unit-tests (MockWebServer) with **no** Android SDK — including the
> access-token cookie on the WS upgrade (`OkHttpAccessTokenTest`).

### Dependency graph (arrows = "depends on")

```
                          :app
        ┌───────────────┬───┴────┬──────────────┬───────────────┐
        ▼               ▼        ▼              ▼               ▼
 :terminal-view   :session-core :api-client  :host-registry  :client-tls-android
        │              │          │                               │
        │              │          │                               ▼
        │              │          │                          :client-tls (pure)
        └──────┬───────┴──────────┴──────────────┬────────────────┘
               ▼                                  ▼
         :wire-protocol   ◀────────────  :transport-okhttp
               ▲
               └──────── :test-support  → test source sets only
```

`:wire-protocol` is the **frozen shared contract** (Android analogue of
`src/types.ts` + WireProtocol) — `ClientMessage`/`ServerMessage`, `MessageCodec`,
`Validation`, `WireConstants`, `HostEndpoint` (the single Origin/wsURL derivation),
`AuthCookie`/`AccessTokenRule`/`AccessTokenSource` (the single access-token-cookie
derivation), and the `TermTransport` / `HttpTransport` / `PingableTermTransport`
boundary interfaces. New wire types are added **only** here (a coordination point).

## Access token (`WEBTERM_TOKEN`) — how the Android client authenticates

A server started with `WEBTERM_TOKEN=<16–512 chars of [A-Za-z0-9._~+/=-]>` gates **every**
HTTP route *and* the WebSocket upgrade behind a `webterm_auth` cookie. The Android
client therefore:

- **hand-writes `Cookie: webterm_auth=<t>` itself** — no OkHttp `CookieJar`, no
  `Set-Cookie` parsing. One derivation point (`AuthCookie`), stamped in exactly three
  places: `:api-client`'s `ApiRoute.toHttpRequest` (all 12+ routes, RO GETs included),
  the pairing probe's two hand-built legs, and `:transport-okhttp`'s WS upgrade. The
  hand-built `GET /projects/diff` fetcher in `:app` stamps it too.
- keeps the header **orthogonal to `Origin`**: the token never replaces the CSWSH
  Origin check (the server tests Origin first, then the cookie), and read-only routes
  still carry no Origin.
- validates a typed token ONCE at pairing time with `POST /auth`
  (`{"token":"…"}`, `Accept: application/json` — an `Accept` containing `text/html`
  makes the server answer 302 instead of 204/401). Four outcomes: 204+`Set-Cookie` =
  correct → store it; 204 **without** `Set-Cookie` = that host has no auth → store
  nothing; 401 = wrong token; 429 = rate-limited (10/min/IP).
- stores it per host (keyed by the canonical origin) in `TinkAccessTokenStore`:
  Tink AEAD under an **AndroidKeystore-wrapped, non-exportable** master key, in an
  app-private `SharedPreferences` file, with `android:allowBackup="false"` +
  `data_extraction_rules.xml` excluding cloud backup and device transfer. The token is
  **never logged, never in a URL, never in app UI state**.
- treats a **401 on the WS upgrade as terminal** (`FailureReason.UNAUTHORIZED`): no
  reconnect back-off loop, and the banner tells the user to re-enter the token. A 401 on
  any REST route is the typed `ApiClientError.Unauthorized`.

A host with no `WEBTERM_TOKEN` is byte-identical to before the feature: no token stored ⇒
no `Cookie` header at all (LAN zero-config preserved).

## Toolchain

- **Gradle** 9.6.1 (via the committed wrapper — always use `./gradlew`).
- **Kotlin** 2.3.21 (matches the Kotlin embedded in Gradle 9.6.1).
- **JVM toolchain** 17 (`jvmToolchain(17)` in every module).
- Versions are pinned in the version catalog
  [`gradle/libs.versions.toml`](gradle/libs.versions.toml): kotlinx-serialization-json,
  kotlinx-coroutines-core/-test, JUnit5 (Jupiter), Turbine, MockK.

Pure modules apply `kotlin("jvm")` + `kotlin("plugin.serialization")`, wire the
`libs.bundles.unit-test` bundle into `testImplementation`, and run tests on the
JUnit Platform (`tasks.test { useJUnitPlatform() }`).

## Build & test

```bash
# Use the committed wrapper for everything.
./gradlew help          # sanity: the build configures
./gradlew projects      # lists the 5 pure modules
./gradlew build         # compile all pure modules
./gradlew test          # run JVM unit tests (JUnit5 + coroutines-test + Turbine + MockK)
```

> Testing target: **≥80% Kover coverage** on the pure modules (`:wire-protocol`,
> `:session-core`, `:api-client`, `:client-tls` pure half — the four that apply
> the Kover plugin). TDD, immutable data, small focused files — same discipline as
> the rest of the repo.

### Status & what is NOT verified here

- **Green gate**: `./gradlew test :app:assembleDebug koverVerify` — JVM unit
  tests, a debug APK, and the 80 % coverage floor on the four gated modules.
- **Emulator**: the app has been built, installed and launched on an
  android-35 arm64 emulator (pairing screen rendered, no crash). See the
  `PROGRESS_LOG.md` entry for that run.
- **DEFERRED — real device**: hardware-backed keys (StrongBox falls back to
  software keys on an emulator), FCM push delivery and the lock-screen
  Allow/Deny walkthrough, and general hand-on-glass QA.
- **DEFERRED — instrumented tests**: everything under `src/androidTest/`
  (`TinkAccessTokenStoreTest`, DataStore stores, AndroidKeyStore importer,
  hardware-key checks) needs a connected device/emulator and is therefore **not**
  part of the `./gradlew test` gate; run them with `connectedAndroidTest` on a
  booted emulator.
- **DEFERRED — end-to-end access token**: the `WEBTERM_TOKEN` path is covered by
  unit tests (`OkHttpAccessTokenTest`, the `:api-client` route tests, the
  `AuthCookie` derivation tests), but no automated leg here starts a real server
  with `WEBTERM_TOKEN` set and completes a cookie-gated WS upgrade.

## Android SDK setup (proven working)

The pure JVM modules need only a JDK + Gradle. The **Android-framework** modules
(`:app`, `:terminal-view`, `:host-registry`, `:client-tls-android` — plan AW2+)
need the Android SDK. This machine is set up and the toolchain is **proven** (an
AGP library module compiled against SDK 35 and produced an AAR):

- **SDK location:** `/usr/local/share/android-commandlinetools`
  (installed via `brew install --cask android-commandlinetools`).
- **Installed packages:** `platform-tools`, `platforms;android-35`, `platforms;android-36`,
  `build-tools;35.0.0`, `build-tools;36.0.0`. (`:app` compiles against SDK **36** — the
  Kotlin-2.3.21-contemporaneous androidx/Compose line refuses SDK 35; `platforms;android-37`
  is not fetchable here as the cmdline-tools are too old to parse the v4 repo XML.)
- **`android/local.properties`** (gitignored) points Gradle at it:
  `sdk.dir=/usr/local/share/android-commandlinetools`.
- **Shell env** (for `sdkmanager`/`adb`): `export ANDROID_HOME=/usr/local/share/android-commandlinetools`.

### Wiring an Android module (the working recipe)

- Repos: `google()` is in both `pluginManagement` and `dependencyResolutionManagement`
  in `settings.gradle.kts` (needed to resolve AGP + androidx).
- Plugin: **AGP 9.2.1** (`libs.plugins.android.library` / `.android.application`),
  compatible with Gradle 9.6.1.
- **Gotcha:** AGP 9 has **built-in Kotlin** — apply ONLY the android plugin. Adding
  `org.jetbrains.kotlin.android` errors with "no longer required since AGP 9.0".
- Module block: `android { namespace = "…"; compileSdk = 36; defaultConfig { minSdk = 29 } }`.
  (Framework modules target `compileSdk = 36`; `targetSdk` stays `35` per plan §2.)
- **`:app` UI-stack version matrix** (A13, proven `:app:assembleDebug` green): AGP 9.2.1 ·
  Kotlin 2.3.21 · Compose-compiler plugin `org.jetbrains.kotlin.plugin.compose` = 2.3.21 ·
  Compose BOM `2025.11.01` (→ material3 1.4.0, ui/foundation 1.9.5, material3.adaptive 1.2.0,
  material3-adaptive-navigation-suite 1.4.0) · Hilt (dagger) 2.60.1 via KSP `2.3.9` ·
  androidx core-ktx 1.17.0 / activity-compose 1.12.4 / lifecycle 2.10.0. Apply plugins:
  `android.application` + `kotlin.plugin.compose` + `ksp` + `dagger.hilt.android` (NEVER
  `kotlin.android`). Bump these together with `compileSdk 37` once platform 37 is installable.

To add more SDK pieces later (e.g. an emulator image for instrumented tests):
`sdkmanager "system-images;android-35;google_apis;arm64-v8a" "emulator"`.