android client for pi rpc

.editorconfig

@@ -0,0 +1,16 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 4
+insert_final_newline = true
+max_line_length = 120
+trim_trailing_whitespace = true
+
+[*.{kt,kts}]
+ktlint_code_style = ktlint_official
+ij_kotlin_allow_trailing_comma = true
+ij_kotlin_allow_trailing_comma_on_call_site = true
+ktlint_function_naming_ignore_when_annotated_with = Composable

.github/workflows/ci.yml

@@ -0,0 +1,51 @@
+name: ci
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  android:
+    name: Android
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 21
+          cache: gradle
+
+      - name: Lint & Test
+        run: ./gradlew ktlintCheck detekt test
+
+  bridge:
+    name: Bridge
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: bridge
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+          cache-dependency-path: bridge/pnpm-lock.yaml
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Lint, Typecheck & Test
+        run: pnpm check

.gitignore

@@ -24,4 +24,17 @@ hs_err_pid*
 replay_pid*
 
 # Kotlin Gradle plugin data, see https://kotlinlang.org/docs/whatsnew20.html#new-directory-for-kotlin-data-in-gradle-projects
-.kotlin/
+.kotlin/
+
+# Gradle
+.gradle/
+**/build/
+**/bin/
+
+# Android
+local.properties
+.idea/
+*.iml
+
+# Keep Gradle wrapper binary
+!gradle/wrapper/gradle-wrapper.jar

README.md

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+# Pi Mobile
+
+An Android client for the [Pi coding agent](https://github.com/badlogic/pi-mono). Control your coding sessions from your phone over Tailscale.
+
+## What This Does
+
+Pi runs on your laptop. This app lets you:
+- Browse and resume coding sessions from anywhere
+- Chat with the agent, send prompts, abort, steer
+- Switch between projects (different working directories)
+- Manage models and thinking levels
+- Handle extension dialogs (confirmations, inputs, selections)
+
+The connection goes over Tailscale, so it works anywhere without port forwarding.
+
+## Architecture
+
+```
+Phone (this app)  <--Tailscale-->  Laptop (bridge)  <--local-->  pi --mode rpc
+```
+
+The bridge is a small Node.js service that translates WebSocket to pi's stdin/stdout JSON protocol. The app connects to the bridge, not directly to pi.
+
+## Setup
+
+### 1. Laptop Setup
+
+Install pi if you haven't:
+```bash
+npm install -g @mariozechner/pi-coding-agent
+```
+
+Clone and start the bridge:
+```bash
+git clone https://github.com/yourusername/pi-mobile.git
+cd pi-mobile/bridge
+pnpm install
+pnpm start
+```
+
+The bridge binds to `127.0.0.1:8787` by default. Set `BRIDGE_HOST` to your laptop Tailscale IP (or `0.0.0.0`) to allow phone access. It spawns pi processes on demand per working directory.
+
+### 2. Phone Setup
+
+Install the APK or build from source:
+```bash
+./gradlew :app:assembleDebug
+adb install app/build/outputs/apk/debug/app-debug.apk
+```
+
+### 3. Connect
+
+1. Add a host in the app:
+   - Host: your laptop's Tailscale IP (100.x.x.x)
+   - Port: 8787 (or whatever the bridge uses)
+   - Token: set this in bridge/.env as `BRIDGE_AUTH_TOKEN`
+
+2. The app will fetch your sessions from `~/.pi/agent/sessions/`
+
+3. Tap a session to resume it
+
+## How It Works
+
+### Sessions
+
+Sessions are grouped by working directory (cwd). Each session is a JSONL file in `~/.pi/agent/sessions/--path--/`. The bridge reads these files directly since pi's RPC doesn't have a list-sessions command.
+
+### Process Management
+
+The bridge manages one pi process per cwd:
+- First connection to a project spawns pi
+- Process stays alive with idle timeout
+- Reconnecting reuses the existing process
+- Crash restart with exponential backoff
+
+### Message Flow
+
+```
+User types prompt
+    ↓
+App sends WebSocket → Bridge
+    ↓
+Bridge writes to pi stdin (JSON line)
+    ↓
+pi processes, writes events to stdout
+    ↓
+Bridge forwards events → App
+    ↓
+App renders streaming text/tools
+```
+
+## Troubleshooting
+
+### Can't connect
+
+1. Check Tailscale is running on both devices
+2. Verify the bridge is running: `curl http://100.x.x.x:8787/health`
+3. Check the token matches exactly (BRIDGE_AUTH_TOKEN)
+4. Try the laptop's Tailscale IP, not hostname
+
+### Sessions don't appear
+
+1. Check `~/.pi/agent/sessions/` exists on laptop
+2. Verify the bridge has read permissions
+3. Check bridge logs for errors
+
+### Streaming is slow/choppy
+
+1. Check logcat for `PerfMetrics` - see actual timing numbers
+2. Look for `FrameMetrics` jank warnings
+3. Verify WiFi/cellular connection is stable
+4. Try closer to the laptop (same room)
+
+### App crashes on resume
+
+1. Check logcat for out-of-memory errors
+2. Large session histories can cause issues
+3. Try compacting the session first: `/compact` in pi, then resume
+
+## Development
+
+### Project Structure
+
+```
+app/              - Android app (Compose UI, ViewModels)
+core-rpc/         - RPC protocol models and parsing
+core-net/         - WebSocket transport and connection management
+core-sessions/    - Session caching and repository
+bridge/           - Node.js bridge service
+```
+
+### Running Tests
+
+```bash
+# Android tests
+./gradlew test
+
+# Bridge tests
+cd bridge && pnpm test
+
+# All quality checks
+./gradlew ktlintCheck detekt test
+```
+
+### Logs to Watch
+
+```bash
+# Performance metrics
+adb logcat | grep "PerfMetrics"
+
+# Frame jank during streaming
+adb logcat | grep "FrameMetrics"
+
+# General app logs
+adb logcat | grep "PiMobile"
+
+# Bridge logs (on laptop)
+pnpm start 2>&1 | tee bridge.log
+```
+
+## Configuration
+
+### Bridge Environment Variables
+
+Create `bridge/.env`:
+
+```env
+BRIDGE_HOST=0.0.0.0              # Use 0.0.0.0 to accept Tailscale connections
+BRIDGE_PORT=8787                 # Port to listen on
+BRIDGE_AUTH_TOKEN=your-secret    # Required authentication token
+BRIDGE_PROCESS_IDLE_TTL_MS=300000  # 5 minutes idle timeout
+BRIDGE_LOG_LEVEL=info            # debug, info, warn, error, silent
+```
+
+### App Build Variants
+
+Debug builds include logging and assertions. Release builds (if you make them) strip these for smaller size.
+
+## Security Notes
+
+- Token auth is required - don't expose the bridge without it
+- The bridge binds to localhost by default; explicitly set `BRIDGE_HOST` to your Tailscale IP for remote access
+- All traffic goes over Tailscale's encrypted mesh
+- Session data stays on the laptop; the app only displays it
+
+## Limitations
+
+- No offline mode - requires live connection to laptop
+- Large tool outputs are truncated (400+ chars collapsed by default)
+- Session history loads once on resume, not incrementally
+- Image attachments not supported (text only)
+
+## Testing
+
+See [docs/testing.md](docs/testing.md) for emulator setup and testing procedures.
+
+Quick start:
+```bash
+# Start emulator, build, install
+./gradlew :app:installDebug
+
+# Watch logs
+adb logcat | grep -E "PiMobile|PerfMetrics"
+```
+
+## License
+
+MIT

app/build.gradle.kts

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+plugins {
+    id("com.android.application")
+    id("org.jetbrains.kotlin.android")
+    id("org.jetbrains.kotlin.plugin.serialization")
+}
+
+android {
+    namespace = "com.ayagmar.pimobile"
+    compileSdk = 34
+
+    defaultConfig {
+        applicationId = "com.ayagmar.pimobile"
+        minSdk = 26
+        targetSdk = 34
+        versionCode = 1
+        versionName = "1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro",
+            )
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    kotlinOptions {
+        jvmTarget = "17"
+    }
+
+    buildFeatures {
+        compose = true
+    }
+
+    composeOptions {
+        kotlinCompilerExtensionVersion = "1.5.14"
+    }
+
+    packaging {
+        resources {
+            excludes += "/META-INF/{AL2.0,LGPL2.1}"
+        }
+    }
+}
+
+dependencies {
+    implementation(project(":core-rpc"))
+    implementation(project(":core-net"))
+    implementation(project(":core-sessions"))
+
+    implementation(platform("androidx.compose:compose-bom:2024.06.00"))
+    implementation("androidx.core:core-ktx:1.13.1")
+    implementation("androidx.activity:activity-compose:1.9.1")
+    implementation("androidx.lifecycle:lifecycle-runtime-ktx:2.8.4")
+    implementation("androidx.lifecycle:lifecycle-runtime-compose:2.8.4")
+    implementation("androidx.lifecycle:lifecycle-viewmodel-compose:2.8.4")
+    implementation("androidx.navigation:navigation-compose:2.7.7")
+    implementation("androidx.security:security-crypto:1.1.0-alpha06")
+    implementation("androidx.compose.material3:material3")
+    implementation("androidx.compose.ui:ui")
+    implementation("androidx.compose.ui:ui-tooling-preview")
+    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.3")
+    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+
+    debugImplementation("androidx.compose.ui:ui-tooling")
+
+    testImplementation("junit:junit:4.13.2")
+}

app/proguard-rules.pro

@@ -0,0 +1 @@
+# Project specific ProGuard rules.