Pi for iOS

Run the Pi coding agent natively on iOS.

Features

• Native Performance: Runs Bun's JavaScript engine directly on iOS using JSC's C_LOOP interpreter
• GPU-Accelerated Terminal: Uses Ghostty's Metal-based terminal renderer
• Full Pi Agent: Complete pi coding agent with tool use, file operations, and more
• Works Offline: No WebView, no remote execution - everything runs locally on device

Requirements

• iOS 17.0+
• iPhone with arm64 processor
• OpenRouter API key (for AI model access)

Installation

From Source

1. Clone the repository

   git clone https://github.com/dannote/pi-ios.git
   cd pi-ios

2. Download pre-built dependencies

   Download the vendor libraries from Releases and extract to vendor/:

   tar -xzf vendor-libs.tar.gz -C vendor/

   Or build from source (see Building Dependencies).

3. Generate Pi bundle

   The Pi agent JavaScript bundle is not included in the repo. Generate it:

   cd /path/to/pi-coding-agent
   bun run build:ios
   cp dist/pi-ios-bundle.js /path/to/pi-ios/app/Pi/Resources/

4. Generate Xcode project

   cd app
   xcodegen generate

5. Open in Xcode and build

   open Pi.xcodeproj

   Select your device and build (⌘B).

Setting Up API Key

Pi requires an OpenRouter API key to access AI models. Create a config.json file in the app's Documents folder:

Option 1: Using devicectl (from Mac)

echo '{"openrouter_api_key": "sk-or-v1-your-key-here"}' > /tmp/config.json
xcrun devicectl device copy to \
  --device YOUR_DEVICE_UDID \
  --domain-type appDataContainer \
  --domain-identifier com.dannote.pi \
  --source /tmp/config.json \
  --destination Documents/config.json

Option 2: Using Files app (on iPhone)

1. Open the Files app
2. Navigate to "On My iPhone" → "Pi"
3. Create a new file called config.json
4. Add: {"openrouter_api_key": "sk-or-v1-your-key-here"}

Building Dependencies

Pi requires three main dependencies to be built for iOS:

1. WebKit/JavaScriptCore

Build WebKit for iOS with C_LOOP interpreter enabled (required since JIT is not available on iOS):

cd ~/Development
git clone https://github.com/ArtSabintsev/WebKit.git
cd WebKit
mkdir build-ios-device && cd build-ios-device

cmake .. \
    -G Ninja \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_SYSTEM_NAME=iOS \
    -DCMAKE_OSX_SYSROOT=iphoneos \
    -DCMAKE_OSX_ARCHITECTURES=arm64 \
    -DPORT=JSCOnly \
    -DENABLE_STATIC_JSC=ON \
    -DENABLE_JIT=OFF \
    -DENABLE_C_LOOP=ON \
    -DENABLE_WEBASSEMBLY=OFF \
    -DENABLE_SAMPLING_PROFILER=OFF

ninja JavaScriptCore

2. Bun

Build Bun for iOS using the iOS port:

git clone https://github.com/dannote/bun.git -b ios-port
cd bun
mkdir build/ios-device && cd build/ios-device

cmake ../.. \
    -G Ninja \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_TOOLCHAIN_FILE=../../cmake/toolchains/ios-device.cmake

ninja

3. Ghostty

Build Ghostty for iOS:

git clone https://github.com/dannote/ghostty.git -b ios-manual-backend
cd ghostty

zig build \
    -Doptimize=ReleaseFast \
    -Dtarget=aarch64-ios \
    --build-file src/build.zig

Architecture

┌─────────────────────────────────────────────────────┐
│                     Pi for iOS                       │
├─────────────────────────────────────────────────────┤
│  SwiftUI App                                        │
│    ├─ TerminalView (UIView + UIKeyInput)            │
│    ├─ KeyboardAccessory (iOS 26 Liquid Glass)       │
│    └─ BunGhosttyBridge (pipes stdin/stdout)         │
├─────────────────────────────────────────────────────┤
│  Ghostty Terminal (Metal GPU rendering)             │
│    └─ Manual termio backend for iOS                 │
├─────────────────────────────────────────────────────┤
│  Bun Runtime (JSC with C_LOOP interpreter)          │
│    ├─ iOS embedding API (bun_start, bun_eval)       │
│    ├─ Stubs for iOS-unsupported features            │
│    └─ Full npm package compatibility                │
├─────────────────────────────────────────────────────┤
│  Pi Coding Agent (bundled JavaScript)               │
│    └─ Interactive mode, tools, AI integration       │
└─────────────────────────────────────────────────────┘

Key Technical Achievements

• Bun on iOS: First working port of Bun to iOS, using JSC's C_LOOP interpreter instead of JIT
• Ghostty on iOS: Manual termio backend for Ghostty's GPU-rendered terminal
• No Private APIs: App Store compliant - no JIT, no private frameworks
• Native Performance: ~600ms cold start, full npm package support

Known Limitations

• No JIT: JavaScript runs in interpreter mode (~10x slower than JIT)
• No WebAssembly: Disabled due to JIT requirement
• No CPU Profiler: Sampling profiler requires JIT
• Memory: C_LOOP interpreter uses more memory than JIT

Related Projects

• pi-coding-agent - The pi coding agent
• Bun iOS Port - Bun runtime for iOS
• Ghostty iOS - Ghostty terminal for iOS

License

MIT License - see LICENSE for details.

Contributing

Contributions welcome! Please read the contributing guidelines before submitting PRs.