### Breaking Changes
- **Extension tool signature change**: `ToolDefinition.execute` now uses `(toolCallId, params, signal, onUpdate, ctx)` parameter order to match `AgentTool.execute`. Previously it was `(toolCallId, params, onUpdate, ctx, signal)`. This makes wrapping built-in tools trivial since the first four parameters now align. Update your extensions by swapping the `signal` and `onUpdate` parameters:
```ts
// Before
async execute(toolCallId, params, onUpdate, ctx, signal) { ... }
// After
async execute(toolCallId, params, signal, onUpdate, ctx) { ... }
```
### New Features
- **Android/Termux support**: Pi now runs on Android via Termux. Install with:
```bash
pkg install nodejs termux-api git
npm install -g @mariozechner/pi-coding-agent
mkdir -p ~/.pi/agent
echo "You are running on Android in Termux." > ~/.pi/agent/AGENTS.md
```
Clipboard operations fall back gracefully when `termux-api` is unavailable. ([#1164](https://github.com/badlogic/pi-mono/issues/1164))
- **Bash spawn hook**: Extensions can now intercept and modify bash commands before execution via `pi.setBashSpawnHook()`. Adjust the command string, working directory, or environment variables. See [docs/extensions.md](docs/extensions.md). ([#1160](https://github.com/badlogic/pi-mono/pull/1160) by [@mitsuhiko](https://github.com/mitsuhiko))
- **Linux ARM64 musl support**: Pi now runs on Alpine Linux ARM64 (linux-arm64-musl) via updated clipboard dependency.
- **Nix/Guix support**: `PI_PACKAGE_DIR` environment variable overrides the package path for content-addressed package managers where store paths tokenize poorly. See [README.md#environment-variables](README.md#environment-variables). ([#1153](https://github.com/badlogic/pi-mono/pull/1153) by [@odysseus0](https://github.com/odysseus0))
- **Named session filter**: `/resume` picker now supports filtering to show only named sessions via Ctrl+N. Configurable via `toggleSessionNamedFilter` keybinding. See [docs/keybindings.md](docs/keybindings.md). ([#1128](https://github.com/badlogic/pi-mono/pull/1128) by [@w-winter](https://github.com/w-winter))
- **Typed tool call events**: Extension developers can narrow `ToolCallEvent` types using `isToolCallEventType()` for better TypeScript support. See [docs/extensions.md#tool-call-events](docs/extensions.md#tool-call-events). ([#1147](https://github.com/badlogic/pi-mono/pull/1147) by [@giuseppeg](https://github.com/giuseppeg))
- **Extension UI Protocol**: Full RPC documentation and examples for extension dialogs and notifications, enabling headless clients to support interactive extensions. See [docs/rpc.md#extension-ui-protocol](docs/rpc.md#extension-ui-protocol). ([#1144](https://github.com/badlogic/pi-mono/pull/1144) by [@aliou](https://github.com/aliou))
### Added
- Added Linux ARM64 musl (Alpine Linux) support via clipboard dependency update
- Added Android/Termux support with graceful clipboard fallback ([#1164](https://github.com/badlogic/pi-mono/issues/1164))
- Added bash tool spawn hook support for adjusting command, cwd, and env before execution ([#1160](https://github.com/badlogic/pi-mono/pull/1160) by [@mitsuhiko](https://github.com/mitsuhiko))
- Added typed `ToolCallEvent.input` per tool with `isToolCallEventType()` type guard for narrowing built-in tool events ([#1147](https://github.com/badlogic/pi-mono/pull/1147) by [@giuseppeg](https://github.com/giuseppeg))
- Exported `discoverAndLoadExtensions` from package to enable extension testing without a local repo clone ([#1148](https://github.com/badlogic/pi-mono/issues/1148))
- Added Extension UI Protocol documentation to RPC docs covering all request/response types for extension dialogs and notifications ([#1144](https://github.com/badlogic/pi-mono/pull/1144) by [@aliou](https://github.com/aliou))
- Added `rpc-demo.ts` example extension exercising all RPC-supported extension UI methods ([#1144](https://github.com/badlogic/pi-mono/pull/1144) by [@aliou](https://github.com/aliou))
- Added `rpc-extension-ui.ts` TUI example client demonstrating the extension UI protocol with interactive dialogs ([#1144](https://github.com/badlogic/pi-mono/pull/1144) by [@aliou](https://github.com/aliou))
- Added `PI_PACKAGE_DIR` environment variable to override package path for content-addressed package managers (Nix, Guix) where store paths tokenize poorly ([#1153](https://github.com/badlogic/pi-mono/pull/1153) by [@odysseus0](https://github.com/odysseus0))
- `/resume` session picker now supports named-only filter toggle (default Ctrl+N, configurable via `toggleSessionNamedFilter`) to show only named sessions ([#1128](https://github.com/badlogic/pi-mono/pull/1128) by [@w-winter](https://github.com/w-winter))
### Fixed
- Fixed `pi update` not updating npm/git packages when called without arguments ([#1151](https://github.com/badlogic/pi-mono/issues/1151))
- Fixed `models.json` validation requiring fields documented as optional. Model definitions now only require `id`; all other fields (`name`, `reasoning`, `input`, `cost`, `contextWindow`, `maxTokens`) have sensible defaults. ([#1146](https://github.com/badlogic/pi-mono/issues/1146))
- Fixed models resolving relative paths in skill files from cwd instead of skill directory by adding explicit guidance to skills preamble ([#1136](https://github.com/badlogic/pi-mono/issues/1136))
- Fixed tree selector losing focus state when navigating entries ([#1142](https://github.com/badlogic/pi-mono/pull/1142) by [@Perlence](https://github.com/Perlence))
- Fixed `cacheRetention` option not being passed through in `buildBaseOptions` ([#1154](https://github.com/badlogic/pi-mono/issues/1154))
- Fixed OAuth login/refresh not using HTTP proxy settings (`HTTP_PROXY`, `HTTPS_PROXY` env vars) ([#1132](https://github.com/badlogic/pi-mono/issues/1132))
- Fixed `pi update <source>` installing packages locally when the source is only registered globally ([#1163](https://github.com/badlogic/pi-mono/pull/1163) by [@aliou](https://github.com/aliou))
- Fixed tree navigation with summarization overwriting editor content typed during the summarization wait ([#1169](https://github.com/badlogic/pi-mono/pull/1169) by [@aliou](https://github.com/aliou))