### Added
- Hook API: `before_agent_start` handlers can now return `systemPromptAppend` to dynamically append text to the system prompt for that turn. Multiple hooks' appends are concatenated.
- Hook API: `before_agent_start` handlers can now return multiple messages (all are injected, not just the first)
- New example hook: `tools.ts` - Interactive `/tools` command to enable/disable tools with session persistence
- New example hook: `pirate.ts` - Demonstrates `systemPromptAppend` to make the agent speak like a pirate
- Tool registry now contains all built-in tools (read, bash, edit, write, grep, find, ls) even when `--tools` limits the initially active set. Hooks can enable any tool from the registry via `pi.setActiveTools()`.
- System prompt now automatically rebuilds when tools change via `setActiveTools()`, updating tool descriptions and guidelines to match the new tool set
- Hook errors now display full stack traces for easier debugging
### Changed
- Removed image placeholders after copy & paste, replaced with inserting image file paths directly. ([#442](https://github.com/badlogic/pi-mono/pull/442) by [@mitsuhiko](https://github.com/mitsuhiko))
### Fixed
- Fixed potential text decoding issues in bash executor by using streaming TextDecoder instead of Buffer.toString()
- External editor (Ctrl-G) now shows full pasted content instead of `[paste #N ...]` placeholders ([#444](https://github.com/badlogic/pi-mono/pull/444) by [@aliou](https://github.com/aliou))