pi

Pi is a terminal coding agent built around a single principle: the harness should adapt to you, not the other way around. Unlike AI coding agents that ship with fixed opinions about plan modes, sub-agents, and permission flows, Pi keeps the core deliberately small and exposes everything through a TypeScript extension system.

The extension model is the real differentiator. You can add tools, commands, keyboard shortcuts, events, custom editors, status bars, and overlays. Bundle those into a package and share it via npm or git. Third-party extensions already exist, including one that turns Pi into a drawing canvas inside the terminal. If you want a feature Pi doesn't have, you ask Pi to build it, hit /reload, and keep going.

Key capabilities:

• 15+ providers including Anthropic, OpenAI, Google, Azure, Bedrock, Mistral, Groq, Cerebras, xAI, Ollama, OpenRouter, and more. Switch models mid-session with /model or cycle favorites with Ctrl+P.
• Tree-structured history so sessions branch rather than scroll. Navigate any prior point with /tree, export to HTML, or upload to a GitHub gist for a shareable URL.
• Context engineering via AGENTS.md (project instructions), SYSTEM.md (custom system prompts), skills (on-demand capability packages), prompt templates, and fully customizable compaction that summarizes older messages before hitting the context limit.
• Steering while running. Press Enter to interrupt the current run with a steering message, or Alt+Enter to queue a follow-up once it finishes.
• Four modes: interactive TUI, print/JSON for scripting, RPC over stdin/stdout for non-Node integrations, and an SDK for embedding Pi in your own apps.

Pi is token-efficient by design. Its system prompt is minimal, and skills use progressive disclosure so you're not burning tokens on capabilities you haven't loaded. Features like Aider or Cline bake more in by default; Pi bets that a smaller, extensible core is more useful to developers who want control over their tooling.

Licensed under MIT and self-hostable.