Pi
Minimal terminal coding harness built for extensibility
Free Coding CLI Open Source
Overview
Pi is a minimal, extensible terminal coding agent that adapts to your workflow rather than imposing one. Supports 15+ providers with hundreds of models including Anthropic, OpenAI, Google, Azure, and Bedrock, with mid-session model switching. Features tree-structured session history with branching, four operational modes (interactive, print/JSON, RPC, and SDK), and a primitives-first philosophy that lets you build custom features via TypeScript extensions. Includes context engineering with AGENTS.md and SYSTEM.md, automatic message compaction, a queuing system for steering messages, and support for skills, prompt templates, and themes.
Architecture: Apple Silicon, Intel
Key Features
- 15+ provider support with hundreds of models and mid-session switching
- Tree-structured session history with branching capabilities
- Four operational modes: interactive, print/JSON, RPC, and SDK
- Extensible via TypeScript — build custom features as extensions
- Context engineering with AGENTS.md, SYSTEM.md, and automatic compaction
- Queuing system for steering messages and follow-ups
- Skills, prompt templates, and theme support
- Primitives-first philosophy — no baked-in opinions
