What Pi is
Pi is a minimal coding agent that runs in the terminal, built by Earendil Inc. and contributors under the MIT license. Its website is pi.dev and its documentation lives at pi.dev/docs/latest. The official tagline is “There are many agent harnesses but this one is yours”: the core stays small so users adapt Pi to their workflows through extensions, not the other way around. Note the naming: this entry covers the terminal coding agent at pi.dev, not Raspberry Pi or other products called Pi.
Uses and boundaries
- Extension mechanisms: TypeScript extensions (custom tools, commands, events, and UI), skills for reusable on-demand capabilities, prompt templates triggered via slash commands, themes, and pi packages that bundle and share extensions, skills, prompts, and themes.
- Models and providers: officially 15+ providers and hundreds of models, switchable mid-session with
/model; local models are also supported via llama.cpp. - Sessions and context: sessions are stored as trees with branching and sharing; context engineering includes AGENTS.md, SYSTEM.md, compaction, and skills.
- Integration modes: interactive, print/JSON, RPC, and SDK usage, embeddable in Node.js applications through the SDK.
- Design tradeoff: officially “Primitives, not features” — the core deliberately omits MCP, sub-agents, plan mode, and permission popups; add them as extensions or packages when needed.
- Installation: an official curl installer script, or the npm package
@earendil-works/pi-coding-agent.
Discussion in the show
- Weekly #001’s chapter “Harness 评测：完成率、Token 成本与’斩杀线’” (Chinese transcript) compares agent harnesses: Xiangyang Qiaomu says many developers like Pi’s harness; Yang Pan relays a third-party evaluation published that day (Runta’s Harness Eval) saying Pi sat inside the “kill line,” overshadowed by DeepSeek Harness; Orange adds that Pi is lightweight but much weaker in extensibility, with poor MCP support. Note: the evaluation figures are relayed through the show, not official Pi data; and omitting MCP from the core is, per official wording, a deliberate design choice — the two assessments come from different angles.
- In Weekly #002’s chapter “Agent API：还需要自己维护一套 Harness 吗”, while discussing growing harness complexity, Xiangyang Qiaomu says Pi was said to be very minimal already, but it has accumulated a lot.
Frequently asked questions
What is Pi?
Pi is the terminal coding agent from pi.dev: a minimal core customized through TypeScript extensions, skills, prompt templates, and themes, MIT-licensed and embeddable via an SDK. It is unrelated to Raspberry Pi or other products named Pi.
How do I install Pi?
The official one-line installer is curl -fsSL https://pi.dev/install.sh | sh; alternatively install the npm package @earendil-works/pi-coding-agent. After installing, run pi and authenticate with /login or an API key. See the official documentation.
Does Pi support MCP?
The core deliberately omits MCP, sub-agents, and plan mode — official wording is “Primitives, not features.” Add MCP support through extensions or community packages when needed.
How does Pi differ from terminal agents like Claude Code or OpenCode?
Per its official positioning, Pi’s differentiator is a minimal core plus user-defined extensions: a very small system prompt, a deliberately narrow core, and workflows built by the user through extensions. Feature comparisons change with versions, so treat the official documentation as the reference and try it yourself.