Pi Agent Harness
An agent harness and coding-agent CLI built from composable packages: a unified multi-provider LLM API, an agent runtime with tool calling, a terminal UI, and an interactive coding agent, with no built-in permission system unless containerized.
Pi Agent Harness is a set of packages for building and running AI agents. pi-ai provides a unified API across LLM providers such as OpenAI, Anthropic and Google; pi-agent-core is the agent runtime that handles tool calling and state; pi-tui is a terminal UI library with differential rendering; and pi-coding-agent is an interactive coding agent CLI built on top of them.
Other packages include pi-durable, a runtime for durable conversations, tasks and documents, pi-telemetry for vendor-neutral telemetry, and chord, a standalone runtime for services, replicated state, RPC and plugins. A companion project, pi-chat, handles Slack and chat automation.
Pi does not include a built-in permission system restricting filesystem, process, network or credential access; it runs with the permissions of the user who launched it, so its documentation describes containerization and sandboxing patterns for stronger isolation. It is written in TypeScript and MIT licensed.