Tau

A small, readable terminal coding agent — and a working example of how coding agents are built.

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What is Tau?

**Tau is a coding agent that lives in your terminal.** You type requests like "explain this repo", "add tests", or "fix this stack trace"; Tau can read files, edit code, run commands, and keep a durable session history while streaming what it is doing.

Tau is also meant to be read. It is a teaching project for understanding the shape of a coding-agent system without starting from a giant production codebase.

tau_coding  →  tau_agent  →  tau_ai

• tau_ai translates model providers into Tau's provider-neutral stream.
• tau_agent owns the portable brain: messages, tools, events, loop, harness, and session primitives.
• tau_coding wraps the brain as a real coding app: CLI, TUI, file/shell tools, provider config, project instructions, skills, and on-disk sessions.

The important boundary is:

AgentHarness = reusable brain
CodingSession = coding-agent environment
TUI = one possible frontend

The core does not know about Textual, Rich, local config paths, slash commands, or rendering. Frontends consume events.

Install

Tau is published on PyPI as `tau-ai` and installs a `tau` command. It requires Python 3.12 or newer. The recommended installers use [`uv`](https