tau-prime is a derivative of Tau for running a terminal coding agent inside a-Shell on iPhone and iPad. It retains Tau's Python agent architecture and tau command, but changes the terminal, shell tools, providers and packaging where the upstream assumptions do not fit a constrained mobile shell.
It also runs on ordinary Python 3.13 installations. On macOS, agent processes and their children are confined by sandbox-exec unless the user explicitly passes --no-sandbox.
The tau_ai package provides provider clients and common events. tau_agent contains messages, tools, the reusable AgentHarness loop and session primitives. tau_coding joins those pieces into coding tools, JSONL persistence, provider configuration, the CLI and the Textual interface.
On a-Shell, command execution uses its constrained sh; the familiar bash tool names remain as compatibility aliases. The interface starts with its sidebar hidden, follows transcript output and polls terminal dimensions when iOS fails to deliver resize events.
Mobile defaults, reliable transcript following, sidebar toggle and resize polling for a-Shell.
Device login, token refresh, live model discovery and the appropriate Copilot endpoints for hosted OpenAI, Claude and Gemini models.
Credential-free local provider with persistent LAN URL configuration, loaded-model discovery and /reload support.
Also supports OpenAI, Codex subscription login, Anthropic, OpenRouter, Hugging Face, DeepSeek, Nebius and custom OpenAI-compatible endpoints.
Append-only JSONL sessions under ~/.tau/sessions/, with history, branching, compaction and export commands.
Restricts writes to the working directory, Tau Prime state, $TMPDIR and required terminal devices. It stops if the sandbox cannot be applied.
The Makefile runs tests, builds the source distribution and smoke-tests it through an isolated uvx installation.