# Armin Ronacher's subagent extension

By Saurabh Kumar · TIL note, Oct 9, 2026 · Tags: pi-agent

Source: https://saurabh-kumar.com/til/1791547200/

[Armin Ronacher's subagent extension](https://github.com/mitsuhiko/agent-stuff/blob/main/extensions/subagent.ts) runs one observable Pi child at a time in tmux. The parent waits for the result, while I can attach to inspect or intervene. Worth preserving when adding hierarchy: synchronous coordination must not mean invisible execution.