Pi Coding Agent Extensions

Extensions are TypeScript modules that receive an ExtensionAPI object and use it to register tools, commands, event handlers, UI components, and providers. Loaded at runtime via jiti — no compilation needed.

Mental Model

Extension = TypeScript file exporting a default function
  ↓
pi starts → discovers extensions → loads via jiti
  ↓
factory(pi: ExtensionAPI) runs → registers tools, commands, events, UI
  ↓
bindCore() → action methods become live (sendMessage, exec, etc.)
  ↓
session_start fires → extension is fully active