READ THIS FIRST. Reports what this server can reach and how to drive it: permitted tools, the default model, models available per provider, and the recipes for delegating. Every other tool refuses until this has been called once.

Delegate a task to a pi agent running in the background. Returns a sessionId immediately, so nothing blocks. Poll with status, redirect with steer, answer its questions with answer. Use this for anything that might take more than a minute.

Fan out several delegates in one call. Each task inherits the batch-level model, cwd, tools and extensions unless it overrides them. The whole batch is validated before any delegate starts, so a bad model name or a duplicate id fails everything instead of leaving half a fan-out running. Poll the result with sessions, which reports all of them at once, rather than one status per delegate.

Delegate a task to a pi agent and wait for the final answer. Blocks until done. Prefer spawn for long work; this is for quick questions.

Check a background pi session. Returns state, turn count, tools used, latest text, and any pending questions the agent is waiting on. A non-empty questions array means it is blocked until you call answer. toolCalls traces every tool the delegate ran, in order.

Redirect a running pi agent mid-task. The message lands after its current tool call finishes, before the next model call. Use this instead of aborting when the agent is going the wrong way.

Answer a question raised by a pi agent. Get requestId from status. Only pi extensions can ask, so questions appear only for delegates spawned with extensions: true; the MCP adapter's tool-approval and elicitation prompts are the usual source. A delegate waiting on one is blocked until you answer it.

Send another prompt to a delegate that has already finished, keeping everything it read and said. Use this instead of spawning a fresh delegate and re-explaining the task: the session still holds its own context, which yours never had to absorb. Returns immediately; poll with status as usual. For a delegate that is still working, use steer instead.

Stop a running pi session. Partial output stays readable via status.

List pi sessions held by this server, running and finished. Finished ones stay readable for review until evicted (keeps the newest 50).

Drop a finished session from the review history, freeing its id for reuse.

List models this delegate may use: pi's own scoped set plus any custom provider. Use to pick a model value.