Carries a question from a running turn to a client that can answer it, and the answer back. Works across nodes: the machine that asks and the client that answers can be on different nodes.

A tool (ask_question) calls ask/3. The broker publishes a ui_request event on the conversation topic and blocks the caller until a client calls respond/2, the conversation is cancelled (cancel_pending/1), every responder has left, or the timeout passes.

ask/4 can publish a permission_request event instead of a ui_request (event: :permission_request). Either way, ui_resolved follows when the question ends, so a second watcher can dismiss a prompt that someone else answered, or that was cancelled or timed out.

Only a client that has registered with register_responder/1 can answer. The CLI chat and an RPC client that watches a conversation register. The HTTP gateway cannot prompt a user, so with no responder ask/3 returns {:error, :no_interactive_client} at once instead of waiting.

Membership lives in :pg process groups (scope :super_pi_pg). :pg spans the connected nodes and drops a process that exits, so no table needs cleaning.

Pending questions are in memory. If the node that asks stops mid-question, the task engine restarts the turn elsewhere and the model asks again. Nothing is answered by default.