pi-until — keep going until the predicate passes

/until [--max N] <command> [-- task]
/until stop
/until            # status

State the exit condition as a command, and the agent cannot stop until it exits 0:

/until npm test -- fix the flaky date test
/until --max 5 gh pr checks 42

Behaviour

• Starting a loop sends a kickoff message (the task, or "make <command> exit 0") and runs the agent.
• Every time the run is about to settle, the command runs via sh -c in the session's cwd (10 minute timeout).
  • exit 0 → loop ends, notification.
  • non-zero → the last 40 lines of output go back to the agent as a message, with the rule: a plateau is not a stop; never relax the predicate. The agent continues.
  • after --max checks (default 20) it gives up and says so.
• An aborted (Esc) or errored run ends the loop instead of fighting you.
• One TSV row per check (ts, iteration, exit, summary) is appended to .pi/runs/until-<timestamp>.tsv in the cwd, so a run you walked away from leaves a trail.

The first -- separates the command from the task, so a command that itself needs -- (e.g. npm test -- --grep x) belongs in a script or sh -c '…'.

The command is yours, typed at the prompt. The model never supplies it.

How

agent_before_settle is pi's final actionable boundary: a handler can append a custom_message draft (the model reads it as a user message) and return continue: true for one more request. The loop re-arms itself at every settle, so no timers or watchers are involved.