/goal <condition> in chat sets a target and keeps the turn loop running until
it is met:
met,
not_yet, or impossible. The worker model never certifies itself; a different
model holds the yardstick. The judge’s verdict is shown in the transcript, and
the loop stops on met or impossible.
ASTER_GOAL_MAX_TURNS caps the loop, default 20. /goal with no argument
clears the current goal.