/yolo and /verbose are safe to dispatch while an agent is running:
/yolo can unblock a pending approval prompt, /verbose cycles the
tool-progress display for the ongoing stream. Both modify session
state without needing agent interaction. Previously they fell through
to the running-agent catch-all (PR #12334) and returned the generic
busy message.
/fast and /reasoning stay on the catch-all — their handlers explicitly
say 'takes effect on next message', so nothing is gained by dispatching
them mid-turn.
Salvaged from #10116 (elkimek), scoped down.