A closed herdr session is not an exited agent, and the `herdr already dead`
path ran no check at all, so stop could remove the files of a live claude
and then its row. New `python -m lib_py.agents in-use <agent> <uuid> [ws]
[--wait s]` gives the purge CLI's own verdict; stop asks it outside the
registry lock and, unless it answers free, exits 4 with nothing changed.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
GodopuandClaude Opus 5.5
ae98cf18c4