Miguel Palhas
ae3091e2a2
The respawn runs with the session map unlocked, so two takes of the lock straddle it. A kill landing in that window deleted the sidecar before resume wrote it back, leaving a file for a session that was gone — the next recovery registered it as a dormant ghost. Resume now deletes the sidecar in the branch where it finds its own record gone. Two resumes both passed the `Running` check for the same reason. The record is marked in-flight under the first lock, so the second request is refused with `already_running` instead of losing a race for the FIFO and reporting a tmux failure. Every path out of resume clears the marker. Both races are driven deterministically in the tests: the manager's tmux spawn is parked mid-resume while the racing kill or resume runs. Closes #175