Follow-up to PR #3507 addressing the Oracle-noted operational limitation:
per-PID isolated session names (getIsolatedSessionName(process.pid)) mean
that when an opencode process is SIGKILL'd (or the machine hard-reboots),
the old omo-agents-<old-pid> tmux session survives forever because nothing
is around to kill it.
Added sweepStaleOmoAgentSessions() that:
1. Lists tmux sessions matching /^omo-agents-(\d+)$/
2. For each, checks process.kill(pid, 0) to detect a dead PID
3. Skips our own PID
4. Calls killTmuxSessionIfExists for every session whose owner process is gone
Wired into TmuxSessionManager.onSessionCreated() as a one-shot (guarded by
staleSweepCompleted flag) so it runs lazily on the first subagent spawn when
isolation="session". The flag is reset in cleanup() so subsequent process
restarts re-run the sweep.
6 new tests cover: outside-tmux no-op, no matching sessions, multiple dead
PIDs, current PID skip, live PID skip, list-sessions failure.
Manual E2E verified on real tmux:
- Created omo-agents-99999, sweep killed it
- Spawned our own omo-agents-<pid>, closeTmuxPane returned true even after
pane auto-destroy from Ctrl+C
- Final tmux list-sessions shows zero omo-agents-* orphans
YeonGyu-Kim
104523051d