Every session dispose broadcast the shutdown abort reason, so an explicit
hard kill of a subagent (release with tombstone, then live.dispose()) tagged
its nested children as shutdown and rediscovered them as parked instead of
terminal.
- Gate ASYNC_JOB_MANAGER_SHUTDOWN_REASON on #ownedAsyncJobManager so only the
top-level owning session's dispose (genuine process shutdown) uses it.
- Subagent disposes propagate a generic cancellation, keeping nested children
terminal.
- Cover the subagent generic-cancel path alongside the owning-session shutdown.
Fixes#8216
Session teardown pre-cancels owner jobs via #cancelOwnAsyncJobs before
manager.dispose(), so the shutdown abort reason must ride along that
cancelAll or an owned subagent job sees a generic caller signal and is
tombstoned instead of parked.
- Forward an abort reason through AsyncJobManager.cancelAll.
- Pass ASYNC_JOB_MANAGER_SHUTDOWN_REASON from #disposeOwnedAsyncJobs.
- Cover owned-job shutdown tagging through a real AgentSession dispose.
Fixes#8216
Bounded aborted post-prompt drains and ran independent subsystem cleanup under one barrier while preserving writers-before-close ordering.
Kept long interactive shutdowns visible with a delayed status refresh.
Fixes#5932
roboomp