Mirror the CLI's exit-path behaviour in the TUI gateway so that
unpersisted conversation messages are flushed to state.db and the
on_session_end plugin hook fires before the session is closed.
Root cause: _finalize_session() only called db.end_session() to
mark the session row as ended, but did NOT flush in-memory messages
via _persist_session() or fire the on_session_end hook. When the
user force-quit (double Ctrl-C, terminal-close, SIGHUP) while the
agent was mid-turn, messages accumulated since the last persist
point were silently lost.
Changes
-------
tui_gateway/server.py - _finalize_session():
- Persist unflushed messages via agent._persist_session() before
db.end_session(). Prefers agent._session_messages (set by the
last _persist_session call inside run_conversation) over
session['history'] (stale when agent is mid-turn).
- Fire on_session_end(interrupted=True) plugin hook so crash-
recovery plugins can flush buffers, matching cli.py behaviour.
tui_gateway/entry.py - _log_signal():
- Explicitly call _shutdown_sessions() before sys.exit(0) in the
SIGHUP/SIGTERM handler as belt-and-suspenders over atexit.
tests/tui_gateway/test_finalize_session_persist.py (new):
- 11 tests covering: history persistence, _session_messages
priority, empty-history skip, missing-agent, double-finalize,
persist-exception resilience, hook firing, hook-exception
resilience, and db.end_session preservation.
Related
-------
Closes the TUI half of #5021 (CLI already handles this via its
atexit handler). Also addresses the session-persistence gap
discussed in #18465 and #18269.
