fix(gateway): end finalized expired sessions as reset

tests/gateway/test_session_store_expiry_finalized.py

@@ -0,0 +1,67 @@
+"""Session expiry finalization closes sessions as session_reset.
+
+Regression coverage for #61220: the expiry watcher marks a session expired,
+then agent cleanup can close it as ``agent_close``. Stale routing recovery treats
+``agent_close`` as recoverable, so expired sessions were reopened with full
+history unless expiry finalization also persisted the real conversation boundary
+as ``end_reason='session_reset'``.
+"""
+
+from datetime import datetime, timedelta
+from unittest.mock import MagicMock, patch
+
+from gateway.config import GatewayConfig, Platform, SessionResetPolicy
+from gateway.session import SessionEntry, SessionStore
+
+
+def _make_store_with_db(tmp_path, db_mock) -> SessionStore:
+    config = GatewayConfig(default_reset_policy=SessionResetPolicy(mode="daily"))
+    with patch("gateway.session.SessionStore._ensure_loaded"):
+        store = SessionStore(sessions_dir=tmp_path, config=config)
+    store._db = db_mock
+    store._loaded = True
+    return store
+
+
+def _entry(session_id: str = "sid-expired") -> SessionEntry:
+    now = datetime.now()
+    return SessionEntry(
+        session_key="agent:main:telegram:dm:8494508720",
+        session_id=session_id,
+        created_at=now - timedelta(days=1),
+        updated_at=now - timedelta(days=1),
+        platform=Platform.TELEGRAM,
+        chat_type="dm",
+        model_override={"provider": "openrouter", "model": "test/model"},
+    )
+
+
+def test_set_expiry_finalized_persists_session_reset_boundary(tmp_path):
+    db = MagicMock()
+    db.set_expiry_finalized.return_value = None
+    db.reopen_session.return_value = None
+    db.end_session.return_value = None
+    store = _make_store_with_db(tmp_path, db)
+    entry = _entry()
+
+    store.set_expiry_finalized(entry)
+
+    assert entry.expiry_finalized is True
+    assert entry.model_override is None
+    db.set_expiry_finalized.assert_called_once_with("sid-expired", True)
+    db.reopen_session.assert_called_once_with("sid-expired")
+    db.end_session.assert_called_once_with("sid-expired", "session_reset")
+
+
+def test_set_expiry_finalized_still_sets_flag_if_end_session_fails(tmp_path):
+    db = MagicMock()
+    db.set_expiry_finalized.return_value = None
+    db.reopen_session.side_effect = RuntimeError("database locked")
+    store = _make_store_with_db(tmp_path, db)
+    entry = _entry()
+
+    store.set_expiry_finalized(entry)
+
+    assert entry.expiry_finalized is True
+    db.set_expiry_finalized.assert_called_once_with("sid-expired", True)
+    db.end_session.assert_not_called()