fix: повторять сохранение присутствия после сбоя

backend/app/session/hub.py

@@ -56,6 +56,7 @@ class SessionHub:
         self._stations: dict[UUID, set[asyncio.Queue]] = {}
         self._trainee_calls: dict[UUID, set[asyncio.Queue]] = {}
         self._trainee_stations: dict[UUID, set[asyncio.Queue]] = {}
+        self._pending_adoptions: dict[UUID, SessionState] = {}
         self._tickers: dict[UUID, asyncio.Task] = {}
         # Задачи, порождённые внутри операции, наследуют контекст; после
         # закрытия операции их события идут напрямую (`_Operation.open`).
@@ -119,6 +120,7 @@ class SessionHub:
 
     def drop(self, session_id: UUID) -> None:
         self._sessions.pop(session_id, None)
+        self._pending_adoptions.pop(session_id, None)
         self.stop_ticker(session_id)
 
     def live_count(self) -> int:
@@ -158,6 +160,18 @@ class SessionHub:
                 log.warning("продление lease занятия %s не удалось", state.session_id,
                             exc_info=True)
                 await self.fence(state)
+        for state in list(self._pending_adoptions.values()):
+            try:
+                await self.store.commit(state)
+            except SessionLeaseLost:
+                self._pending_adoptions.pop(state.session_id, None)
+            except Exception:
+                log.warning("повторное сохранение занятия %s после takeover не удалось",
+                            state.session_id, exc_info=True)
+            else:
+                self._pending_adoptions.pop(state.session_id, None)
+                self.register(state)
+                self.start_ticker(state.session_id)
         try:
             claimed = await self.store.claim_expired()
         except Exception:  # следующий оборот попробует снова
@@ -183,9 +197,13 @@ class SessionHub:
             state.socket_connected_at_checkpoint = False
             try:
                 await self.store.commit(state)
+            except SessionLeaseLost:
+                return False
             except Exception:
                 log.exception("не удалось сохранить присутствие после takeover %s", state.session_id)
+                self._pending_adoptions[state.session_id] = state
                 return False
+        self._pending_adoptions.pop(state.session_id, None)
         self.register(state)
         self.start_ticker(state.session_id)
         return True

backend/tests/test_session_signals.py

@@ -461,3 +461,33 @@ def test_failed_presence_commit_closes_station_with_fencing_code(client, monkeyp
         assert not hub.station_connected(session_id)
     finally:
         control.__exit__(None, None, None)
+
+
+def test_takeover_retries_failed_presence_checkpoint():
+    class FlakyStore(MemorySessionStore):
+        def __init__(self):
+            self.commits = 0
+
+        async def commit(self, _state, _records=()):
+            self.commits += 1
+            if self.commits == 1:
+                raise OSError("temporary database outage")
+
+    store = FlakyStore()
+    local_hub = SessionHub(store)
+    state = SessionState(
+        session_id=uuid4(), scenario_id="test", scenario_title="Тест", level="L1",
+        mode=SessionMode.TRAINING, exercise=Exercise.DDS,
+        socket_last_seen_at=datetime.now(UTC) - timedelta(minutes=10),
+        socket_connected_at_checkpoint=True,
+    )
+
+    async def recover():
+        assert not await local_hub._adopt(state)
+        assert local_hub.get(state.session_id) is None
+        await local_hub.maintain_lease()
+        assert local_hub.get(state.session_id) is state
+        assert store.commits == 2
+        await local_hub.shutdown()
+
+    asyncio.run(recover())