fix: учёт связи курсанта по сокетам и фазе ДДС

backend/app/api/http/sessions.py

@@ -113,6 +113,7 @@ class ActiveSessionOut(BaseModel):
     dds_statuses: dict[str, str]
     dds_snapshot: StationSnapshot | None = None
     signals: list[Signal] = []
+    presence_known: bool = True
 
 
 def _out(session) -> SessionOut:
@@ -206,11 +207,8 @@ def _signals(
     подписчика в хабе этого узла; окно нужно, чтобы короткий разрыв
     соединения не сразу считался потерей связи курсанта.
 
-    `live=False` — снимок собран из checkpoint (сессию не держит хаб этого
-    процесса: рестарт до переподключения сокета или чужой узел в кластере).
-    Такой объект живёт один запрос и выбрасывается: писать в него
-    `socket_last_seen_at` бессмысленно — на следующем опросе присутствие
-    неизвестно снова. Честнее не утверждать «на связи», чем соврать.
+    `live=False` — снимок чужого узла: его сокеты здесь не видны, поэтому
+    присутствие неизвестно. Чтение реестра не меняет состояние занятия.
     """
     settings = get_settings()
     signals: list[Signal] = []
@@ -226,16 +224,14 @@ def _signals(
         ))
     if live:
         connected = (
-            hub.station_connected(state.session_id) if state.exercise is Exercise.DDS
+            hub.station_connected(state.session_id) if state.dds_phase
             else hub.trainee_connected(state.session_id)
         )
-        if connected:
-            state.socket_last_seen_at = now
         offline_seconds = (
-            (now - state.socket_last_seen_at).total_seconds()
-            if state.socket_last_seen_at is not None else 0
+            (now - (state.socket_last_seen_at or state.started_at)).total_seconds()
+            if (state.socket_last_seen_at or state.started_at) is not None else 0
         )
-        if offline_seconds >= settings.signal_offline_window_seconds:
+        if not connected and offline_seconds >= settings.signal_offline_window_seconds:
             signals.append(Signal(
                 kind="offline", severity="violated",
                 text=f"Курсант не на связи {int(offline_seconds)} с",
@@ -256,9 +252,8 @@ async def active(
         state.session_id: state
         for state in hub.active_sessions(who.login)
     }
-    #: Снимки без живой записи в хабе этого узла — рестарт до переподключения
-    #: сокета либо чужой узел в кластере. Присутствие сокета для них здесь
-    #: не проверяется: объект живёт один запрос, а не хаб (см. `_signals`).
+    #: Снимки без живой записи в хабе этого узла — чужой узел или сессия,
+    #: ожидающая восстановления. Её сокеты нельзя проверить этим процессом.
     checkpoint_only: set[UUID] = set()
     if db is not None:
         rows = (
@@ -293,7 +288,7 @@ async def active(
     for state in states.values():
         elapsed = (max(0, int((now - state.started_at).total_seconds()))
                    if state.started_at else 0)
-        station = state.station_snapshot() if state.exercise is Exercise.DDS else None
+        station = state.station_snapshot() if state.dds_phase else None
         queue = station.queue_cards if station else []
         card = state.desk.active
         status_log = card.status_log if card is not None else []
@@ -327,6 +322,7 @@ async def active(
             dds_statuses=latest_statuses,
             dds_snapshot=station,
             signals=_signals(state, queue, now, live=state.session_id not in checkpoint_only),
+            presence_known=state.session_id not in checkpoint_only,
         ))
     return result
 

backend/app/api/ws/call.py

@@ -14,7 +14,7 @@ from uuid import UUID, uuid4
 from fastapi import APIRouter, WebSocket, WebSocketDisconnect
 from pydantic import TypeAdapter, ValidationError
 
-from app.api.ws.session import pump, run_command, session_socket
+from app.api.ws.session import close_fenced, pump, run_command, session_socket
 from app.domain.events import (
     BgStart,
     CallEnded,
@@ -390,9 +390,14 @@ async def call(ws: WebSocket, session_id: UUID) -> None:
     )
     if entered is None:
         return
-    _who, state = entered
+    who, state = entered
 
-    with hub.trainee(session_id) as queue:
+    async with hub.trainee_socket(
+        session_id, station=False, trainee=who.role is Role.TRAINEE,
+    ) as queue:
+        if hub.is_lease_fenced(session_id):
+            await close_fenced(ws)
+            return
         if state.exercise is Exercise.CARD:
             from app.api.ws.control import card_briefing
 

backend/app/api/ws/control.py

@@ -104,6 +104,7 @@ def _build_state(session_id: UUID, event, who, scenario, scenarios,
         dds_service=identity.service or event.dds_service,
         attempt=identity.attempt,
         criteria=event.criteria,
+        socket_last_seen_at=now_utc(),
     )
     state.timers.limits[TimerCode.DDS_ACK] = event.criteria.decision_time_limit_seconds * 1000
     state.timers.limits[TimerCode.CARD_FILL] = event.criteria.card_fill_time_limit_seconds * 1000

backend/app/api/ws/station.py

@@ -17,7 +17,7 @@ from uuid import UUID
 from fastapi import APIRouter, WebSocket, WebSocketDisconnect
 from pydantic import TypeAdapter, ValidationError
 
-from app.api.ws.session import pump, run_command, session_socket
+from app.api.ws.session import close_fenced, pump, run_command, session_socket
 from app.domain.events import (
     CallEndReason,
     ErrorEvent,
@@ -59,9 +59,14 @@ async def station(ws: WebSocket, session_id: UUID, role: str = "dds") -> None:
     entered = await session_socket(ws, session_id, (Role.INSTRUCTOR, Role.TRAINEE))
     if entered is None:
         return
-    _who, state = entered
+    who, state = entered
 
-    with hub.station(session_id) as queue:
+    async with hub.trainee_socket(
+        session_id, station=True, trainee=who.role is Role.TRAINEE,
+    ) as queue:
+        if hub.is_lease_fenced(session_id):
+            await close_fenced(ws)
+            return
         sender = asyncio.create_task(pump(ws, queue))
         try:
             # Карточка, переданная до подключения станции, не теряется:

backend/app/session/hub.py

@@ -24,6 +24,7 @@ from app.domain.events import (
 )
 from app.session.state import SessionState
 from app.session.store import MemorySessionStore, Record, SessionLeaseLost, SessionStore
+from app.session.timers import now_utc
 
 #: Очередь одного подписчика. Медленный наблюдатель не тормозит занятие:
 #: очередь ограничена, переполнение роняет соединение, а не сессию.
@@ -53,6 +54,8 @@ class SessionHub:
         self._observers: dict[UUID, set[asyncio.Queue]] = {}
         self._trainees: dict[UUID, set[asyncio.Queue]] = {}
         self._stations: dict[UUID, set[asyncio.Queue]] = {}
+        self._trainee_calls: dict[UUID, set[asyncio.Queue]] = {}
+        self._trainee_stations: dict[UUID, set[asyncio.Queue]] = {}
         self._tickers: dict[UUID, asyncio.Task] = {}
         # Задачи, порождённые внутри операции, наследуют контекст; после
         # закрытия операции их события идут напрямую (`_Operation.open`).
@@ -135,9 +138,10 @@ class SessionHub:
         if not self.store.persistent:
             return 0
         restored = await self.store.restore_active()
+        adopted = 0
         for state in restored:
-            self._adopt(state)
-        return len(restored)
+            adopted += await self._adopt(state)
+        return adopted
 
     async def maintain_lease(self) -> None:
         """Один оборот супервизора: продлить свои lease, подхватить просроченные чужие.
@@ -163,17 +167,28 @@ class SessionHub:
             current = self._sessions.get(state.session_id)
             if current is not None and not current.lease_fenced:
                 continue
-            self._adopt(state)
+            await self._adopt(state)
 
     async def supervise_lease(self, interval: float) -> None:
         while True:
             await asyncio.sleep(interval)
             await self.maintain_lease()
 
-    def _adopt(self, state: SessionState) -> None:
+    async def _adopt(self, state: SessionState) -> bool:
         self.stop_ticker(state.session_id)
+        if state.socket_connected_at_checkpoint:
+            # Разрыв произошёл при потере узла; старое время подключения не
+            # доказывает, что курсант отсутствовал всё это время.
+            state.socket_last_seen_at = now_utc()
+            state.socket_connected_at_checkpoint = False
+            try:
+                await self.store.commit(state)
+            except Exception:
+                log.exception("не удалось сохранить присутствие после takeover %s", state.session_id)
+                return False
         self.register(state)
         self.start_ticker(state.session_id)
+        return True
 
     async def save_all(self) -> None:
         """Снимок живых занятий при остановке узла: следующий владелец продолжит с него."""
@@ -285,6 +300,44 @@ class SessionHub:
     def station(self, session_id: UUID):
         return self._subscribe(self._stations, session_id)
 
+    async def _record_presence(self, session_id: UUID, *, station: bool) -> None:
+        state = self.get(session_id)
+        if state is None or state.ended or state.dds_phase != station:
+            return
+        async with self.operation(session_id):
+            state.socket_last_seen_at = now_utc()
+            present = self._trainee_stations if station else self._trainee_calls
+            state.socket_connected_at_checkpoint = bool(present.get(session_id))
+
+    @contextlib.asynccontextmanager
+    async def trainee_socket(
+        self, session_id: UUID, *, station: bool, trainee: bool,
+    ) -> AsyncIterator[asyncio.Queue]:
+        """Учесть только сокет курсанта; вещание преподавателю остаётся общим."""
+        registry = self._stations if station else self._trainees
+        presence = self._trainee_stations if station else self._trainee_calls
+        with self._subscribe(registry, session_id) as queue:
+            if trainee:
+                presence.setdefault(session_id, set()).add(queue)
+            try:
+                if trainee:
+                    try:
+                        await self._record_presence(session_id, station=station)
+                    except Exception:
+                        if not self.is_lease_fenced(session_id):
+                            raise
+                yield queue
+            finally:
+                if trainee:
+                    presence[session_id].discard(queue)
+                    if not presence[session_id]:
+                        presence.pop(session_id)
+                    try:
+                        await self._record_presence(session_id, station=station)
+                    except Exception:
+                        if not self.is_lease_fenced(session_id):
+                            raise
+
     # ── вещание ──
 
     @staticmethod
@@ -315,10 +368,10 @@ class SessionHub:
         return len(self._observers.get(session_id, set()))
 
     def station_connected(self, session_id: UUID) -> bool:
-        return bool(self._stations.get(session_id))
+        return bool(self._trainee_stations.get(session_id))
 
     def trainee_connected(self, session_id: UUID) -> bool:
-        return bool(self._trainees.get(session_id))
+        return bool(self._trainee_calls.get(session_id))
 
     # ── такт таймеров ──
 

backend/app/session/state.py

@@ -127,11 +127,12 @@ class PersistedSession(BaseModel):
     #: Подряд идущих первичных отказов без принятой карточки между ними —
     #: сигнал реестра преподавателя, не влияет на балл.
     consecutive_refusals: int = 0
-    #: Когда реестр преподавателя последний раз видел подключённый сокет
-    #: курсанта (станция ДДС или звонок 112) — для сигнала "не на связи".
-    #: Персистится: без этого рестарт/failover обнуляет отсчёт окна
-    #: присутствия и сигнал никогда не срабатывает для восстановленных сессий.
+    #: Последнее подключение/отключение сокета курсанта или начало фазы ДДС.
+    #: Сохраняется вместе с занятием, чтобы чтение реестра не меняло состояние.
     socket_last_seen_at: datetime | None = None
+    #: На момент последнего checkpoint курсант был подключён на текущем АРМ.
+    #: После аварии узла момент потери связи неизвестен: окно начинается при takeover.
+    socket_connected_at_checkpoint: bool = False
 
     @field_validator("processed_station_commands")
     @classmethod
@@ -214,6 +215,9 @@ class SessionState(PersistedSession):
         self.dispatched_at = now_utc()
         if self.exercise is Exercise.CALL:
             self._receive_call_card()
+        if self.handoff_to_dds:
+            self.socket_last_seen_at = self.dispatched_at
+            self.socket_connected_at_checkpoint = False
         return self.dispatched_card
 
     def _receive_call_card(self) -> None:

backend/tests/test_checkpoint_model.py

@@ -163,6 +163,7 @@ def full_state() -> SessionState:
         text_revealed_facts={"f_address": "улица Ленина, 14"},
         consecutive_refusals=2,
         socket_last_seen_at=AT,
+        socket_connected_at_checkpoint=True,
     )
 
 

backend/tests/test_session_signals.py

@@ -1,16 +1,26 @@
 """Колонка сигналов реестра: очередь, повторные отказы, курсант не на связи."""
 
+import asyncio
 import time
 from datetime import UTC, datetime, timedelta
+from types import SimpleNamespace
 from uuid import uuid4
 
 import pytest
 from fastapi.testclient import TestClient
+from starlette.websockets import WebSocketDisconnect
 
+from app.api.auth import Principal
 from app.api.http import sessions as sessions_http
+from app.api.ws import session as session_ws
 from app.config import get_settings
+from app.domain.events import Exercise, SessionMode
+from app.domain.roles import Role
 from app.main import app
-from app.session.hub import hub
+from app.session.checkpoint import dump_state, load_state
+from app.session import hub as hub_module
+from app.session.hub import SessionHub, hub
+from app.session.state import SessionState
 from app.session.store import MemorySessionStore
 
 POOL = ["fire-apartment-l2", "t01-1-fire-container"]
@@ -35,7 +45,12 @@ def client(monkeypatch):
         with TestClient(app) as test_client:
             test_client.post("/api/auth/dev-token")
             hub.store = MemorySessionStore()
-            yield test_client
+            before = set(hub._sessions)
+            try:
+                yield test_client
+            finally:
+                for session_id in set(hub._sessions) - before:
+                    hub.drop(session_id)
     finally:
         get_settings.cache_clear()
 
@@ -60,7 +75,7 @@ def read_until(socket, wanted):
     raise AssertionError(f"событие {wanted} не пришло; получены: {received}")
 
 
-def start_two_card_dds(client):
+def start_two_card_dds(client, scenario_ids=POOL):
     session_id = uuid4()
     context = client.websocket_connect(f"/ws/control/{session_id}")
     control = context.__enter__()
@@ -70,7 +85,32 @@ def start_two_card_dds(client):
         "trainee": "Иванов",
         "mode": "training",
         "exercise": "dds",
-        "random_scenario_ids": POOL,
+        "random_scenario_ids": scenario_ids,
+    })
+    wait_for(lambda: hub.get(session_id))
+    return session_id, control
+
+
+def start_card_handoff(client):
+    session_id = uuid4()
+    context = client.websocket_connect(f"/ws/control/{session_id}")
+    control = context.__enter__()
+    control.send_json({
+        "type": "scenario.start", "scenario_id": POOL[0], "trainee": "Иванов",
+        "mode": "training", "exercise": "card", "handoff_to_dds": True,
+        "scenario_ids": POOL,
+    })
+    wait_for(lambda: hub.get(session_id))
+    return session_id, control
+
+
+def start_call(client):
+    session_id = uuid4()
+    context = client.websocket_connect(f"/ws/control/{session_id}")
+    control = context.__enter__()
+    control.send_json({
+        "type": "scenario.start", "scenario_id": POOL[0], "trainee": "Иванов",
+        "mode": "training", "exercise": "call",
     })
     wait_for(lambda: hub.get(session_id))
     return session_id, control
@@ -85,6 +125,22 @@ def signal_kinds(row):
     return {signal["kind"] for signal in row["signals"]}
 
 
+def assigned_trainee(state, monkeypatch):
+    state.trainee_id = uuid4()
+    who = Principal(login="курсант", full_name="Курсант", role=Role.TRAINEE,
+                    trainee_id=state.trainee_id)
+    monkeypatch.setattr(session_ws, "principal_of", lambda _ws: who)
+
+
+def registry_time(monkeypatch, since, seconds):
+    class Clock(datetime):
+        @classmethod
+        def now(cls, tz=None):
+            return since + timedelta(seconds=seconds)
+
+    monkeypatch.setattr(sessions_http, "datetime", Clock)
+
+
 def test_signal_backlog_when_queue_reaches_threshold(client, monkeypatch):
     monkeypatch.setenv("SIGNAL_BACKLOG_THRESHOLD", "2")
     get_settings.cache_clear()
@@ -134,19 +190,274 @@ def test_signal_refusals_after_two_consecutive_declines(client):
         control.__exit__(None, None, None)
 
 
-def test_signal_offline_when_station_socket_is_closed_past_the_window(client):
-    session_id, control = start_two_card_dds(client)
+def test_acceptance_clears_refusal_streak(client):
+    session_id, control = start_two_card_dds(
+        client, [*POOL, "t20-2-stroke"],
+    )
     try:
         state = hub.get(session_id)
-        with client.websocket_connect(f"/ws/station/{session_id}?role=dds") as station:
+        with client.websocket_connect(f"/ws/station/{session_id}") as station:
             read_until(station, "station.state")
-            row = row_for(client, session_id)
-            assert "offline" not in signal_kinds(row), "сокет подключён — сигнала быть не должно"
-
-        window = get_settings().signal_offline_window_seconds
-        state.socket_last_seen_at = datetime.now(UTC) - timedelta(seconds=window + 1)
-        row = row_for(client, session_id)
-        assert "offline" in signal_kinds(row)
+            for card in state.desk.ordered()[:2]:
+                station.send_json({"type": "card.open", "card_id": str(card.card_id)})
+                read_until(station, "station.state")
+                station.send_json({
+                    "type": "card.status", "service": state.card_services(card)[0],
+                    "status": "declined", "comment": "Не наша территория, передано дежурному",
+                })
+                read_until(station, "station.state")
+            assert state.consecutive_refusals == 2
+            third = state.desk.ordered()[2]
+            station.send_json({"type": "card.open", "card_id": str(third.card_id)})
+            read_until(station, "station.state")
+            station.send_json({
+                "type": "card.status", "service": state.card_services(third)[0],
+                "status": "accepted", "comment": "Карточка принята диспетчером",
+            })
+            read_until(station, "station.state")
+            assert state.consecutive_refusals == 0
+            assert "refusals" not in signal_kinds(row_for(client, session_id))
     finally:
         hub.stop_ticker(session_id)
         control.__exit__(None, None, None)
+
+
+def test_signal_offline_when_station_socket_is_closed_past_the_window(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        assigned_trainee(state, monkeypatch)
+        with client.websocket_connect(f"/ws/station/{session_id}?role=dds") as station:
+            read_until(station, "station.state")
+            assert hub.station_connected(session_id)
+        assert not hub.station_connected(session_id)
+        disconnected_at = state.socket_last_seen_at
+        assert disconnected_at is not None
+        window = get_settings().signal_offline_window_seconds
+        registry_time(monkeypatch, disconnected_at, window - 1)
+        assert "offline" not in signal_kinds(row_for(client, session_id))
+        registry_time(monkeypatch, disconnected_at, window + 1)
+        row = row_for(client, session_id)
+        assert "offline" in signal_kinds(row)
+        assert state.socket_last_seen_at == disconnected_at, "GET реестра не должен менять занятие"
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_signal_offline_without_first_connection(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        started = state.socket_last_seen_at
+        assert started is not None
+        registry_time(monkeypatch, started, get_settings().signal_offline_window_seconds + 1)
+        assert "offline" in signal_kinds(row_for(client, session_id))
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_call_socket_disconnection_triggers_offline(client, monkeypatch):
+    session_id, control = start_call(client)
+    try:
+        state = hub.get(session_id)
+        assigned_trainee(state, monkeypatch)
+        with client.websocket_connect(f"/ws/call/{session_id}") as call:
+            read_until(call, "call.incoming")
+            assert hub.trainee_connected(session_id)
+        assert not hub.trainee_connected(session_id)
+        disconnected_at = state.socket_last_seen_at
+        registry_time(monkeypatch, disconnected_at,
+                      get_settings().signal_offline_window_seconds + 1)
+        assert "offline" in signal_kinds(row_for(client, session_id))
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_teacher_socket_does_not_hide_offline(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        with client.websocket_connect(f"/ws/station/{session_id}") as station:
+            read_until(station, "station.state")
+            assert not hub.station_connected(session_id)
+            registry_time(monkeypatch, state.socket_last_seen_at,
+                          get_settings().signal_offline_window_seconds + 1)
+            assert "offline" in signal_kinds(row_for(client, session_id))
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_last_of_two_trainee_sockets_starts_offline_window(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        assigned_trainee(state, monkeypatch)
+        with client.websocket_connect(f"/ws/station/{session_id}") as first:
+            read_until(first, "station.state")
+            with client.websocket_connect(f"/ws/station/{session_id}") as second:
+                read_until(second, "station.state")
+            assert hub.station_connected(session_id)
+            registry_time(monkeypatch, state.socket_last_seen_at,
+                          get_settings().signal_offline_window_seconds + 1)
+            assert "offline" not in signal_kinds(row_for(client, session_id))
+        disconnected_at = state.socket_last_seen_at
+        registry_time(monkeypatch, disconnected_at,
+                      get_settings().signal_offline_window_seconds + 1)
+        assert "offline" in signal_kinds(row_for(client, session_id))
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_offline_window_survives_checkpoint_restore(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        assigned_trainee(state, monkeypatch)
+        with client.websocket_connect(f"/ws/station/{session_id}") as station:
+            read_until(station, "station.state")
+        disconnected_at = state.socket_last_seen_at
+        restored = load_state(dump_state(state), datetime.now(UTC))
+        hub.drop(session_id)
+        asyncio.run(hub._adopt(restored))
+        assert restored.socket_last_seen_at == disconnected_at
+        registry_time(monkeypatch, disconnected_at,
+                      get_settings().signal_offline_window_seconds + 1)
+        assert "offline" in signal_kinds(row_for(client, session_id))
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_takeover_starts_window_when_socket_was_open(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        assigned_trainee(state, monkeypatch)
+        with client.websocket_connect(f"/ws/station/{session_id}") as station:
+            read_until(station, "station.state")
+            assert state.socket_connected_at_checkpoint
+            snapshot = dump_state(state)
+        old_time = state.socket_last_seen_at
+        takeover_at = old_time + timedelta(minutes=10)
+        monkeypatch.setattr(hub_module, "now_utc", lambda: takeover_at)
+        restored = load_state(snapshot, datetime.now(UTC))
+
+        class CapturingStore(MemorySessionStore):
+            def __init__(self):
+                self.saved = None
+
+            async def commit(self, state, _records=()):
+                self.saved = dump_state(state)
+
+        store = CapturingStore()
+        local_hub = SessionHub(store)
+        try:
+            assert asyncio.run(local_hub._adopt(restored))
+            assert restored.socket_last_seen_at == takeover_at
+            assert not restored.socket_connected_at_checkpoint
+            assert datetime.fromisoformat(
+                store.saved["socket_last_seen_at"].replace("Z", "+00:00")
+            ) == takeover_at
+            assert store.saved["socket_connected_at_checkpoint"] is False
+        finally:
+            local_hub.stop_ticker(session_id)
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_card_handoff_uses_trainee_station_presence(client, monkeypatch):
+    session_id, control = start_card_handoff(client)
+    try:
+        state = hub.get(session_id)
+        assigned_trainee(state, monkeypatch)
+        with monkeypatch.context() as clock:
+            with client.websocket_connect(f"/ws/call/{session_id}") as call:
+                read_until(call, "card.briefing")
+                call.send_json({"type": "card.submit"})
+                read_until(call, "call.ended")
+                handoff_at = state.socket_last_seen_at
+                clock.setattr(hub_module, "now_utc", lambda: handoff_at + timedelta(minutes=1))
+        assert state.socket_last_seen_at == handoff_at, "старый call-сокет не сбрасывает окно ДДС"
+        assert state.exercise.value == "card" and state.dds_phase
+        assert state.desk.scenarios
+        with client.websocket_connect(f"/ws/station/{session_id}") as station:
+            read_until(station, "station.state")
+            registry_time(monkeypatch, state.socket_last_seen_at,
+                          get_settings().signal_offline_window_seconds + 1)
+            row = row_for(client, session_id)
+            assert row["dds_open_cards"] > 0
+            assert "offline" not in signal_kinds(row)
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_checkpoint_on_another_node_marks_presence_unknown(client, monkeypatch):
+    session_id, control = start_two_card_dds(client)
+    try:
+        state = hub.get(session_id)
+        snapshot = dump_state(state)
+        checkpoint_at = datetime.now(UTC)
+        hub.drop(session_id)
+
+        class CheckpointDB:
+            async def scalars(self, _query):
+                row = SimpleNamespace(id=session_id, owner_login="dev",
+                                      live_state=snapshot, checkpoint_at=checkpoint_at)
+                return SimpleNamespace(all=lambda: [row])
+
+        monkeypatch.setattr(sessions_http, "require", lambda _request, _role:
+                            Principal(login="dev", full_name="Преподаватель",
+                                      role=Role.INSTRUCTOR))
+        rows = asyncio.run(sessions_http.active(None, db=CheckpointDB()))
+        row = next(item for item in rows if item.session_id == session_id)
+        assert row.presence_known is False
+        assert "offline" not in {item.kind for item in row.signals}
+    finally:
+        hub.stop_ticker(session_id)
+        control.__exit__(None, None, None)
+
+
+def test_failed_presence_commit_does_not_leave_connected_socket():
+    class BrokenStore(MemorySessionStore):
+        async def commit(self, _state, _records=()):
+            raise OSError("test commit failure")
+
+    local_hub = SessionHub(BrokenStore())
+    state = local_hub.register(SessionState(
+        session_id=uuid4(), scenario_id="test", scenario_title="Тест", level="L1",
+        mode=SessionMode.TRAINING, exercise=Exercise.DDS,
+    ))
+
+    async def connect():
+        async with local_hub.trainee_socket(state.session_id, station=True, trainee=True):
+            assert local_hub.is_lease_fenced(state.session_id)
+
+    asyncio.run(connect())
+    assert not local_hub.station_connected(state.session_id)
+
+
+def test_failed_presence_commit_closes_station_with_fencing_code(client, monkeypatch):
+    class BrokenStore(MemorySessionStore):
+        async def commit(self, _state, _records=()):
+            raise OSError("test commit failure")
+
+    session_id, control = start_two_card_dds(client)
+    try:
+        assigned_trainee(hub.get(session_id), monkeypatch)
+        hub.store = BrokenStore()
+        with client.websocket_connect(f"/ws/station/{session_id}") as station:
+            event = station.receive_json()
+            assert event["type"] == "error" and event["code"] == "internal"
+            with pytest.raises(WebSocketDisconnect) as closed:
+                station.receive_json()
+            assert closed.value.code == 1012
+        assert not hub.station_connected(session_id)
+    finally:
+        control.__exit__(None, None, None)

frontend/src/pages/instructor/Instructor.tsx

@@ -390,10 +390,11 @@ export function Instructor() {
                     ? `Просрочено: первичная реакция ${item.dds_overdue_cards}; отработка карточки ${item.dds_work_overdue_cards}`
                     : "Нормативы не нарушены"}
                 </td>
-                <td className={`state-${worstSignalSeverity(item.signals) ?? "ok"}`}>
+                <td className={worstSignalSeverity(item.signals) ? `state-${worstSignalSeverity(item.signals)}` : item.presence_known ? "state-ok" : undefined}>
                   {item.signals.length
                     ? item.signals.map((signal) => <span key={signal.kind}>{signal.text}<br /></span>)
-                    : "Сигналов нет"}
+                    : item.presence_known ? "Сигналов нет" : null}
+                  {!item.presence_known && <span>Связь курсанта не проверена</span>}
                 </td>
                 <td><button type="button" onClick={() => openActiveSession(item)}>
                   {sessionId === item.session_id ? "Открыто" : "Наблюдать"}

frontend/src/shared/api/http.ts

@@ -116,6 +116,7 @@ export interface ActiveSessionInfo {
   dds_statuses: Record<string, string>;
   dds_snapshot: StationSnapshot | null;
   signals: Signal[];
+  presence_known: boolean;
 }
 
 export const useActiveSessions = () =>