refactor: запись хода занятия — один commit SessionStore на операцию вместо журнала и checkpoint

Правка балла с пульта и из отчёта идёт одной доменной операцией: раньше WS-путь не обновлял full_report живой сессии.

backend/tests/test_session_store.py

@@ -0,0 +1,70 @@
+"""Одна операция занятия — один commit хранилища, события только после него."""
+
+import asyncio
+
+import pytest
+
+from app.domain.events import CallStarted, Speaker
+from app.session.hub import LEASE_FENCED_MESSAGE, SessionHub
+from app.session.state import now_utc
+from app.session.store import MemorySessionStore, UtteranceAppended
+from tests.test_session_checkpoint import dds_state
+
+
+class FailingStore(MemorySessionStore):
+    async def commit(self, state, records=()):
+        raise OSError("simulated database partition")
+
+
+def test_operation_commits_snapshot_and_records_once_then_publishes():
+    store = MemorySessionStore()
+    local_hub = SessionHub(store=store)
+    state = local_hub.register(dds_state())
+    sid = state.session_id
+
+    with local_hub.trainee(sid) as trainee:
+        async def operation():
+            async with local_hub.operation(sid):
+                entry = state.append(Speaker.OPERATOR, "Адрес?")
+                local_hub.record(sid, UtteranceAppended(entry))
+                local_hub.to_trainee(sid, CallStarted(started_at=now_utc()))
+                assert trainee.empty(), "событие ушло до коммита"
+                assert store.commits == []
+
+        asyncio.run(operation())
+        assert isinstance(trainee.get_nowait(), CallStarted)
+
+    assert len(store.commits) == 1
+    committed_id, records = store.commits[0]
+    assert committed_id == sid
+    assert [type(item) for item in records] == [UtteranceAppended]
+    assert store.snapshot(sid)["transcript"][0]["text"] == "Адрес?"
+
+
+def test_failed_commit_drops_events_and_fences_session():
+    local_hub = SessionHub(store=FailingStore())
+    state = local_hub.register(dds_state())
+    sid = state.session_id
+
+    with local_hub.observer(sid) as observers, \
+         local_hub.trainee(sid) as trainee, \
+         local_hub.station(sid) as station:
+        async def operation():
+            async with local_hub.operation(sid):
+                local_hub.to_trainee(sid, CallStarted(started_at=now_utc()))
+
+        with pytest.raises(OSError, match="partition"):
+            asyncio.run(operation())
+
+        assert state.lease_fenced
+        assert local_hub.get(sid) is None
+        for queue in (observers, trainee, station):
+            assert queue.get_nowait().message == LEASE_FENCED_MESSAGE
+            assert queue.empty(), "событие несостоявшейся операции утекло"
+
+
+def test_record_outside_operation_is_rejected():
+    local_hub = SessionHub(store=MemorySessionStore())
+    state = local_hub.register(dds_state())
+    with pytest.raises(RuntimeError):
+        local_hub.record(state.session_id, UtteranceAppended(state.append(Speaker.OPERATOR, "x")))