세션 평가·라이브코치·교수자 분석 라운드 마감 + 문서 정리 + 코드품질 리팩터

- 누적 작업트리 커밋: 회기 평가 복구·durable 저장, 라이브 코치 이력/근거, 교수자 학생분석, 음성 비언어 메타, PII 마스킹, 운영 티켓/헬스 등
- 문서: 완료 기록 docs/archive/ 냉동 보관, docs/ 단일 인덱스(docs/README.md)+통합 TODO(docs/TODO.md)로 정리
- 리팩터(행위 보존): Stage enum SSOT(taxonomy 소유·state_machine re-export), store recent/masked_turns 중복 제거, speaker_ko_label 단일 헬퍼, _list_sessions N+1 제거(state/turns 배치 + 턴평가 하이드레이션 배치)
- 검증: 백엔드 pytest 352 passed, _list_sessions E2E chromium-single-run 2 passed

apps/api/app/test_notifications.py

@@ -228,6 +228,71 @@ class NotificationTriggerTest(unittest.IsolatedAsyncioTestCase):
             logs.output,
         )
 
+    async def test_missing_session_evaluation_recovery_schedules_stale_sessions(self) -> None:
+        sess = _ended_session()
+
+        with (
+            patched_settings(session_evaluation_timeout=10.0),
+            patch.object(
+                sessions.session_persistence,
+                "list_sessions_missing_session_evaluation",
+                AsyncMock(return_value=([sess], True)),
+            ) as list_missing,
+            patch.object(
+                sessions,
+                "_schedule_session_evaluation",
+                return_value=object(),
+            ) as schedule_evaluation,
+        ):
+            scheduled = await sessions.recover_missing_session_evaluations(limit=2)
+
+        self.assertEqual(scheduled, 1)
+        list_missing.assert_awaited_once_with(older_than_seconds=40.0, limit=2)
+        schedule_evaluation.assert_called_once_with(sess)
+
+    async def test_missing_session_evaluation_recovery_requires_durable_store(self) -> None:
+        sess = _ended_session()
+
+        with (
+            patch.object(
+                sessions.session_persistence,
+                "list_sessions_missing_session_evaluation",
+                AsyncMock(return_value=([sess], False)),
+            ),
+            patch.object(sessions, "_schedule_session_evaluation") as schedule_evaluation,
+        ):
+            scheduled = await sessions.recover_missing_session_evaluations(limit=2)
+
+        self.assertEqual(scheduled, 0)
+        schedule_evaluation.assert_not_called()
+
+    async def test_session_evaluation_scheduler_deduplicates_in_flight_session(self) -> None:
+        sess = _ended_session()
+        gate = asyncio.Event()
+        sessions._SESSION_EVALUATION_IN_FLIGHT.clear()
+
+        async def wait_until_released(_sess: InProcSession) -> None:
+            await gate.wait()
+
+        try:
+            with patch.object(
+                sessions,
+                "_generate_and_save_session_evaluation",
+                wait_until_released,
+            ):
+                task = sessions._schedule_session_evaluation(sess)
+                self.assertIsNotNone(task)
+                self.assertIsNone(sessions._schedule_session_evaluation(sess))
+                self.assertIn(sess.session_id, sessions._SESSION_EVALUATION_IN_FLIGHT)
+                gate.set()
+                assert task is not None
+                await task
+                await asyncio.sleep(0)
+        finally:
+            sessions._SESSION_EVALUATION_IN_FLIGHT.clear()
+
+        self.assertNotIn(sess.session_id, sessions._SESSION_EVALUATION_IN_FLIGHT)
+
 
 if __name__ == "__main__":
     unittest.main()