fix(archive): preserve prepared sessions across restarts

tests/test_session_api.py

@@ -574,6 +574,39 @@ def test_cold_replay_returns_quick_202_then_status_returns_ready_launch(
         manager.close()
 
 
+def test_catalog_read_never_prepares_a_cold_historical_session(tmp_path: Path) -> None:
+    repository = tmp_path / "repo"
+    sessions = repository / "sessions"
+    session = make_legacy_session(sessions, "20260716T205632Z_viewer_live")
+    store = SessionStore(repository, data_dir=tmp_path / "data")
+    store.reconcile_archive(xgrids_k1_archive_source(sessions))
+    calls = 0
+
+    def exporter(_source: Path, _destination: Path) -> dict[str, object]:
+        nonlocal calls
+        calls += 1
+        raise AssertionError("catalog reads must not invoke the exporter")
+
+    materializer = SessionRecordingMaterializer(store.data_dir, exporter=exporter)
+    manager = SessionRecordingPreparationManager(materializer)
+    router = build_session_router(
+        store,
+        recording_materializer=materializer,
+        recording_preparation_manager=manager,
+    )
+    list_route = endpoint(router, "/api/v1/observation-sessions", "GET")
+    try:
+        item = list_route(limit=20, cursor=None)["items"][0]
+        time.sleep(0.02)
+
+        assert item["id"] == session.name
+        assert item["preparation"] is None
+        assert manager.status(session.name) is None
+        assert calls == 0
+    finally:
+        manager.close()
+
+
 def test_recording_response_releases_pin_once_when_asgi_send_fails(
     tmp_path: Path,
 ) -> None: