fix(observatory): preserve source identity on unchanged reindex

tests/test_session_store.py

@@ -186,6 +186,62 @@ def test_evidence_root_is_private_and_configurable(
     assert resolve_missioncore_evidence_dir(repository) == configured.resolve()
 
 
+def test_unchanged_archive_preserves_exact_snapshot_across_reopen(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    repository = tmp_path / "repo"
+    sessions = repository / "sessions"
+    session = make_legacy_session(sessions, "20260716T205632Z_viewer_live")
+    monkeypatch.setattr("k1link.sessions.store.utc_now_iso", lambda: "2026-09-03T08:00:00.000Z")
+    store = SessionStore(repository, data_dir=tmp_path / "data")
+    archive = xgrids_k1_archive_source(sessions)
+    store.reconcile_archive(archive)
+    before = store.get_session_with_catalog_snapshot(session.name)
+    with sqlite3.connect(store.database_path) as connection:
+        rows = tuple(connection.iterdump())
+
+    monkeypatch.setattr("k1link.sessions.store.utc_now_iso", lambda: "2026-09-03T09:00:00.000Z")
+    reopened = SessionStore(repository, data_dir=store.data_dir)
+    for _ in range(2):
+        assert reopened.reconcile_archive(archive) == (session.name,)
+        assert reopened.get_session_with_catalog_snapshot(session.name) == before
+    with sqlite3.connect(store.database_path) as connection:
+        assert tuple(connection.iterdump()) == rows
+
+
+@pytest.mark.parametrize("table,assignment", [
+    ("observation_sessions", "total_bytes = total_bytes + 1"),
+    ("observation_sessions", "duration_seconds = duration_seconds + 1"),
+    ("observation_session_sources", "seekable = 0"),
+    ("observation_session_artifacts", "byte_length = byte_length + 1"),
+    ("observation_session_artifacts", "sha256 = NULL"),
+])
+def test_reconcile_retains_clock_change_for_real_catalog_differences(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, table: str, assignment: str,
+) -> None:
+    repository = tmp_path / "repo"
+    sessions = repository / "sessions"
+    session = make_legacy_session(sessions, "20260716T205632Z_viewer_live")
+    monkeypatch.setattr("k1link.sessions.store.utc_now_iso", lambda: "2026-09-03T08:00:00.000Z")
+    store = SessionStore(repository, data_dir=tmp_path / "data")
+    archive = xgrids_k1_archive_source(sessions)
+    store.reconcile_archive(archive)
+    original = store.get_session_with_catalog_snapshot(session.name)
+    with sqlite3.connect(store.database_path) as connection:
+        connection.execute(f"UPDATE {table} SET {assignment}")  # noqa: S608 - fixed test cases
+    changed = store.get_session_with_catalog_snapshot(session.name)
+    assert changed[1] != original[1]
+    monkeypatch.setattr("k1link.sessions.store.utc_now_iso", lambda: "2026-09-03T09:00:00.000Z")
+    store.reconcile_archive(archive)
+    after = store.get_session_with_catalog_snapshot(session.name)
+    assert after[1] not in (original[1], changed[1])
+    with sqlite3.connect(store.database_path) as connection:
+        assert connection.execute(
+            "SELECT updated_at_utc FROM observation_sessions WHERE session_id = ?",
+            (session.name,),
+        ).fetchone()[0] == "2026-09-03T09:00:00.000Z"
+
+
 def test_catalog_reconciles_sessions_removed_from_one_evidence_root(tmp_path: Path) -> None:
     repository = tmp_path / "repo"
     sessions = repository / "sessions"