fix(sessions): heal missing last_read_at on read-only GET /api/sessions opens

hermes_cli/web_server.py

@@ -11199,9 +11199,17 @@ def _import_sessions_for_profile(profile: Optional[str], sessions: List[Dict[str
 # the dashboard read paths query. Reads at most one row per table. Read-only
 # opens skip _reconcile_columns(), so an older store would otherwise 500 on
 # every poll until something opened it writable.
+#
+# MAINTENANCE: any new column added to hermes_state_common.py's sessions/
+# messages schema that a dashboard read path (list_sessions_rich et al.)
+# queries must be added here too, or an existing pre-feature database will
+# 500 on GET /api/sessions until a write connection happens to open first
+# (e.g. creating a new session) -- issue #80037, where last_read_at was
+# never added to this list when the read-state feature shipped.
 _SESSION_DB_READ_PROBE_SQL = (
     "SELECT (SELECT archived FROM sessions LIMIT 1), "
     "(SELECT pinned FROM sessions LIMIT 1), "
+    "(SELECT last_read_at FROM sessions LIMIT 1), "
     "(SELECT active FROM messages LIMIT 1), "
     "(SELECT compacted FROM messages LIMIT 1)"
 )

tests/hermes_cli/test_web_server.py

@@ -398,7 +398,7 @@ def test_get_sessions_fresh_store_returns_empty_list(self):
         assert response.json()["sessions"] == []
         assert response.json()["total"] == 0
 
-    @pytest.mark.parametrize("missing_column", ["archived", "pinned"])
+    @pytest.mark.parametrize("missing_column", ["archived", "pinned", "last_read_at"])
     def test_get_sessions_heals_stale_schema_store(self, missing_column):
         import sqlite3