ALTER TABLE staff_work_sessions
  ADD COLUMN source_event_ids JSONB NOT NULL DEFAULT '[]'::jsonb,
  ADD COLUMN auto_closed BOOLEAN NOT NULL DEFAULT FALSE,
  ADD CONSTRAINT staff_work_sessions_source_events_array
    CHECK (jsonb_typeof(source_event_ids) = 'array');

COMMENT ON COLUMN staff_work_sessions.source_event_ids IS
  'Immutable attendance event ids used to derive the latest session revision.';
COMMENT ON COLUMN staff_work_sessions.auto_closed IS
  'True when a scheduler cutoff supplied the end time; manager confirmation is still required.';