type CheckpointEvent = Extract<WorkflowEvent, {
  type:   | "STEP_FINISHED"
     | "STEP_FAILED"
     | "SIGNAL_RESOLVED"
     | "APPROVAL_RESOLVED"
     | "NOW_RECORDED"
     | "UUID_RECORDED"
     | "RUN_FINISHED"
     | "RUN_ERRORED";
}>;