ProcessActivityRetry : automatic-retry detail attached to a ProcessActivityStatus. Present only when the element’s most recent dispatch carried a retry policy. next_attempt_at set means the activity failed and is waiting to be retried at that instant – the process is running, not broken, and no incident exists yet. next_attempt_at absent with attempt == max_attempts means the budget is spent; if the element also carries an error, that is the dead-lettered activity.