There's one question that opens almost every AI engineering interview's prompt-design section: "Walk me through how you'd design a production prompt for a structured extraction task." It sounds open-ended. It isn't. Interviewers are listening for five specific beats, and the follow-up questions below are how they check for the ones you skip. This is the companion piece to the hands-on Colab notebook where we measured an 80%-to-0% format-drift swing from adding few-shot examples — if ...