Spec-Driven Development

Part of the Vibe Coding: Advanced Engineering course

The fastest way to get correct code out of a model is to stop describing what you want and start defining it. A prompt is a wish. A spec is a contract, and a contract can be checked. This lesson converts the thing you would normally hold in your head into an artifact the model must satisfy and you can verify in one command.

Watch what happens when a request is underspecified. "Write me a robust duration parser" produces something. It will handle "5m". It will probably handle "1h30m". What it does with "30m1h", "1h1h", "-5m", "", or the integer 90 is unknown to you and, more importantly, unknown to the model, so it picks. It might return None. It might return 0. It might raise a TypeError from deep inside a regex. ...