"Done" is the most expensive word in AI-assisted work, because it is usually free to say. A worker that has finished and a worker that believes it has finished produce the same sentence. The contract below is what replaces that sentence: conditions, written down before the work starts, evaluated afterwards by something that was not doing the work.
Turn any line off below and watch what the command does. It does not warn. It refuses, names the line, and tells you the command that reproduces the failure.