Define done before starting

Why this rule exists

Most project friction isn't about effort; it's about two people holding different pictures of 'finished' and discovering the gap at the worst possible moment. Without an agreed definition of done, work expands, reviews turn into surprises, and someone feels their effort was wasted. A clear finish line lets people pace themselves, make trade-offs, and know when to stop. Ambiguity about the goal doesn't keep options open; it just relocates the hard conversation to the end, when it's expensive and personal instead of cheap and abstract.