Spec-driven input — plans and specs as the primary artifact

Both methodologies relocate the engineer's effort upstream of the code. In compound
engineering "plans are the new code": the plan document becomes the source of truth
agents use to generate, test, and validate. In the dark factory the human writes a
spec — feature specs say what to build (goal, requirements, constraints); bug
specs describe only the symptom and explicitly forbid assuming the cause — plus
acceptance criteria, and nothing else. Students learn to write specs that are
precise about outcomes and deliberately silent about implementation, and why fixing
a decision on paper is far cheaper than fixing it in code.