For most of software history the spec was a temporary planning artifact and the code was ground truth. Spec-driven development inverts that: the versioned specification becomes the primary artifact, and code is generated or verified against it. The idea is old — formal methods, design-by-contract, BDD all contain versions. What’s new is the motive: AI agents need explicit, durable intent because prompts evaporate and sessions reset.
Three skill frameworks promise to make coding agents write better code: an autonomous pipeline, a full-lifecycle system with adversarial guards, and a requirements-first toolkit. Their repos differ in philosophy — and a measured same-feature bake-off puts numbers on the tradeoffs: 78 minutes and $34 against 148 minutes and $92.
Most spec-driven setups fail the same way: a solid plan-implement skill gets used diligently for a week, then quietly abandoned the first time a deadline gets close. Nothing in a hand-rolled skill stops that drift. Superpowers answers the discipline problem directly — a skills package that makes brainstorming, planning, subagent review, and strict TDD mandatory steps the agent checks before every task.