Field Guide 02: a 63-item checklist for component contracts that people and AI agents both build from. The kit adds a JSON Schema 2020-12 contract format with a stable gate, a complete Button contract, union types whose forbidden combinations do not compile, a CI validator and a generator that expands a contract into only the prop combinations it allows (192 permutations become 99 for the Button).
When agents or new contributors keep inventing props and variants, or when a component is about to be promoted to stable and you want the promotion to be a passing build.