What problem does it solve? When backend responses, endpoint contracts, or database schemas change, frontend consumers and type definitions often drift out of sync, causing runtime errors and broken UI states. This Skill keeps backend handlers, generated DB types, frontend API clients, and Zod/TS schemas aligned through a structured compatibility procedure. ## Core Features & Use Cases - Contract Change Planning: Identifies endpoints and consumers, then defines request/response shapes and error semantics before implementation. - Cross-Layer Synchronization: Updates backend types, handlers, and stores alongside frontend API clients, schemas, and hooks in one coordinated pass. - Compatibility Testing: Adds tests for malformed or missing fields and enforces decision rules for nullable fields, breaking changes, and error contracts. - Use Case: A backend adds a nullable field to an endpoint response. The Skill ensures the frontend schema handles absent/null values, regenerates SQL types via make sqlc, and produces typed compatibility notes with evidence. ## Quick Start Use the api-compatibility skill to plan and apply the contract changes for the updated endpoint, keeping the backend handler, frontend client, and schemas in sync.
