What problem does it solve? HTTP APIs often ship with inconsistent contracts: verbs in URIs, failures hidden under 200 status codes, offset pagination that duplicates or skips rows, and breaking changes rolled out without deprecation. This Skill provides a complete rule set and gated workflows for designing, reviewing, and evolving REST API contracts so the wire surface stays consistent and compatible. ## Core Features & Use Cases - Contract design workflow: Model resources from client-facing nouns, assign methods and status codes by HTTP semantics, design collections with cursor or keyset pagination, and define an RFC 9457 problem-details error contract. - Contract review and evolution: Audit an existing endpoint list or OpenAPI document against 25 core rules, classify proposed changes on wire, source, and semantic compatibility axes, and plan deprecation with Deprecation and Sunset headers. - Executable validation gates: Every design ends with redocly lint exiting clean and a prism mock server exercising the happy path, pagination, validation failures, and auth failures. - Use Case: Given a legacy endpoint list with /getWarehouse and /createOrder style paths, produce a redesigned contract with noun-based resources, correct status codes, an idempotency strategy for retried writes, and a validated OpenAPI 3.1 document. ## Quick Start Ask the agent to redesign your service's endpoint list as a proper REST contract with resources, methods, status codes, pagination, and an OpenAPI document validated by redocly lint and prism mock.