API and Interface Design
Defines and locks robust API, CLI, SDK, and webhook contracts prior to implementation to prevent accidental breaking changes.
API and Interface Design enforces a contract-first workflow for public and cross-team interface boundaries. It guides developers and AI agents through specifying inputs, outputs, invariants, and validation rules before writing code, applying Hyrum's Law reviews to prevent accidental dependencies on uncommitted behaviors. Whether building REST endpoints, SDK surfaces, CLI tools, or webhooks, this skill ensures consistent versioning, clear migration strategies, and seamless compatibility across systems.
Key Features
01Contract-first drafting for REST, CLI, SDK, and webhook interfaces
02Compatibility and migration planning for breaking interface changes
03Boundary-layer validation design to isolate untrusted input handling
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05Hyrum's Law risk reviews to identify unintended observable behaviors
06Clear separation of interface invariants from non-goals
Use Cases
01Architecting a new public HTTP API or developer SDK with strict stability guarantees
02Refactoring an existing CLI command or webhook payload consumed by external teams
03Establishing breaking-change and versioning policies prior to feature implementation