API Design And Evolution

Design an interface as a durable agreement with its consumers, not a route list. Start with the consumer job, domain meaning, authority boundary, and failure modes; then choose the interface style and contract format. Keep facts, assumptions, and policy decisions distinguishable.

When to use

Use for a new or changed REST/HTTP API, GraphQL schema, RPC operation, event or message contract, webhook, or streaming interface. Use it before implementation and again whenever consumer-visible behavior changes.

When not to use