api-and-interface-design

Contract-first API design defines interface schemas and error handling rules before coding. It ensures a shared understanding between teams, clarifies public surfaces, and prevents misuse or accidental breaking changes across REST or GraphQL endpoints.

Evolve REST and GraphQL APIs through additive evolution by extending schemas with new fields and endpoints rather than modifying existing ones. This approach prevents breaking changes while allowing frontend-backend contracts to grow safely.

Apply consistent error semantics by using uniform error shapes and status mappings across all APIs. Combine this with boundary validation to validate inputs at the API boundary, preventing invalid data from entering the system.

Yes, this approach applies to designing module boundaries and frontend-backend contracts across software projects. It enforces clear surface boundaries, naming conventions, and contract-first design for any public interface beyond just REST or GraphQL endpoints.

Establish naming conventions by using consistent REST and GraphQL patterns with clear surface boundaries. Defining these conventions early during contract-first design ensures interfaces remain stable, well-documented, and predictable for all consumers.

Contract-first interface design may not suit rapid prototyping or exploratory coding where public surfaces are still undefined. It is most effective when stabilizing module boundaries, REST or GraphQL endpoints, and frontend-backend contracts to prevent accidental breaking changes.