E3: Contract-First Development
Implementation-first creates tight coupling, undocumented behaviors, and integration friction. APIs become "whatever the code does" rather than intentional design. Retroactive documentation never catches up with code changes, and verbal agreements have no enforcement and forgotten details.
Contracts are executable specifications. Defining contracts before implementation enables parallel development, clear boundaries, and testable interfaces. AI agents work better with explicit contracts than implicit behaviors.
Principle
- All teams MUST practice API-First, Spec-First, Contract-First culture.
OpenAPI specs produced during API design are machine-readable contracts that AI agents can understand, generate from, and validate against. The discipline of API-First development directly enables effective AI collaboration. Clear contracts allow frontend and backend development to proceed independently.