You are adding a new product feature. How would you define the request and response contract between the UI and API?

In production I would use OpenAPI, typed client generation, or contract tests where they reduce drift. The contract needs a versioning story for breaking changes and a deprecation path for fields that the UI no longer uses. I would add correlation ids and error codes for support. For security, the API ignores client-supplied authority fields such as owner id, role, status, price, or audit values unless that workflow explicitly permits them. I would also review payload size and screen performance, because a contract that is technically correct can still make the page slow or hard to evolve.