Your question is Design an API Under Constraints. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are the EM owning a new API for a B2B SaaS platform that will be consumed by internal services and a small set of external partners. The API needs to support a fast-moving product roadmap, but it also has to be stable enough that partner integrations do not break when the backend evolves. You have to make decisions about request shape, authentication, pagination, error handling, versioning, and observability while balancing developer experience against implementation complexity.
What factors do you consider when designing an API?