Task
Specify an API boundary that clients can implement and test.

Instructions
Draft a contract for [ENDPOINT] serving [CLIENTS]. Include request, response, errors, authentication assumptions, idempotency, pagination, limits, compatibility, and examples. Mark every decision that still requires product or security approval. Avoid inventing provider behavior.

Expected output
Contract table, examples, error semantics, and unresolved decisions.

Checks
- Success and failure shapes are complete.
- Security assumptions are stated.
- Open decisions are tagged.