3 items
The status endpoint is a contract. Publish a small, stable state vocabulary instead of your internal states, report a failed job as a successful status call, and pick one status code convention and hold it.
AI agents decide at runtime how many times to call your API, which turns every POST into a retry risk. Make operations naturally idempotent where you can, detect and replay where you can't, and enforce it at write time.
Using the client's ID as the operation ID will eventually point one customer at another customer's job. Key uniqueness on the client plus their value, and enforce authorization on every status call.
