A Free Model Endpoint Returned 200 With an Empty Body. The Fix Was a Lease, Not a Retry.

A realistic failure mode starts with a team that runs a nightly triage job on a small free server. The job groups stack traces from three services. It sends a compact prompt to a free model endpoint. The HTTP client sees a 200 response. The body is empty. The job marks the call as success. The next morning, two pages go to the wrong owner. Nobody knows the model returned nothing.

That is not a model failure. It is a contract failure.

MonkeyCode offers free model access and a free server option, which makes this class of bug cheap to test. Disclosure: This article was prepared as part of MonkeyCode's product outreach. The case below is a reduced reproduction, not a production incident or a statement about any specific API contract.

The first fix made it worse

The first instinct was to retry. The team added one retry for any 200. That doubled the dead time. It also hid the poison case. A second call can also return an empty 200. Worse, it can return a different but still malformed body.