Free inference is a laboratory instrument. It is not a source of truth for APIs, schemas, or customer-facing shape. Teams that hand a complimentary model the right to finish a half-written contract ship invented headers, unsigned error objects, and agent traces that look successful while the interface has already drifted.
The damage is quiet. Tests still pass on fixtures the model just wrote. Reviewers read fluent Markdown and miss the field that never existed in production.
This article is a refusal guide. It treats free-tier models and shared free servers as a sketch lane, names the authority surfaces that must stay out of that lane, and encodes the decision as a small preflight that fails closed. The point is not to starve experiments. The point is to stop pattern-completion from minting the public shape of a system.
Agent write-ups keep circling the same bruise. A model fills gaps. It will invent X-Request-Id because many APIs have one, pick a timeout that looks professional, and name error codes after a popular gateway. Cheap generation makes that habit inexpensive. Inexpensive habits spread. When the generator is an unpinned free endpoint, the cost of a wrong assumption is paid later, in review and in the incident that looks like a product bug.
