prompt_cache_options is no longer accepted

What changed

Usually ignored rather than rejected, so the call succeeds and does something subtly different.

Affects prompt_cache_options on CreateModelResponseProperties reachable from 2 operations. Grep for it: nothing else will tell you.

Who is affected

Code that sends OpenAI's CreateModelResponseProperties objects, used by 2 OpenAI operations.

Before and after

Code that breaks

await client.post("/…", {
  // prompt_cache_options is now ignored, not rejected
  prompt_cache_options: value,
});

Based on OpenAI’s published API specification. How severity is decided.