Round 19 added scale to /v1/responses based on the openai-python
SDK type, but round 20 reviewers (3/10 against) and the round 18
aggregator both noted that the live OpenAI Responses reference
limits Responses service tiers to auto/default/flex/priority. The
PR contract in the original description also lists scale only for
Chat Completions, not Responses. Studio routes OpenAI through
Responses, so forwarding scale risks a 400 from the upstream and
exposes a picker option the API does not accept.
Restore the conservative drop behaviour: only documented Responses
tiers reach the wire; legacy scale settings still validate (the
ServiceTier Literal and chat-settings storage allowlist keep it
for forward-compat).
5d4ddd6b37