[Responses] Return 400 for unsupported forced tool_choice on Harmony - #8
[Responses] Return 400 for unsupported forced tool_choice on Harmony#8Juno13340 wants to merge 1 commit into
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A forced named-function tool_choice on gpt-oss/Harmony currently raises NotImplementedError, which maps to HTTP 501. On the OCI data-plane the stateless path retries that 501 four times and surfaces it as a 500, tripping the Responses 5xx alarm; the stateful (SMG) path passes the 501 through. This is client-driven input, not a server fault, so return a 400 by raising VLLMValidationError instead (mapped to BadRequestError by create_error_response). Behavior for auto/none/required is unchanged. Signed-off-by: Juno13340 <35788036+Juno13340@users.noreply.github.com>
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Superseded — landing this through our internal build source instead. Closing here. |
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Summary
A forced named-function
tool_choice(e.g.{"type":"function","name":"get_weather"}) on gpt-oss / Harmony Responses requests currently raisesNotImplementedError, whichcreate_error_responsemaps to HTTP 501. This is a client-driven input case, not a server fault, so it should be a 4xx.Impact on the OCI data-plane (OCASGS-25555):
OpenAi.Responses.Create5xx alarm.Both surface as 5xx to customers. This change raises
VLLMValidationErrorinstead, whichcreate_error_responsemaps to 400 BadRequestError — so the stateless path no longer retries (fast 400, no alarm) and the stateful path returns a clean 400.Scope is limited to the already-guarded forced-named case;
auto/none/required(with function tools) are unchanged.VLLMValidationErroris already imported and used in this file.Note: this returns a proper client error for the unsupported case. Actually implementing forced-named tool_choice (constrained decoding) landed upstream in v0.27.0 (vllm-project#45560) and would return 200; that is a separate, larger change.
Test Plan
tool_choiceonopenai.gpt-oss-120b/-20breturns 400 (was 500 stateless / 501 stateful).tool_choice: "required"(with function tools) still returns 200.tool_choice: "auto"/"none"unchanged.toolsstill returns 400.