gpt-5.x models served via the OpenAI Responses API reject requests that
include temperature or top_p with:
{"detail":"Unsupported parameter: temperature"}
This caused ClaudeCode agent/subagent tool requests to fail with a 400
error when an OpenAI group had the Messages-format support enabled.
Root cause: AnthropicToResponses and ChatCompletionsToResponses were
unconditionally forwarding temperature and top_p from the incoming
request to the ResponsesRequest, even though all gpt-5.x reasoning
models reject these sampling parameters.
Fix:
- Add isReasoningModel(model string) bool helper that returns true for
any model whose name starts with "gpt-5".
- Skip temperature and top_p when converting to ResponsesRequest for
reasoning models. Non-reasoning models (e.g. gpt-4o) are unaffected.
- ResponsesRequest.Temperature and TopP are already *float64 with
omitempty, so nil values are safely omitted from the JSON body.
Tests:
- TestAnthropicToResponses_TemperatureStrippedForReasoningModel
- TestAnthropicToResponses_TemperatureStrippedForAllGpt5Variants
- TestChatCompletionsToResponses_TemperatureStrippedForReasoningModel
- TestChatCompletionsToResponses_TemperaturePreservedForNonReasoningModel
Fixes#2487
DeepSeek thinking-mode tool-call conversations may require the assistant
reasoning_content from previous turns to be sent back in later requests. Without
preserving it, those conversations can fail or lose reasoning context.
Changes:
- Preserve assistant reasoning_content when converting Chat Completions messages
to Responses input by wrapping it as a thinking block.
- Add regression coverage for non-streaming DeepSeek responses.
- Add regression coverage for streaming DeepSeek deltas.
- Add regression coverage that request-side messages[].reasoning_content is
passed through with tool calls.
Tests:
go test -tags=unit ./internal/pkg/apicompat ./internal/service -run
'TestChatCompletionsToResponses_AssistantReasoningContentPreserved|
TestChatCompletionsToResponses_AssistantThinkingTagPreserved|
TestForwardAsRawChatCompletions_PreservesDeepSeekReasoningContent|
TestForwardAsRawChatCompletions_ForcesStreamUsageUpstreamAndPassesUsageDownstream
When a chat-completions message has no usable content parts (empty array,
empty text part, or filtered-out image part), marshalChatInputContent
marshalled a nil slice to JSON null. The upstream Responses API rejects a
null content field with HTTP 400. Fall back to an empty string instead.
Fixes#2515
- apply default mapped model only when scheduling fallback is actually used
- preserve reasoning in OpenAI-compatible output via reasoning_content and avoid invalid input function_call ids
