Revert "Enhance response handling with reasoning content"

This reverts commit 35582b2.

Author: sjy3

model/openai.go

@@ -530,7 +530,6 @@ func (m *openAIModel) generateStream(ctx context.Context, openaiReq *openAIReque
 
 		scanner := bufio.NewScanner(httpResp.Body)
 		var textBuffer strings.Builder
-		var reasoningBuffer strings.Builder
 		var toolCalls []toolCall
 		var usage *usage
 
@@ -560,24 +559,6 @@ func (m *openAIModel) generateStream(ctx context.Context, openaiReq *openAIReque
 				continue
 			}
 
-			if delta.ReasoningContent != nil {
-				if text, ok := delta.ReasoningContent.(string); ok && text != "" {
-					reasoningBuffer.WriteString(text)
-					llmResp := &model.LLMResponse{
-						Content: &genai.Content{
-							Role: "model",
-							Parts: []*genai.Part{
-								{Text: text, Thought: true},
-							},
-						},
-						Partial: true,
-					}
-					if !yield(llmResp, nil) {
-						return
-					}
-				}
-			}
-			
 			if delta.Content != nil {
 				if text, ok := delta.Content.(string); ok && text != "" {
 					textBuffer.WriteString(text)
@@ -623,7 +604,7 @@ func (m *openAIModel) generateStream(ctx context.Context, openaiReq *openAIReque
 			}
 
 			if choice.FinishReason != "" {
-				finalResp := m.buildFinalResponse(textBuffer.String(), reasoningBuffer.String(), toolCalls, usage, choice.FinishReason)
+				finalResp := m.buildFinalResponse(textBuffer.String(), toolCalls, usage, choice.FinishReason)
 				yield(finalResp, nil)
 				return
 			}
@@ -635,7 +616,7 @@ func (m *openAIModel) generateStream(ctx context.Context, openaiReq *openAIReque
 		}
 
 		if textBuffer.Len() > 0 || len(toolCalls) > 0 {
-			finalResp := m.buildFinalResponse(textBuffer.String(), reasoningBuffer.String(), toolCalls, usage, "stop")
+			finalResp := m.buildFinalResponse(textBuffer.String(), toolCalls, usage, "stop")
 			yield(finalResp, nil)
 		}
 	}
@@ -751,16 +732,9 @@ func (m *openAIModel) convertResponse(resp *response) (*model.LLMResponse, error
 	return llmResp, nil
 }
 
-func (m *openAIModel) buildFinalResponse(text string, reasoningText string, toolCalls []toolCall, usage *usage, finishReason string) *model.LLMResponse {
+func (m *openAIModel) buildFinalResponse(text string, toolCalls []toolCall, usage *usage, finishReason string) *model.LLMResponse {
 	var parts []*genai.Part
 
-	if reasoningText != "" {
-		parts = append(parts, &genai.Part{
-			Text:    reasoningText,
-			Thought: true,
-		})
-	}
-	
 	if text != "" {
 		parts = append(parts, genai.NewPartFromText(text))
 	}