Add support for delta.reasoning field to properly display CoT streaming

app.py

@@ -207,36 +207,61 @@ def process_message(message, history, images, system_prompt, temperature, max_to
         in_reasoning = False
         reasoning_content = ""
         final_content = ""
+        has_reasoning_field = False
         
         for chunk in response:
-            if chunk.choices and chunk.choices[0].delta:
-                delta_content = chunk.choices[0].delta.content
-                if delta_content:
-                    full_response += delta_content
+            if chunk.choices and chunk.choices[0]:
+                delta = chunk.choices[0].delta
+                
+                # 优先检查 delta.reasoning 字段（Step-3 API 的 CoT 内容）
+                if hasattr(delta, 'reasoning') and delta.reasoning:
+                    has_reasoning_field = True
+                    reasoning_content += delta.reasoning
+                    print(f"[DEBUG] CoT chunk: {delta.reasoning[:50] if len(delta.reasoning) > 50 else delta.reasoning}")
                     
-                    # 检测reasoning标签
-                    if '<reasoning>' in full_response and not in_reasoning:
-                        in_reasoning = True
-                        parts = full_response.split('<reasoning>')
-                        if len(parts) > 1:
-                            reasoning_content = parts[1]
+                    # 实时更新显示 CoT 内容
+                    if final_content:
+                        display_text = f"💭 **Chain of Thought:**\n\n{reasoning_content}\n\n---\n\n📝 **Answer:**\n\n{final_content}"
+                    else:
+                        display_text = f"💭 **Chain of Thought:**\n\n{reasoning_content}\n\n---\n\n📝 **Answer:**\n\n*Generating...*"
                     
-                    if in_reasoning and '</reasoning>' in full_response:
-                        in_reasoning = False
-                        parts = full_response.split('</reasoning>')
-                        if len(parts) > 1:
-                            reasoning_content = parts[0].split('<reasoning>')[-1]
-                            final_content = parts[1]
-                    elif in_reasoning:
-                        reasoning_content = full_response.split('<reasoning>')[-1]
-                    elif '</reasoning>' in full_response:
-                        parts = full_response.split('</reasoning>')
-                        if len(parts) > 1:
-                            final_content = parts[1]
+                    history[-1][1] = display_text
+                    yield history
+                
+                # 处理常规 content 字段
+                delta_content = delta.content if hasattr(delta, 'content') else None
+                if delta_content:
+                    # 如果通过 reasoning 字段获取了 CoT，content 就是最终答案
+                    if has_reasoning_field:
+                        final_content += delta_content
+                        full_response += delta_content
                     else:
-                        # 没有reasoning标签的情况
-                        if '<reasoning>' not in full_response:
-                            final_content = full_response
+                        # 否则尝试解析 <reasoning> 标签
+                        full_response += delta_content
+                        
+                        # 检测reasoning标签
+                        if '<reasoning>' in full_response and not in_reasoning:
+                            in_reasoning = True
+                            parts = full_response.split('<reasoning>')
+                            if len(parts) > 1:
+                                reasoning_content = parts[1]
+                        
+                        if in_reasoning and '</reasoning>' in full_response:
+                            in_reasoning = False
+                            parts = full_response.split('</reasoning>')
+                            if len(parts) > 1:
+                                reasoning_content = parts[0].split('<reasoning>')[-1]
+                                final_content = parts[1]
+                        elif in_reasoning:
+                            reasoning_content = full_response.split('<reasoning>')[-1]
+                        elif '</reasoning>' in full_response:
+                            parts = full_response.split('</reasoning>')
+                            if len(parts) > 1:
+                                final_content = parts[1]
+                        else:
+                            # 没有reasoning标签的情况
+                            if '<reasoning>' not in full_response:
+                                final_content = full_response
                     
                     # 格式化显示
                     if reasoning_content and final_content: