diff --git a/backend/src/services/conversationService.ts b/backend/src/services/conversationService.ts
index ab65c930..8a6d9ad8 100644
--- a/backend/src/services/conversationService.ts
+++ b/backend/src/services/conversationService.ts
@@ -141,6 +141,13 @@ export class ConversationService {
     userInput: string,
     knowledgeBaseContext?: string
   ): Promise<Message[]> {
+    console.log('🔧 [assembleContext] 开始组装上下文', {
+      conversationId,
+      agentId,
+      hasKnowledgeBaseContext: !!knowledgeBaseContext,
+      knowledgeBaseContextLength: knowledgeBaseContext?.length || 0
+    });
+
     // 获取系统Prompt
     const systemPrompt = agentService.getSystemPrompt(agentId);
 
@@ -161,6 +168,7 @@ export class ConversationService {
 
     // 判断是否是第一条消息
     const isFirstMessage = historyMessages.length === 0;
+    console.log(`📜 [assembleContext] 历史消息数: ${historyMessages.length}, 是否首次: ${isFirstMessage}`);
 
     // 渲染用户Prompt
     let userPromptContent: string;
@@ -172,12 +180,16 @@ export class ConversationService {
         userInput,
         knowledgeBaseContext,
       });
+      console.log(`📝 [assembleContext] 首次消息，使用完整模板，长度: ${userPromptContent.length}`);
     } else {
       // 后续消息：只发送用户输入和知识库上下文（如果有）
       if (knowledgeBaseContext) {
         userPromptContent = `${userInput}\n\n## 参考文献（来自知识库）\n${knowledgeBaseContext}`;
+        console.log(`📝 [assembleContext] 后续消息+知识库，总长度: ${userPromptContent.length}`);
+        console.log(`📋 [assembleContext] userPromptContent预览:\n${userPromptContent.substring(0, 300)}...`);
       } else {
         userPromptContent = userInput;
+        console.log(`📝 [assembleContext] 后续消息，仅用户输入: ${userPromptContent}`);
       }
     }
 
@@ -203,6 +215,7 @@ export class ConversationService {
       content: userPromptContent,
     });
 
+    console.log(`✅ [assembleContext] 组装完成，消息总数: ${messages.length}`);
     return messages;
   }
 
@@ -334,6 +347,7 @@ export class ConversationService {
     const conversation = await this.getConversationById(conversationId, userId);
 
     // 获取知识库上下文（如果有@知识库）
+    console.log('📚 [sendMessageStream] 开始处理知识库', { knowledgeBaseIds });
     let knowledgeBaseContext = '';
     if (knowledgeBaseIds && knowledgeBaseIds.length > 0) {
       const knowledgeResults: string[] = [];
@@ -341,6 +355,7 @@ export class ConversationService {
       // 对每个知识库进行检索
       for (const kbId of knowledgeBaseIds) {
         try {
+          console.log(`🔎 [sendMessageStream] 检索知识库 ${kbId}`);
           const searchResult = await knowledgeBaseService.searchKnowledgeBase(
             userId,
             kbId,
@@ -348,6 +363,11 @@ export class ConversationService {
             3 // 每个知识库返回3个最相关的段落
           );
 
+          console.log(`✅ [sendMessageStream] 检索结果`, { 
+            kbId,
+            recordCount: searchResult.records?.length || 0 
+          });
+
           // 格式化检索结果
           if (searchResult.records && searchResult.records.length > 0) {
             const kbInfo = await prisma.knowledgeBase.findUnique({
@@ -355,25 +375,34 @@ export class ConversationService {
               select: { name: true },
             });
 
-            knowledgeResults.push(
-              `【知识库：${kbInfo?.name || '未命名'}】\n` +
+            const formattedResult = `【知识库：${kbInfo?.name || '未命名'}】\n` +
               searchResult.records
                 .map((record: any, index: number) => {
                   const score = (record.score * 100).toFixed(1);
                   return `${index + 1}. [相关度${score}%] ${record.segment.content}`;
                 })
-                .join('\n\n')
-            );
+                .join('\n\n');
+
+            console.log(`📄 [sendMessageStream] 格式化结果长度: ${formattedResult.length} 字符`);
+            knowledgeResults.push(formattedResult);
+          } else {
+            console.warn(`⚠️ [sendMessageStream] 知识库 ${kbId} 没有检索到记录`);
           }
         } catch (error) {
-          console.error(`Failed to search knowledge base ${kbId}:`, error);
+          console.error(`❌ [sendMessageStream] 检索知识库失败 ${kbId}:`, error);
           // 检索失败不阻止对话，继续处理
         }
       }
 
       if (knowledgeResults.length > 0) {
         knowledgeBaseContext = knowledgeResults.join('\n\n---\n\n');
+        console.log(`💾 [sendMessageStream] 知识库上下文总长度: ${knowledgeBaseContext.length} 字符`);
+        console.log(`📋 [sendMessageStream] 知识库上下文预览:\n${knowledgeBaseContext.substring(0, 500)}...`);
+      } else {
+        console.warn('⚠️ [sendMessageStream] 没有构建任何知识库上下文');
       }
+    } else {
+      console.log('ℹ️ [sendMessageStream] 未选择知识库');
     }
 
     // 组装上下文
diff --git a/backend/src/services/knowledgeBaseService.ts b/backend/src/services/knowledgeBaseService.ts
index bc10b9c9..3e7ee5d9 100644
--- a/backend/src/services/knowledgeBaseService.ts
+++ b/backend/src/services/knowledgeBaseService.ts
@@ -231,8 +231,6 @@ export async function searchKnowledgeBase(
       retrieval_model: {
         search_method: 'semantic_search',
         top_k: topK,
-        score_threshold_enabled: true,
-        score_threshold: 0.3,
       },
     }
   );