debug: add detailed logging for knowledge base search

backend/src/services/knowledgeBaseService.ts

@@ -196,6 +196,8 @@ export async function searchKnowledgeBase(
   query: string,
   topK: number = 3
 ) {
+  console.log('🔍 [searchKnowledgeBase] 开始检索', { kbId, query, topK });
+  
   // 1. 验证权限
   const knowledgeBase = await prisma.knowledgeBase.findFirst({
     where: {
@@ -205,10 +207,23 @@ export async function searchKnowledgeBase(
   });
 
   if (!knowledgeBase) {
+    console.error('❌ [searchKnowledgeBase] 知识库不存在', { kbId, userId });
     throw new Error('Knowledge base not found or access denied');
   }
 
+  console.log('📚 [searchKnowledgeBase] 找到知识库', { 
+    id: knowledgeBase.id,
+    name: knowledgeBase.name,
+    difyDatasetId: knowledgeBase.difyDatasetId 
+  });
+
   // 2. 调用Dify检索API
+  console.log('🌐 [searchKnowledgeBase] 调用Dify检索API', {
+    difyDatasetId: knowledgeBase.difyDatasetId,
+    query,
+    topK
+  });
+  
   const results = await difyClient.retrieveKnowledge(
     knowledgeBase.difyDatasetId,
     query,
@@ -222,6 +237,22 @@ export async function searchKnowledgeBase(
     }
   );
 
+  console.log('✅ [searchKnowledgeBase] Dify返回结果', {
+    recordCount: results.records?.length || 0,
+    hasRecords: results.records && results.records.length > 0
+  });
+
+  if (results.records && results.records.length > 0) {
+    console.log('📄 [searchKnowledgeBase] 检索到的记录:', 
+      results.records.map((r: any) => ({
+        score: r.score,
+        contentPreview: r.segment?.content?.substring(0, 100)
+      }))
+    );
+  } else {
+    console.warn('⚠️ [searchKnowledgeBase] 没有检索到任何记录');
+  }
+
   return results;
 }