chore: 完成知识库迁移与检索验证收口

ai_knowledge_base_v2/apps/backend/app/services/knowledge_agent_service.py

@@ -274,7 +274,11 @@ class KnowledgeAgentService:
         selected = [item_id for score, item_id in ranked if score >= 0.04][:4]
         if business and not selected:
             selected = [item_id for _, item_id in ranked[:3]]
-        return business or bool(selected), selected, "涉及课程/老师/业务知识" if business else "问题与知识目录主题相关"
+        if business:
+            return True, selected, "涉及课程/老师/业务知识"
+        if selected:
+            return True, selected, "问题与知识目录主题相关"
+        return False, [], "问题与当前知识目录无关，无需调用知识库"
 
     @staticmethod
     def _query_terms(question: str) -> list[str]: