Resolve the Issue of Search History not Displaying

@@ -58,11 +58,17 @@ class Research:
     def add_search_results(self, query: str, results: List[Dict[str, Any]]):
         """批量添加搜索结果"""
         for result in results:
+            # 防御空值，避免下游展示时报错
+            url = result.get("url") or ""
+            title = result.get("title") or ""
+            content = result.get("content") or ""
+            if not isinstance(content, str):
+                content = str(content)
             search = Search(
-                query=query,
-                url=result.get("url", ""),
-                title=result.get("title", ""),
-                content=result.get("content", ""),
+                query=query or "",
+                url=url,
+                title=title,
+                content=content,
                 score=result.get("score")
             )
             self.add_search(search)

@@ -220,11 +220,16 @@ def display_results(agent: DeepSearchAgent, final_report: str):
 
         if all_searches:
             for i, search in enumerate(all_searches):
-                with st.expander(f"搜索 {i + 1}: {search.query}"):
+                query_label = search.query if search.query else "未记录查询"
+                with st.expander(f"搜索 {i + 1}: {query_label}"):
+                    preview = search.content or ""
+                    if not isinstance(preview, str):
+                        preview = str(preview)
+                    if len(preview) > 200:
+                        preview = preview[:200] + "..."
                     st.write("**URL:**", search.url)
                     st.write("**标题:**", search.title)
-                    st.write("**内容预览:**",
-                             search.content[:200] + "..." if len(search.content) > 200 else search.content)
+                    st.write("**内容预览:**", preview if preview else "无可用内容")
                     if search.score:
                         st.write("**相关度评分:**", search.score)