feat: enhance agent orchestration, knowledge flow and UI refinements

backend/app/agents/tools/search.py

@@ -5,12 +5,14 @@ Agent 工具集 - 知识库 & 图谱相关
 由于 LangChain 工具系统是同步的，内部用 run_in_executor 处理 async 逻辑。
 """
 
-from langchain_core.tools import tool
 from concurrent.futures import ThreadPoolExecutor
-from app.database import async_session
-from app.agents.context import get_current_user
 import asyncio
 
+from langchain_core.tools import tool
+
+from app.agents.context import get_current_user
+from app.database import async_session
+
 _executor = ThreadPoolExecutor(max_workers=4)
 
 
@@ -151,9 +153,56 @@ def hybrid_search(query: str, top_k: int = 5) -> str:
         return f"混合搜索失败: {str(e)}"
 
 
+@tool
+def web_search(query: str, top_k: int = 5) -> str:
+    """
+    通过 SearxNG 搜索外部网页信息，返回标题、链接和摘要。
+
+    Args:
+        query: 搜索关键词
+        top_k: 返回结果数量，默认 5 条
+
+    Returns:
+        适合模型综合的网页结果文本
+    """
+    from app.services.web_search_service import (
+        WebSearchConfigurationError,
+        WebSearchRequestError,
+        WebSearchService,
+    )
+
+    async def _search():
+        service = WebSearchService()
+        results = await service.search(query, limit=top_k)
+        if not results:
+            return "未找到相关网页结果。"
+
+        texts = []
+        for index, result in enumerate(results, 1):
+            source = f"\n来源: {result.source}" if result.source else ""
+            published_at = f"\n时间: {result.published_at}" if result.published_at else ""
+            snippet = result.snippet or "(无摘要)"
+            texts.append(
+                f"[{index}] {result.title}\n"
+                f"链接: {result.url}{source}{published_at}\n"
+                f"摘要: {snippet}"
+            )
+        return "\n\n---\n\n".join(texts)
+
+    try:
+        return _run_async(_search(), timeout=30)
+    except WebSearchConfigurationError as exc:
+        return f"网页搜索不可用: {exc}"
+    except WebSearchRequestError as exc:
+        return f"网页搜索失败: {exc}"
+    except Exception as exc:
+        return f"网页搜索失败: {exc}"
+
+
 __all__ = [
     "search_knowledge",
     "get_knowledge_graph_context",
     "build_knowledge_graph",
     "hybrid_search",
+    "web_search",
 ]