fix: simplify search web providers

tests/test_agent_search_web_tool.py

@@ -3,7 +3,11 @@ import json
 import unittest
 from unittest.mock import AsyncMock, patch
 
-from app.agent.tools.impl.search_web import DEFAULT_SEARCH_ENGINE, SearchWebTool
+from app.agent.tools.impl.search_web import (
+    DDGS_AUTO_BACKEND,
+    DEFAULT_SEARCH_ENGINE,
+    SearchWebTool,
+)
 from app.core.config import settings
 
 
@@ -28,7 +32,10 @@ class TestAgentSearchWebTool(unittest.TestCase):
 
         self.assertEqual(
             "asyncio site:docs.python.org",
-            SearchWebTool._build_search_query("asyncio site:docs.python.org", site_filter),
+            SearchWebTool._build_search_query(
+                "asyncio site:docs.python.org",
+                site_filter,
+            ),
         )
 
     def test_filter_results_by_site_matches_domain_and_path(self):
@@ -50,14 +57,36 @@ class TestAgentSearchWebTool(unittest.TestCase):
         )
 
     def test_auto_search_plan_falls_back_to_search_engine(self):
-        """没有 API Key 时自动模式应退回搜索引擎后端"""
-        with patch.object(settings, "EXA_API_KEY", ""), patch.object(
-            settings, "TAVILY_API_KEY", []
-        ):
-            search_plan = SearchWebTool._get_search_plan(DEFAULT_SEARCH_ENGINE)
+        """自动模式应只使用 DDGS 搜索引擎后端"""
+        search_plan = SearchWebTool._get_search_plan(DEFAULT_SEARCH_ENGINE)
 
         self.assertEqual([DEFAULT_SEARCH_ENGINE], search_plan)
 
+    def test_auto_ddgs_backend_excludes_bing(self):
+        """DDGS 自动搜索后端不应包含 Bing"""
+        auto_backends = SearchWebTool._get_ddgs_backend(
+            DEFAULT_SEARCH_ENGINE
+        ).split(",")
+
+        self.assertNotIn("bing", auto_backends)
+        self.assertIn("duckduckgo", auto_backends)
+        self.assertEqual(DDGS_AUTO_BACKEND, ",".join(auto_backends))
+
+    def test_bing_search_engine_is_not_supported(self):
+        """Bing 不应再作为可选 DDGS 搜索后端暴露"""
+        tool = SearchWebTool(session_id="session-1", user_id="10001")
+
+        result = asyncio.run(tool.run(query="asyncio", search_engine="bing"))
+
+        self.assertIn("不支持的搜索源 'bing'", result)
+
+    def test_ddgs_alias_uses_auto_backend(self):
+        """DDGS 别名应映射到自动 DDGS 后端"""
+        self.assertEqual(
+            DEFAULT_SEARCH_ENGINE,
+            SearchWebTool._normalize_search_engine("ddgs"),
+        )
+
     def test_run_uses_specific_search_engine_and_site_filter(self):
         """显式搜索引擎和指定网址应传入后端搜索调用"""
 
@@ -95,6 +124,36 @@ class TestAgentSearchWebTool(unittest.TestCase):
         self.assertEqual(1, payload["total_results"])
         self.assertEqual("DuckDuckGo", payload["results"][0]["source"])
 
+    def test_ddgs_uses_system_proxy_by_default(self):
+        """DDGS 搜索默认应使用系统代理配置"""
+
+        async def _run_tool():
+            """执行一次带 mock DDGS 后端的搜索工具调用"""
+            tool = SearchWebTool(session_id="session-1", user_id="10001")
+            with patch.object(
+                settings, "PROXY_HOST", "http://proxy.example.com:7890"
+            ), patch("app.agent.tools.impl.search_web.DDGS") as ddgs_mock:
+                ddgs = ddgs_mock.return_value.__enter__.return_value
+                ddgs.text.return_value = [
+                    {
+                        "title": "asyncio",
+                        "body": "Python asyncio docs",
+                        "href": "https://docs.python.org/3/library/asyncio.html",
+                    }
+                ]
+
+                results = await tool._search_ddgs(
+                    query="asyncio",
+                    max_results=1,
+                    search_engine="duckduckgo",
+                )
+                return results, ddgs_mock.call_args.kwargs
+
+        results, ddgs_kwargs = asyncio.run(_run_tool())
+
+        self.assertEqual("http://proxy.example.com:7890", ddgs_kwargs["proxy"])
+        self.assertEqual(1, len(results))
+
 
 if __name__ == "__main__":
     unittest.main()