websearch: SearXNG 默认只查 bing,360search

默认 general 类别在 Docker 任务容器里要 20.0 秒才回
（wikipedia/wikidata/brave/duckduckgo/google 引擎全超时，
只有 bing+360search 回），撞 MCP 默认 20 秒超时；随后
DuckDuckGo 经代理也超时，整条链失败。代理本身无问题
（Tinyproxy 白名单早已放行 searx 与 duckduckgo）。
修法：_provider_searxng 默认 engines=bing,360search，
SEARXNG_ENGINES 可覆盖、空值恢复旧行为；worker 搜索
env 透传补 SEARXNG_ENGINES。容器实测：钉住后 0.26 秒
回 3 条（首条北京天气），auto 链 0.15 秒成功；旧 20.0 秒。
测试：新增 test_websearch_searxng 3 项，MCP/worker 共
21 项全过。生产未部署。

cloud/tests/test_websearch_searxng.py

@@ -0,0 +1,52 @@
+"""SearXNG provider: engines are pinned, not left to the default
+general category (2026-10-30: default took 20s in a Docker task,
+pinned bing,360search took 0.47s via the same egress proxy)."""
+
+import json
+import os
+import sys
+import unittest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", ".."))
+from cloud.websearch import _provider_searxng  # noqa: E402
+
+
+class _FakeHttp:
+    def __init__(self):
+        self.urls = []
+
+    def get(self, url, headers=None):
+        self.urls.append(url)
+        body = json.dumps({"results": [
+            {"title": "Beijing weather", "url": "https://example.test/w",
+             "content": "sunny"}]}).encode("utf-8")
+        return 200, body, "application/json"
+
+
+class TestSearXNGEngines(unittest.TestCase):
+    def test_default_pins_bing_360search(self):
+        http = _FakeHttp()
+        results, _ = _provider_searxng(
+            "Beijing weather", 3, {"SEARXNG_URL": "http://searx.test"},
+            http)
+        self.assertEqual(len(results), 1)
+        self.assertIn("engines=bing%2C360search", http.urls[0])
+
+    def test_env_overrides_pin(self):
+        http = _FakeHttp()
+        _provider_searxng(
+            "q", 3, {"SEARXNG_URL": "http://searx.test",
+                     "SEARXNG_ENGINES": "bing"}, http)
+        self.assertIn("engines=bing", http.urls[0])
+        self.assertNotIn("360search", http.urls[0])
+
+    def test_empty_env_restores_unpinned(self):
+        http = _FakeHttp()
+        _provider_searxng(
+            "q", 3, {"SEARXNG_URL": "http://searx.test",
+                     "SEARXNG_ENGINES": ""}, http)
+        self.assertNotIn("engines=", http.urls[0])
+
+
+if __name__ == "__main__":
+    unittest.main()

cloud/websearch.py

@@ -267,8 +267,22 @@ def _provider_searxng(query, limit, env, http):
     base = (env.get("SEARXNG_URL") or "").rstrip("/")
     if not base:
         raise WebSearchError("searxng not configured (SEARXNG_URL unset)")
-    url = (base + "/search?"
-           + urllib.parse.urlencode({"q": query, "format": "json"}))
+    # Engines are pinned, not left to SearXNG's default "general"
+    # category. Measured 2026-10-30 on the production host:
+    # default general search took 20.0s in a Docker task container
+    # (wikipedia / wikidata / brave / duckduckgo / google engines
+    # all timing out, only bing + 360search returning), which hits
+    # the MCP's 20s timeout and then falls through to DuckDuckGo,
+    # which itself times out via the egress proxy -- so the whole
+    # chain fails even though SearXNG can answer. Pinning to the
+    # two proven-fast engines cuts the same query to 0.47s via
+    # the same proxy. SEARXNG_ENGINES overrides the pin; an empty
+    # value restores the old unpinned behaviour.
+    params = {"q": query, "format": "json"}
+    engines = env.get("SEARXNG_ENGINES", "bing,360search")
+    if engines:
+        params["engines"] = engines
+    url = base + "/search?" + urllib.parse.urlencode(params)
     _status, body, _ctype = http.get(url, _default_headers(env, "searxng"))
     data = json.loads(body.decode("utf-8", errors="replace"))
     results = []

cloud/worker.py

@@ -2816,7 +2816,8 @@ class Worker:
         # 走 extra_env（容器内进程本就需要它调 API）。
         search_env = {
             k: os.environ[k]
-            for k in ("SEARXNG_URL", "PERPLEXITY_API_KEY", "EXA_API_KEY",
+            for k in ("SEARXNG_URL", "SEARXNG_ENGINES",
+                      "PERPLEXITY_API_KEY", "EXA_API_KEY",
                       "TAVILY_API_KEY", "BRAVE_API_KEY")
             if os.environ.get(k)
         }