websearch: MCP env 写进租户 config，不只靠 docker -e

2026-10-30 实测：Codex bash 里有 SEARXNG_URL + proxy，
MCP 链却只有 duckduckgo、DNS 瞬间失败——Codex 的 MCP
子进程不继承 Codex 进程 env；给租户 config 加
[mcp_servers.websearch.env] 后同一任务立刻返回真实
SearXNG 结果。修法：worker 在 _docker_task_context
算出网关后、容器启动前，用 ensure_websearch_mcp_env
把 proxy + 搜索 env 写进租户 config（网关此时才已知，
播种时写不死；写失败只记日志不阻塞）。
测试：新增 test_websearch_mcp_env 4 项，相关共 33 项全过。

cloud/tests/test_websearch_mcp_env.py

@@ -0,0 +1,71 @@
+"""ensure_websearch_mcp_env: MCP env lives in config.toml, because
+Codex's MCP subprocess does not inherit the Codex process env
+(2026-10-30: Codex bash had SEARXNG_URL + proxy, MCP chain was
+still ["duckduckgo"] only; adding the config env section made
+the same task return real SearXNG results)."""
+
+import os
+import sys
+import tempfile
+import unittest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", ".."))
+from cloud.websearch import ensure_websearch_mcp_env  # noqa: E402
+
+
+BASE = ("model = \"gpt-6.1-sol\"\n\n"
+        "[mcp_servers.websearch]\n"
+        "command = \"python3\"\n"
+        "args = [\"/var/lib/codex-app-server/codex-home/"
+        "websearch_mcp.py\"]\n")
+
+
+class TestMcpEnv(unittest.TestCase):
+    def _home(self, text):
+        tmp = tempfile.mkdtemp()
+        with open(os.path.join(tmp, "config.toml"), "w") as fh:
+            fh.write(text)
+        return tmp
+
+    def _read(self, home):
+        with open(os.path.join(home, "config.toml")) as fh:
+            return fh.read()
+
+    def test_insert_env_after_websearch_section(self):
+        home = self._home(BASE)
+        self.assertTrue(ensure_websearch_mcp_env(
+            home, {"SEARXNG_URL": "http://searx.test",
+                   "http_proxy": "http://10.0.0.1:8888"}))
+        text = self._read(home)
+        self.assertIn("[mcp_servers.websearch.env]", text)
+        self.assertIn('SEARXNG_URL = "http://searx.test"', text)
+        self.assertIn('http_proxy = "http://10.0.0.1:8888"', text)
+        self.assertIn('command = "python3"', text)
+
+    def test_replace_existing_env_preserves_other_sections(self):
+        home = self._home(BASE + "[mcp_servers.websearch.env]\n"
+                          "SEARXNG_URL = \"http://old.test\"\n\n"
+                          "[other]\nfoo = 1\n")
+        self.assertTrue(ensure_websearch_mcp_env(
+            home, {"SEARXNG_URL": "http://new.test"}))
+        text = self._read(home)
+        self.assertIn('SEARXNG_URL = "http://new.test"', text)
+        self.assertNotIn("old.test", text)
+        self.assertIn("[other]\nfoo = 1", text)
+
+    def test_empty_env_writes_nothing(self):
+        home = self._home(BASE)
+        self.assertFalse(ensure_websearch_mcp_env(home, {}))
+        self.assertEqual(self._read(home), BASE)
+
+    def test_idempotent_second_write(self):
+        home = self._home(BASE)
+        env = {"SEARXNG_URL": "http://searx.test"}
+        self.assertTrue(ensure_websearch_mcp_env(home, env))
+        self.assertFalse(ensure_websearch_mcp_env(home, env))
+        self.assertEqual(self._read(home).count(
+            "[mcp_servers.websearch.env]"), 1)
+
+
+if __name__ == "__main__":
+    unittest.main()