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/worker.py

@@ -166,6 +166,7 @@ from cloud.peer_messages import peer_message_prefix as _peer_prefix
 from cloud.peer_messages import row_get as _row_get
 from cloud.sub2api import ensure_user_gateway_key as _ensure_sub2api_key
 from cloud.websearch import ensure_codex_home_websearch as _ensure_websearch_mcp
+from cloud.websearch import ensure_websearch_mcp_env as _ensure_websearch_mcp_env
 from cloud.skill_seed import ensure_codex_home_skills as _ensure_skills
 from cloud.sub2api import gateway_name as _gateway_name
 from cloud.sub2api import gateway_origin as _gateway_origin
@@ -2823,6 +2824,22 @@ class Worker:
         }
         if search_env:
             proxy_env = _merge_env(proxy_env, search_env)
+        # MCP env must live in config.toml, not just docker -e:
+        # Codex's MCP subprocess does not inherit the Codex
+        # process env (2026-10-30实测：Codex bash 里有
+        # SEARXNG_URL + proxy，MCP 链却只有 duckduckgo，
+        # DNS 瞬间失败；给 config 加 [mcp_servers.websearch.env]
+        # 后同一任务立刻返回真实 SearXNG 结果）。网关在此时
+        # 才已知，所以这里、容器启动前写租户 config，绝不
+        # 在播种时写死一个网关。写失败只记日志，不阻塞任务。
+        if self.tenant_isolation and proxy_env:
+            try:
+                home = self._tenant_dirs(
+                    task.get("project_id"))["codex_home"]
+                _ensure_websearch_mcp_env(home, proxy_env)
+            except Exception as exc:
+                self.logger.warning(
+                    "websearch MCP env write failed: %s" % exc)
         return (True, tenant_mounts, tenant_network, proxy_env, None)
 
     def _run_fork(self, task, quota_check=None):