diff --git a/nginx/default.conf b/nginx/default.conf
index a0e217a..8f49bc6 100644
--- a/nginx/default.conf
+++ b/nginx/default.conf
@@ -400,6 +400,20 @@ server {
     proxy_pass http://$saju_backend$request_uri;
   }
 
+  # co-gahusb — FastMCP streamable-http bus
+  # Authorization forward required (Bearer key auth), no buffering, long read timeout
+  # trailing slash on proxy_pass strips /api/co/ prefix: /api/co/mcp → /mcp
+  location /api/co/ {
+    proxy_pass http://co-gahusb:8000/;
+    proxy_http_version 1.1;
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header Authorization $http_authorization;
+    proxy_set_header Connection "";
+    proxy_buffering off;
+    proxy_read_timeout 3600s;
+  }
+
   # agent-office API + WebSocket
   location /api/agent-office/ {
     resolver 127.0.0.11 valid=10s;