update subscription algorithm

apps/admin/next.config.js

@@ -2,8 +2,15 @@
 const apiOrigin = (process.env.API_INTERNAL_URL ?? process.env.API_URL ?? 'http://localhost:4000').replace(/\/api\/v1\/?$/, '')
 const apiUrl = new URL(apiOrigin)
 
+// In Docker dev the admin app runs on port 3002 while the marketplace proxy
+// serves it from port 3000. When ADMIN_ASSET_PREFIX is set, Next emits
+// absolute chunk URLs so /admin pages load their JS/CSS and HMR directly from
+// port 3002, bypassing the proxy (which can't upgrade WebSocket connections).
+const assetPrefix = process.env.ADMIN_ASSET_PREFIX || undefined
+
 const nextConfig = {
   basePath: '/admin',
+  ...(assetPrefix ? { assetPrefix } : {}),
   images: {
     remotePatterns: [
       {