diff --git a/vite.config.ts b/vite.config.ts
index 0506f1b..b0925cf 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -17,8 +17,11 @@ export default defineConfig(({mode}) => {
     },
     server: {
       // HMR is disabled in AI Studio via DISABLE_HMR env var.
-      // Do not modify—file watching is disabled to prevent flickering during agent edits.
+      // Do not modify—file watching is disabled to prevent flickering during agent edits.
       hmr: process.env.DISABLE_HMR !== 'true',
     },
+    preview: {
+      allowedHosts: ['neuron-second-brain-production.up.railway.app', 'localhost'],
+    },
   };
 });