diff --git a/vite.config.ts b/vite.config.ts
index 7638414..a588652 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -3,6 +3,8 @@ import { defineConfig } from "vite";
 // https://vitejs.dev/config/
 export default defineConfig({
   worker: {
-    format: "es",
+    rollupOptions: {
+      external: ["@codex/sdk-js"],
+    },
   },
 });