update

electron.vite.config.ts

@@ -9,7 +9,13 @@ export default defineConfig({
   },
   preload: {
     plugins: [externalizeDepsPlugin()],
-    build: { outDir: 'out/preload' },
+    build: {
+      outDir: 'out/preload',
+      // CommonJS preload (.cjs): loads synchronously before the page, so the
+      // contextBridge is exposed by the time the renderer mounts. ESM preload
+      // (.mjs) can expose late and leave window.helder briefly undefined.
+      rollupOptions: { output: { format: 'cjs', entryFileNames: 'index.cjs' } },
+    },
   },
   renderer: {
     root: 'src/renderer',