diff --git a/packages/electron-app/electron.vite.config.ts b/packages/electron-app/electron.vite.config.ts
index 1161176a..105b2d3f 100644
--- a/packages/electron-app/electron.vite.config.ts
+++ b/packages/electron-app/electron.vite.config.ts
@@ -1,6 +1,7 @@
 import { defineConfig, externalizeDepsPlugin } from "electron-vite"
 import solid from "vite-plugin-solid"
 import { resolve } from "path"
+import fs from "fs"
 
 const uiRoot = resolve(__dirname, "../ui")
 const uiSrc = resolve(uiRoot, "src")
@@ -8,6 +9,92 @@ const uiRendererRoot = resolve(uiRoot, "src/renderer")
 const uiRendererEntry = resolve(uiRendererRoot, "index.html")
 const uiRendererLoadingEntry = resolve(uiRendererRoot, "loading.html")
 
+function copyMonacoPublicAssets(opts: { warn: (message: string) => void }) {
+  const publicDir = resolve(uiRendererRoot, "public")
+  const destRoot = resolve(publicDir, "monaco/vs")
+
+  const candidates = [
+    // Workspace root hoisted deps.
+    resolve(__dirname, "../../node_modules/monaco-editor/min/vs"),
+    // UI package local deps.
+    resolve(uiRoot, "node_modules/monaco-editor/min/vs"),
+  ]
+  const sourceRoot = candidates.find((p) => fs.existsSync(resolve(p, "loader.js")))
+  if (!sourceRoot) {
+    opts.warn("Monaco source directory not found; skipping copy")
+    return
+  }
+
+  const copyRecursive = (src: string, dest: string) => {
+    const stat = fs.statSync(src)
+    if (stat.isDirectory()) {
+      fs.mkdirSync(dest, { recursive: true })
+      for (const entry of fs.readdirSync(src)) {
+        copyRecursive(resolve(src, entry), resolve(dest, entry))
+      }
+      return
+    }
+    fs.copyFileSync(src, dest)
+  }
+
+  // Keep the working tree clean; these assets are generated.
+  try {
+    fs.rmSync(destRoot, { recursive: true, force: true })
+  } catch {
+    // ignore
+  }
+  fs.mkdirSync(destRoot, { recursive: true })
+
+  // Copy core Monaco runtime.
+  for (const dir of ["base", "editor", "platform"] as const) {
+    const src = resolve(sourceRoot, dir)
+    if (fs.existsSync(src)) {
+      copyRecursive(src, resolve(destRoot, dir))
+    }
+  }
+
+  // loader.js is required.
+  copyRecursive(resolve(sourceRoot, "loader.js"), resolve(destRoot, "loader.js"))
+
+  // Copy baseline rich language packages + workers.
+  for (const lang of ["typescript", "html", "json", "css"] as const) {
+    const src = resolve(sourceRoot, "language", lang)
+    if (fs.existsSync(src)) {
+      copyRecursive(src, resolve(destRoot, "language", lang))
+    }
+  }
+
+  // Copy baseline basic tokenizers.
+  for (const lang of ["python", "markdown", "cpp", "kotlin"] as const) {
+    const src = resolve(sourceRoot, "basic-languages", lang)
+    if (fs.existsSync(src)) {
+      copyRecursive(src, resolve(destRoot, "basic-languages", lang))
+    }
+  }
+
+  // Copy monaco.contribution.js entrypoints (needed by some loads).
+  const monacoContribution = resolve(sourceRoot, "basic-languages", "monaco.contribution.js")
+  if (fs.existsSync(monacoContribution)) {
+    copyRecursive(monacoContribution, resolve(destRoot, "basic-languages", "monaco.contribution.js"))
+  }
+  const underscoreContribution = resolve(sourceRoot, "basic-languages", "_.contribution.js")
+  if (fs.existsSync(underscoreContribution)) {
+    copyRecursive(underscoreContribution, resolve(destRoot, "basic-languages", "_.contribution.js"))
+  }
+}
+
+function prepareMonacoPublicAssets() {
+  return {
+    name: "prepare-monaco-public-assets",
+    configureServer(server: any) {
+      copyMonacoPublicAssets({ warn: (msg) => server.config.logger.warn(msg) })
+    },
+    buildStart(this: any) {
+      copyMonacoPublicAssets({ warn: (msg) => this.warn(msg) })
+    },
+  }
+}
+
 export default defineConfig({
   main: {
     plugins: [externalizeDepsPlugin()],
@@ -40,7 +127,7 @@ export default defineConfig({
   },
   renderer: {
     root: uiRendererRoot,
-    plugins: [solid()],
+    plugins: [solid(), prepareMonacoPublicAssets()],
     css: {
       postcss: resolve(uiRoot, "postcss.config.js"),
     },