diff --git a/.changeset/fix-missing-sandbox-worker.md b/.changeset/fix-missing-sandbox-worker.md
new file mode 100644
index 00000000000..25ecfb93d99
--- /dev/null
+++ b/.changeset/fix-missing-sandbox-worker.md
@@ -0,0 +1,5 @@
+---
+"kilo-code": patch
+---
+
+Fix missing kilo-sandbox-mutation-worker.js in VS Code extension bundle, which caused sandboxed file operations to fail with "Module not found".
diff --git a/packages/kilo-vscode/script/build.ts b/packages/kilo-vscode/script/build.ts
index 74abe402ab8..c6dd9b4b9a2 100644
--- a/packages/kilo-vscode/script/build.ts
+++ b/packages/kilo-vscode/script/build.ts
@@ -2,7 +2,11 @@
 import { $ } from "bun"
 import { join } from "node:path"
 import { existsSync, mkdirSync, rmSync, chmodSync } from "node:fs"
-import { copySandboxResources, copyTreeSitterResources } from "../src/services/cli-backend/cli-resources"
+import {
+  copyKiloSandboxWorker,
+  copySandboxResources,
+  copyTreeSitterResources,
+} from "../src/services/cli-backend/cli-resources"
 import { ensureFfmpegForTarget } from "./ffmpeg-helper"
 
 const packageJsonPath = join(import.meta.dir, "..", "package.json")
@@ -78,6 +82,7 @@ for (const config of targets) {
   await $`cp ${sourceBinary} ${targetBinary}`
   await copyTreeSitterResources(sourceBinary, targetBinary)
   await copySandboxResources(sourceBinary, targetBinary)
+  await copyKiloSandboxWorker(sourceBinary, targetBinary)
 
   if (config.binary !== "kilo.exe") {
     chmodSync(targetBinary, 0o755)