diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 6941a93..c9bdef3 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -52,19 +52,17 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Sync Protocol Constants
+      - name: Build Extensions
         run: |
-          chmod +x ./scripts/sync-constants.sh
-          ./scripts/sync-constants.sh
-
-      - name: Create Extension Zip
-        run: |
-          zip -r koala-sync-extension.zip extension/ -x "*.DS_Store*"
+          npm install
+          npm run build:extension
 
       - name: Create GitHub Release
         uses: softprops/action-gh-release@v1
         with:
-          files: koala-sync-extension.zip
+          files: |
+            dist/koalasync-chrome.zip
+            dist/koalasync-firefox.zip
           name: Release ${{ github.ref_name }}
           generate_release_notes: true
           draft: false
diff --git a/extension/manifest.json b/extension/manifest.base.json
similarity index 90%
rename from extension/manifest.json
rename to extension/manifest.base.json
index 6976083..ca7cace 100644
--- a/extension/manifest.json
+++ b/extension/manifest.base.json
@@ -22,10 +22,6 @@
       "128": "icons/icon128.png"
     }
   },
-  "background": {
-    "service_worker": "background.js",
-    "type": "module"
-  },
   "content_scripts": [
     {
       "matches": ["https://koalasync.shik3i.net/*"],
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..c1fa042
--- /dev/null
+++ b/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "koalasync",
+  "version": "1.2.1",
+  "description": "KoalaSync Build Scripts",
+  "private": true,
+  "scripts": {
+    "build:extension": "node scripts/build-extension.js"
+  },
+  "devDependencies": {
+    "archiver": "^7.0.1",
+    "fs-extra": "^11.2.0"
+  }
+}
diff --git a/scripts/build-extension.js b/scripts/build-extension.js
new file mode 100644
index 0000000..2d526e8
--- /dev/null
+++ b/scripts/build-extension.js
@@ -0,0 +1,122 @@
+const fs = require('fs');
+const path = require('path');
+const archiver = require('archiver');
+
+const rootDir = path.join(__dirname, '..');
+const extDir = path.join(rootDir, 'extension');
+const distDir = path.join(rootDir, 'dist');
+const baseManifestPath = path.join(extDir, 'manifest.base.json');
+
+// Ensure dist directory exists
+if (fs.existsSync(distDir)) {
+  fs.rmSync(distDir, { recursive: true, force: true });
+}
+fs.mkdirSync(distDir, { recursive: true });
+
+// Sync shared constants from root /shared to /extension/shared
+console.log('Syncing protocol constants...');
+const masterSharedDir = path.join(rootDir, 'shared');
+const extSharedDir = path.join(extDir, 'shared');
+
+if (!fs.existsSync(extSharedDir)) {
+  fs.mkdirSync(extSharedDir, { recursive: true });
+}
+
+const sharedFiles = ['constants.js', 'blacklist.js'];
+for (const file of sharedFiles) {
+  const src = path.join(masterSharedDir, file);
+  const dest = path.join(extSharedDir, file);
+  if (fs.existsSync(src)) {
+    fs.copyFileSync(src, dest);
+  }
+}
+console.log('✓ constants.js and blacklist.js synced to extension/shared/');
+
+// Read the base manifest
+const baseManifest = JSON.parse(fs.readFileSync(baseManifestPath, 'utf8'));
+
+// Helper to copy files, ignoring manifest.json and manifest.base.json
+function copyExtensionFiles(targetDir) {
+  fs.mkdirSync(targetDir, { recursive: true });
+  const items = fs.readdirSync(extDir);
+  for (const item of items) {
+    if (item === 'manifest.json' || item === 'manifest.base.json') continue;
+    const srcPath = path.join(extDir, item);
+    const destPath = path.join(targetDir, item);
+    if (fs.lstatSync(srcPath).isDirectory()) {
+      fs.cpSync(srcPath, destPath, { recursive: true });
+    } else {
+      fs.copyFileSync(srcPath, destPath);
+    }
+  }
+}
+
+// Helper to zip a directory
+function zipDirectory(sourceDir, outPath) {
+  return new Promise((resolve, reject) => {
+    const archive = archiver('zip', { zlib: { level: 9 } });
+    const stream = fs.createWriteStream(outPath);
+
+    archive
+      .directory(sourceDir, false)
+      .on('error', err => reject(err))
+      .pipe(stream);
+
+    stream.on('close', () => resolve());
+    archive.finalize();
+  });
+}
+
+async function buildBrowser(browserName, manifestModifier) {
+  console.log(`Building for ${browserName}...`);
+  const browserDistDir = path.join(distDir, browserName);
+  
+  // 1. Copy files
+  copyExtensionFiles(browserDistDir);
+  
+  // 2. Modify and write manifest
+  const browserManifest = manifestModifier(JSON.parse(JSON.stringify(baseManifest)));
+  fs.writeFileSync(
+    path.join(browserDistDir, 'manifest.json'),
+    JSON.stringify(browserManifest, null, 2)
+  );
+
+  // 3. Zip it
+  const zipPath = path.join(distDir, `koalasync-${browserName}.zip`);
+  await zipDirectory(browserDistDir, zipPath);
+  console.log(`Successfully built and zipped ${browserName} -> ${zipPath}`);
+}
+
+async function run() {
+  try {
+    // Build Chrome
+    await buildBrowser('chrome', (manifest) => {
+      manifest.background = {
+        service_worker: "background.js",
+        type: "module"
+      };
+      return manifest;
+    });
+
+    // Build Firefox
+    await buildBrowser('firefox', (manifest) => {
+      manifest.background = {
+        scripts: ["background.js"],
+        type: "module"
+      };
+      manifest.browser_specific_settings = {
+        gecko: {
+          id: "koalasync@shik3i.net"
+        }
+      };
+      return manifest;
+    });
+
+    console.log('Build complete!');
+  } catch (error) {
+    console.error('Build failed:', error);
+    process.exit(1);
+  }
+}
+
+run();
diff --git a/scripts/sync-constants.bat b/scripts/sync-constants.bat
deleted file mode 100644
index 2ff54fa..0000000
--- a/scripts/sync-constants.bat
+++ /dev/null
@@ -1,12 +0,0 @@
-@echo off
-REM KoalaSync - Protocol Synchronization Script (Windows)
-REM
-REM This script copies the master constants.js file from the shared directory
-REM to the extension directory. Since Chrome Extensions cannot load files
-REM outside their root, this manual sync is required after any changes to
-REM the shared protocol.
-
-if not exist extension\shared mkdir extension\shared
-copy /y shared\constants.js extension\shared\constants.js
-copy /y shared\blacklist.js extension\shared\blacklist.js
-echo ✓ constants.js and blacklist.js synced to extension\shared\
diff --git a/scripts/sync-constants.sh b/scripts/sync-constants.sh
deleted file mode 100755
index 8ac72ba..0000000
--- a/scripts/sync-constants.sh
+++ /dev/null
@@ -1,12 +0,0 @@
-#!/bin/sh
-# KoalaSync - Protocol Synchronization Script (Linux/macOS)
-#
-# This script copies the master constants.js file from the shared directory
-# to the extension directory. Since Chrome Extensions cannot load files
-# outside their root, this manual sync is required after any changes to
-# the shared protocol.
-
-mkdir -p extension/shared
-cp shared/constants.js extension/shared/constants.js
-cp shared/blacklist.js extension/shared/blacklist.js
-echo "✓ constants.js and blacklist.js synced to extension/shared/"