Agent Skills: Electron desktop development

Electron desktop development

Patterns and practices for building production-quality Electron applications with React and TypeScript.

Security baseline (Electron 30+)

Electron's defaults have hardened over the past several releases. As of Electron 28+, contextIsolation: true and sandbox: true are the defaults for new BrowserWindow instances — most security advice from older guides assumed you had to opt in. You don't anymore; you have to opt OUT, and you should not.

Set explicitly anyway, so a config drift never weakens the security model:

const win = new BrowserWindow({
  webPreferences: {
    contextIsolation: true,        // default since 12, mandatory for any prod app
    sandbox: true,                  // default since 28; renderer runs sandboxed
    nodeIntegration: false,         // never enable in renderer
    webSecurity: true,              // never disable
    preload: path.join(__dirname, 'preload.cjs')
  }
});

Validate every IPC message in main. Don't trust the renderer.

Electron Fuses + ASAR integrity

Electron Fuses are package-time toggles baked into the binary. The two relevant for security distribution:

• EnableEmbeddedAsarIntegrityValidation — verifies the app.asar hash at runtime against a hash embedded in the binary. Defends against attackers swapping the asar contents post-install.
• OnlyLoadAppFromAsar — refuses to load app code from anywhere except the validated asar.

These are opt-in, not default. Enable both for production. Requires @electron/asar 3.1.0+ to generate the asar with embeddable integrity. electron-builder configures this via electronFuses in the build config; @electron/fuses does it programmatically.

CVE-2023-44402 (ASAR integrity bypass via filetype confusion) was the canonical motivation here — without integrity + only-load-from-asar, an attacker who can modify app files can swap behavior silently.

Common renderer-side risks

• Preload script confusion — only expose narrow, typed surfaces via contextBridge.exposeInMainWorld. Never re-export ipcRenderer itself; expose specific methods that map to specific channels.
• file:// IPC and navigation — restrict navigation with webContents.on('will-navigate', e => e.preventDefault()) for windows that shouldn't change URL. Deny setWindowOpenHandler requests by default; allow-list specific origins.
• shell.openExternal with user input — validate the URL scheme before opening. An attacker-controlled file:// or javascript: URL hands them code execution.

Architecture patterns

Project structure

app/
├── electron/
│   ├── main.cjs              # Main process (CommonJS required)
│   ├── preload.cjs           # Context bridge for secure IPC
│   └── server.cjs            # Optional: WebSocket/HTTP server
├── src/
│   ├── components/           # React components
│   ├── services/             # Business logic (API clients, Firebase)
│   ├── utils/                # Utilities (audio, formatting)
│   ├── types.ts              # TypeScript interfaces
│   ├── App.tsx               # Root component
│   └── index.tsx             # React entry
├── assets/                   # Icons, sounds, images
├── package.json
├── vite.config.ts
└── electron-builder.yml      # Build configuration

IPC communication pattern

Main process (main.cjs):

const { ipcMain } = require('electron');

// Handle async requests from renderer
ipcMain.handle('action-name', async (event, args) => {
  try {
    const result = await someAsyncOperation(args);
    return { success: true, data: result };
  } catch (error) {
    return { success: false, error: error.message };
  }
});

// Send data to renderer
mainWindow.webContents.send('event-name', data);

Preload script (preload.cjs):

const { contextBridge, ipcRenderer } = require('electron');

contextBridge.exposeInMainWorld('electron', {
  actionName: (args) => ipcRenderer.invoke('action-name', args),
  onEventName: (callback) => {
    const handler = (event, data) => callback(data);
    ipcRenderer.on('event-name', handler);
    return () => ipcRenderer.removeListener('event-name', handler);
  }
});

Renderer (React):

const result = await window.electron.actionName(args);

useEffect(() => {
  return window.electron.onEventName((data) => {
    setState(data);
  });
}, []);

System tray integration

const { Tray, Menu, nativeImage } = require('electron');

let tray = null;

function createTray() {
  const icon = nativeImage.createFromPath(path.join(__dirname, '../assets/tray-icon.png'));
  tray = new Tray(icon.resize({ width: 16, height: 16 }));

  tray.setToolTip('App Name');
  tray.setContextMenu(Menu.buildFromTemplate([
    { label: 'Show', click: () => mainWindow.show() },
    { label: 'Quit', click: () => app.quit() }
  ]));

  tray.on('click', () => {
    mainWindow.isVisible() ? mainWindow.hide() : mainWindow.show();
  });
}

// Hide to tray instead of closing
mainWindow.on('close', (event) => {
  if (!app.isQuitting) {
    event.preventDefault();
    mainWindow.hide();
  }
});

Global shortcuts

const { globalShortcut } = require('electron');

app.whenReady().then(() => {
  // Register with conflict detection
  const registered = globalShortcut.register('Alt+S', () => {
    mainWindow.webContents.send('shortcut-triggered', 'toggle-recording');
  });

  if (!registered) {
    console.error('Shortcut registration failed - conflict detected');
  }
});

app.on('will-quit', () => {
  globalShortcut.unregisterAll();
});

PTY terminal integration (node-pty)

const pty = require('node-pty');

const shell = process.platform === 'win32' ? 'powershell.exe' : process.env.SHELL || '/bin/bash';

const ptyProcess = pty.spawn(shell, [], {
  name: 'xterm-256color',
  cols: 80,
  rows: 24,
  cwd: process.env.HOME,
  env: process.env
});

ptyProcess.onData((data) => {
  mainWindow.webContents.send('terminal-data', { tabId, data });
});

ipcMain.on('terminal-write', (event, { tabId, data }) => {
  ptyProcess.write(data);
});

ipcMain.on('terminal-resize', (event, { tabId, cols, rows }) => {
  ptyProcess.resize(cols, rows);
});

Audio recording workflow

// Request microphone access
const stream = await navigator.mediaDevices.getUserMedia({
  audio: {
    echoCancellation: true,
    noiseSuppression: true,
    autoGainControl: true
  }
});

// Record audio
const mediaRecorder = new MediaRecorder(stream, { mimeType: 'audio/webm' });
const chunks: Blob[] = [];

mediaRecorder.ondataavailable = (e) => chunks.push(e.data);
mediaRecorder.onstop = async () => {
  const blob = new Blob(chunks, { type: 'audio/webm' });
  const base64 = await blobToBase64(blob);
  // Send to transcription API
};

mediaRecorder.start();
// Later: mediaRecorder.stop();

WebRTC patterns (PeerJS)

import Peer from 'peerjs';

const peer = new Peer(userId, {
  host: 'peerjs-server.com',
  port: 443,
  secure: true
});

// Answer incoming calls
peer.on('call', (call) => {
  call.answer(localStream);
  call.on('stream', (remoteStream) => {
    audioElement.srcObject = remoteStream;
  });
});

// Make outgoing calls
const call = peer.call(remoteUserId, localStream);
call.on('stream', (remoteStream) => {
  audioElement.srcObject = remoteStream;
});

// Screen sharing via replaceTrack (no renegotiation)
const screenStream = await navigator.mediaDevices.getDisplayMedia({ video: true });
const videoTrack = screenStream.getVideoTracks()[0];
const sender = peerConnection.getSenders().find(s => s.track?.kind === 'video');
await sender.replaceTrack(videoTrack);

Build configuration (electron-builder.yml)

appId: com.yourname.appname
productName: AppName
directories:
  output: release

win:
  target:
    - target: nsis
      arch: [x64]
  icon: assets/icon.ico

nsis:
  oneClick: false
  allowToChangeInstallationDirectory: true
  installerIcon: assets/icon.ico
  uninstallerIcon: assets/icon.ico

mac:
  target:
    - target: dmg
      arch: [x64, arm64]
  icon: assets/icon.icns
  hardenedRuntime: true
  gatekeeperAssess: false
  entitlements: build/entitlements.mac.plist
  entitlementsInherit: build/entitlements.mac.plist
  notarize:
    teamId: YOUR_APPLE_TEAM_ID

linux:
  target:
    - target: AppImage
      arch: [x64]
  icon: assets/icon.png

publish:
  provider: github
  owner: username
  repo: repo-name

extraResources:
  - from: "node_modules/node-pty/build/Release/"
    to: "node-pty/"
    filter: ["*.node"]

macOS notarization is required for distribution outside the App Store; Gatekeeper blocks unnotarized apps on first launch. Set the env vars APPLE_ID, APPLE_APP_SPECIFIC_PASSWORD, and APPLE_TEAM_ID (or use an App Store Connect API key) before running npm run package. electron-builder ≥ 24.13 handles notarization natively via the mac.notarize field; older versions require the electron-notarize afterSign hook.

For Windows, code signing with an EV cert is increasingly necessary to avoid SmartScreen warnings. electron-builder reads CSC_LINK (PFX) and CSC_KEY_PASSWORD env vars.

Common pitfalls

Stale closures in callbacks:

// Problem: State is stale in async callbacks
const [state, setState] = useState(initialValue);
peer.on('call', () => {
  console.log(state); // Always shows initialValue
});

// Solution: Use refs for async callback access
const stateRef = useRef(state);
useEffect(() => { stateRef.current = state; }, [state]);
peer.on('call', () => {
  console.log(stateRef.current); // Current value
});

Context isolation security:

• Never expose ipcRenderer directly to renderer
• Always use contextBridge.exposeInMainWorld()
• Validate all IPC arguments in main process
• Use TypeScript interfaces for IPC contracts

BrowserView is deprecated — use WebContentsView:

BrowserView was deprecated in Electron 30 (April 2024) and the underlying implementation has been replaced. BrowserView still works as a compatibility shim over WebContentsView, but new code should target WebContentsView directly. The constructors take the same webPreferences shape, so the migration is mostly mechanical. The differences worth knowing:

• WebContentsView is added via win.contentView.addChildView(view) instead of win.addBrowserView(view)
• Sizing is via view.setBounds({x, y, width, height}) — no setAutoResize. You wire your own resize handlers if you want auto-resize.
• Z-order is the order of addChildView calls; removeChildView then re-addChildView to bring forward.

const { WebContentsView } = require('electron');

const view = new WebContentsView({
  webPreferences: { contextIsolation: true, sandbox: true }
});
view.webContents.loadURL('https://example.com');
mainWindow.contentView.addChildView(view);
view.setBounds({ x: 0, y: 80, width: 800, height: 520 });

See the official BrowserView → WebContentsView migration guide for edge cases (popups, devtools, focus management).

Cross-platform shell detection:

const shell = process.platform === 'win32'
  ? 'powershell.exe'
  : process.env.SHELL || '/bin/bash';

const shellArgs = process.platform === 'win32'
  ? ['-NoLogo']
  : [];

Development workflow

# Development (hot reload)
npm run electron:dev

# Production build
npm run electron:build

# Run built app locally
npx electron dist/

# Package for distribution
npm run package