Electron Internals Skill

Process Architecture

Main Process

• Node.js environment with full OS access
• Manages BrowserWindow instances
• Handles app lifecycle (startup, quit, focus)
• Single-instance lock prevents multiple app copies

Preload Script

• Runs in renderer context BUT with Node.js access
• Bridge between main and renderer via contextBridge.exposeInMainWorld()
• Must be minimal — every import adds to startup time

Renderer Process

• Standard web environment (Chromium)
• No direct Node.js access (security)
• Communicates with main via exposed bridges

contextBridge Pattern

The preload script (packages/suite-desktop/src/preload/index.ts) exposes four separate bridges to the renderer — not a single desktopBridge:

// packages/suite-desktop/src/preload/index.ts
contextBridge.exposeInMainWorld("ctxbridge", ctx);            // main app/context API (Desktop)
contextBridge.exposeInMainWorld("menuBridge", menuBridge);    // native menu event subscription
contextBridge.exposeInMainWorld("storageBridge", storageBridge); // local file storage CRUD
contextBridge.exposeInMainWorld("desktopBridge", desktopBridge); // desktop-specific operations

// renderer — consuming a bridge
const desktopBridge = (global as { desktopBridge: Desktop }).desktopBridge;
const storageBridge = (global as { storageBridge: Storage }).storageBridge;
await storageBridge.list("layouts");

Security Rules

• Never expose ipcRenderer directly
• Class instances do not survive the bridge — only plain functions/objects are exposed (prototypes are lost), which is why storage methods are .bind()-attached in preload
• Each bridge method is a typed, scoped function
• No eval(), no remote module usage
• CSP headers prevent inline scripts

BrowserWindow Management (StudioWindow)

class StudioWindow {
  #window: BrowserWindow;

  constructor() {
    this.#window = new BrowserWindow({
      webPreferences: {
        preload: path.join(__dirname, "preload.js"),
        contextIsolation: true,
        nodeIntegration: false,
        sandbox: false,  // needed for preload Node access
      },
    });
  }
}

Window Lifecycle

1. App starts → StudioWindow created
2. Preload runs → bridges exposed
3. Renderer loads → React app mounts
4. Deep links → forwarded to renderer via bridge
5. Close → cleanup, save state, quit

Native Menu Integration

// Main process builds menu template
const template: MenuItemConstructorOptions[] = [
  { label: "File", submenu: [
    { label: "Open File...", click: () => sendToRenderer("open-file") },
  ]},
];

// Renderer receives via menuBridge
menuBridge.on("menu-event", (event: ForwardedMenuEvent) => {
  switch (event) {
    case "open-file": // show file picker
  }
});

File System Access

Layout / Storage Loading

• Local storage entries are read/written via storageBridge (list, all, get, put, delete)
• The renderer's DesktopLayoutLoader (packages/suite-desktop/src/renderer/services/DesktopLayoutLoader.ts) wraps these calls

Extension Loading

• .foxe files in extension directory
• DesktopExtensionLoader (filesystem type) reads directly via bridge
• Supports install/uninstall by copying/deleting files

Deep Links

lichtblick://open?url=https://example.com/recording.mcap

• OS protocol registration uses the legacy foxglove scheme: app.setAsDefaultProtocolClient("foxglove") (packages/suite-desktop/src/main/index.ts)
• Handled deep-link URLs use the lichtblick:// scheme — the open-url handler and second-instance argv filter both match arg.startsWith("lichtblick://")
• Recognized links include lichtblick://open?... and lichtblick://signin-complete
• Second-instance handler re-emits open-url and forwards to the existing window
• Parsed in renderer to open the appropriate data source

⚠️ The protocol-client registration argument ("foxglove") differs from the URL scheme the app actually parses (lichtblick://). Do not assume they are the same string.

Build & Packaging

• desktop/electronBuilderConfig.js — electron-builder configuration
• desktop/webpack.config.ts — webpack for main/preload/renderer
• Output: .dmg (macOS), .exe/.msi (Windows), .deb/.AppImage (Linux)
• Auto-update via electron-updater (if configured)

Performance Tips

1. Preload weight: Keep preload imports minimal — delays window show
2. IPC serialization: Large objects are serialized — prefer transferring file paths over file contents
3. Window show: Use show: false + ready-to-show event for smooth startup
4. Background throttling: Electron throttles background tabs by default — respect this for power usage