Make browser windows use Chrome-like user agent

src/main/browser/BrowserPanelManager.test.ts

@@ -63,7 +63,10 @@ describe("BrowserPanelManager", () => {
 
   it("rejects the host window WebContents as a browser tab target", async () => {
     const { BrowserPanelManager } = await import("./BrowserPanelManager");
-    const manager = new BrowserPanelManager({ settingsPath: "settings.json" } as never);
+    const manager = new BrowserPanelManager(
+      { settingsPath: "settings.json" } as never,
+      "Mozilla/5.0 Chrome/141.0.0.0 Safari/537.36",
+    );
     const { tab, host } = createManagerWithTab();
 
     manager.bindHost(host as never);
@@ -76,7 +79,10 @@ describe("BrowserPanelManager", () => {
 
   it("attaches a non-host WebContents to the browser tab", async () => {
     const { BrowserPanelManager } = await import("./BrowserPanelManager");
-    const manager = new BrowserPanelManager({ settingsPath: "settings.json" } as never);
+    const manager = new BrowserPanelManager(
+      { settingsPath: "settings.json" } as never,
+      "Mozilla/5.0 Chrome/141.0.0.0 Safari/537.36",
+    );
     const { tab, host } = createManagerWithTab();
     const guestWebContents = { id: 99 };
     resolveWebContentsById.mockReturnValue(guestWebContents);

src/main/browser/BrowserPanelManager.ts

@@ -63,7 +63,10 @@ export class BrowserPanelManager {
     hasHostWindow: () => this.host !== null && !this.host.isDestroyed(),
   });
 
-  constructor(private readonly paths: LightcodePaths) {
+  constructor(
+    private readonly paths: LightcodePaths,
+    private readonly browserUserAgent: string,
+  ) {
     this.unsubscribePicker = onPickerCommit((commit) => this.onPickerCommit(commit));
   }
 
@@ -260,6 +263,7 @@ export class BrowserPanelManager {
     const tab = new BrowserTab({
       tabId,
       ...(payload.url ? { initialUrl: payload.url } : {}),
+      userAgent: this.browserUserAgent,
       onUpdate: (snap) => {
         this.emit({ type: "tab-updated", tab: { ...snap } });
         this.schedulePersist();

src/main/browser/BrowserTab.test.ts

@@ -0,0 +1,81 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const installSessionPermissions = vi.hoisted(() => vi.fn<() => void>());
+const installNavigationGuards = vi.hoisted(() =>
+  vi.fn<() => () => void>(() => vi.fn<() => void>()),
+);
+const dialogEnable = vi.hoisted(() => vi.fn<() => Promise<void>>().mockResolvedValue(undefined));
+
+vi.mock("electron", () => ({
+  webContents: { fromId: vi.fn<() => null>(() => null) },
+}));
+
+vi.mock("./cdp/cdpClient", () => ({
+  CdpClient: class CdpClient {
+    attach = vi.fn<() => Promise<void>>().mockResolvedValue(undefined);
+    detach = vi.fn<() => void>();
+  },
+}));
+
+vi.mock("./cdp/dialogController", () => ({
+  DialogController: class DialogController {
+    enable = dialogEnable;
+    dispose = vi.fn<() => void>();
+  },
+}));
+
+vi.mock("./cdp/networkCapture", () => ({
+  NetworkCapture: class NetworkCapture {
+    dispose = vi.fn<() => void>();
+  },
+}));
+
+vi.mock("./permissions", () => ({
+  installSessionPermissions,
+  installNavigationGuards,
+  isNavigationUrlAllowed: () => true,
+}));
+
+function createWebContents() {
+  return {
+    session: {},
+    setUserAgent: vi.fn<(userAgent: string) => void>(),
+    getURL: vi.fn<() => string>(() => "https://example.com/"),
+    getTitle: vi.fn<() => string>(() => "Example"),
+    isDestroyed: vi.fn<() => boolean>(() => false),
+    isLoadingMainFrame: vi.fn<() => boolean>(() => false),
+    on: vi.fn<() => void>(),
+    removeListener: vi.fn<() => void>(),
+    navigationHistory: {
+      canGoBack: vi.fn<() => boolean>(() => false),
+      canGoForward: vi.fn<() => boolean>(() => false),
+      clear: vi.fn<() => void>(),
+    },
+  };
+}
+
+describe("BrowserTab", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("applies the configured browser user agent to attached webContents", async () => {
+    const { BrowserTab } = await import("./BrowserTab");
+    const userAgent =
+      "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36";
+    const tab = new BrowserTab({
+      tabId: "tab-1",
+      userAgent,
+      onUpdate: vi.fn<() => void>(),
+      onAttention: vi.fn<() => void>(),
+      onPopup: vi.fn<() => void>(),
+    });
+    const webContents = createWebContents();
+
+    tab.attach(webContents as never);
+
+    expect(webContents.setUserAgent).toHaveBeenCalledWith(userAgent);
+    expect(installSessionPermissions).toHaveBeenCalledWith(webContents.session);
+    expect(installNavigationGuards).toHaveBeenCalled();
+  });
+});

src/main/browser/BrowserTab.ts

@@ -22,6 +22,7 @@ export interface BrowserTabSnapshot {
 export interface BrowserTabOptions {
   tabId: string;
   initialUrl?: string;
+  userAgent: string;
   onUpdate(snapshot: BrowserTabSnapshot): void;
   onAttention(tabId: string): void;
   onPopup(tabId: string, url: string): void;
@@ -101,6 +102,7 @@ export class BrowserTab {
       this.teardownListeners();
     }
     this._webContents = webContents;
+    webContents.setUserAgent(this.opts.userAgent);
     this._cdp = new CdpClient(webContents);
     installSessionPermissions(webContents.session);
     const removeNavGuards = installNavigationGuards(webContents, (popupUrl) => {

src/main/browser/userAgent.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+import { buildChromeLikeUserAgent } from "./userAgent";
+
+describe("buildChromeLikeUserAgent", () => {
+  it("removes Electron while preserving the current Chromium user agent", () => {
+    expect(
+      buildChromeLikeUserAgent(
+        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Electron/41.7.0 Safari/537.36",
+      ),
+    ).toBe(
+      "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36",
+    );
+  });
+
+  it("removes an app product token before Chrome", () => {
+    expect(
+      buildChromeLikeUserAgent(
+        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Lightcode/1.2.1 Chrome/141.0.0.0 Electron/41.7.0 Safari/537.36",
+      ),
+    ).toBe(
+      "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36",
+    );
+  });
+
+  it("matches the equivalent real Chrome user agent", () => {
+    const realChromeLinuxUserAgent =
+      "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36";
+
+    expect(
+      buildChromeLikeUserAgent(
+        "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Lightcode/1.2.1 Chrome/141.0.0.0 Electron/41.7.0 Safari/537.36",
+      ),
+    ).toBe(realChromeLinuxUserAgent);
+  });
+});

src/main/browser/userAgent.ts

@@ -0,0 +1,9 @@
+const ELECTRON_PRODUCT_RE = /\sElectron\/[^\s]+/g;
+const APP_PRODUCT_BEFORE_CHROME_RE =
+  /(\(KHTML, like Gecko\)\s+)(?:(?!Chrome\/)\S+\/\S+\s+)+(Chrome\/)/;
+
+export function buildChromeLikeUserAgent(defaultUserAgent: string): string {
+  const withoutElectron = defaultUserAgent.replace(ELECTRON_PRODUCT_RE, "");
+  const withoutAppProduct = withoutElectron.replace(APP_PRODUCT_BEFORE_CHROME_RE, "$1$2");
+  return withoutAppProduct.replace(/\s{2,}/g, " ").trim();
+}

src/main/main.ts

@@ -1,7 +1,7 @@
 import { watch } from "node:fs";
 import { homedir } from "node:os";
 import { join } from "node:path";
-import { app, BrowserWindow, Menu, nativeTheme } from "electron";
+import { app, BrowserWindow, Menu, nativeTheme, session as electronSession } from "electron";
 import { resolveThemeMode } from "@/shared/themeMode";
 import { closeDatabase, dbGetThreads, initDatabase } from "./db";
 import { cleanupOrphanedAttachments, prepareLightcodeDataRoot } from "./lightcodeData";
@@ -18,6 +18,7 @@ import {
   installPickerProtocolHandler,
   registerPickerProtocolScheme,
 } from "./browser";
+import { buildChromeLikeUserAgent } from "./browser/userAgent";
 import { SupervisorClient } from "./supervisor/SupervisorClient";
 import { createAutoUpdaterController } from "./updates/autoUpdater";
 import { createMainWindow } from "./window/createMainWindow";
@@ -41,6 +42,9 @@ if (process.env.LIGHTCODE_CDP_PORT) {
   app.commandLine.appendSwitch("remote-debugging-port", process.env.LIGHTCODE_CDP_PORT);
 }
 
+const chromeLikeUserAgent = buildChromeLikeUserAgent(app.userAgentFallback);
+app.userAgentFallback = chromeLikeUserAgent;
+
 if (baseDirOverride) {
   app.setPath("userData", join(baseDirOverride, "userData"));
 } else if (isDev) {
@@ -182,6 +186,7 @@ if (!hasSingleInstanceLock) {
 
     installLocalFileProtocolHandler();
     installPickerProtocolHandler();
+    electronSession.fromPartition("persist:lightcode-browser").setUserAgent(chromeLikeUserAgent);
 
     lightcodePaths = prepareLightcodeDataRoot(
       baseDirOverride ??
@@ -256,7 +261,7 @@ if (!hasSingleInstanceLock) {
       },
     );
 
-    browserPanelManager = new BrowserPanelManager(lightcodePaths);
+    browserPanelManager = new BrowserPanelManager(lightcodePaths, chromeLikeUserAgent);
     browserMcpIngress = new BrowserMcpIngress();
     browserMcpIngress.setManagerAccessor(() => browserPanelManager);
     primeBrowserAllowFlags();
@@ -290,6 +295,7 @@ if (!hasSingleInstanceLock) {
       posthogKey,
       sentryEnabled,
       windowChromeHeight: WINDOW_CHROME_HEIGHT,
+      browserUserAgent: chromeLikeUserAgent,
       appearance: resolveAppAppearance(),
       ...(process.env.VITE_DEV_SERVER_URL ? { devServerUrl: process.env.VITE_DEV_SERVER_URL } : {}),
       onClosed: () => {
@@ -378,6 +384,7 @@ if (!hasSingleInstanceLock) {
           posthogKey,
           sentryEnabled,
           windowChromeHeight: WINDOW_CHROME_HEIGHT,
+          browserUserAgent: chromeLikeUserAgent,
           appearance: resolveAppAppearance(),
           ...(process.env.VITE_DEV_SERVER_URL
             ? { devServerUrl: process.env.VITE_DEV_SERVER_URL }

src/main/window/createMainWindow.test.ts

@@ -0,0 +1,107 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const installSessionPermissions = vi.hoisted(() => vi.fn<() => void>());
+const dbGetState = vi.hoisted(() => vi.fn<() => string | null>(() => null));
+const dbSetState = vi.hoisted(() => vi.fn<() => void>());
+const setUserAgent = vi.hoisted(() => vi.fn<(userAgent: string) => void>());
+
+let browserWindowOptions: Record<string, unknown> | null = null;
+let webContentsHandlers: Record<string, (...args: never[]) => void> = {};
+
+vi.mock("electron", () => ({
+  BrowserWindow: class BrowserWindow {
+    webContents = {
+      session: {},
+      send: vi.fn<() => void>(),
+      openDevTools: vi.fn<() => void>(),
+      setWindowOpenHandler: vi.fn<() => void>(),
+      setUserAgent,
+      on: vi.fn<(event: string, handler: (...args: never[]) => void) => void>((event, handler) => {
+        webContentsHandlers[event] = handler;
+      }),
+    };
+
+    constructor(options: Record<string, unknown>) {
+      browserWindowOptions = options;
+    }
+
+    once = vi.fn<() => void>();
+    on = vi.fn<() => void>();
+    isMaximized = vi.fn<() => boolean>(() => false);
+    isDestroyed = vi.fn<() => boolean>(() => false);
+    getNormalBounds = vi.fn<() => { x: number; y: number; width: number; height: number }>(() => ({
+      x: 0,
+      y: 0,
+      width: 1460,
+      height: 920,
+    }));
+    loadURL = vi.fn<() => Promise<void>>().mockResolvedValue(undefined);
+    loadFile = vi.fn<() => Promise<void>>().mockResolvedValue(undefined);
+    show = vi.fn<() => void>();
+    maximize = vi.fn<() => void>();
+  },
+  screen: {
+    getDisplayMatching: vi.fn<
+      () => { workArea: { x: number; y: number; width: number; height: number } }
+    >(() => ({
+      workArea: { x: 0, y: 0, width: 1920, height: 1080 },
+    })),
+  },
+}));
+
+vi.mock("../db", () => ({
+  dbGetState,
+  dbSetState,
+}));
+
+vi.mock("../browser/permissions", () => ({
+  installSessionPermissions,
+}));
+
+describe("createMainWindow", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    browserWindowOptions = null;
+    webContentsHandlers = {};
+  });
+
+  it("applies the browser user agent to the window and sanitizes attached webviews", async () => {
+    const { createMainWindow } = await import("./createMainWindow");
+    const userAgent =
+      "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36";
+
+    createMainWindow({
+      title: "Lightcode",
+      isDev: false,
+      channel: "stable",
+      preloadPath: "/tmp/preload.cjs",
+      rendererHtmlPath: "/tmp/index.html",
+      appVersion: "1.2.1",
+      posthogEnableDev: false,
+      posthogEnabled: false,
+      posthogHost: "",
+      posthogKey: "",
+      sentryEnabled: false,
+      windowChromeHeight: 32,
+      browserUserAgent: userAgent,
+      appearance: "dark",
+      onClosed: vi.fn<() => void>(),
+    });
+
+    expect(setUserAgent).toHaveBeenCalledWith(userAgent);
+    expect((browserWindowOptions?.webPreferences as { webviewTag?: boolean })?.webviewTag).toBe(
+      true,
+    );
+
+    const webPreferences = {
+      preload: "/tmp/unsafe.cjs",
+      nodeIntegration: true,
+      contextIsolation: false,
+    };
+    webContentsHandlers["will-attach-webview"]?.({} as never, webPreferences as never);
+
+    expect(webPreferences.preload).toBeUndefined();
+    expect(webPreferences.nodeIntegration).toBe(false);
+    expect(webPreferences.contextIsolation).toBe(true);
+  });
+});

src/main/window/createMainWindow.ts

@@ -60,6 +60,7 @@ export interface CreateMainWindowOptions {
   posthogKey: string;
   sentryEnabled: boolean;
   windowChromeHeight: number;
+  browserUserAgent: string;
   /** Saved appearance, so the native window opens matching the theme. */
   appearance: "light" | "dark";
   onClosed(): void;
@@ -118,6 +119,7 @@ export function createMainWindow(options: CreateMainWindowOptions): BrowserWindo
     },
   });
   installSessionPermissions(window.webContents.session);
+  window.webContents.setUserAgent(options.browserUserAgent);
 
   // Lock the privileged top frame to the app's own origin. The main renderer
   // holds the full `lightcode` preload bridge (DB, file pickers, openExternal,