feat(browser): give the embedded browser a faithful Chrome user-agent

packages/desktop-electron/src/main/browser/controller.ts

@@ -1,6 +1,7 @@
-import { BrowserWindow, WebContentsView, shell } from "electron"
+import { BrowserWindow, WebContentsView, session, shell } from "electron"
 import type { BrowserState, BrowserViewLayout } from "@opencode-ai/app/desktop-api"
-import { browserViewWebPreferences } from "./options"
+import { BROWSER_PARTITION, browserViewWebPreferences } from "./options"
+import { configurePartitionUserAgent } from "./user-agent"
 import {
   clearDataReloadAction,
   computeViewBounds,
@@ -23,6 +24,19 @@ export const BROWSER_DISPLAY_TAKEN_CHANNEL = "browser:display-taken"
  */
 const DEFAULT_VIEW_BOUNDS = { x: 0, y: 0, width: 1280, height: 720 }
 
+let partitionUserAgentConfigured = false
+/**
+ * Configure the browser partition's UA before the first view/request, exactly
+ * once: present the partition as the faithful Chrome it is (rewrite + rationale
+ * in user-agent.ts and the PR). Scoped to the browser partition; the app
+ * renderer keeps its own UA.
+ */
+function ensureBrowserPartitionUserAgent() {
+  if (partitionUserAgentConfigured) return
+  partitionUserAgentConfigured = true
+  configurePartitionUserAgent(session.fromPartition(BROWSER_PARTITION), process.versions.chrome ?? "")
+}
+
 /**
  * Owns one embedded browser per CONVERSATION (root session) — or a per-window
  * draft on Home. The view lives unattached to any window; a window is just a
@@ -41,6 +55,9 @@ export class BrowserViewController {
   private throttlingBefore: boolean | null = null
 
   constructor(private target: string) {
+    // Configure the partition UA before the view exists, so its very first
+    // request already carries the faithful Chrome UA.
+    ensureBrowserPartitionUserAgent()
     this.view = new WebContentsView({ webPreferences: browserViewWebPreferences() })
     this.view.setVisible(false)
     this.view.setBounds(DEFAULT_VIEW_BOUNDS)

packages/desktop-electron/src/main/browser/user-agent.test.ts

@@ -0,0 +1,80 @@
+import { describe, expect, test } from "bun:test"
+import { chromeMajorVersion, configurePartitionUserAgent, toChromeUserAgent } from "./user-agent"
+
+// Real Electron 40.8.0 UA shapes (Chromium 144). The app product token is
+// "PawWork Dev/<ver>" by default and "opencode/<ver>" after index.ts's rewrite —
+// both must be stripped.
+const MAC_ELECTRON =
+  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) PawWork Dev/2026.6.7 Chrome/144.0.7559.236 Electron/40.8.0 Safari/537.36"
+const MAC_ELECTRON_REWRITTEN =
+  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) opencode/2026.6.7 Chrome/144.0.7559.236 Electron/40.8.0 Safari/537.36"
+const WIN_ELECTRON =
+  "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) opencode/2026.6.7 Chrome/144.0.7559.236 Electron/40.8.0 Safari/537.36"
+
+const MAC_CHROME =
+  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"
+const WIN_CHROME =
+  "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"
+
+describe("toChromeUserAgent", () => {
+  test("strips Electron + spaced app token and pins the reduced Chrome version (macOS)", () => {
+    expect(toChromeUserAgent(MAC_ELECTRON, "144.0.7559.236")).toBe(MAC_CHROME)
+  })
+
+  test("handles the index.ts-rewritten opencode token", () => {
+    expect(toChromeUserAgent(MAC_ELECTRON_REWRITTEN, "144.0.7559.236")).toBe(MAC_CHROME)
+  })
+
+  test("preserves the Windows platform token", () => {
+    expect(toChromeUserAgent(WIN_ELECTRON, "144.0.7559.236")).toBe(WIN_CHROME)
+  })
+
+  test("leaves no Electron / opencode / PawWork token or double space behind", () => {
+    const ua = toChromeUserAgent(MAC_ELECTRON, "144.0.7559.236")
+    expect(ua).not.toContain("Electron")
+    expect(ua).not.toContain("opencode")
+    expect(ua).not.toContain("PawWork")
+    expect(ua).not.toMatch(/ {2,}/)
+  })
+
+  test("is idempotent on an already-clean Chrome UA", () => {
+    expect(toChromeUserAgent(MAC_CHROME, "144.0.7559.236")).toBe(MAC_CHROME)
+  })
+
+  test("accepts a major-only version", () => {
+    expect(toChromeUserAgent(MAC_ELECTRON, "144")).toContain("Chrome/144.0.0.0")
+  })
+
+  test("leaves the Chrome token alone when the version is unparseable", () => {
+    expect(toChromeUserAgent(MAC_ELECTRON, "unknown")).toContain("Chrome/144.0.7559.236")
+  })
+})
+
+describe("configurePartitionUserAgent", () => {
+  test("sets the cleaned Chrome UA on the partition session (no Electron/app token)", () => {
+    let applied: string | undefined
+    const sess = {
+      getUserAgent: () => MAC_ELECTRON,
+      setUserAgent: (ua: string) => {
+        applied = ua
+      },
+    }
+    configurePartitionUserAgent(sess, "144.0.7559.236")
+    // The seam must hand the partition the cleaned UA — this is what is in place
+    // before the controller creates the first view.
+    expect(applied).toBe(MAC_CHROME)
+    expect(applied).not.toContain("Electron")
+  })
+})
+
+describe("chromeMajorVersion", () => {
+  test("extracts the major", () => {
+    expect(chromeMajorVersion("144.0.7559.236")).toBe("144")
+    expect(chromeMajorVersion("144")).toBe("144")
+  })
+
+  test("returns null for a non-numeric version", () => {
+    expect(chromeMajorVersion("unknown")).toBeNull()
+    expect(chromeMajorVersion("")).toBeNull()
+  })
+})

packages/desktop-electron/src/main/browser/user-agent.ts

@@ -0,0 +1,47 @@
+/**
+ * The embedded browser's user-agent. The view is real Chromium, so the faithful
+ * identity is a plain Chrome UA: strip Electron's `Electron/` and app product
+ * tokens (a real Chrome UA has nothing where Electron injects them) and pin the
+ * Chrome token to the `<major>.0.0.0` form, deriving the major from the running
+ * engine (`process.versions.chrome`). Pure (no electron import) so it stays
+ * unit-tested; the partition wiring is configurePartitionUserAgent, called from
+ * controller.ts. Full rationale in the PR description.
+ */
+
+/** Major version of a Chromium version string, or null if it has no leading number. */
+export function chromeMajorVersion(chromeVersion: string): string | null {
+  const major = chromeVersion.trim().split(".")[0]
+  return /^\d+$/.test(major) ? major : null
+}
+
+/**
+ * Rewrite an Electron user-agent into the faithful Chrome UA the embedded view
+ * should present. Idempotent: an already-clean Chrome UA passes through unchanged.
+ */
+export function toChromeUserAgent(rawUserAgent: string, chromeVersion: string): string {
+  const major = chromeMajorVersion(chromeVersion)
+  let ua = rawUserAgent
+    // Drop the Electron product token — the loudest non-Chrome tell.
+    .replace(/ Electron\/\S+/g, "")
+    // Drop the app/product token Electron injects between the engine comment and
+    // the Chrome token (a real Chrome UA has nothing there).
+    .replace(/(\(KHTML, like Gecko\) ).*?(Chrome\/)/, "$1$2")
+  // Pin the Chrome token to the reduced major.0.0.0 form real Chrome reports.
+  if (major) ua = ua.replace(/Chrome\/\S+/, `Chrome/${major}.0.0.0`)
+  return ua.replace(/ {2,}/g, " ").trim()
+}
+
+/** Minimal Session surface the partition wiring needs — narrowed so the rewrite is testable without an Electron runtime. */
+export interface UserAgentSession {
+  getUserAgent(): string
+  setUserAgent(userAgent: string): void
+}
+
+/**
+ * Apply the faithful Chrome UA to the embedded browser's partition session. The
+ * seam controller.ts calls (on the real partition session) before the first view
+ * is created, so the cleaned UA is in place before any embedded load.
+ */
+export function configurePartitionUserAgent(sess: UserAgentSession, chromeVersion: string): void {
+  sess.setUserAgent(toChromeUserAgent(sess.getUserAgent(), chromeVersion))
+}