[BUG] Windows Desktop: Google sign-in fails in the Code tab's Browser pane (Something went wrong), though the docs say Google OAuth works there

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Google sign-in can't be completed in the Claude Desktop Code tab's built-in Browser pane on Windows.

Google's sign-in page loads in the pane. As soon as sign-in starts, Google shows a dialog: "Something went wrong. Sorry, something went wrong there. Try again." with a Restart button. It happens with a passkey and with typing an email and clicking Next, so it fails before any password or second factor.

The app does not crash or close, so this is not the MSIX GPU crash in #85145 / #81341.

What Should Happen?

The Desktop docs (https://code.claude.com/docs/en/desktop, "Browse external sites") say:

You can sign in to sites in the pane, including popup sign-in flows such as Google OAuth.

Google sign-in should complete in the pane. Failing that, the app should hand Google sign-in to the system browser, which is what Google's OAuth policy asks desktop apps to do.

Error Messages/Logs

Google dialog, shown on "Sign in with Google: to continue to OpenAI":
Something went wrong
Sorry, something went wrong there. Try again.
[Restart]

Steps to Reproduce

1. On Windows 11, open Claude Desktop (MSIX build) and start a Code tab session.
2. Click a link that opens a "Sign in with Google" flow. My case was OpenAI's device sign-in page, https://auth.openai.com/codex/device, opened from a link printed in the Terminal panel; the link opened in the Browser pane.
3. Choose to continue with Google.
4. Sign in with a passkey, or type the account's email and click Next.
5. Google shows the "Something went wrong" dialog, and sign-in can't continue. Restart gives the same result.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop 2.26454.2 (MSIX), Code tab. claude --version on the same PC: 2.1.285 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

• OS: Windows 11 Home 10.0.26300.
• The pane's user agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Claude/2.26454.2 Chrome/152.0.7977.130 Safari/537.36 MSIX
• Its navigator.userAgentData.brands are only "Chromium" 152 and "Not?A_Brand" 24, and navigator.webdriver is false.
• Passkeys are not the cause. In the pane, PublicKeyCredential.getClientCapabilities() reports passkeyPlatformAuthenticator, userVerifyingPlatformAuthenticator, hybridTransport and conditionalGet all true.
• For comparison: on the same PC and the same Google account, Google sign-in completes in the ChatGPT/Codex desktop app's built-in browser, which is also embedded Chromium (Electron).
• Related, not duplicates:
• #85145 and #81341: the app crashing during Google sign-in in the pane.
• #76582: OAuth popups from cross-site iframes.
• #97168: "Open links in built-in browser" ignored for some links.
• Suggestions:
• Send accounts.google.com and "Sign in with Google" flows to the system browser automatically. Or make the pane pass Google's checks as documented.
• Make links from the Terminal panel follow the "Open links in built-in browser" choice. Better still, add a permanent "always open links in my default browser" setting.
• Until it's fixed, correct the docs so they don't promise that Google OAuth works in the pane.
• Screenshots of the dialog are available on request; I've left them out because they show the account's email.