[BUG] OAuth login flow loops indefinitely at authorization grant screen, never completes

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?

Claude Code signed me out unexpectedly. When attempting to re-authenticate via the standard browser OAuth flow, the flow enters an infinite loop and never completes. (I attempted with an incognito no cookies enabled browser session as well and the same thing happpened)

What Should Happen?

After authorizing and completing sign-in (including email verification), the flow should complete and hand control back to the CLI with a valid session.

Error Messages/Logs

None, it was a infinite loop.

Steps to Reproduce

1. Claude Code prompts for sign-in after being signed out
2. Browser opens to the Claude authorization grant screen
3. Click "Authorize"
4. Redirected to a sign-in screen instead of completing auth asking us to sign back in...
5. Sign in with email, receive a verification code by email, enter the code
6. Redirected back to the authorization grant screen (step 3) and so the infinite loop continues...
7. Repeat from step 3, loop never resolves :[

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.223

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_