[BUG] Magic link fails with "unable to verify" unless opened in incognito window

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?

Clicking the magic link in a regular browser window (with an active session) fails with "We were unable to verify you with this link." Opening the exact same link in an incognito tab works immediately.

What Should Happen?

Magic link works in a normal browser window

Error Messages/Logs

Steps to Reproduce

Steps to reproduce:

• Run claude and choose to log in via browser
• Click the magic link from the email in a normal browser window
• See "We were unable to verify you with this link"
• Open the same link in an incognito window → succeeds

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.183 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_