[BUG] Login redirects to "Create account" onboarding for existing account with active Pro subscription

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?

I cannot log in to my existing Claude account from my MacBook. Every login attempt redirects me to the onboarding page showing "Let's create your account" with "Email verified as shia.mcshia@gmail.com" at the bottom — instead of logging me into my existing account.

Account details:

• Active Pro subscription
• Account works normally on my iPhone (existing logged-in session) — chats, projects, and Pro plan all intact

Steps to reproduce:

1. Go to claude.ai on MacBook (or open Claude Desktop app)
2. Log in via "Continue with Google" → redirected to "Let's create your account"
3. Log in via "Continue with email" → receive magic link / verification code → enter it on same device → again redirected to "Let's create your account"

Already tried:

• Both login methods (Google OAuth and email magic link/code) — same result
• Cleared cache and cookies in all browsers, tried multiple browsers
• Claude Desktop app — same behavior

Additional context:

• Started immediately after connecting the Google Drive connector, after which I was logged out on the Mac
• I have NOT clicked "Create account" to avoid creating a duplicate
• Repeated login attempts triggered "You have exceeded your authentication rate limit" — side effect, not the core issue
• Emailed support@anthropic.com, no response yet
• Looks identical to issue #36797

This is blocking my daily workflow on desktop.

What Should Happen?

Logging in with my existing email (via Google OAuth or email magic link) should take me to my existing account with my chats and Pro subscription — not to the "Create account" onboarding screen.

Error Messages/Logs

"You have exceeded your authentication rate limit. Please try again later."
(appears after repeated login attempts caused by the core bug)

Steps to Reproduce

1. On MacBook, go to claude.ai (or open Claude Desktop app)
2. Click "Continue with Google" and authenticate with shia.mcshia@gmail.com — Google auth completes successfully
3. Instead of logging into my existing account, I'm dropped on the "Let's create your account" onboarding screen with "Email verified as shia.mcshia@gmail.com" shown at the bottom
4. Same result with "Continue with email" — magic link / verification code entered on the same device leads to the same onboarding screen

Related issues with the same failure mode: #67097, #51002, #57164, #36797

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A — issue affects claude.ai web and Claude Desktop login, not Claude Code

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_