[BUG] Simultaneous accounts session collision in Claude Code CLI

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?

A recent update to Claude Code has completely broken parallel workflows when using multiple accounts. Previously, it was possible to run simultaneous development tasks using two separate accounts in different terminal windows.

Now, the CLI seems to share a single global state or authentication token across all instances. When I log into a second account in Terminal B, Terminal A silently switches to this second account's identity instead of staying on the first account. This completely corrupts the ongoing context of Terminal A, mixes up account permissions, prevents me from completing the initial task, and messes up my message limits.

What Should Happen?

Different terminal windows/sessions should maintain isolated authentication states. Activating or logging into an account in one terminal should not affect, alter, or hijack the identity/account currently in use by an active Claude Code instance in another terminal.

Error Messages/Logs

Steps to Reproduce

Open Terminal A, authenticate with Account 1, and initiate a long-running development task.

Open Terminal B and authenticate with Account 2 to start a parallel task.

Return to Terminal A: the active session has now silently switched to Account 2's context, disrupting the initial workflow and causing data/context loss.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.80 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_