[BUG] Security: Cross-account session data exposure between Personal Pro and Teams accounts

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?

Platform: [Your OS - Windows/Mac/Linux]
Claude Code Version: [Run claude --version to find this]
Account Types Affected: Personal Pro → Teams

Bug Description:
When enabling Claude Code with a Teams account on a system that previously had a Personal Pro account, the Teams instance can access, view, and continue previous coding sessions from the Personal Pro account. This creates a data leakage risk between accounts that should be completely isolated.

Steps to Reproduce:

1. Use Claude Code with Personal Pro account
2. Add/enable Claude Code Teams account on same system
3. Teams account can access Personal Pro session history

*

What Should Happen?

Expected Behavior:*
Accounts should be completely isolated with no cross-account data access.

Security Impact:
Personal development work, proprietary code, and sensitive prompts can be exposed across organizational boundaries.

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce:

1. Use Claude Code with Personal Pro account
2. Add/enable Claude Code Teams account on same system
3. Teams account can access Personal Pro session history

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Sonnet 4.5 (model ID: claude-sonnet-4-5-20250929

Platform

Other

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_