[BUG] Conversations become corrupted and history lost when opening a new session while another is active

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?

When a new session is opened while another session is already active in the Claude desktop app, the conversations from both sessions become mixed together and incoherent. Additionally, the prior conversation history from both sessions disappears.

What Should Happen?

Each session should be completely independent. Messages in one session should never appear in or affect another session, and all prior conversation history should remain intact.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude desktop app (Claude Code v2.1.49)
2. Start a conversation (Session A) and exchange several messages
3. Without closing Session A, open a new session (Session B) from the app UI
4. Begin a new conversation in Session B
5. Observe that messages from both sessions become mixed, and history from both sessions disappears

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.49

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_