[BUG] VS Code Extension: Chat state does not sync between dedicated view and native VS Code chat panel

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?

VS Code Extension session split-brain / lack of synchronization between the dedicated Claude Code view and the native VS Code Chat sidebar toggle.

What Should Happen?

Both entry points within the same VS Code workspace should bind to the exact same active local session ID so that context is preserved seamlessly regardless of UI routing.

Error Messages/Logs

Steps to Reproduce

1. Open a workspace project in VS Code.
2. Open the dedicated Claude Code extension view and start an active chat session.
3. Open VS Code's native built-in Chat panel (Copilot/Chat sidebar).
4. Slide right / switch the active agent/chat provider to Claude Code within that panel.
5. Notice that it opens a completely independent instance that does not sync or reflect the conversation state, active context, or session index of the first view.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.144

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_