[BUG] Claude Code extension for VS Code / Cursor fails to load on upstart

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 I upstart my project repo on Cursor, if there are Claude Code extensions tabs open (not the terminal CLI), Claude Code won't load the sidebar nor the tabs themselves. The tabs keep loading indefinetely, and the extension tab on the sidebar does not ever appear. Even when trying to use "> Claude" to launch, it breaks.

The ways I've found to troubleshoot this so far are:

• find Claude Code extension, disable, restart, enable (does not always work)
• close all Claude Code extensions tabs (has worked everytime so far)

What Should Happen?

Claude Code sidebar and open tabs from previoius sessions should load correctly when I upstart my project repo on Cursor, so I can resume working from where I left off.

Error Messages/Logs

Steps to Reproduce

Use Claude Code extension on Cursor for a few sessions, then close the application leaving the Claude Code extension tabs open.

Then, try to relaunch it and see if tabs load.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Code 2.1.144

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Cursor

Additional Information

_No response_