[BUG] Cursor IDE integration fails: option disappears after brief availability

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?

The Claude Code extension for Cursor fails to maintain a connection.

1. Upon launching claude in the Cursor terminal, a red "IDE disconnected" message appears briefly.
2. If /ide is run immediately: "Cursor" appears in the list. Selecting it results in no connection established (state remains disconnected).
3. If /ide is run after a few seconds delay (or for a second time): The "Cursor" option disappears entirely ("No available IDEs detected").

What Should Happen?

The connection to Cursor IDE should be established and maintained stably, the "Cursor" option should remain available in /ide menu.

Error Messages/Logs

Debug logs show a repeated reconnection loop:

[DEBUG] MCP server "ide": Successfully connected to ws-ide server in 48ms
[DEBUG] MCP server "ide": WS-IDE connection closed after 0s (cleanly)
[ERROR] MCP server "ide" Failed to fetch tools: MCP error -32000: Connection closed
... (repeats indefinitely)

System state verified:
- .claude/ide/*.lock file exists and matches Cursor process
- netstat confirms ESTABLISHED TCP connection to localhost port from lockfile

Steps to Reproduce

1. Environment: Windows 11, Cursor 2.4.21 (x64), Claude Code 2.1.19.
2. Open a terminal in Cursor (PowerShell or Git Bash).
3. Run claude.
4. Observe the brief "IDE disconnected" flash.
5. Run /ide immediately -> try to select "Cursor" -> connection fails.
6. Run /ide again -> "Cursor" option is gone.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.19 (Claude Code)

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_