[BUG] Claude Code VS Code extension crashes extension host when GitHub Copilot Chat is enabled

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 GitHub Copilot Chat is enabled, running even a small task in the Claude Code VS Code extension causes the VS Code extension host to become repeatedly unresponsive and eventually crash.

Observed process signals include SIGBUS, SIGILL, and SIGTRAP.

The issue reproduces on both Wayland and X11 and occurs with plenty of available RAM.

Disabling GitHub Copilot Chat completely stops the crashes. With Copilot Chat disabled, three Claude Code tasks run concurrently without hangs or crashes.

What Should Happen?

Claude Code and GitHub Copilot Chat should be able to coexist without hanging or crashing the VS Code extension host.

Error Messages/Logs

Extension host (LocalProcess pid: 5177) is unresponsive

chatParticipant must be declared in package.json: claude-code

No bundle location found for extension GitHub.copilot-chat

Failed to create database. Falling back to in-memory db:
Error: unable to open database file

Failed to save config with lock:
Error: Lock file is already being held

claude-vscode notification channel error:
Received a response for an unknown message ID

Linux process crashes observed:
- SIGBUS
- SIGILL
- SIGTRAP

Steps to Reproduce

1. Install and enable both:

• Anthropic Claude Code VS Code extension
• GitHub Copilot Chat

1. Start VS Code normally.

1. Open a project and run a small Claude Code task.

1. The extension host becomes repeatedly unresponsive and VS Code eventually crashes.

1. Fully stop VS Code and its Claude child processes.

1. Start VS Code with:

code --disable-extension GitHub.copilot-chat

1. Run three Claude Code tasks concurrently.

Result:

• Three concurrent Claude Code tasks remain stable.
• VS Code + Claude use approximately 6 GiB RSS in total.
• No extension-host hangs or crashes occur.

Re-enabling GitHub Copilot Chat restores the failing configuration.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.220 (Claude Code)

Platform

Other

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

Environment:

• Claude Code VS Code extension 2.1.220
• VS Code 1.130.0
• VS Code commit: 1b6a188127eeaf9194f945eb6eb89a657e93c54c
• Electron 42.6.0
• Kubuntu / Ubuntu 26.04 LTS
• Kernel 7.0.0-28-generic
• AMD Ryzen 7 PRO 4750U
• 32 GB RAM

Session storage at the time of reproduction:

• ~/.claude total size: 2.8 GiB
• ~/.claude/projects size: 2.2 GiB
• Claude project directories: 19
• ~/.copilot/session-state does not exist
• I have never knowingly used Copilot CLI sessions
• No Copilot session data was manually deleted during troubleshooting

The crashes occurred with approximately 16–19 GiB of RAM still available, so this was not a normal system OOM condition.

The issue was also reported on the VS Code side:
https://github.com/microsoft/vscode/issues/318595

I can provide the relevant VS Code logs and system journal excerpts from the reproduced crashes if needed. The original core dump files were removed during troubleshooting.