### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

I tried to proxy my Github Copilot model into Claude Code via litellm, it worked well but somehow broken today.

I've tested like `curl -X POST http://localhost:4444/chat/completions \ -H "Content-Type: application/json" \ -H "Authorization: Bearer $$(grep LITELLM_MASTER_KEY .env | cut -d'=' -f2 | tr -d '\"')" \ -d '{"model": "claude-sonnet-4", "messages": [{"role": "user", "content": "Hello"}]}'` and it returned response in 200, also my VSCode Github Copilot can respond and work as normal, so I think something might be wrong between litellm or claude code.

My configuration:

```copilot-config.yaml litellm_settings: drop_params: true set_verbose: true

model_list: - model_name: claude-3-5-sonnet-20241022 litellm_params: model: github_copilot/claude-sonnet-4.6 extra_headers: &copilot_headers Editor-Version: "vscode/1.85.1" Copilot-Integration-Id: "vscode-chat" - model_name: claude-sonnet-4 litellm_params: model: github_copilot/claude-sonnet-4 extra_headers: *copilot_headers

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