[BUG] Claude Code Extension does not support Vertex

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 using claude-sonnet-4-5@20250929 in vertex and claude code desktop version 2.0.1, upon launching vscode and updating to the latest extension in the marketplace we are prompted with an anthropic.ai login prompt, without any new extension settings to configure vertex:

<img width="720" height="641" alt="Image" src="https://github.com/user-attachments/assets/7dff7592-b8ac-42a4-85ea-1acfa700e5da" />

What Should Happen?

I should be able to use the claude code plugin without an anthropic.ai account.

Error Messages/Logs

Steps to Reproduce

Simply let claude code automatically update itself to v2.0.1 with vertex configured as the model provider, then open vscode and then claude, finally restart the claude extension once it has updated and it will prompt for login credentials.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.0.127

Claude Code Version

2.0.1

Platform

Google Vertex AI

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

I have had to roll back to continue working with vscode:

npm install -g @anthropic-ai/claude-code@1.0.127
# Add this to your RC file, e.g. ~/.bashrc or ~/.zshrc
export DISABLE_AUTOUPDATER=1

Then use _Install specific version_ option in the vscode interface to roll back the plug in to 1.0.127 too:

<img width="530" height="250" alt="Image" src="https://github.com/user-attachments/assets/e1a36eed-7d8b-478c-b3b0-3d6c2d176a4b" />