[BUG] fast mode doesnt turn on in vscode plugin

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 you select the Fast Mode option in VS Code Plug-In,

1. It opens a side terminal window which seems to launch another instance of Claude Code in the terminal with the fast mode
2. But the actual VS Code view does not get the fast mode

What Should Happen?

Fast mode should work in the VSCode view.

Error Messages/Logs

Steps to Reproduce

Open the VS Code Claude Code plugin view and then try to enable fast mode.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.37

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

<img width="2212" height="1264" alt="Image" src="https://github.com/user-attachments/assets/e6f743e9-53f3-4790-9657-41433cbc1e5a" />