[BUG] Unexpected "Effort" toggle UI button behavior

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?

Default effort in new session/conversation is "auto". Clicking on "Effort" UI toggles it between Low, Med, High and Max. But it never shows "auto" again.

What Should Happen?

Effort button should toggle "auto" like other options

Error Messages/Logs

Steps to Reproduce

1. Click " / " in conversation bar.
2. Click "Effort".
3. Cannot switch to "auto".

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.72

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_