[BUG] Ultrathink not setting effort to max, sets it to high instead.

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?

Typing the keyword to ultrathink causes the effort to be set to high, instead of max. Max is the highest thinking effort you can have, so one would think ultrathink would set that.

What Should Happen?

Ultrathink should always set the thinking effort to the highest possible effort your plan allows. Thus the ultra part.

Error Messages/Logs

Steps to Reproduce

<img width="847" height="100" alt="Image" src="https://github.com/user-attachments/assets/a0570969-084b-4183-a91f-a81f480660d3" />

Type ultrathink, and see that it sets its effort to high instead of max.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.75

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_