[BUG] ultrathink[7m [27m

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 writing 'ultrathink' in claude code terminal and hitting the last letter 'k' the following shows: ultrathink[7m [27m
It goes away if ending with period or space.

What Should Happen?

should be 'ultrathink' without '[7m [27m'

Error Messages/Logs

Steps to Reproduce

1. write 'ultrathink' in claude code terminal.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.10

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Xterm

Additional Information

_No response_