[BUG] /terminal-setup fails over ttyd

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 I try to run /terminal-setup from my ttyd terminal, I see

 /terminal-setup                                                                                                                                   
  ⎿  Terminal setup cannot be run from xterm-256color

What Should Happen?

I would like to be able to use shift+enter from my terminal

Error Messages/Logs

Steps to Reproduce

Open a claude code shell over ttyd

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.161

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_