[BUG] fullwidth input behaves weirdly

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 accidentally have my input language as Japanese and try to approve something in Claude, say:

Do you want to overwrite PLAN.md?
 ❯ 1. Yes
   2. Yes, allow all edits during this session (shift+tab)
   3. No

I'll press my keyboard's 1 key and it'll generate a fullwidth １. The number shows up at the bottom of the command line, and it's confusing why exactly this happens.

What Should Happen?

I'm not sure if the right behavior is to accept it as 1 (hey, Perl 6 will accept roman numeral Ⅰ as a 1!), or diagnose the invalid input. But the current behavior seems surprising!

Error Messages/Logs

`１`

Steps to Reproduce

Be me, be confused, have keyboard in Japanese, respond with fullwidth １ when Claude expects 1. Show confusion. Hilarity ensues.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

２．１．７

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

I'm using ghostty.