[BUG] v2.1.83 broke uppercase letters in xterm under Linux

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 typing input into Claude Code, shift+letter is rendered as lowercase instead of uppercase. The problem only appeared today, likely with a fresh update of Claude Code.

What Should Happen?

Of course uppercase should again be rendered as uppercase.

Error Messages/Logs

Steps to Reproduce

Run Claude Code, get to the first prompt, enter 'x', get 'X'.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.83 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Xterm

Additional Information

_No response_