[BUG] Unwanted backslash appended when using Shift+Enter for line breaks

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 press shift enter in CC on WSL or Powershell it leaves a trailing backslash on the end of the line. It does creates a new line.

When using Codex in WSL this issue doesn't happen while using shift+enter for a new line.

What Should Happen?

It shouldn't add a trailing backslash.

Error Messages/Logs

Steps to Reproduce

On windows install WSL2 ( WSL version: 2.5.9.0 )
Install CC in both WSL and through Powershell on Windows.
Run the /terminal-setup command

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Version 1.0.120

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

WSL (Windows Subsystem for Linux)

Additional Information

<img width="280" height="109" alt="Image" src="https://github.com/user-attachments/assets/cf29dd71-340b-4a05-969f-b57c2a58b787" />