[BUG] Multi-line user input text should have consistent padding after submit

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 user input text using line breaks (Shift + Enter), the text has proper left padding for each line break. However, when accepting the message / submitting to the chat, the padding is removed and looks off balanced compared to both the first line of text, as well as the LLMs text.

<img width="831" height="305" alt="Image" src="https://github.com/user-attachments/assets/566db38c-383e-478d-99fd-1a0696a354eb" />

<img width="562" height="136" alt="Image" src="https://github.com/user-attachments/assets/674b298e-dfa5-4d99-aec7-fa5727d3caf2" />

What Should Happen?

<img width="952" height="110" alt="Image" src="https://github.com/user-attachments/assets/7111c58b-5171-46d9-9180-e154b45a8702" />

Error Messages/Logs

Steps to Reproduce

1. Type a multi-line message using Shift + Enter, and submit to chat.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.81

Platform

Other

Operating System

macOS

Terminal/Shell

Other

Additional Information

• tested in Kitty terminal, Ghostty, VSCode integrated terminal, and Cursor integrated terminal