[BUG] Prompt gets lost

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?

Admittedly this only happens if the user makes two mistakes; yet its impact is bad enough IMHO that it might be worth looking into.

If you need to enter a long multi-line prompt you may at one point hit shift+enter for a newline instead of CMD+J. You then hit Esc to interrupt evaluation of the incomplete prompt; hit UP to bring the prompt back and continue working on it. But if you make the fatal mistake of moving up and down the text (perhaps it has outgrown the input area and you need to see something at the top) and you go past your last line, your prompt is gone for good and you can only get back the incomplete version you sent by accident.

What Should Happen?

If there was a way to get the buffer back in full it would be a huge time saver from time to time.

Error Messages/Logs

Steps to Reproduce

1. Enter an incomplete prompt
2. Hit Shif+Enter
3. Hit Esc
4. Add several lines to the prompt
5. Use UP arrow key to go previous lines, then Press DOWN and go past your last line

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.63

Platform

Anthropic API

Operating System

Xubuntu

Terminal/Shell

Terminal.app (linux)

Additional Information

_No response_