[BUG] Shift-Enter sometimes creates newline, sometimes sends prompt

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 use claude code I use shift-enter to create newlines, however (& I'm not sure what the difference is here), sometimes, it will simply cease to work and change it's behaviour to simply sending the prompt.

Restarts of claude do not seem to work if you continue conversations, but starting a new conversation does seem to work. It's possible this only occurs after the ai has compressed the conversation, though I cannot confirm this with certainty.

What Should Happen?

Shift enter -> newline

Error Messages/Logs

Steps to Reproduce

1. Start conversation -> shift enter works fine
2. Continue until compression happens (or just continue for a while)
3. Shift enter will start sending prompts rather than newline.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.14

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

PHPStorm terminal & Gnome terminal on Ubuntu 24.10