[BUG] Desktop Code tab: chat input box is a single line and can't be resized, causing eye strain on longer prompts

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?

In the Claude Desktop app's Code tab on macOS, the message input box starts as a single line of text. It only grows as you add lines with Shift+Enter, and there is no drag handle, divider, or setting to make it taller.

Writing or reviewing a prompt longer than a sentence means working inside a cramped one-line box. That is hard to read and causes real eye strain.

What Should Happen?

The input box should be comfortable for multi-line writing. For example, it could have a taller default height (several lines), a draggable divider between the transcript and the input, or a setting for the input's minimum height.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude Desktop app on macOS and go to the Code tab.
2. Start or open a session.
3. Look at the message input at the bottom: it is one line tall.
4. Try to make it taller by dragging its edge or looking in Settings. There is no way to do it.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Desktop 2.16120.0 (Code tab)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

macOS 26.5.2, Claude Desktop 2.16120.0.

Related: #94604 asks for a draggable divider because the input grows too tall. This report is the opposite problem (too short by default), and the same divider would fix both.