[BUG] Desktop Code tab: "+" button moved inside the message box and indents every line of text

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?

After a Claude desktop update on 14 Oct 2026 (macOS), the "+" (attach) button in the Code tab now sits inside the message box at the bottom-left. It reserves a left column for the whole box, so every line of text starts about 30 pt further right than before. The mic button also moved inside the box, on the right.

Before the update, "+", the mic and the mode picker sat in a row under the box, and the text started about 11 pt from the box's left edge.

Long multi-line pastes (templates, lists) lose width and look misaligned, and the empty column above the "+" is wasted space.

<img width="806" height="161" alt="Image" src="https://github.com/user-attachments/assets/19f8a9ed-af80-4096-8929-8f437552d73f" />
<img width="1100" height="320" alt="Image" src="https://github.com/user-attachments/assets/eabf7cc3-52c7-4c70-9597-e95a6760875b" />

What Should Happen?

Text uses the full width of the message box. The "+" button takes space only on its own row, or goes back under the box as before.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude desktop app (macOS), Code tab, any session.
2. Paste several lines of text into the message box.
3. See that every line starts after an empty left column reserved for the "+" button at the bottom-left.
4. Compare with a version before 14 Oct 2026: "+" and mic were under the box and text started near the left edge.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Claude desktop build in use before 14 Oct 2026, ~17:30 (exact version unknown)

Claude Code Version

Claude desktop 2.37337.1 (Code tab) · Claude Code 2.1.261 · macOS 15.7.4

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Desktop app UI issue (Code tab message box), not the terminal CLI. Before/after screenshots from the same day and window size are attached below.