Preview pane: bring back the device-size / viewport switcher button

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?

Description:

A recent Claude Code update removed the device-size switcher button from the preview pane toolbar. Previously this button let me toggle the preview viewport between mobile / tablet / desktop directly from the UI.

Impact:

I work on a mobile-first Ionic/Angular app, so I need to view the preview at mobile dimensions almost constantly. With the button gone, the only way to resize the viewport is to ask Claude to call the preview_resize MCP tool each time. That's a slower, indirect workaround for what used to be a one-click action, and it means I can't quickly flip between sizes while eyeballing a responsive layout.

Expected behavior:

The preview toolbar should include a viewport/device-size control (mobile / tablet / desktop presets, ideally custom dimensions too), as it did before.

Environment:

Claude Code on Windows 10
Preview pane / Claude Preview MCP

What Should Happen?

Just add the botton back

Error Messages/Logs

Steps to Reproduce

Look at the preview of your running code, there is no button anymore

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Version 1.7196.0 (2dbd78)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_