[BUG] Preview button greyed out in Claude Desktop

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?

Environment
Platform: Linux (kernel 4.4.0)
Claude Code model: Opus 4.6 (claude-opus-4-6)
Session context: Claude Desktop with Preview/Diff/Terminal/Tasks/Plan menu
Summary
The Preview menu item is disabled/non-clickable even though a dev server is running and reachable on the expected port.

Reproduction
Start a Next.js dev server inside the Claude Desktop sandbox:
npx next dev -p 3000 (binds to localhost:3000)
Also tried npx next dev -H 0.0.0.0 -p 3000 (binds to all interfaces)
Server confirmed healthy — curl http://localhost:3000 returns HTTP 200.
Open the menu shown in the screenshot — Preview is greyed out and cannot be clicked. Diff, Tasks, and Plan are clickable.
Expected
Preview should activate once a dev server is detected on a forwarded port.

Actual
Preview stays disabled regardless of host binding (localhost or 0.0.0.0) or port.

Additional notes
Keyboard shortcut shown: ⇧⌘P
Diff (⇧⌘D) works; Terminal also appears disabled.
User suspects this started after a recent Claude Desktop update.
Next.js version: 14.2.35
Attach the screenshot you shared.

What Should Happen?

I should be able to click preview

Error Messages/Logs

Steps to Reproduce

By using claude code and then trying to click preview

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.108

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_