[BUG] Cowork Beta - Critical Bug: System Input/Output Hijacking

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?

Cowork is causing my laptop to crash and is overtaking control of my keyboard and speaker, making my system unusable. I’m unable to type or regain normal input control while the application is running.
Impact: Required force quit/hard restart to regain system functionality.

What Should Happen?

Cowork should not take exclusive control of system input devices (keyboard) or audio output. User should maintain ability to use system controls at all times.

Error Messages/Logs

No error message displayed — app became unresponsive and took over keyboard/audio with no warning or error dialog.

Steps to Reproduce

1. Open Cowork
2. Select/use the Excel integration (“Claude in Excel”)
3. [What happened next? Did you give it a specific command or open a specific file?]

1. Opened Cowork

and that’s it

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude cowork

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_