[BUG] Cowork tab missing — yukonSilver misdetection, build 1.3109.0, Windows 11 MSIX

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?

The Cowork tab is completely absent from the navigation bar — only Chat and Code are visible, with no error message. Logs confirm the yukonSilver platform detection is incorrectly marking the system as unsupported, even though the VM module loads successfully.

The cowork_vm_node.log shows only a repeating three-line cycle on every launch:

2026-04-16 17:06:12 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-16 17:06:39 [info] [VM] Loading vmClient (TypeScript) module...
2026-04-16 17:06:39 [info] [VM] Module loaded successfully

This repeats across every launch from April 16–17 with no variation. The VM never attempts to boot.

Related issues: #25136, #47327, #48407, #48995. I'm on a newer build (1.3109.0) than #48407 (1.2581.0), so the fix either hasn't shipped or hasn't resolved the issue for MSIX installs.

Expected Behaviour

Cowork tab should appear alongside Chat and Code, and the VM should boot normally.

Steps to Reproduce

1. Install Claude Desktop via MSIX on Windows 11
2. Confirm Virtual Machine Platform is enabled, CPU virtualization is enabled, and CoworkVMService is running
3. Launch Claude Desktop
4. Observe: only Chat and Code tabs are visible — no Cowork tab

Environment

• Plan: Max
• OS: Windows 11
• Claude Desktop version: 1.3109.0 (35cbf6)
• Install method: MSIX

Additional Notes

• Logs are at the MSIX-sandboxed path (%LOCALAPPDATA%\Packages\Claude_<id>\LocalCache\Roaming\Claude\logs\) rather than the commonly referenced %APPDATA%\Claude\logs\ — the standard path is empty. This may be relevant for reproduction on MSIX installs.
• Full restart of both the app and machine has been attempted. Issue persists.
• VM prerequisites verified via PowerShell: Virtual Machine Platform enabled, CPU virtualization enabled, CoworkVMService running.

What Should Happen?

Cowork should work and be accessible

Error Messages/Logs

Steps to Reproduce

N/Ap

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.3109.0 (35cbf6)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_