Título: Cowork tab missing — CoworkVMService/CoworkVMServiceStore not created despite Hyper-V enabled

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?

Claude Desktop (MSIX, v1.18286.0.0), Windows 10 Pro, AMD Ryzen 7 5800X.

Cowork tab never appears in sidebar (only Home/Code). Settings > Cowork shows config as if enabled (Cowork files path, Trusted folders, Global instructions all present).

Verified:

• Hyper-V feature: Enabled (Get-WindowsOptionalFeature)
• HypervisorPresent: True
• BIOS virtualization: Enabled
• sc query CoworkVMService / CoworkVMServiceStore: service does not exist
• Get-AppxPackage confirms MSIX install (not legacy .exe)

Log (cowork_vm_node.log) repeatedly shows:
[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Tried: full reinstall (clean %APPDATA%\Claude, %LOCALAPPDATA%\Packages\Claude_*, AppX removal), reboot, re-enabling Hyper-V — issue persists. Appears to be a false-negative in platform capability detection ("yukonSilver") preventing VM service installation.

What Should Happen?

Cowork tab should appear in sidebar, and CoworkVMService should install/start normally when Hyper-V is enabled and detected.

Error Messages/Logs

[cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...

Steps to Reproduce

Instale Claude Desktop MSIX (claude.com/download)
Confirme Hyper-V habilitado (BIOS + Windows feature)
Abra Settings > Cowork
Note aba Cowork ausente na sidebar (só Home/Code)
Rode sc query CoworkVMServiceStore → serviço não existe

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

N/A (Desktop app)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Cowork settings UI shows fully configured (folders, global instructions) despite service never having been created — suggests UI doesn't verify service state before rendering config options.

<img width="513" height="784" alt="Image" src="https://github.com/user-attachments/assets/9366e63e-c585-4070-8667-b00ae8c99b17" />