[BUG] Cowork regression in v1.1348.0: yukonSilver incorrectly marks Windows 11 Home as unsupported — was working on prior version

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 was fully functional on my Windows 11 Home system immediately prior to updating to v1.1348.0. After the update, Cowork displays "Cowork requires a newer installation" and refuses to start. The VM never boots. The yukonSilver platform detection marks the system as unsupported and actively deletes the VM bundle files on every launch.

This is a clear regression — the log shows the VM successfully started at 11:33 AM, then after the update landed at 11:39 AM, every subsequent attempt fails with yukonSilver not supported (status=unsupported).

System info:

OS: Windows 11 Home, 25H2
HypervisorPlatform: Enabled
Claude Desktop: 1.1348.0
CoworkVMService: Not registered (gone after update)
Get-AppxPackage -Name "Claude" -AllUsers: Returns nothing (clean MSIX state)
Subscription: Pro

What Should Happen?

Cowork should start successfully, as it did on the prior version minutes earlier on the same system with zero configuration changes.

Error Messages/Logs

Log evidence (from %APPDATA%\Claude\logs\cowork_vm_node.log):

Working (pre-update):

2026-04-09 11:33:52 [info] [postConnect] Installing SDK: subpath=c/Users/[USERNAME]/AppData/Roaming/Claude/claude-code-vm, version=2.1.92
2026-04-09 11:33:54 [info] [VM] API reachability: REACHABLE
2026-04-09 11:33:54 [info] [VM:steps] sdk_install completed (2703ms)
2026-04-09 11:33:54 [info] [VM:start] Startup complete, total time: 12320ms
2026-04-09 11:38:17 [info] [VM:shutdown] App quit, stopping VM

Broken (post-update, repeating on every launch):

2026-04-09 11:40:13 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-04-09 11:40:13 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\[USERNAME]\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-04-09 11:40:13 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)

This pattern repeats at 11:41, 11:43, 11:58, 12:31, and 12:32 — the app deletes its own VM bundle on every launch attempt.

Steps to Reproduce

Have a working Cowork setup on Windows 11 Home
Update to v1.1348.0 (or allow auto-update)
Launch Claude Desktop
Observe "Cowork requires a newer installation" banner
Check logs — yukonSilver marks system as unsupported

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.1348.0

Claude Code Version

2.1.81

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

No system changes between working and broken states — only the Claude Desktop update
The "Reinstall" button in the Cowork banner does nothing
"Check for Updates" reports latest version
Related issues: #27397, #25663, #25136