[BUG] Cowork VM works correctly but cleanupVMBundleIfUnsupported deletes VM bundle on every app exit — Windows 11 Pro 25H2

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 runs perfectly — the VM spawns, processes execute, tasks complete — but every time Claude Desktop is closed, the cleanupVMBundleIfUnsupported routine incorrectly flags the system as yukonSilver not supported and deletes the VM bundle files. On next launch, the Cowork tab shows "Cowork requires a newer installation" because the bundle was deleted.
This means Cowork only works for a single session. Closing the app destroys the VM files, requiring a full reinstall each time.

Environment

OS: Windows 11 Pro 25H2 (Build 26200.8039)
CPU/RAM: 16 cores / 32 GB RAM
Claude Desktop Version: Latest from claude.ai/download (MSIX install)
Virtualization: VirtualMachinePlatform enabled, Hyper-V enabled, HyperVisorPresent = True
User context: Non-admin user, installed via Add-AppxPackage

What Should Happen?

Closing Claude Desktop should not delete the VM bundle. The Cowork tab should remain functional across app restarts.

Error Messages/Logs

On every app exit, the cleanup routine deletes the VM bundle because platform detection returns status=unsupported, despite the VM having just run successfully.

From %APPDATA%\Claude\logs\cowork_vm_node.log:

2026-03-30 13:29:36 [info] [Spawn:vm] Spawn succeeded in 51ms
2026-03-30 13:29:59 [info] [Process] Exited, code=0, signal=null, duration=23016ms, oom=false
...
2026-03-30 13:30:35 [info] [Spawn:vm] Spawn succeeded in 47ms
2026-03-30 13:30:49 [info] [Process] Exited, code=0, signal=null, duration=13692ms, oom=false
...
2026-03-30 13:31:12 [info] [VM:shutdown] App quit, stopping VM...
2026-03-30 13:31:12 [info] [VM:shutdown] Completed in 448ms
2026-03-30 13:31:21 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-30 13:31:21 [info] [deleteVMBundle] Deleting reinstall files from C:\Users\billb\AppData\Roaming\Claude\vm_bundles\claudevm.bundle
2026-03-30 13:31:21 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)

Steps to Reproduce

Clean install Claude Desktop on Windows 11 Pro 25H2
Open Claude Desktop, switch to Cowork tab — it works
Run a Cowork task — completes successfully
Close Claude Desktop (quit from system tray)
Reopen Claude Desktop
Cowork tab now shows "Cowork requires a newer installation"

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Version 1.1.9493 (b58a0b)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

PowerShell

Additional Information

Root Cause Analysis
The cleanupVMBundleIfUnsupported function runs on app exit and checks yukonSilver support status. This check returns unsupported on this system despite the VM functioning correctly. The function then deletes the VM bundle files, requiring a full reinstall on next launch.
The platform detection logic is clearly incorrect — if the VM just ran successfully, the platform is by definition supported.
Suggested Fix

Skip the cleanup if the VM was successfully used during the current session
Or fix the yukonSilver platform detection to correctly identify Windows 11 Pro 25H2 as supported
At minimum, do not delete a working VM bundle based on a status check that contradicts runtime behavior

Additional Context

The CoworkVMService also cannot be deleted even with Administrator privileges (sc.exe delete returns Access Denied), which complicates reinstallation
Related issues: #25136, #25142, #28963, #28998