[BUG] Missing HCS services: vfpext — confirmed missing even in official Windows 11 ISO (install.esd), after DISM repair and full Hyper-V reinstall

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?

aClaude Desktop's Cowork tab shows "Missing HCS services: vfpext" and remains permanently disabled, even after an exhaustive investigation confirming the underlying driver is genuinely absent from every possible source, including a fresh official Windows 11 ISO.

What Should Happen?

aCowork should either successfully enable (if the detection is a false positive, as suggested in issue #80122), or Anthropic should provide a clear remediation path for this specific Windows configuration where vfpext.sys is missing even from the official Windows 11 install media.

Error Messages/Logs

Steps to Reproduce

a1. Open Claude Desktop on Windows 11 Pro

1. Click on the Cowork tab
2. 3. Tooltip shows "Missing HCS services: vfpext"
3. 4. Cowork tab is disabled and cannot be used

Environment checks performed:

• Get-Service vmcompute, hns -> both Running
• - Test-Path C:\Windows\System32\drivers\vfpext.sys -> False

Remediation attempts (all failed to produce vfpext.sys):

1. DISM repair:
2. DISM /Online /Cleanup-Image /RestoreHealth
3. Completed 100% successfully. vfpext.sys still absent afterward.
4. SFC scan:
5. sfc /scannow
6. Result: "Windows Resource Protection did not find any integrity violations." File still missing.
7. Full Hyper-V feature removal + reinstall (two reboots):
8. Disabled Hyper-V via "Turn Windows features on or off", rebooted, re-enabled, rebooted again. vfpext.sys still absent.
9. Extracted directly from official Windows 11 installation media:
10. Downloaded the Windows 11 ISO via the official Microsoft Media Creation Tool, mounted it, then mounted the install image directly:
11. Dism /Mount-Image /ImageFile:E:\sources\install.esd /Index:6 /MountDir:C:\WimMount /ReadOnly
12. Mount succeeded 100%. Checked:
13. Test-Path C:\WimMount\Windows\System32\drivers\vfpext.sys
14. Result: False

This last result is the most significant finding: the driver is not present even inside a clean, official Windows 11 install image straight from Microsoft's servers. This suggests either the driver isn't shipped for this Windows edition/build/language combination, or Cowork's detection logic is checking for the wrong condition entirely (e.g. checking for a Running service rather than a properly registered on-demand driver, as suggested in #80122).

Related/duplicate issues: #74649, #77277, #78858, #78866, #80584, #81396, #80122

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

N/A - Claude Desktop (Cowork), not CLI

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_