[BUG] Cowork VM hangs at "Configuring Windows VM service" after yukonSilver bundle cleanup deletes VM registration

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?

yukonSilver was flagged as "unsupported" at 11:23 AM on 3/8/2026, triggering
a bundle cleanup that deleted VM reinstall files. By 15:14 the same day,
yukonSilver was back to status=supported — meaning the unsupported flag was
transient or incorrect. After the cleanup, the VM was left completely
unregistered in Hyper-V (Get-VM returns empty). On every subsequent launch,
the app hangs indefinitely at:

[VM:start] Configuring Windows VM service...

No error is ever logged. The main thread locks up, Windows prompts "wait or
close," and the app never recovers. Full reinstall required to resolve.

What Should Happen?

The app should detect that the VM is unregistered in Hyper-V after a bundle
cleanup and automatically re-provision it rather than hanging silently at
"Configuring Windows VM service". If re-provisioning fails, it should log an
error and surface a message to the user instead of locking up the main thread
indefinitely. The yukonSilver cleanup logic should also verify the status is
stable before destroying VM registration — a transient unsupported flag should
not trigger irreversible bundle modifications.

Error Messages/Logs

No, I didn't see any.  The app hung silently.  In the logs it was:

[VM:start] Configuring Windows VM service...

And then nothing. No timeout, no error, no failure message. Windows itself was the only thing that surfaced anything, with the generic "wait or close" prompt. That's worth noting in the report — the absence of any error logging made it very difficult to diagnose.

Steps to Reproduce

1. App flags yukonSilver as unsupported (appears to be server-side/transient)
2. cleanupVMBundleIfUnsupported runs, deletes reinstall files
3. yukonSilver flips back to supported
4. App attempts VM startup, hangs indefinitely at

"Configuring Windows VM service" with no error logged

1. Get-VM returns empty — VM was never re-registered with Hyper-V
2. App is completely unresponsive on every subsequent launch

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

App version: 1.1.5368

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Related issues: #25136, #25142, #25505, #27248 — all related to yukonSilver unsupported flag on Windows.

LOGS

2026-03-08 11:23:57 [info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
2026-03-08 11:23:57 [info] [deleteVMBundle] Deleting reinstall files from ...\claudevm.bundle
2026-03-08 11:23:57 [info] [deleteVMBundle] Reinstall files deleted (sessiondata.img and rootfs.img.zst preserved)
2026-03-08 12:55:52 [info] [VM:start] Configuring Windows VM service...
[no further output — app hangs indefinitely]
2026-03-08 15:14:39 feature: yukonSilver, status: supported, unsupported_code: null
2026-03-08 15:14:42 [info] [VMCLIRunner] Ensuring VM is started
[hangs again]