Cowork VM download fails with EXDEV: cross-device link not permitted (Windows MSIX sandbox, v1.1.4498)

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 fails to start because cowork-svc.exe downloads rootfs.vhdx to a temp directory and then attempts a rename() to move it into the app's data directory. This fails with EXDEV: cross-device link not permitted because the MSIX filesystem virtualization treats the temp path and the virtualized AppData\Roaming path as different filesystems — even though both resolve to C:\ on the host.
The root cause is that rename() (or fs.rename in Node.js) cannot move files across filesystem boundaries. The fix is to use copyFile + unlink (or a library like move-file that handles cross-device moves) instead of rename.
This is not specific to any particular temp directory location. I have tried:

Default user temp (C:\Users\<user>\AppData\Local\Temp)
Custom temp at C:\temp (root of the same physical drive)
Junction points from AppData\Roaming\Claude\vm_bundles to the MSIX LocalCache path

None of these workarounds resolve the issue because the MSIX sandbox virtualizes paths regardless of their physical location on disk.

What Should Happen?

The VM image should download and be placed into the vm_bundles directory successfully, allowing the Cowork VM to start.

Error Messages/Logs

2026-03-03 20:02:42 [info] rootfs.vhdx not found, downloading...
2026-03-03 20:02:42 [info] Downloading rootfs.vhdx...
2026-03-03 20:04:39 [info] rootfs.vhdx.zst checksum validated
2026-03-03 20:04:41 [error] [download] VM download failed: EXDEV: cross-device link not permitted, rename 'c:\temp\wvm-xlLbyq\rootfs.vhdx' -> 'C:\Users\userXYZ\AppData\Roaming\Claude\vm_bundles\claudevm.bundle\rootfs.vhdx'

Steps to Reproduce

Install Claude Desktop v1.1.4498.0 on Windows 11 Pro
Have Hyper-V, VirtualMachinePlatform, and HypervisorPlatform all enabled
Open Claude Desktop → Click Cowork
Observe "Failed to start Claude's workspace — VM service not running"
Check cowork_vm_node.log for EXDEV error

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.1.4498

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_