[BUG] Cowork VM crashes on first launch - "HCS not initialized - call InitHCS() first" - MSIX on Windows 11

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?

Claude Desktop crashes every time on first launch when opening the Code tab. Requires 2-3 full crash/relaunch cycles before the VM sandbox initializes successfully.

Environment:

• OS: Windows 11
• Install method: Windows Store (MSIX)
• Claude version: 1.3109.0.0
• Package: Claude_1.3109.0.0_x64__pzs8sxrjxfjjc

Error from cowork_vm_node.log:
HCS operation failed: failed to create compute system: HCS not initialized - call InitHCS() first

What Should Happen?

Claude Desktop should initialize the HCS (Host Compute System) sandbox successfully on the first cold launch without requiring multiple crash/relaunch cycles. The Code tab should be accessible immediately after launch.

Error Messages/Logs

HCS operation failed: failed to create compute system: HCS not initialized - call InitHCS() first

Steps to Reproduce

1. Cold launch Claude Desktop (no prior instance running)
2. Click Code tab
3. Claude crashes completely within ~12 seconds (not visible in Task Manager)
4. Repeat step 1-2: crashes again
5. Third launch: works normally

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.3109.0.0

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

What I've tried:

• Installed WSL2
• Started CoworkVMService, vmcompute, hns manually
• Granted SYSTEM full control on MSIX package directory
• Deleted and redownloaded vm_bundles
• Created HCS warm-up scheduled task at login

None of these resolved the cold-start crash. The 3-launch workaround suggests HCS is not being initialized inside the MSIX app container on first call.

Related issues: #25914, #38188