[Windows] VMP prerequisite check fails on non-English Windows

Start in src/backend_win/prereq.c and inspect how the DISM command output is used to determine whether VirtualMachinePlatform is enabled. Reproduce the headless prerequisite check on a non-English Windows installation, then verify that an enabled feature is accepted without the false prerequisite error.

Your issue

Description

On Windows 11 with a non-English system language, App Sandbox v0.1.8 incorrectly reports that the VirtualMachinePlatform feature is not enabled, even when it is enabled.

Environment

App Sandbox: v0.1.8
Windows 11 Home 25H2
Windows build: 26200.9445
System language: French
VirtualMachinePlatform: Enabled
HCS: Available
HCN: Available

Problem

Running:

dism.exe /Online /Get-FeatureInfo /FeatureName:VirtualMachinePlatform

on my French Windows installation returns localized output:

État : Activé

However, src/backend_win/prereq.c checks the DISM output for the hard-coded English string:

State : Enabled

As a result, App Sandbox reports:

App Sandbox --headless requires the 'VirtualMachinePlatform' Windows feature, which is not enabled.

even though the feature is actually enabled.

Reproduction
Enable VirtualMachinePlatform on a non-English Windows installation.
Run App Sandbox v0.1.8 in headless mode.
App Sandbox incorrectly reports that VirtualMachinePlatform is not enabled.

Workaround / tested fix

I changed the DISM invocation in src/backend_win/prereq.c from:

L"C:\Windows\System32\dism.exe /online /Get-FeatureInfo /FeatureName:%ls"

to:

L"C:\Windows\System32\dism.exe /English /online /Get-FeatureInfo /FeatureName:%ls"

After rebuilding App Sandbox v0.1.8 with this one-line change, AppSandbox.exe --headless no longer reports the false prerequisite error on my French Windows installation.

The change also avoids depending on localized DISM output.

A more robust long-term solution may be possible by avoiding parsing localized DISM text entirely, but /English appears to be a minimal fix.

Thanks for the project!