LHWS Game Bar Widget

An Xbox Game Bar (Win+G) widget that displays hardware sensors (temperatures, load, power, fans) from LibreHardwareService — a Windows service exposing LibreHardwareMonitor data through memory-mapped files.

How it works

• LibreHardwareService runs as LocalSystem, owns the ring0 driver, and publishes sensor data into named shared memory (Global\LibreHardwareService/json/sensors/data) once per second.
• This widget is a UWP app (modern UWP on .NET 9, UseUwp=true) hosted by Xbox Game Bar. It opens the shared memory read-only, guarded by the service's mutex, and renders the sensors.
• Because Game Bar widgets run in an AppContainer, the service must grant ALL APPLICATION PACKAGES read access to its named objects. Until the upstream patch is merged, install the service from that branch.

Installing (end users)

1. Install and start LibreHardwareService (with the AppContainer ACL patch, see above).
2. Download LhwsGameBarWidget_<version>_x64.zip from the releases page and extract it (bleeding-edge builds live in the nightly prerelease, rebuilt automatically on days that have new commits).
3. Right-click Install.ps1 → Run with PowerShell. The script:
   • imports the bundled .cer into Local Machine → Trusted People (asks for admin elevation — the package is signed with a self-signed certificate, so Windows must be told to trust it once);
   • installs the Microsoft.VCLibs framework dependency if missing;
   • installs the widget package.
4. Press Win+G, find LHWS Sensors in the widget menu, and configure rows via the widget's settings (title-bar gear button).

To uninstall: Settings → Apps → LHWS Sensors → Uninstall (or Get-AppxPackage LhwsGameBarWidget | Remove-AppxPackage). The trusted certificate can be removed from certlm.msc → Trusted People.

Building the installer

Prerequisites (beyond the dev build requirements below): the Desktop development with C++ VS workload — Native AOT needs the MSVC linker.

.\pack.ps1            # x64 (default)
.\pack.ps1 -Zip       # + zip the output folder for a GitHub release
.\pack.ps1 -Platform ARM64

The script produces AppPackages\LhwsGameBarWidget_<version>_<platform>_Test\ with the signed .msix, the public .cer, the Install.ps1/Add-AppDevPackage.ps1 sideloading scripts, and the Dependencies\ folder (VCLibs). What it does:

• Finds VS MSBuild via vswhere and puts the VS Installer directory on PATH (the Native AOT toolchain invokes vswhere.exe by bare name to locate link.exe).
• Finds a code-signing certificate in Cert:\CurrentUser\My whose Subject equals the Publisher in Package.appxmanifest (CN=Phoenix-), creating a self-signed one on first run. The Subject must match the manifest Publisher or Windows rejects the package.
• Builds Release with -p:PublishAot=true -p:SelfContained=true -p:GenerateAppxPackageOnBuild=true -p:UapAppxPackageBuildMode=SideloadOnly, so the package contains a single native AOT executable — end users don't need the .NET runtime.
• Signs the package with the certificate (AppxPackageSigningEnabled + PackageCertificateThumbprint).

To publish a new version: bump Version in Package.appxmanifest, run .\pack.ps1 -Zip, upload the zip as a release asset.

Nightlies: .github/workflows/nightly.yml runs daily (03:00 UTC; skipped when there are no new commits) and refreshes the rolling nightly prerelease. It stamps the manifest revision with the run number (<major>.<minor>.<build>.<run>), installs the VS Universal Windows Platform tools component on the runner (the image ships without it), and signs with the CN=Phoenix- certificate from the SIGNING_CERT_PFX / SIGNING_CERT_PASSWORD repository secrets — the same certificate as local builds, so one trusted cert covers both.

Note: GenerateAppxPackageOnBuild must not flow into referenced projects — the MSIX tooling's Pack target collides with NuGet's Pack (MSB4006 cycle). The main csproj strips it with UndefineProperties on the ProjectReference.

Native AOT gotcha: the app csproj must keep AllowUnsafeBlocks=true. The CsWinRT AOT optimizer emits vtable lookup code for generic collections crossing the WinRT ABI (e.g. ObservableCollection<T> assigned to ItemsSource) only when unsafe code is allowed — without it the types are silently skipped and the widget dies at activation with ArgumentException: Value does not fall within the expected range in set_ItemsSource (AOT builds only; Debug/CoreCLR works because CsWinRT builds CCW vtables dynamically at runtime).

Requirements

• Windows 11 (or Windows 10 19041+), Xbox Game Bar
• LibreHardwareService with the AppContainer ACL patch, running
• To build: Visual Studio 2026 with the Universal Windows Platform tools component, Windows 11 SDK (26100), .NET 9+ SDK; for pack.ps1 also Desktop development with C++

Build & run (dev)

Build with VS MSBuild, not dotnet build — core MSBuild lacks the UWP XAML targets (InitializeComponent won't be generated):

& "C:\Program Files\Microsoft Visual Studio\18\Community\MSBuild\Current\Bin\amd64\MSBuild.exe" `
    src/LhwsGameBarWidget/LhwsGameBarWidget.csproj -restore -p:Platform=x64
# register the loose layout (requires Developer Mode):
Add-AppxPackage -Register src/LhwsGameBarWidget/bin/x64/Debug/net9.0-windows10.0.26100.0/AppxManifest.xml

Then press Win+G and open the LHWS Sensors widget from the widget menu.

Dev-loop notes:

• Debug builds additionally need the Microsoft.VCLibs.140.00.Debug framework package (install from C:\Program Files (x86)\Microsoft SDKs\Windows Kits\10\ExtensionSDKs\Microsoft.VCLibs\14.0\Appx\Debug\x64\).
• Code-only changes don't need re-registration (loose-file package) — rebuild and restart Game Bar. Manifest changes do: bump Version and re-register (same-version re-register fails with 0x80073CFB).
• Remove-AppxPackage wipes LocalState (user config, widget.log) — avoid it during dev; re-register over the existing package instead.