WAP project with WindowsAppSDKSelfContained=true will have conflict with WinRTCOMServer project & CsWinRT project

[zhuxb711]

Describe the bug

WAP project will place all referenced project into separate output directory if WindowsAppSDKSelfContained set to false

WAP_Output_Directory
├── CsWinRTProject // for example: IBackgroundTask
│   ├── ......
└── WinRTCOMServer
    ├── ......

Things changed if WindowsAppSDKSelfContained set to true. WAP project will place all referenced project into same output directory.

WAP_Output_Directory
├── ...... (CsWinRTProject)
└── ...... (WinRTCOMServer)

Consider a scenario:

CsWinRTProject

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <IsTrimmable>true</IsTrimmable>
    <RootNamespace>CsWinRTProject</RootNamespace>
  </PropertyGroup>
  <PropertyGroup Label="CsWinRTInformation">
    <CsWinRTComponent>true</CsWinRTComponent>
    <CsWinRTWindowsMetadata>$(TargetWindowsVersion)</CsWinRTWindowsMetadata>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Windows.CsWinRT">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
  </ItemGroup>
</Project>

WinRTCOMServer

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <SelfContained>true</SelfContained>
    <IsAotCompatible>true</IsAotCompatible>
    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
    <TrimmerSingleWarn>false</TrimmerSingleWarn>
    <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
    <RootNamespace>WinRTCOMServer</RootNamespace>
    <CsWin32RunAsBuildTask>true</CsWin32RunAsBuildTask>
    <DisableRuntimeMarshalling>true</DisableRuntimeMarshalling>
  </PropertyGroup>
  <PropertyGroup Label="CsWinRTInformation">
    <CsWinRTComponent>true</CsWinRTComponent>
    <CsWinRTWindowsMetadata>$(TargetWindowsVersion)</CsWinRTWindowsMetadata>
  </PropertyGroup>
  <PropertyGroup Label="Optimization" Condition="'$(Configuration)' == 'Release'">
    <PublishAot>true</PublishAot>
    <PublishTrimmed>true</PublishTrimmed>
    <OptimizationPreference>Speed</OptimizationPreference>
  </PropertyGroup>
  <ItemGroup Condition="'$(PublishTrimmed)' == 'true'">
    <TrimmerRootAssembly Include="WinRTCOMServer" />
  </ItemGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Windows.CsWin32">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.Windows.CsWinRT">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
  </ItemGroup>
</Project>

if CsWinRTProject outputs a .dll file but WinRTCOMServer outputs an exe file. However, WinRTCOMServer build with SelfContained=true, but CsWinRTProject isn't. SettingWindowsAppSDKSelfContained=true on WAP project will force those two projects being placed on same directory instead of place them into separate directory. Which cause conflict and might override files with same name.

To run CsWinRTProject using backgroundTaskHost.exe require the CsWinRTProject must not SelfContained. Due to the conflict, I believe CsWinRTProject's WinRT.Host.dll might be overrided by the WinRTCOMServer and therefore, it was changed and will run in SelfContained mode.

backgroundtaskhost initialization for self-contained components is not supported

Workaround:
Set WindowsAppSDKSelfContained to false

Steps to reproduce the bug

Described above

Expected behavior

WAP should place all the project into separate directory in output directory even WindowsAppSDKSelfContained is true

Screenshots

No response

NuGet package version

1.8.260317003

Packaging type

Packaged (MSIX)

Windows version

Windows 11 version 24H2 (26100, June 2025 Update)

IDE

Visual Studio 2022

Additional context

No response