build: migrate to .NET 10 (LTS)

Upgrade all 102 csproj files from net9.0 to net10.0,
pin SDK via global.json (10.0.100/latestFeature), and
update CI workflows, docs, and templates.

Fix C# 14 'field' keyword conflict in
ValidationContext.InvalidFields property accessor.

Fix TFM and project path in SKILL.md.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: sundaramramaswamy

.github/workflows/ci.yml

@@ -65,7 +65,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@c2fa09f4bde5ebb9d1777cf28262a3eb3db3ced7 # v5.2.0
         with:
-          dotnet-version: 9.0.x
+          dotnet-version: 10.0.x
 
       - name: Restore
         run: dotnet restore tests/Reactor.Tests/Reactor.Tests.csproj
@@ -84,7 +84,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@c2fa09f4bde5ebb9d1777cf28262a3eb3db3ced7 # v5.2.0
         with:
-          dotnet-version: 9.0.x
+          dotnet-version: 10.0.x
 
       - name: Restore
         run: dotnet restore tests/Reactor.SelfTests/Reactor.SelfTests.csproj
@@ -103,7 +103,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@c2fa09f4bde5ebb9d1777cf28262a3eb3db3ced7 # v5.2.0
         with:
-          dotnet-version: 9.0.x
+          dotnet-version: 10.0.x
 
       - name: Restore
         run: dotnet restore Reactor.sln

.github/workflows/coverage.yml

@@ -58,7 +58,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@c2fa09f4bde5ebb9d1777cf28262a3eb3db3ced7 # v5.2.0
         with:
-          dotnet-version: 9.0.x
+          dotnet-version: 10.0.x
 
       - name: Install dotnet-coverage
         run: dotnet tool install -g dotnet-coverage
@@ -81,7 +81,7 @@ jobs:
         shell: pwsh
         run: |
           dotnet-coverage instrument `
-            "tests/Reactor.AppTests.Host/bin/x64/Debug/net9.0-windows10.0.22621.0/Reactor.dll" `
+            "tests/Reactor.AppTests.Host/bin/x64/Debug/net10.0-windows10.0.22621.0/Reactor.dll" `
             -s coverage.settings.xml
 
       - name: Collect selftest coverage

.github/workflows/release.yml

@@ -65,7 +65,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@c2fa09f4bde5ebb9d1777cf28262a3eb3db3ced7 # v5.2.0
         with:
-          dotnet-version: 9.0.x
+          dotnet-version: 10.0.x
 
       - name: Install minver-cli
         run: dotnet tool install --global minver-cli --version 5.0.0
@@ -104,7 +104,7 @@ jobs:
           -p:Platform=x64
           -o artifacts/nupkg
 
-      # Framework-dependent: the consumer's machine supplies the .NET 9
+      # Framework-dependent: the consumer's machine supplies the .NET 10
       # runtime — saves ~70 MB per RID. install-skill-kit.ps1 checks for it
       # and errors out with an install hint if it's missing. See spec 022 §6.
       - name: Publish mur (win-x64)

CONTRIBUTING.md

@@ -22,7 +22,7 @@ This project has adopted the [Microsoft Open Source Code of Conduct](https://ope
 
 ## Prerequisites
 
-- [.NET 8 SDK](https://dotnet.microsoft.com/download/dotnet/8.0)
+- [.NET 10 SDK](https://dotnet.microsoft.com/download/dotnet/10.0)
 - Windows App SDK 2.0 — restored automatically from NuGet, no manual install required
 - Visual Studio 2022 (17.8+) or VS Code with C# Dev Kit
 
@@ -179,7 +179,7 @@ dotnet build tests/Reactor.AppTests.Host      -c Debug -p:Optimize=false -p:Debu
 # Step 2: Instrument Reactor.dll statically
 #         (dynamic instrumentation skips referenced assemblies)
 dotnet-coverage instrument \
-  "tests/Reactor.AppTests.Host/bin/$(RuntimeIdentifier)/Debug/net9.0-windows10.0.22621.0/Reactor.dll" \
+  "tests/Reactor.AppTests.Host/bin/$(RuntimeIdentifier)/Debug/net10.0-windows10.0.22621.0/Reactor.dll" \
   -s coverage.settings.xml
 
 # Step 3: Collect

README.md

@@ -133,9 +133,9 @@ If you're building line-of-business applications:
 
 ### Prerequisites
 
-- [.NET 8 SDK](https://dotnet.microsoft.com/download/dotnet/8.0)
+- [.NET 10 SDK](https://dotnet.microsoft.com/download/dotnet/10.0)
 - Windows App SDK 2.0 — pulled automatically on `dotnet restore`
-- Visual Studio 2022 (17.8+) or just the .NET 8 CLI
+- Visual Studio 2022 (17.8+) or just the .NET 10 CLI
 
 > This project uses Windows App SDK 2.0 (`Microsoft.WindowsAppSDK` 2.0.1). The package comes from NuGet — no manual SDK installer is needed.
 
@@ -151,7 +151,7 @@ Or create a `.csproj` manually:
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net8.0-windows10.0.22621.0</TargetFramework>
+    <TargetFramework>net10.0-windows10.0.22621.0</TargetFramework>
     <UseWinUI>true</UseWinUI>
     <WindowsPackageType>None</WindowsPackageType>
     <WindowsAppSDKSelfContained>true</WindowsAppSDKSelfContained>

SKILL.md

@@ -44,7 +44,7 @@ re-renders automatically. No XAML. No data binding. No ViewModels.
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.WindowsAppSDK" Version="2.0.1" />
-    <ProjectReference Include="..\Reactor\Reactor.csproj" />
+    <ProjectReference Include="..\src\Reactor\Reactor.csproj" />
   </ItemGroup>
 </Project>
 ```
@@ -311,7 +311,7 @@ For lightweight demos, skip the `.csproj` entirely. Add a file-level header:
 #:project ./src/Reactor
 #:package Microsoft.WindowsAppSDK@2.0.1
 #:property OutputType=WinExe
-#:property TargetFramework=net9.0-windows10.0.22621.0
+#:property TargetFramework=net10.0-windows10.0.22621.0
 #:property UseWinUI=true
 #:property WindowsPackageType=None
 #:property WindowsAppSDKSelfContained=true

docs/_pipeline/ai-author-skill.md

@@ -63,7 +63,7 @@ The pipeline replaces `screenshot://` with a relative path like
 
 ```markdown
 <!-- ai:lock -->
-> **Prerequisites:** .NET 9+ and the Windows App SDK.
+> **Prerequisites:** .NET 10+ and the Windows App SDK.
 <!-- /ai:lock -->
 ```
 
@@ -90,7 +90,7 @@ docs/_pipeline/apps/my-topic/
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net9.0-windows10.0.22621.0</TargetFramework>
+    <TargetFramework>net10.0-windows10.0.22621.0</TargetFramework>
     <Platforms>x64;ARM64</Platforms>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>

docs/_pipeline/apps/accessibility/accessibility.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net9.0-windows10.0.22621.0</TargetFramework>
+    <TargetFramework>net10.0-windows10.0.22621.0</TargetFramework>
     <Platforms>x64;ARM64</Platforms>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>

docs/_pipeline/apps/advanced/advanced.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net9.0-windows10.0.22621.0</TargetFramework>
+    <TargetFramework>net10.0-windows10.0.22621.0</TargetFramework>
     <Platforms>x64;ARM64</Platforms>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>

docs/_pipeline/apps/animation/animation.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net9.0-windows10.0.22621.0</TargetFramework>
+    <TargetFramework>net10.0-windows10.0.22621.0</TargetFramework>
     <Platforms>x64;ARM64</Platforms>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>