Add multi-version .NET Copilot workflow with deterministic package restores

.github/workflows/copilot-setup-steps.yml

@@ -0,0 +1,80 @@
+name: Copilot Setup Steps for Multi-Version .NET
+
+# This workflow sets up a multi-version .NET environment for GitHub Copilot
+# It configures .NET 6, 8, and 10 SDKs with proper caching and tooling
+on:
+  # Allow manual triggering from Actions tab
+  workflow_dispatch:
+
+  # Run when this workflow file is modified to validate changes
+  push:
+    paths:
+      - '.github/workflows/copilot-setup-steps.yml'
+
+  pull_request:
+    paths:
+      - '.github/workflows/copilot-setup-steps.yml'
+
+# Security: Use minimum required permissions
+# Only read access to repository contents is needed
+permissions:
+  contents: read
+
+jobs:
+  # Job name must be 'copilot-setup-steps' for GitHub Copilot recognition
+  copilot-setup-steps:
+    runs-on: ubuntu-latest
+
+    steps:
+      # Checkout with full history for better context
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      # Setup multiple .NET SDK versions in a single step for efficiency
+      # Using specific versions for reproducibility (not wildcards)
+      # Versions: .NET 6.0 LTS, .NET 8.0 LTS, .NET 9.0 (latest stable)
+      - name: Setup .NET SDK (Multi-Version)
+        uses: actions/setup-dotnet@v4
+        with:
+          # Multi-version syntax: separate versions with newlines
+          dotnet-version: |
+            6.0.428
+            8.0.416
+            9.0.101
+
+          # Enable NuGet package caching for performance optimization
+          cache: true
+
+          # Cache dependency path points to lock files for deterministic restores
+          # This ensures exact package versions are restored from cache
+          cache-dependency-path: '**/packages.lock.json'
+
+      # Restore dependencies with locked mode for deterministic builds
+      # --locked-mode ensures exact versions from packages.lock.json are used
+      # This prevents supply chain attacks and ensures reproducible builds
+      - name: Restore dependencies (locked mode)
+        run: dotnet restore --locked-mode
+
+      # Install dotnet-format tool globally for code formatting
+      # This is commonly used by Copilot for code formatting suggestions
+      - name: Install dotnet-format
+        run: dotnet tool install -g dotnet-format
+
+      # Setup .NET environment variables for optimal operation
+      # DOTNET_ROOT: Ensures consistent SDK discovery
+      # DOTNET_CLI_TELEMETRY_OPTOUT: Disables telemetry for privacy/performance
+      - name: Configure .NET environment variables
+        run: |
+          echo "DOTNET_ROOT=$HOME/.dotnet" >> $GITHUB_ENV
+          echo "DOTNET_CLI_TELEMETRY_OPTOUT=1" >> $GITHUB_ENV
+
+      # Validate the setup by building the solution
+      # This ensures all SDKs are properly configured and dependencies are resolved
+      - name: Build validation
+        run: dotnet build --configuration Release --no-restore
+
+      # Optional: Display .NET SDK information for troubleshooting
+      - name: Display .NET info
+        run: dotnet --info

src/Fennel/Fennel.fsproj

@@ -17,6 +17,7 @@
       # 0.2.0
       - Adds Prometheus.CSharp namespace with a more C# friendly API
     </PackageReleaseNotes>
+    <RestorePackagesWithLockFile>true</RestorePackagesWithLockFile>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Result.fs" />

src/Fennel/packages.lock.json

@@ -0,0 +1,36 @@
+{
+  "version": 1,
+  "dependencies": {
+    ".NETStandard,Version=v2.0": {
+      "FParsec": {
+        "type": "Direct",
+        "requested": "[1.1.1, )",
+        "resolved": "1.1.1",
+        "contentHash": "Wdjf/gCNLEwd+0nUCDh9jAIIcKGwfhRramySTnTcVVgNC6i4Vp5aJklUJJfvFkEZMYNZEDGcI8pCa36/TmwmSg==",
+        "dependencies": {
+          "FSharp.Core": "4.3.4"
+        }
+      },
+      "FSharp.Core": {
+        "type": "Direct",
+        "requested": "[10.0.100, )",
+        "resolved": "10.0.100",
+        "contentHash": "vWHaY4Pk7mUv5gJN9+rbods+QnPjhrw3sdGw2R9pFLIBzHkkN26eMgubPHZVoS7xwLA9TZuoHGLrboY5QOBcdA=="
+      },
+      "NETStandard.Library": {
+        "type": "Direct",
+        "requested": "[2.0.3, )",
+        "resolved": "2.0.3",
+        "contentHash": "st47PosZSHrjECdjeIzZQbzivYBJFv6P2nv4cj2ypdI204DO+vZ7l5raGMiX4eXMJ53RfOIg+/s4DHVZ54Nu2A==",
+        "dependencies": {
+          "Microsoft.NETCore.Platforms": "1.1.0"
+        }
+      },
+      "Microsoft.NETCore.Platforms": {
+        "type": "Transitive",
+        "resolved": "1.1.0",
+        "contentHash": "kz0PEW2lhqygehI/d6XsPCQzD7ff7gUJaVGPVETX611eadGsA3A877GdSlU0LRVMCTH/+P3o2iDTak+S08V2+A=="
+      }
+    }
+  }
+}

test/Fennel.CSharp.Tests/Fennel.CSharp.Tests.csproj

@@ -4,6 +4,7 @@
         <TargetFramework>net5.0</TargetFramework>
 
         <IsPackable>false</IsPackable>
+        <RestorePackagesWithLockFile>true</RestorePackagesWithLockFile>
     </PropertyGroup>
 
     <ItemGroup>