Here’s a Windows‑MSVC GitHub Actions workflow that builds a CMake + vcpkg (manifest mode) project and automatically caches vcpkg artifacts.
It uses Ninja + MSVC, restores the vcpkg cache based on your vcpkg.json, and bootstraps vcpkg only when needed.
✅ Windows + MSVC + vcpkg + Cache (GitHub Actions)
yaml

name: Build (Windows + MSVC)

on:
  push:
  pull_request:

jobs:
  build:
    runs-on: windows-latest

    env:
      VCPKG_ROOT: ${{ github.workspace }}\vcpkg
      BUILD_DIR: ${{ github.workspace }}\build

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4

      - name: Install Ninja
        uses: seanmiddleditch/gha-setup-ninja@v4

      - name: Cache vcpkg
        uses: actions/cache@v4
        with:
          path: |
            ${{ env.VCPKG_ROOT }}\installed
            ${{ env.VCPKG_ROOT }}\buildtrees
            ${{ env.VCPKG_ROOT }}\packages
          key: vcpkg-${{ runner.os }}-${{ hashFiles('vcpkg.json') }}
          restore-keys: |
            vcpkg-${{ runner.os }}-

      - name: Clone vcpkg (if not cached)
        shell: pwsh
        run: |
          if (-not (Test-Path "${env:VCPKG_ROOT}")) {
            git clone https://github.com/microsoft/vcpkg.git $env:VCPKG_ROOT
            & "$env:VCPKG_ROOT\bootstrap-vcpkg.bat"
          }

      - name: Configure CMake (MSVC + Ninja)
        run: >
          cmake -S . -B %BUILD_DIR%
          -G "Ninja"
          -DCMAKE_BUILD_TYPE=Release
          -DCMAKE_TOOLCHAIN_FILE=%VCPKG_ROOT%\scripts\buildsystems\vcpkg.cmake

      - name: Build
        run: cmake --build %BUILD_DIR% --config Release

🧠 What this workflow gets right

    Uses MSVC automatically (default compiler on windows-latest)

    Uses Ninja for fast, parallel builds

    Caches vcpkg buildtrees, packages, installed  
    → huge speed‑up on subsequent runs

    Cache key tied to vcpkg.json  
    → cache invalidates when dependencies change

    Bootstraps vcpkg only when missing  
    → avoids unnecessary work