diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
new file mode 100644
index 00000000..5367be83
--- /dev/null
+++ b/.github/workflows/windows.yml
@@ -0,0 +1,110 @@
+name: Windows Build
+
+on:
+  workflow_dispatch:
+
+jobs:
+  build_windows:
+    name: Windows x64 build (library)
+    runs-on: windows-latest
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          submodules: recursive
+
+      - uses: compnerd/gha-setup-swift@main
+        with:
+          swift-version: swift-6.3-release
+          swift-build: 6.3-RELEASE
+
+      - name: Configure, build, and verify (library only, vendors disabled)
+        shell: pwsh
+        run: |
+          $programFilesX86 = [Environment]::GetEnvironmentVariable("ProgramFiles(x86)")
+          $vsWhere = Join-Path $programFilesX86 "Microsoft Visual Studio\Installer\vswhere.exe"
+          if (-not (Test-Path $vsWhere)) { throw "vswhere.exe not found: $vsWhere" }
+
+          $vsRoot = & $vsWhere -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath
+          if (-not $vsRoot) { throw "Visual Studio with MSVC tools not found" }
+
+          $vsDevCmd = Join-Path $vsRoot "Common7\Tools\VsDevCmd.bat"
+          if (-not (Test-Path $vsDevCmd)) { throw "VsDevCmd.bat not found: $vsDevCmd" }
+
+          cmd /s /c "`"$vsDevCmd`" -arch=amd64 -host_arch=amd64 >nul && set" | ForEach-Object {
+            if ($_ -match "^(.*?)=(.*)$") {
+              $name = $matches[1]
+              if ($name -and -not $name.StartsWith("=")) {
+                Set-Item -Path "Env:$name" -Value $matches[2]
+              }
+            }
+          }
+
+          $swiftCommand = Get-Command swift.exe -ErrorAction SilentlyContinue
+          if (-not $swiftCommand) { throw "swift.exe not found on PATH" }
+          $swiftExe = $swiftCommand.Source
+          $toolchainBin = Split-Path $swiftExe -Parent
+          $usrDir = Split-Path $toolchainBin -Parent
+          $toolchainDir = Split-Path $usrDir -Parent
+          $toolchainsDir = Split-Path $toolchainDir -Parent
+          $swiftRoot = Split-Path $toolchainsDir -Parent
+
+          if (-not $env:SDKROOT -or -not (Test-Path $env:SDKROOT)) {
+            $sdkPath = Get-ChildItem (Join-Path $swiftRoot "Platforms\*\Windows.platform\Developer\SDKs\Windows.sdk") -Directory | Select-Object -First 1
+            if (-not $sdkPath) { throw "Windows.sdk not found under Swift install root: $swiftRoot" }
+            $env:SDKROOT = $sdkPath.FullName
+          }
+
+          $targetInfo = swift -print-target-info | ConvertFrom-Json
+          $runtimePaths = @($targetInfo.paths.runtimeLibraryPaths | Where-Object { Test-Path $_ })
+          if ($runtimePaths.Count -eq 0) { throw "Swift runtime paths not found" }
+
+          $env:PATH = "$toolchainBin;$($runtimePaths -join ';');$env:PATH"
+
+          $clangCl = Join-Path $toolchainBin "clang-cl.exe"
+          if (-not (Test-Path $clangCl)) { throw "clang-cl.exe not found: $clangCl" }
+          $ninjaExe = (Get-Command ninja.exe).Source
+          $linkExe = (Get-Command link.exe).Source
+          $libExe = (Get-Command lib.exe).Source
+
+          swift --version
+          cmake --version
+          ninja --version
+          & $clangCl --version
+
+          $repoRoot = (Get-Location).Path
+          New-Item -ItemType Directory -Path .cmake -Force | Out-Null
+          Set-Location .cmake
+
+          cmake -G Ninja `
+            -DCMAKE_MAKE_PROGRAM="$ninjaExe" `
+            -DCMAKE_C_COMPILER="$clangCl" `
+            -DCMAKE_CXX_COMPILER="$clangCl" `
+            -DCMAKE_LINKER="$linkExe" `
+            -DCMAKE_AR="$libExe" `
+            -DCMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY `
+            -DPP_BUILD_USE_OPENSSL=OFF `
+            -DPP_BUILD_USE_MBEDTLS=OFF `
+            -DPP_BUILD_USE_OPENVPN=OFF `
+            -DPP_BUILD_USE_WIREGUARD=OFF `
+            -DPP_BUILD_LIBRARY=ON `
+            ..
+
+          if ($LASTEXITCODE -ne 0) { throw "CMake configure failed" }
+
+          cmake --build . --verbose
+
+          if ($LASTEXITCODE -ne 0) { throw "Build failed" }
+
+          Set-Location $repoRoot
+          $libs = @(
+            "bin\windows-amd64\partout\libpartout.lib",
+            "bin\windows-amd64\partout\libpartout_c.lib"
+          )
+
+          foreach ($lib in $libs) {
+            if (-not (Test-Path $lib)) { throw "Missing artifact: $lib" }
+            Write-Host "$lib : $((Get-Item $lib).Length) bytes"
+          }
+
+          dumpbin /headers "bin\windows-amd64\partout\libpartout_c.lib" | Select-String "machine"