Stop Windows builds failing when the Chocolatey feed is down (#16482)

.github/workflows/build_orca.yml

@@ -33,6 +33,8 @@ jobs:
       ubuntu-ver: '2404'
       ubuntu-ver-str: '_Ubuntu2404'
       ORCA_UPDATER_SIG_KEY: ${{ secrets.ORCA_UPDATER_SIG_KEY }}
+      NSIS_VERSION: '3.13'
+      NSIS_SHA256: BA63DFFC4410EE89193E1CB5A41989991BD77C61068DA17E3156D136B7B0B3D8
 
     steps:
       - name: Checkout
@@ -427,29 +429,46 @@ jobs:
         if: runner.os == 'Windows'
         uses: microsoft/setup-msbuild@v3
 
-      - name: Install nsis
+      # NSIS builds the installer. A pinned portable copy is kept in the Actions
+      # cache, so most runs never download it, and a cache miss fetches the
+      # release archive from SourceForge instead of going through the Chocolatey
+      # community feed, which hosted runners often cannot reach. Prepending it to
+      # PATH also makes cpack use it over the NSIS preinstalled on some images.
+      - name: Restore NSIS
+        id: nsis-cache
+        if: runner.os == 'Windows' && !vars.SELF_HOSTED
+        uses: actions/cache/restore@v6
+        with:
+          path: ${{ runner.temp }}/nsis
+          key: nsis-${{ env.NSIS_VERSION }}
+
+      - name: Install NSIS
         if: runner.os == 'Windows' && !vars.SELF_HOSTED
         shell: pwsh
-        # The Chocolatey community feed intermittently 504s, and `choco install`
-        # exits 0 when package resolution fails that way. Unchecked, the job then
-        # builds for ~25 minutes before `cpack -G NSIS` reports a missing makensis.
-        # Retry the install and verify makensis itself, so a real failure stops here.
         run: |
           dir "C:/Program Files (x86)/Windows Kits/10/Include"
-          $nsisDir = Join-Path ${env:ProgramFiles(x86)} 'NSIS'
+          $nsisDir = Join-Path $env:RUNNER_TEMP 'nsis'
           $makensis = Join-Path $nsisDir 'makensis.exe'
-          for ($attempt = 1; $attempt -le 3 -and -not (Test-Path $makensis); $attempt++) {
-            if ($attempt -gt 1) { Start-Sleep -Seconds (15 * $attempt) }
-            Write-Host "::group::choco install nsis (attempt $attempt)"
-            choco install nsis --yes --no-progress
-            Write-Host "::endgroup::"
-          }
           if (-not (Test-Path $makensis)) {
-            throw "NSIS install failed: $makensis not found after 3 attempts."
+            $zip = Join-Path $env:RUNNER_TEMP "nsis-$env:NSIS_VERSION.zip"
+            curl.exe -fsSL --retry 5 --retry-all-errors --retry-delay 15 -o $zip "https://downloads.sourceforge.net/project/nsis/NSIS%203/$env:NSIS_VERSION/nsis-$env:NSIS_VERSION.zip"
+            if ($LASTEXITCODE -ne 0) { throw "NSIS $env:NSIS_VERSION download failed." }
+            if ((Get-FileHash $zip -Algorithm SHA256).Hash -ne $env:NSIS_SHA256) {
+              throw "NSIS $env:NSIS_VERSION archive does not match its pinned SHA256."
+            }
+            Expand-Archive $zip $env:RUNNER_TEMP
+            Move-Item (Join-Path $env:RUNNER_TEMP "nsis-$env:NSIS_VERSION") $nsisDir
           }
           & $makensis /VERSION
           $nsisDir | Out-File -Append -FilePath $env:GITHUB_PATH -Encoding utf8
 
+      - name: Save NSIS
+        if: runner.os == 'Windows' && !vars.SELF_HOSTED && steps.nsis-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v6
+        with:
+          path: ${{ runner.temp }}/nsis
+          key: nsis-${{ env.NSIS_VERSION }}
+
       - name: Build slicer Win
         if: runner.os == 'Windows'
         working-directory: ${{ github.workspace }}