Windows installation overhaul

.github/actions/setup-randlapack-deps-windows/action.yml

@@ -1,11 +1,17 @@
 name: setup-randlapack-deps-windows
 description: >
-  Builds/restores RandLAPACK's native Windows dependencies (oneMKL via vcpkg,
-  GoogleTest, Random123, BLAS++, LAPACK++) and exports their locations as
-  environment variables (MKLROOT, googletest_PREFIX, Random123_DIR, blaspp_DIR,
-  lapackpp_DIR). Requires an initialized MSVC environment (ilammy/msvc-dev-cmd).
+  Builds/restores RandLAPACK's native Windows dependencies (a BLAS/LAPACK
+  backend -- oneMKL from Intel's NuGet packages or OpenBLAS release binaries --
+  plus GoogleTest, Random123, BLAS++, LAPACK++) and exports their locations as
+  environment variables (RANDNLA_BLAS_BACKEND, RANDNLA_BLAS_BIN, MKLROOT for
+  mkl, googletest_PREFIX, Random123_DIR, blaspp_DIR, lapackpp_DIR). Requires an
+  initialized MSVC environment (ilammy/msvc-dev-cmd).
 
 inputs:
+  blas-backend:
+    description: "BLAS/LAPACK backend for the dependency stack: mkl or openblas."
+    required: false
+    default: "mkl"
   sanitize-address:
     description: Build an AddressSanitizer-instrumented GoogleTest.
     required: false
@@ -14,50 +20,67 @@ inputs:
 runs:
   using: composite
   steps:
-    # Caches live beside the workspace, keyed on the setup script so any recipe
-    # change invalidates them.
-    - name: cache oneMKL (vcpkg)
+    # Cache keys use MANUAL revision literals (-r<N>), bumped here whenever
+    # the corresponding recipe in setup.ps1 changes. Do NOT key on
+    # hashFiles(): it resolves paths relative to GITHUB_WORKSPACE, and the
+    # install-script workflow checks this repo out under RandLAPACK\, where
+    # the glob matches nothing and hashFiles() silently returns "" -- the two
+    # workflows then read/write DIFFERENT caches while appearing to share.
+    - name: cache oneMKL (NuGet)
+      if: inputs.blas-backend == 'mkl'
+      uses: actions/cache@v4
+      with:
+        path: ${{ github.workspace }}\..\windows-deps\onemkl-2025.2.0.627
+        key: windows-nuget-intel-mkl-2026.1.0.226-r1
+
+    - name: cache OpenBLAS (release binaries)
+      if: inputs.blas-backend == 'openblas'
       uses: actions/cache@v4
       with:
-        path: ${{ github.workspace }}\..\windows-deps\vcpkg-installed
-        key: windows-vcpkg-intel-mkl-1-${{ hashFiles('.github/actions/setup-randlapack-deps-windows/setup.ps1') }}
+        path: ${{ github.workspace }}\..\windows-deps\openblas-0.3.34
+        key: windows-openblas-0.3.34-r1
 
     - name: cache GoogleTest
       if: inputs.sanitize-address != 'true'
       uses: actions/cache@v4
       with:
         path: ${{ github.workspace }}\..\windows-deps\googletest-install
-        key: windows-msvc-googletest-1.17.0-1-${{ hashFiles('.github/actions/setup-randlapack-deps-windows/setup.ps1') }}
+        key: windows-msvc-googletest-1.18.0-ninja-r1
 
     - name: cache GoogleTest (ASan)
       if: inputs.sanitize-address == 'true'
       uses: actions/cache@v4
       with:
         path: ${{ github.workspace }}\..\windows-deps\googletest-asan-install
-        key: windows-msvc-googletest-asan-1.17.0-1-${{ hashFiles('.github/actions/setup-randlapack-deps-windows/setup.ps1') }}
+        key: windows-msvc-googletest-asan-1.18.0-ninja-r1
 
     - name: cache Random123
       uses: actions/cache@v4
       with:
         path: ${{ github.workspace }}\..\windows-deps\Random123-install
-        key: windows-random123-1-${{ hashFiles('.github/actions/setup-randlapack-deps-windows/setup.ps1') }}
+        key: windows-random123-1.14.0-r1
 
     - name: cache BLAS++
       uses: actions/cache@v4
       with:
-        path: ${{ github.workspace }}\..\windows-deps\blaspp-install
-        key: windows-msvc-blaspp-remove-symv-debug-print-ilp64-sequential-1-${{ hashFiles('.github/actions/setup-randlapack-deps-windows/setup.ps1') }}
+        path: ${{ github.workspace }}\..\windows-deps\blaspp-${{ inputs.blas-backend }}-install
+        key: windows-msvc-blaspp-upstream-3057185-${{ inputs.blas-backend }}-ninja-r2
 
     - name: cache LAPACK++
       uses: actions/cache@v4
       with:
-        path: ${{ github.workspace }}\..\windows-deps\lapackpp-install
-        key: windows-msvc-lapackpp-msvc-direct-includes-ilp64-sequential-1-${{ hashFiles('.github/actions/setup-randlapack-deps-windows/setup.ps1') }}
+        path: ${{ github.workspace }}\..\windows-deps\lapackpp-${{ inputs.blas-backend }}-install
+        key: windows-msvc-lapackpp-upstream-40b9d0d-${{ inputs.blas-backend }}-ninja-r2
 
     - name: build missing dependencies
       shell: pwsh
       run: |
         $sanitizeAddress = '${{ inputs.sanitize-address }}' -eq 'true'
+        # -Yes: never prompt. Prompts are already skipped when stdin is not
+        # a terminal, but stating it makes the intent explicit and survives
+        # any future change to that detection.
         & "$env:GITHUB_ACTION_PATH/setup.ps1" `
           -DependencyRoot "${env:GITHUB_WORKSPACE}\..\windows-deps" `
+          -Backend '${{ inputs.blas-backend }}' `
+          -Yes `
           -SanitizeAddress:$sanitizeAddress