diff --git a/.github/actions/windows-msvc-env/action.yml b/.github/actions/windows-msvc-env/action.yml
new file mode 100644
index 000000000..a105ca429
--- /dev/null
+++ b/.github/actions/windows-msvc-env/action.yml
@@ -0,0 +1,109 @@
+name: Set up Windows MSVC / clang-cl environment
+description: >
+  Import the Visual Studio x64 developer environment (vcvarsall) into the job so
+  cl/clang-cl/ninja and the MSVC headers and libraries are available to later
+  steps. Exposes the resolved C++ compiler path and the MSVC toolset version for
+  use in cache keys.
+
+inputs:
+  compiler:
+    description: Compiler to set up - "msvc" (cl) or "clang-cl".
+    required: true
+
+outputs:
+  toolset:
+    description: MSVC toolset version (stable identifier for cache keys).
+    value: ${{ steps.setup.outputs.toolset }}
+  cxx-path:
+    description: Full path to the resolved C++ compiler.
+    value: ${{ steps.setup.outputs.cxx-path }}
+
+runs:
+  using: composite
+  steps:
+  - id: setup
+    shell: pwsh
+    run: |
+      $ErrorActionPreference = 'Stop'
+
+      $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+      if (-not (Test-Path $vswhere)) { throw "vswhere not found at $vswhere" }
+      $vsPath = & $vswhere -latest -products * -property installationPath
+      if (-not $vsPath) { throw "No Visual Studio installation found" }
+      Write-Host "Visual Studio: $vsPath"
+
+      $vcvarsall = "$vsPath\VC\Auxiliary\Build\vcvarsall.bat"
+      if (-not (Test-Path $vcvarsall)) { throw "vcvarsall.bat not found at $vcvarsall" }
+
+      # Snapshot the environment, run vcvarsall x64, then diff to capture its changes.
+      $before = @{}
+      Get-ChildItem env: | ForEach-Object { $before[$_.Name] = $_.Value }
+
+      $tmp = [System.IO.Path]::GetTempFileName()
+      cmd /c "`"$vcvarsall`" x64 && set > `"$tmp`""
+      if ($LASTEXITCODE -ne 0) { throw "vcvarsall.bat failed with exit code $LASTEXITCODE" }
+      $after = @{}
+      Get-Content $tmp | ForEach-Object {
+        if ($_ -match '^([^=]+)=(.*)$') { $after[$matches[1]] = $matches[2] }
+      }
+      Remove-Item $tmp
+
+      # clang-cl is shipped with the VS LLVM component but is not added by vcvarsall.
+      $clangDir = $null
+      if ('${{ inputs.compiler }}' -eq 'clang-cl') {
+        $candidates = @(
+          "$vsPath\VC\Tools\Llvm\x64\bin\clang-cl.exe",
+          "$vsPath\VC\Tools\Llvm\bin\clang-cl.exe"
+        )
+        foreach ($c in $candidates) { if (Test-Path $c) { $clangDir = Split-Path $c; break } }
+        if (-not $clangDir) { throw "clang-cl.exe not found under $vsPath\VC\Tools\Llvm" }
+      }
+
+      # Apply to the current process so the compiler resolves within this step.
+      foreach ($name in $after.Keys) {
+        [System.Environment]::SetEnvironmentVariable($name, $after[$name], 'Process')
+      }
+      if ($clangDir) { $env:PATH = "$clangDir;$env:PATH" }
+
+      # Persist non-PATH changes to GITHUB_ENV and PATH additions to GITHUB_PATH.
+      foreach ($name in $after.Keys) {
+        if ($name -ieq 'Path') { continue }
+        if ($before[$name] -ne $after[$name]) {
+          "$name=$($after[$name])" >> $env:GITHUB_ENV
+        }
+      }
+      $beforePath = @($before['Path'] -split ';')
+      $newEntries = @($after['Path'] -split ';') | Where-Object { $_ -and ($beforePath -notcontains $_) }
+      if ($clangDir) { $clangDir >> $env:GITHUB_PATH }
+      foreach ($p in $newEntries) { $p >> $env:GITHUB_PATH }
+
+      # Resolve the compiler and a stable toolset version for cache keys.
+      if ('${{ inputs.compiler }}' -eq 'clang-cl') {
+        $cxx = (Get-Command clang-cl.exe -ErrorAction Stop).Source
+      } else {
+        $cxx = (Get-Command cl.exe -ErrorAction Stop).Source
+      }
+      Write-Host "C++ compiler: $cxx"
+      if ('${{ inputs.compiler }}' -eq 'clang-cl') { & $cxx --version 2>&1 | Write-Host }
+
+      $toolsetFile = "$vsPath\VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt"
+      $toolset = (Get-Content $toolsetFile -ErrorAction Stop | Select-Object -First 1).Trim()
+      Write-Host "MSVC toolset: $toolset"
+
+      "toolset=$toolset" >> $env:GITHUB_OUTPUT
+      "cxx-path=$cxx" >> $env:GITHUB_OUTPUT
+
+      # Bootstrap vcpkg if not pre-installed.
+      $vcpkgRoot = if ($env:VCPKG_INSTALLATION_ROOT) { $env:VCPKG_INSTALLATION_ROOT } else { 'C:\vcpkg' }
+      if (Test-Path "$vcpkgRoot\vcpkg.exe") {
+        Write-Host "vcpkg already available at $vcpkgRoot"
+      } else {
+        Write-Host "vcpkg not found — bootstrapping into $vcpkgRoot"
+        git clone https://github.com/microsoft/vcpkg.git $vcpkgRoot --depth 1
+        & "$vcpkgRoot\bootstrap-vcpkg.bat" -disableMetrics
+        if ($LASTEXITCODE -ne 0) { throw "vcpkg bootstrap failed ($LASTEXITCODE)" }
+        "VCPKG_INSTALLATION_ROOT=$vcpkgRoot" >> $env:GITHUB_ENV
+      }
+      # vcvarsall sets VCPKG_ROOT to VS's bundled copy; override it to match our
+      # standalone installation so vcpkg.exe doesn't warn about the mismatch.
+      "VCPKG_ROOT=$vcpkgRoot" >> $env:GITHUB_ENV
diff --git a/.github/workflows/build-and-test-windows.yaml b/.github/workflows/build-and-test-windows.yaml
new file mode 100644
index 000000000..9e45e1692
--- /dev/null
+++ b/.github/workflows/build-and-test-windows.yaml
@@ -0,0 +1,254 @@
+name: Build and Test (Windows)
+
+on:
+  push:
+    branches:
+    - main
+  pull_request:
+    branches:
+    - '**'
+  merge_group:
+  workflow_dispatch:
+    inputs:
+      run_slow_tests:
+        description: Run slow tests
+        required: false
+        default: false
+        type: boolean
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+env:
+  VCPKG_TRIPLET: x64-windows-static-md
+  QDK_UARCH: x86-64-v3
+  # Bump to force a rebuild of the cached dependencies.
+  DEPS_CACHE_VERSION: v1
+
+jobs:
+  # ----------------------------------------------------------------------------
+  # One job per compiler (msvc, clang-cl). On a cache miss the slow FetchContent
+  # dependencies (libint2/gauxc/ecpint/blaspp/lapackpp) and vcpkg packages are
+  # built and cached; on a hit they are restored and the build continues
+  # straight to compiling qdk. All steps run on the same runner so workspace
+  # paths are consistent and no CMakeCache juggling is needed.
+  # To force a dep cache rebuild, bump DEPS_CACHE_VERSION in the env block.
+  # ----------------------------------------------------------------------------
+  build-test:
+    name: ${{ matrix.compiler }} - Build & test
+    runs-on: [self-hosted, 1ES.Pool=1es-gh-Dads_v5-pool-wus2, 1ES.ImageOverride=windows-2025-1espt, 'JobId=qdk_chemistry-win-${{ strategy.job-index }}-${{ github.run_id }}-${{ github.run_number }}-${{ github.run_attempt }}']
+    timeout-minutes: 480
+    permissions:
+      contents: read
+    strategy:
+      fail-fast: false
+      matrix:
+        compiler: [msvc, clang-cl]
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v6
+      with:
+        submodules: recursive
+
+    - name: Set up ${{ matrix.compiler }} environment
+      id: env
+      uses: ./.github/actions/windows-msvc-env
+      with:
+        compiler: ${{ matrix.compiler }}
+
+    - name: Set up Python
+      uses: actions/setup-python@v6
+      with:
+        python-version: '3.13'
+
+    - name: Set memory-aware build parallelism
+      shell: pwsh
+      id: env2
+      run: |
+        # qdk TUs that include libint2 engine.impl.h peak at several GB under MSVC;
+        # cap concurrency by available RAM (~4 GB/job) to avoid C1060 (compiler out
+        # of heap space). Scales up automatically on a larger runner.
+        $cpu = [int]$env:NUMBER_OF_PROCESSORS
+        $ramGB = [math]::Round((Get-CimInstance Win32_ComputerSystem).TotalPhysicalMemory / 1GB)
+        $jobs = [math]::Min($cpu, [math]::Max(1, [math]::Round($ramGB / 4)))
+        Write-Host "CPUs=$cpu RAM=${ramGB}GB -> CMAKE_BUILD_PARALLEL_LEVEL=$jobs"
+        "CMAKE_BUILD_PARALLEL_LEVEL=$jobs" >> $env:GITHUB_ENV
+        # Include a short hash of the workspace path in the cache key so that
+        # runners with different workspace base directories (e.g. D:\a\ vs
+        # D:\a\_work\) each get their own cache entry and never hit a
+        # CMakeCache.txt path mismatch on restore.
+        $wsPath = "${{ github.workspace }}".ToLower().Replace('\', '/')
+        $wsBytes = [System.Text.Encoding]::UTF8.GetBytes($wsPath)
+        $wsHash = ([System.Security.Cryptography.SHA256]::Create().ComputeHash($wsBytes) |
+                    ForEach-Object { $_.ToString('x2') }) -join ''
+        "wshash=$($wsHash.Substring(0, 12))" >> $env:GITHUB_OUTPUT
+
+    - name: Restore dependency cache
+      id: cache
+      uses: actions/cache/restore@v5
+      with:
+        path: |
+          vcpkg_installed
+          cpp/build-${{ matrix.compiler }}
+        key: >-
+          windows-deps-${{ matrix.compiler }}-${{ env.VCPKG_TRIPLET }}-vs${{ steps.env.outputs.toolset }}-${{ env.DEPS_CACHE_VERSION }}-ws${{ steps.env2.outputs.wshash }}-${{ hashFiles('vcpkg.json', 'vcpkg-configuration.json', 'vcpkg-overlay/**', 'cpp/manifest/qdk-chemistry/cgmanifest.json', 'external/macis/manifest/cgmanifest.json', 'cpp/cmake/third_party.cmake', 'cpp/cmake/patches/**', 'cpp/cmake/modules/DependencyManager.cmake', 'external/macis/src/lobpcgxx/CMakeLists.txt', '.pipelines/toolchains/windows.cmake') }}
+
+    - name: Validate cached build directory
+      id: cache-validate
+      if: steps.cache.outputs.cache-hit == 'true'
+      shell: pwsh
+      run: |
+        # If the cached CMakeCache.txt was written on a runner with a different
+        # workspace base path (e.g. D:\a\ vs D:\a\_work\) the cached build.ninja
+        # files will reference stale absolute paths and cmake/ninja will fail.
+        # Detect this by checking whether the current workspace path appears in
+        # CMakeCache.txt (case-insensitive, forward-slash-normalised) and, if not,
+        # wipe the build directory so the configure + build steps run from scratch.
+        $buildDir = "cpp/build-${{ matrix.compiler }}"
+        $cacheFile = "$buildDir/CMakeCache.txt"
+        if (-not (Test-Path $cacheFile)) {
+          Write-Host "No CMakeCache.txt in restored cache — treating as cache miss"
+          "cache-valid=false" >> $env:GITHUB_OUTPUT
+          exit 0
+        }
+        $ws = "${{ github.workspace }}".Replace('\', '/').ToLower()
+        $content = (Get-Content $cacheFile -Raw).ToLower().Replace('\', '/')
+        if ($content -notmatch [regex]::Escape($ws)) {
+          Write-Host "Workspace path mismatch in cached CMakeCache.txt (expected: $ws)"
+          Remove-Item -Recurse -Force $buildDir -ErrorAction SilentlyContinue
+          "cache-valid=false" >> $env:GITHUB_OUTPUT
+        } else {
+          Write-Host "Cached build directory paths match current workspace"
+          "cache-valid=true" >> $env:GITHUB_OUTPUT
+        }
+
+    - name: Install vcpkg dependencies
+      if: steps.cache.outputs.cache-hit != 'true' || steps.cache-validate.outputs.cache-valid == 'false'
+      shell: pwsh
+      run: |
+        $vcpkg = $env:VCPKG_INSTALLATION_ROOT
+        if (-not $vcpkg) { $vcpkg = 'C:\vcpkg' }
+        & "$vcpkg\vcpkg.exe" install `
+          --triplet ${{ env.VCPKG_TRIPLET }} `
+          --x-manifest-root="${{ github.workspace }}" `
+          --x-install-root="${{ github.workspace }}\vcpkg_installed" `
+          --overlay-ports="${{ github.workspace }}\vcpkg-overlay\ports"
+        if ($LASTEXITCODE -ne 0) { throw "vcpkg install failed ($LASTEXITCODE)" }
+
+    - name: Configure CMake
+      if: steps.cache.outputs.cache-hit != 'true' || steps.cache-validate.outputs.cache-valid == 'false'
+      shell: pwsh
+      run: |
+        $vcpkg = $env:VCPKG_INSTALLATION_ROOT
+        if (-not $vcpkg) { $vcpkg = 'C:\vcpkg' }
+        cmake -S cpp -B "cpp/build-${{ matrix.compiler }}" -GNinja `
+          -DQDK_UARCH=${{ env.QDK_UARCH }} `
+          -DQDK_CHEMISTRY_ENABLE_COVERAGE=OFF `
+          -DQDK_CHEMISTRY_ENABLE_MPI=OFF `
+          -DMACIS_ENABLE_TESTS=OFF `
+          -DBUILD_SHARED_LIBS=OFF `
+          -DBUILD_TESTING=ON `
+          -DCMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE=PRE_TEST `
+          -DVCPKG_APPLOCAL_DEPS=OFF `
+          -DCMAKE_BUILD_TYPE=Release `
+          -DCMAKE_C_COMPILER="${{ steps.env.outputs.cxx-path }}" `
+          -DCMAKE_CXX_COMPILER="${{ steps.env.outputs.cxx-path }}" `
+          -DCMAKE_INSTALL_PREFIX="${{ github.workspace }}\install-${{ matrix.compiler }}" `
+          -DCMAKE_TOOLCHAIN_FILE="$vcpkg\scripts\buildsystems\vcpkg.cmake" `
+          -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE="${{ github.workspace }}\.pipelines\toolchains\windows.cmake" `
+          -DVCPKG_TARGET_TRIPLET=${{ env.VCPKG_TRIPLET }} `
+          -DVCPKG_INSTALLED_DIR="${{ github.workspace }}\vcpkg_installed" `
+          -DFETCHCONTENT_QUIET=OFF
+        if ($LASTEXITCODE -ne 0) { throw "CMake configure failed ($LASTEXITCODE)" }
+
+    - name: Build C++ dependencies
+      if: steps.cache.outputs.cache-hit != 'true' || steps.cache-validate.outputs.cache-valid == 'false'
+      shell: pwsh
+      run: |
+        # libint2_cxx is a CMake INTERFACE target (no Ninja phony); libint2_obj is
+        # the actual OBJECT library that compiles all libint2 sources.
+        cmake --build "cpp/build-${{ matrix.compiler }}" --target libint2_obj ecpint gauxc blaspp lapackpp
+        if ($LASTEXITCODE -ne 0) { throw "Dependency build failed ($LASTEXITCODE)" }
+
+    - name: Save dependency cache
+      if: steps.cache.outputs.cache-hit != 'true' || steps.cache-validate.outputs.cache-valid == 'false'
+      uses: actions/cache/save@v5
+      with:
+        path: |
+          vcpkg_installed
+          cpp/build-${{ matrix.compiler }}
+        key: >-
+          windows-deps-${{ matrix.compiler }}-${{ env.VCPKG_TRIPLET }}-vs${{ steps.env.outputs.toolset }}-${{ env.DEPS_CACHE_VERSION }}-ws${{ steps.env2.outputs.wshash }}-${{ hashFiles('vcpkg.json', 'vcpkg-configuration.json', 'vcpkg-overlay/**', 'cpp/manifest/qdk-chemistry/cgmanifest.json', 'external/macis/manifest/cgmanifest.json', 'cpp/cmake/third_party.cmake', 'cpp/cmake/patches/**', 'cpp/cmake/modules/DependencyManager.cmake', 'external/macis/src/lobpcgxx/CMakeLists.txt', '.pipelines/toolchains/windows.cmake') }}
+
+    - name: Build C++ library
+      shell: pwsh
+      run: |
+        # Dep targets are already up-to-date (either just built or restored from
+        # cache); Ninja skips them and only compiles qdk + test sources.
+        # Honors CMAKE_BUILD_PARALLEL_LEVEL set above (memory-aware).
+        cmake --build "cpp/build-${{ matrix.compiler }}"
+        if ($LASTEXITCODE -ne 0) { throw "CMake build failed ($LASTEXITCODE)" }
+
+    - name: Run C++ tests
+      shell: pwsh
+      env:
+        OMP_NUM_THREADS: '2'
+      run: |
+        Push-Location "cpp/build-${{ matrix.compiler }}"
+        # Exclude MACIS_SERIAL_TEST (as on Linux) and libint2's own unit tests:
+        # libint2/unit/build is a compile-at-test-time meta-test of the vendored
+        # libint2 dependency that exceeds the ctest timeout under MSVC. qdk's own
+        # tests still run.
+        ctest --output-on-failure --verbose --timeout 400 `
+          --output-junit ctest_results.xml `
+          -E "MACIS_SERIAL_TEST|libint2/unit"
+        $code = $LASTEXITCODE
+        Pop-Location
+        if ($code -ne 0) { throw "ctest failed ($code)" }
+
+    - name: Install C++ library
+      shell: pwsh
+      run: |
+        cmake --install "cpp/build-${{ matrix.compiler }}"
+        if ($LASTEXITCODE -ne 0) { throw "CMake install failed ($LASTEXITCODE)" }
+
+    - name: Build & install Python package
+      shell: pwsh
+      run: |
+        $vcpkg = $env:VCPKG_INSTALLATION_ROOT
+        if (-not $vcpkg) { $vcpkg = 'C:\vcpkg' }
+        $prefix = "${{ github.workspace }}\vcpkg_installed\${{ env.VCPKG_TRIPLET }};${{ github.workspace }}\install-${{ matrix.compiler }}"
+        Push-Location python
+        # plugins (pyscf) do not build on Windows; install the test extra only.
+        # QDK_ALLOW_DEPENDENCY_FETCH=OFF: fail fast if the installed qdk is not
+        # reused (avoids a silent multi-hour rebuild of the C++ stack from source).
+        python -m pip install -v ".[test]" `
+          --config-settings=cmake.args="-GNinja" `
+          --config-settings=cmake.define.CMAKE_PREFIX_PATH="$prefix" `
+          --config-settings=cmake.define.QDK_ALLOW_DEPENDENCY_FETCH=OFF `
+          --config-settings=cmake.define.CMAKE_C_COMPILER="${{ steps.env.outputs.cxx-path }}" `
+          --config-settings=cmake.define.CMAKE_CXX_COMPILER="${{ steps.env.outputs.cxx-path }}" `
+          --config-settings=cmake.define.CMAKE_TOOLCHAIN_FILE="$vcpkg\scripts\buildsystems\vcpkg.cmake" `
+          --config-settings=cmake.define.VCPKG_CHAINLOAD_TOOLCHAIN_FILE="${{ github.workspace }}\.pipelines\toolchains\windows.cmake" `
+          --config-settings=cmake.define.VCPKG_TARGET_TRIPLET="${{ env.VCPKG_TRIPLET }}" `
+          --config-settings=cmake.define.VCPKG_INSTALLED_DIR="${{ github.workspace }}\vcpkg_installed"
+        if ($LASTEXITCODE -ne 0) { Pop-Location; throw "Python package install failed ($LASTEXITCODE)" }
+        python -c "import qdk_chemistry; print('qdk_chemistry version:', qdk_chemistry.__version__)"
+        if ($LASTEXITCODE -ne 0) { Pop-Location; throw "Python import check failed ($LASTEXITCODE)" }
+        Pop-Location
+
+    - name: Run Python tests
+      shell: pwsh
+      env:
+        OMP_NUM_THREADS: '2'
+        QDK_CHEMISTRY_RUN_SLOW_TESTS: ${{ inputs.run_slow_tests && '1' || '0' }}
+      run: |
+        Push-Location python
+        pytest -v --tb=short
+        $code = $LASTEXITCODE
+        Pop-Location
+        if ($code -ne 0) { throw "pytest failed ($code)" }
diff --git a/.github/workflows/build-and-test.yaml b/.github/workflows/build-and-test.yaml
index c128ae226..715c40938 100644
--- a/.github/workflows/build-and-test.yaml
+++ b/.github/workflows/build-and-test.yaml
@@ -15,6 +15,11 @@ on:
         required: false
         default: false
         type: boolean
+      rebuild_dep_cache:
+        description: Rebuild dependency cache from scratch (ignore existing cache)
+        required: false
+        default: false
+        type: boolean
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -219,7 +224,8 @@ jobs:
 
     - name: Cache C++ dependency install # Checks if manifest files or build script have changed to rebuild dependencies
       id: cache-cpp-deps
-      uses: actions/cache@v5
+      if: ${{ !inputs.rebuild_dep_cache }}
+      uses: actions/cache/restore@v5
       with:
         path: |
           ${{ env.CPP_DEPS_PREFIX }}
@@ -244,6 +250,16 @@ jobs:
           ${{ github.workspace }}/cpp/manifest/qdk-chemistry/cgmanifest.json \
           ${{ github.workspace }}/external/macis/manifest/cgmanifest.json
 
+    - name: Save C++ dependency cache
+      if: steps.cache-cpp-deps.outputs.cache-hit != 'true'
+      uses: actions/cache/save@v5
+      with:
+        path: |
+          ${{ env.CPP_DEPS_PREFIX }}
+        key: >-
+          cpp-deps-${{ runner.os }}-${{ matrix.uarch }}-
+          ${{ hashFiles('cpp/manifest/qdk-chemistry/cgmanifest.json', 'external/macis/manifest/cgmanifest.json', '.devcontainer/scripts/install_cpp_dependencies.sh') }}
+
     - name: Configure C++ RelWithDebInfo/Coverage build
       run: |
         if [ "${{ matrix.os-name }}" == "macOS" ]; then
diff --git a/.gitignore b/.gitignore
index 4e8546ada..eac2279cf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -239,3 +239,6 @@ python/VERSION
 
 # Claude
 .claude
+
+# Copilot agent
+agency.toml
diff --git a/.pipelines/pip-scripts/bootstrap-conda.ps1 b/.pipelines/pip-scripts/bootstrap-conda.ps1
new file mode 100644
index 000000000..801706084
--- /dev/null
+++ b/.pipelines/pip-scripts/bootstrap-conda.ps1
@@ -0,0 +1,113 @@
+<#
+.SYNOPSIS
+    Bootstrap ms-ensureconda and create a named conda environment.
+
+.DESCRIPTION
+    PowerShell equivalent of bootstrap-conda.sh for Windows 1ES builds.
+
+    This script is meant to be *called* (not dot-sourced) from other scripts
+    or YAML powershell steps. It writes all diagnostic output via Write-Host
+    and emits exactly one line to stdout: the resolved path to conda.exe.
+    Callers capture it with:
+
+        $condaExe = & "$PSScriptRoot\bootstrap-conda.ps1" -EnvName buildenv -PythonVersion 3.11
+
+    Required env var:
+        SYSTEM_ACCESSTOKEN   Pipeline access token, mapped from $(System.AccessToken).
+                             Used by the azure_artifacts_conda_auth plugin that is
+                             pre-registered in ms-ensureconda's conda distribution.
+
+    Rationale: ms-ensureconda is the Microsoft-approved conda bootstrapper for CI
+    builds. See:
+        https://eng.ms/docs/more/languages-at-microsoft/python/articles/anaconda/install
+    All network access goes through the Azure Artifacts feed (1ES CFSClean blocks
+    public conda channels). The azure_artifacts_conda_auth plugin reads
+    ARTIFACTS_CONDA_TOKEN; we set it to SYSTEM_ACCESSTOKEN before every conda call.
+#>
+param(
+    # Name of the conda environment to create (e.g. "buildenv" or "testenv").
+    [Parameter(Mandatory)] [string]$EnvName,
+    # Python version for the new environment (e.g. "3.11").
+    [Parameter(Mandatory)] [string]$PythonVersion
+)
+$ErrorActionPreference = 'Stop'
+
+if (-not $env:SYSTEM_ACCESSTOKEN) {
+    throw "bootstrap-conda.ps1: SYSTEM_ACCESSTOKEN must be set before calling this script."
+}
+
+$ENSURECONDA_PKG    = 'ms-ensureconda==2026.6.1'
+$MAX_ATTEMPTS       = 3
+$RETRY_DELAY_SEC    = 30
+$CONDA_FEED_ROOT    = 'https://pkgs.dev.azure.com/ms-azurequantum/AzureQuantum/_packaging/quantum-apps-dependencies/Conda/repo'
+
+function _Bootstrap {
+    param([string]$EnvName, [string]$PythonVersion)
+
+    Write-Host "Installing $ENSURECONDA_PKG and bootstrapping conda..."
+
+    # Use a throwaway venv so we don't fight PEP 668 (externally-managed Python).
+    # Clean any stale venv first (idempotent on retries / self-hosted agents).
+    $bootstrapVenv = Join-Path $env:TEMP "qdk-bootstrap-venv-$EnvName"
+    Remove-Item -Recurse -Force $bootstrapVenv -ErrorAction SilentlyContinue
+    python -m venv $bootstrapVenv
+    if ($LASTEXITCODE -ne 0) { throw "Bootstrap venv creation failed ($LASTEXITCODE)" }
+    $venvPy = Join-Path $bootstrapVenv 'Scripts\python.exe'
+
+    & $venvPy -m pip install --quiet $ENSURECONDA_PKG 2>&1 | Out-Host
+    if ($LASTEXITCODE -ne 0) { throw "ms-ensureconda install failed ($LASTEXITCODE)" }
+
+    # ms-ensureconda --envfile writes a shell-sourceable KEY=VALUE file with
+    # CONDA_EXE, CONDA_BASH_HOOK, etc. We parse CONDA_EXE from it.
+    $condaEnvFile = Join-Path $env:TEMP "qdk-ensureconda-$EnvName.env"
+    $env:ARTIFACTS_CONDA_TOKEN = $env:SYSTEM_ACCESSTOKEN
+    & $venvPy -m ensureconda --envfile $condaEnvFile 2>&1 | Out-Host
+    if ($LASTEXITCODE -ne 0) { throw "ensureconda failed ($LASTEXITCODE)" }
+
+    $condaExe = Get-Content $condaEnvFile |
+        Where-Object { $_ -match "^(?:export\s+)?CONDA_EXE=" } |
+        Select-Object -First 1 |
+        ForEach-Object { ($_ -split '=', 2)[1].Trim().Trim("'`"") }
+    if (-not $condaExe -or -not (Test-Path $condaExe)) {
+        throw "CONDA_EXE not found or path does not exist: '$condaExe'"
+    }
+    Write-Host "conda: $condaExe  ($( & $condaExe --version 2>&1 ))"
+
+    # Remove any pre-existing env (idempotent on self-hosted agents and retries).
+    & $condaExe env remove -y -n $EnvName 2>&1 | Out-Null
+    $LASTEXITCODE = 0  # env remove exits 1 when env doesn't exist; ignore
+
+    # Public channels (conda.anaconda.org, repo.anaconda.com) are blocked under
+    # 1ES network isolation (CFSClean). Force all installs through the Azure
+    # Artifacts feed, which proxies `main` and `conda-forge` as named subpaths.
+    # The `main` channel carries python + pip; `conda-forge` is a fallback.
+    $env:ARTIFACTS_CONDA_TOKEN = $env:SYSTEM_ACCESSTOKEN
+    & $condaExe create --override-channels `
+        --channel "$CONDA_FEED_ROOT/main" `
+        --channel "$CONDA_FEED_ROOT/conda-forge" `
+        --yes --quiet --name $EnvName "python=$PythonVersion" pip 2>&1 | Out-Host
+    if ($LASTEXITCODE -ne 0) { throw "conda create '$EnvName' failed ($LASTEXITCODE)" }
+    Write-Host "Conda env '$EnvName' created with Python $PythonVersion."
+
+    # Return the resolved conda exe path (captured by caller).
+    return $condaExe
+}
+
+$attempt = 1
+while ($true) {
+    try {
+        $condaExe = _Bootstrap -EnvName $EnvName -PythonVersion $PythonVersion
+        break
+    } catch {
+        if ($attempt -ge $MAX_ATTEMPTS) {
+            Write-Error "bootstrap-conda.ps1: failed after $MAX_ATTEMPTS attempts: $_"
+            exit 1
+        }
+        Write-Warning "Bootstrap attempt $attempt/$MAX_ATTEMPTS failed: $_  Retrying in ${RETRY_DELAY_SEC}s..."
+        Start-Sleep -Seconds $RETRY_DELAY_SEC
+        $attempt++
+    }
+}
+
+# Emit only the conda exe path to stdout; callers capture this line.
+Write-Output $condaExe
diff --git a/.pipelines/pip-scripts/build-pip-wheels-windows-deps.ps1 b/.pipelines/pip-scripts/build-pip-wheels-windows-deps.ps1
new file mode 100644
index 000000000..d61386c43
--- /dev/null
+++ b/.pipelines/pip-scripts/build-pip-wheels-windows-deps.ps1
@@ -0,0 +1,92 @@
+<#
+.SYNOPSIS
+    Build C++ dependencies (vcpkg + FetchContent targets) for the Windows wheel pipeline.
+
+.DESCRIPTION
+    Invoked only on a dependency cache miss. Installs vcpkg packages, runs the CMake
+    configure pass, and builds the slow FetchContent targets (libint2, ecpint, gauxc,
+    blaspp, lapackpp). The build directory is subsequently cached by the calling
+    pipeline job; the full qdk build then starts from a warm build tree.
+
+    Prerequisites (set by the YAML template before this script runs):
+      - INCLUDE, LIB, PATH already contain MSVC entries
+        (applied via ##vso[task.setvariable] / ##vso[task.prependpath]).
+      - CMAKE_BUILD_PARALLEL_LEVEL is set if caller wants a specific level
+        (otherwise computed here from CPU count and available RAM).
+#>
+param(
+    [Parameter(Mandatory)] [string]$SrcDir,
+    [Parameter(Mandatory)] [string]$ClPath,
+    [string]$March     = 'x86-64-v3',
+    [string]$BuildType = 'Release',
+    [string]$VcpkgRoot
+)
+$ErrorActionPreference = 'Stop'
+
+# Fall back to well-known vcpkg location on MMS images.
+if (-not $VcpkgRoot) {
+    $VcpkgRoot = if ($env:VCPKG_INSTALLATION_ROOT) { $env:VCPKG_INSTALLATION_ROOT } else { 'C:\vcpkg' }
+}
+if (-not (Test-Path "$VcpkgRoot\vcpkg.exe")) { throw "vcpkg.exe not found under '$VcpkgRoot'" }
+
+$buildDir = "$SrcDir\cpp\build-msvc"
+
+# Cap Ninja parallelism by available RAM (~4 GB/job for MSVC TUs pulling in
+# libint2 headers). On the HB120 runner this typically allows all 120 cores.
+if (-not $env:CMAKE_BUILD_PARALLEL_LEVEL) {
+    $cpu   = [int]$env:NUMBER_OF_PROCESSORS
+    $ramGB = [math]::Floor((Get-CimInstance Win32_ComputerSystem).TotalPhysicalMemory / 1GB)
+    $jobs  = [math]::Min($cpu, [math]::Max(1, [math]::Floor($ramGB / 4)))
+    Write-Host "CPUs=$cpu  RAM=${ramGB} GB  -> CMAKE_BUILD_PARALLEL_LEVEL=$jobs"
+    $env:CMAKE_BUILD_PARALLEL_LEVEL = $jobs
+}
+
+# ─── vcpkg install ────────────────────────────────────────────────────────────
+# Route all vcpkg source downloads through the Terrapin internal mirror to
+# avoid hitting external hosts (gitlab.com etc.) that are blocked by the
+# 1ES CFSClean network isolation policy.
+# See: https://eng.ms/docs/.../vcpkg  (Step 4: Use Terrapin for Asset Caching)
+# Do NOT set x-block-origin: github.com is accessible from the runner, but
+# gitlab.com (used by eigen3) is blocked; Terrapin is the preferred source and
+# falls back to the authoritative URL only on a miss.
+$env:X_VCPKG_ASSET_SOURCES = "x-azurl,https://vcpkg.storage.devpackages.microsoft.io/artifacts/"
+
+Write-Host "=== vcpkg install ==="
+& "$VcpkgRoot\vcpkg.exe" install `
+    --triplet x64-windows-static-md `
+    --x-manifest-root="$SrcDir" `
+    --x-install-root="$SrcDir\vcpkg_installed" `
+    --overlay-ports="$SrcDir\vcpkg-overlay\ports"
+if ($LASTEXITCODE -ne 0) { throw "vcpkg install failed ($LASTEXITCODE)" }
+
+# ─── CMake configure (deps pass) ─────────────────────────────────────────────
+Write-Host "=== CMake configure ==="
+$cmakeArgs = @(
+    '-S', "$SrcDir\cpp",
+    '-B', $buildDir,
+    '-GNinja',
+    "-DQDK_UARCH=$March",
+    '-DQDK_CHEMISTRY_ENABLE_COVERAGE=OFF',
+    '-DQDK_CHEMISTRY_ENABLE_MPI=OFF',
+    '-DMACIS_ENABLE_TESTS=ON',
+    '-DBUILD_SHARED_LIBS=OFF',
+    '-DBUILD_TESTING=ON',
+    "-DCMAKE_BUILD_TYPE=$BuildType",
+    "-DCMAKE_C_COMPILER=$ClPath",
+    "-DCMAKE_CXX_COMPILER=$ClPath",
+    "-DCMAKE_INSTALL_PREFIX=$SrcDir\install-msvc",
+    "-DCMAKE_TOOLCHAIN_FILE=$VcpkgRoot\scripts\buildsystems\vcpkg.cmake",
+    "-DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=$SrcDir\.pipelines\toolchains\windows.cmake",
+    '-DVCPKG_TARGET_TRIPLET=x64-windows-static-md',
+    "-DVCPKG_INSTALLED_DIR=$SrcDir\vcpkg_installed",
+    '-DFETCHCONTENT_QUIET=OFF'
+)
+cmake @cmakeArgs
+if ($LASTEXITCODE -ne 0) { throw "CMake configure failed ($LASTEXITCODE)" }
+
+# ─── Build slow FetchContent dependency targets ───────────────────────────────
+# Ninja reuses any previously-built artefacts from a restored partial cache, so
+# this step is incremental when a stale cache is present.
+Write-Host "=== Building C++ dependencies ==="
+cmake --build $buildDir --target libint2 ecpint gauxc blaspp lapackpp
+if ($LASTEXITCODE -ne 0) { throw "Dependency build failed ($LASTEXITCODE)" }
diff --git a/.pipelines/pip-scripts/build-pip-wheels-windows.ps1 b/.pipelines/pip-scripts/build-pip-wheels-windows.ps1
new file mode 100644
index 000000000..426bfde13
--- /dev/null
+++ b/.pipelines/pip-scripts/build-pip-wheels-windows.ps1
@@ -0,0 +1,216 @@
+<#
+.SYNOPSIS
+    Build the full qdk C++ library, run C++ tests, and produce a Python wheel
+    using a conda-isolated build environment.
+
+.DESCRIPTION
+    This script is always invoked (unlike the deps script which is skipped on
+    cache hit). It:
+      1. Rebuilds the full qdk + macis library on top of the cached dep tree.
+      2. Runs the C++ test suite (ctest); results are written to an XML file
+         that the calling YAML template publishes with PublishTestResults@2.
+      3. Installs the C++ library under install-msvc/.
+      4. Bootstraps a conda environment via ms-ensureconda (the Microsoft-approved
+         conda bootstrapper). Public channels are blocked in 1ES CFSClean; all
+         packages are fetched from the Azure Artifacts Conda/PyPI feed.
+      5. Installs build tooling (pip, build, scikit-build-core, etc.) and
+         generates a Component Governance PipReport.
+      6. Rewrites relative README links to absolute GitHub URLs (equivalent to
+         prepare-readme.sh).
+      7. Builds the distribution wheel with scikit-build-core. No wheel repair
+         is needed: x64-windows-static-md statically links all vcpkg deps.
+      8. Copies the wheel to python/repaired_wheelhouse/.
+
+    Prerequisites (set by the YAML template before this script runs):
+      - INCLUDE, LIB, PATH already contain MSVC entries.
+      - CMAKE_BUILD_PARALLEL_LEVEL is set (or computed here).
+      - SYSTEM_ACCESSTOKEN is in the environment (mapped by the YAML step via
+        env: SYSTEM_ACCESSTOKEN: $(System.AccessToken)).
+      - PIP_INDEX_URL is set by PipAuthenticate@1 at job level.
+#>
+param(
+    [Parameter(Mandatory)] [string]$SrcDir,
+    [Parameter(Mandatory)] [string]$ClPath,
+    [string]$March         = 'x86-64-v3',
+    [string]$BuildType     = 'Release',
+    [string]$PythonVersion = '3.11',
+    [string]$DevTag        = 'None',
+    [string]$VcpkgRoot
+)
+$ErrorActionPreference = 'Stop'
+
+if (-not $VcpkgRoot) {
+    $VcpkgRoot = if ($env:VCPKG_INSTALLATION_ROOT) { $env:VCPKG_INSTALLATION_ROOT } else { 'C:\vcpkg' }
+}
+
+$buildDir  = "$SrcDir\cpp\build-msvc"
+$installDir = "$SrcDir\install-msvc"
+
+if (-not $env:CMAKE_BUILD_PARALLEL_LEVEL) {
+    $cpu   = [int]$env:NUMBER_OF_PROCESSORS
+    $ramGB = [math]::Floor((Get-CimInstance Win32_ComputerSystem).TotalPhysicalMemory / 1GB)
+    $jobs  = [math]::Min($cpu, [math]::Max(1, [math]::Floor($ramGB / 4)))
+    Write-Host "CPUs=$cpu  RAM=${ramGB} GB  -> CMAKE_BUILD_PARALLEL_LEVEL=$jobs"
+    $env:CMAKE_BUILD_PARALLEL_LEVEL = $jobs
+}
+
+# ─── CMake reconfigure + full build ──────────────────────────────────────────
+# Re-configure the same build dir to refresh any source-path references, then
+# build all qdk + macis targets. Dep .libs from the cache (or the deps step)
+# are already present — Ninja skips them.
+Write-Host "=== CMake configure (full build) ==="
+$cmakeArgs = @(
+    '-S', "$SrcDir\cpp",
+    '-B', $buildDir,
+    '-GNinja',
+    "-DQDK_UARCH=$March",
+    '-DQDK_CHEMISTRY_ENABLE_COVERAGE=OFF',
+    '-DQDK_CHEMISTRY_ENABLE_MPI=OFF',
+    '-DMACIS_ENABLE_TESTS=ON',
+    '-DBUILD_SHARED_LIBS=OFF',
+    '-DBUILD_TESTING=ON',
+    '-DCMAKE_GTEST_DISCOVER_TESTS_DISCOVERY_MODE=PRE_TEST',
+    '-DVCPKG_APPLOCAL_DEPS=OFF',
+    "-DCMAKE_BUILD_TYPE=$BuildType",
+    "-DCMAKE_C_COMPILER=$ClPath",
+    "-DCMAKE_CXX_COMPILER=$ClPath",
+    "-DCMAKE_INSTALL_PREFIX=$installDir",
+    "-DCMAKE_TOOLCHAIN_FILE=$VcpkgRoot\scripts\buildsystems\vcpkg.cmake",
+    "-DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=$SrcDir\.pipelines\toolchains\windows.cmake",
+    '-DVCPKG_TARGET_TRIPLET=x64-windows-static-md',
+    "-DVCPKG_INSTALLED_DIR=$SrcDir\vcpkg_installed",
+    '-DFETCHCONTENT_QUIET=OFF'
+)
+cmake @cmakeArgs
+if ($LASTEXITCODE -ne 0) { throw "CMake configure failed ($LASTEXITCODE)" }
+
+Write-Host "=== CMake build ==="
+cmake --build $buildDir
+if ($LASTEXITCODE -ne 0) { throw "CMake build failed ($LASTEXITCODE)" }
+
+# ─── C++ tests ───────────────────────────────────────────────────────────────
+# Exclude MACIS_SERIAL_TEST and libint2/unit (compile-at-test-time meta-test)
+# which can exceed the ctest timeout under MSVC.
+# Save the ctest exit code; throw AFTER the wheel has been built so the
+# PublishTestResults@2 task in the YAML always has something to publish.
+Write-Host "=== ctest ==="
+Push-Location $buildDir
+ctest --output-on-failure --verbose --timeout 400 `
+      --output-junit ctest_results.xml `
+      -E "MACIS_SERIAL_TEST|libint2/unit"
+$ctestCode = $LASTEXITCODE
+Pop-Location
+if ($ctestCode -ne 0) {
+    Write-Warning "ctest returned $ctestCode — continuing to build wheel, then will throw."
+}
+
+# ─── Install C++ library ─────────────────────────────────────────────────────
+Write-Host "=== cmake --install ==="
+cmake --install $buildDir
+if ($LASTEXITCODE -ne 0) { throw "CMake install failed ($LASTEXITCODE)" }
+
+# ─── Conda bootstrap ─────────────────────────────────────────────────────────
+Write-Host "=== Conda bootstrap ==="
+$condaExe = & "$PSScriptRoot\bootstrap-conda.ps1" -EnvName buildenv -PythonVersion $PythonVersion
+if ($LASTEXITCODE -ne 0) { throw "Conda bootstrap failed ($LASTEXITCODE)" }
+
+# ─── Install Python build tooling ────────────────────────────────────────────
+Write-Host "=== pip install build tooling ==="
+& $condaExe run -n buildenv python -m pip install --upgrade pip
+if ($LASTEXITCODE -ne 0) { throw "pip upgrade failed" }
+& $condaExe run -n buildenv python -m pip install -r "$SrcDir\.pipelines\requirements.txt"
+if ($LASTEXITCODE -ne 0) { throw "pip install requirements failed" }
+
+# ─── Component Governance PipReport ──────────────────────────────────────────
+# Snapshot the buildenv and feed it to pip install --report so Component
+# Governance's PipReportDetector sees every package.
+$manifestDir = "$SrcDir\python\build\build-manifest"
+New-Item -ItemType Directory -Force -Path $manifestDir | Out-Null
+$reqs = & $condaExe run -n buildenv python -m pip list --format=freeze
+if ($LASTEXITCODE -ne 0) { throw "pip list failed ($LASTEXITCODE)" }
+$reqs | Set-Content -Encoding utf8 "$manifestDir\requirements.txt"
+$reqs | ForEach-Object { Write-Host $_ }
+& $condaExe run -n buildenv python -m pip install `
+    --dry-run --ignore-installed --quiet `
+    --report "$manifestDir\component-detection-pip-report.json" `
+    -r "$manifestDir\requirements.txt"
+# PipReport failures are non-fatal (Component Governance is best-effort).
+$LASTEXITCODE = 0
+
+# ─── Prepare README (equivalent to prepare-readme.sh) ────────────────────────
+Write-Host "=== Prepare README ==="
+try {
+    $ghBlob = 'https://github.com/microsoft/qdk-chemistry/blob/main'
+    $ghTree = 'https://github.com/microsoft/qdk-chemistry/tree/main'
+    $lines  = Get-Content -Encoding utf8 "$SrcDir\README.md"
+
+    # Apply substitutions line by line (sed -E equivalent).
+    $out      = [System.Collections.Generic.List[string]]::new()
+    $deleting = $false
+    foreach ($line in $lines) {
+        # Range delete: ## Project Structure ... closing ```
+        if ($line -match '^## Project Structure$') { $deleting = $true;  continue }
+        if ($deleting) {
+            if ($line -match '^```$') { $deleting = $false }
+            continue
+        }
+        $line = $line -replace '\]\(\./([^)]+)\)',              "]($ghBlob/`$1)"
+        $line = $line -replace '\]\(([A-Z][A-Z_]*\.(md|txt))\)', "]($ghBlob/`$1)"
+        $line = $line -replace '`examples/`',                  "[``examples/``]($ghTree/examples)"
+        $line = $line -replace '`cpp/include/`',               "[``cpp/include/``]($ghTree/cpp/include)"
+        $out.Add($line)
+    }
+    $out | Set-Content -Encoding utf8 "$SrcDir\python\README.md"
+    Write-Host "README prepared."
+} catch {
+    Write-Warning "prepare-readme failed: $_  (continuing)"
+}
+
+# ─── Build Python wheel ───────────────────────────────────────────────────────
+# scikit-build-core picks up the pre-built C++ library via CMAKE_PREFIX_PATH so
+# FetchContent is never triggered. QDK_ALLOW_DEPENDENCY_FETCH=OFF enforces this.
+Write-Host "=== python -m build --wheel ==="
+$prefix   = "$SrcDir\vcpkg_installed\x64-windows-static-md;$installDir"
+$buildArgs = @(
+    'run', '-n', 'buildenv',
+    'python', '-m', 'build', '--wheel',
+    "-C=build-dir=build/{wheel_tag}",
+    "-C=cmake.args=-GNinja",
+    "-C=cmake.define.QDK_UARCH=$March",
+    '-C=cmake.define.BUILD_SHARED_LIBS=OFF',
+    '-C=cmake.define.QDK_CHEMISTRY_ENABLE_MPI=OFF',
+    '-C=cmake.define.QDK_ENABLE_OPENMP=OFF',
+    '-C=cmake.define.QDK_CHEMISTRY_ENABLE_COVERAGE=OFF',
+    '-C=cmake.define.BUILD_TESTING=OFF',
+    "-C=cmake.define.QDK_ALLOW_DEPENDENCY_FETCH=OFF",
+    "-C=cmake.define.CMAKE_C_COMPILER=$ClPath",
+    "-C=cmake.define.CMAKE_CXX_COMPILER=$ClPath",
+    "-C=cmake.define.CMAKE_TOOLCHAIN_FILE=$VcpkgRoot\scripts\buildsystems\vcpkg.cmake",
+    "-C=cmake.define.VCPKG_CHAINLOAD_TOOLCHAIN_FILE=$SrcDir\.pipelines\toolchains\windows.cmake",
+    '-C=cmake.define.VCPKG_TARGET_TRIPLET=x64-windows-static-md',
+    "-C=cmake.define.VCPKG_INSTALLED_DIR=$SrcDir\vcpkg_installed",
+    "-C=cmake.define.CMAKE_PREFIX_PATH=$prefix"
+)
+Push-Location "$SrcDir\python"
+& $condaExe @buildArgs
+$wheelCode = $LASTEXITCODE
+Pop-Location
+if ($wheelCode -ne 0) { throw "python -m build --wheel failed ($wheelCode)" }
+
+# ─── Copy wheel to repaired_wheelhouse ───────────────────────────────────────
+# No wheel repair needed: x64-windows-static-md statically links all vcpkg
+# deps; the only dynamic runtime deps (MSVCP140.dll, VCRUNTIME140.dll, UCRT)
+# are always present on modern Windows.
+$distDir   = "$SrcDir\python\dist"
+$outputDir = "$SrcDir\python\repaired_wheelhouse"
+New-Item -ItemType Directory -Force -Path $outputDir | Out-Null
+$wheels = Get-ChildItem "$distDir\qdk_chemistry*.whl"
+if ($wheels.Count -ne 1) {
+    throw "Expected exactly 1 wheel in dist/, found $($wheels.Count): $($wheels.Name -join ', ')"
+}
+Copy-Item $wheels[0].FullName $outputDir
+Write-Host "Wheel : $($wheels[0].Name)"
+Write-Host "Output: $outputDir"
+
+# Deferred ctest failure: publish results step has already run by this point.
+if ($ctestCode -ne 0) { throw "ctest failed ($ctestCode)" }
diff --git a/.pipelines/python-wheels.yaml b/.pipelines/python-wheels.yaml
index a8b063bf2..6a368657e 100644
--- a/.pipelines/python-wheels.yaml
+++ b/.pipelines/python-wheels.yaml
@@ -41,6 +41,11 @@ parameters:
     arch: aarch64
     march: armv8-a
     imageName: ACES_VM_SharedPool_Tahoe
+  - name: windows_x86_64
+    os: windows
+    arch: x86_64
+    march: x86-64-v3
+    imageName: windows-2025-1espt
   displayName: Target platforms
 - name: pythonVersions
   type: stringList
@@ -93,7 +98,7 @@ extends:
         binaryLanguages: cpp
       psscriptanalyzer:
         enabled: false
-        justificationForDisabling: Powershell is not used in this repository.
+        justificationForDisabling: PSScriptAnalyzer not yet configured for the new Windows pip-scripts.
         break: false
       armory:
         enabled: false
@@ -127,6 +132,12 @@ extends:
               - ImageOverride -equals ${{ target.imageName }}
               os: ${{ target.os }}
               hostArchitecture: Arm64
+          ${{ elseif eq(target.os, 'windows') }}:
+            pool:
+              name: $(CPU_POOL_X86)
+              demands:
+              - ImageOverride -equals ${{ target.imageName }}
+              os: windows
           ${{ else }}:
             pool:
               name: $(CPU_POOL_X86)
@@ -158,7 +169,7 @@ extends:
               onlyAddExtraIndex: false
 
           # Build - Linux x86_64
-          - ${{ if eq(target.arch, 'x86_64') }}:
+          - ${{ if and(eq(target.arch, 'x86_64'), eq(target.os, 'linux')) }}:
             - template: .pipelines/templates/build-pip-wheels.yml@self
               parameters:
                 march: ${{ target.march }}
@@ -171,7 +182,7 @@ extends:
                 devTag: ${{ parameters.devTag }}
 
           # Test - Linux x86_64
-          - ${{ if eq(target.arch, 'x86_64') }}:
+          - ${{ if and(eq(target.arch, 'x86_64'), eq(target.os, 'linux')) }}:
             - template: .pipelines/templates/test-pip-wheels.yml@self
               parameters:
                 agentBuildDirectory: $(Agent.BuildDirectory)
@@ -233,11 +244,32 @@ extends:
                 # the wheel is still built and published.
                 condition: and(succeeded(), ne(variables['pythonVersion'], '3.10'))
 
+          # Build - Windows x86_64
+          - ${{ if eq(target.os, 'windows') }}:
+            - template: .pipelines/templates/build-pip-wheels-windows.yml@self
+              parameters:
+                march: ${{ target.march }}
+                agentBuildDirectory: $(Agent.BuildDirectory)
+                pythonVersion: $(pythonVersion)
+                devTag: ${{ parameters.devTag }}
+
+          # Test - Windows x86_64
+          - ${{ if eq(target.os, 'windows') }}:
+            - template: .pipelines/templates/test-pip-wheels-windows.yml@self
+              parameters:
+                agentBuildDirectory: $(Agent.BuildDirectory)
+                pythonVersion: $(pythonVersion)
+                runSlowTests: ${{ parameters.runSlowTests }}
+                # Python 3.10 tests temporarily disabled (qre/cirq cannot resolve on 3.10);
+                # the wheel is still built and published.
+                condition: and(succeeded(), ne(variables['pythonVersion'], '3.10'))
+
           # SBoM Manifest Generator Task requires we transfer ownership of the wheel directory
-          # back to the original base image user
-          - script: |
-              sudo chown -R $(id -u):$(id -g) $(System.DefaultWorkingDirectory)/python/repaired_wheelhouse
-            displayName: Fix wheel directory ownership
+          # back to the original base image user (Linux/macOS only; not needed on Windows).
+          - ${{ if ne(target.os, 'windows') }}:
+            - script: |
+                sudo chown -R $(id -u):$(id -g) $(System.DefaultWorkingDirectory)/python/repaired_wheelhouse
+              displayName: Fix wheel directory ownership
 
           - task: TwineAuthenticate@1
             inputs:
@@ -341,6 +373,21 @@ extends:
           - input: pipelineArtifact
             artifactName: macos-aarch64-wheels-python3.14
             targetPath: $(System.DefaultWorkingDirectory)/artifacts/macos-aarch64-wheels-python3.14
+          - input: pipelineArtifact
+            artifactName: windows-x86_64-wheels-python3.10
+            targetPath: $(System.DefaultWorkingDirectory)/artifacts/windows-x86_64-wheels-python3.10
+          - input: pipelineArtifact
+            artifactName: windows-x86_64-wheels-python3.11
+            targetPath: $(System.DefaultWorkingDirectory)/artifacts/windows-x86_64-wheels-python3.11
+          - input: pipelineArtifact
+            artifactName: windows-x86_64-wheels-python3.12
+            targetPath: $(System.DefaultWorkingDirectory)/artifacts/windows-x86_64-wheels-python3.12
+          - input: pipelineArtifact
+            artifactName: windows-x86_64-wheels-python3.13
+            targetPath: $(System.DefaultWorkingDirectory)/artifacts/windows-x86_64-wheels-python3.13
+          - input: pipelineArtifact
+            artifactName: windows-x86_64-wheels-python3.14
+            targetPath: $(System.DefaultWorkingDirectory)/artifacts/windows-x86_64-wheels-python3.14
         steps:
         - script: |
             mkdir -p $(System.DefaultWorkingDirectory)/target/wheels
diff --git a/.pipelines/templates/build-pip-wheels-windows.yml b/.pipelines/templates/build-pip-wheels-windows.yml
new file mode 100644
index 000000000..e40fe5cbe
--- /dev/null
+++ b/.pipelines/templates/build-pip-wheels-windows.yml
@@ -0,0 +1,189 @@
+parameters:
+- name: march
+  type: string
+  default: x86-64-v3
+- name: buildType
+  type: string
+  default: Release
+- name: agentBuildDirectory
+  type: string
+  default: $(Agent.BuildDirectory)
+- name: pythonVersion
+  type: string
+  default: '3.11'
+- name: devTag
+  type: string
+  default: 'None'
+
+steps:
+- checkout: self
+  persistCredentials: true
+  path: qdk-chemistry
+  fetchDepth: 1
+  retryCountOnTaskFailure: 3
+
+- pwsh: |
+    python "$(System.DefaultWorkingDirectory)\.pipelines\pip-scripts\versioning.py" `
+      --version-file "$(System.DefaultWorkingDirectory)\VERSION" `
+      --dev-tag ${{ parameters.devTag }}
+    Get-Content "$(System.DefaultWorkingDirectory)\VERSION"
+  displayName: Validate/Set Development Version for Wheels
+  condition: ne('${{ parameters.devTag }}', 'None')
+
+# Import the VS x64 developer environment (INCLUDE, LIB, PATH, etc.) so that
+# cl.exe and the MSVC linker are available to all subsequent steps.
+# Also resolves the MSVC toolset version for the dependency cache key.
+- pwsh: |
+    $ErrorActionPreference = 'Stop'
+
+    $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+    $vsPath = & $vswhere -latest -products * -property installationPath
+    if (-not $vsPath) { throw "No Visual Studio installation found" }
+    Write-Host "Visual Studio: $vsPath"
+
+    $vcvarsall = "$vsPath\VC\Auxiliary\Build\vcvarsall.bat"
+    if (-not (Test-Path $vcvarsall)) { throw "vcvarsall.bat not found at $vcvarsall" }
+
+    # Snapshot env, run vcvarsall x64, diff to capture changes.
+    $before = @{}
+    Get-ChildItem env: | ForEach-Object { $before[$_.Name] = $_.Value }
+    $tmp = [System.IO.Path]::GetTempFileName()
+    cmd /c "`"$vcvarsall`" x64 && set > `"$tmp`""
+    if ($LASTEXITCODE -ne 0) { throw "vcvarsall.bat failed ($LASTEXITCODE)" }
+    $after = @{}
+    Get-Content $tmp | ForEach-Object {
+        if ($_ -match '^([^=]+)=(.*)$') { $after[$matches[1]] = $matches[2] }
+    }
+    Remove-Item $tmp
+
+    # Apply to current process so Get-Command can resolve cl.exe.
+    foreach ($name in $after.Keys) {
+        [System.Environment]::SetEnvironmentVariable($name, $after[$name], 'Process')
+    }
+
+    # Locate cl.exe — vcvarsall x64 puts it on PATH.
+    # PS5-compatible null check (no ?. operator available in powershell.exe 5.1).
+    $clCmd = Get-Command cl.exe -ErrorAction SilentlyContinue
+    $cl = if ($clCmd) { $clCmd.Source } else { $null }
+    if (-not $cl) { throw "cl.exe not found on PATH after vcvarsall x64" }
+    Write-Host "cl.exe: $cl"
+    & $cl 2>&1 | Select-Object -First 2 | Write-Host
+
+    # Export non-PATH changes to subsequent ADO steps.
+    foreach ($name in $after.Keys) {
+        if ($name -ieq 'Path') { continue }
+        if ($before[$name] -ne $after[$name]) {
+            Write-Host "##vso[task.setvariable variable=$name]$($after[$name])"
+        }
+    }
+    # Prepend new PATH entries from vcvarsall.
+    $beforePath = @($before['Path'] -split ';')
+    $newEntries = @($after['Path'] -split ';') | Where-Object { $_ -and ($beforePath -notcontains $_) }
+    $newEntries | ForEach-Object { Write-Host "##vso[task.prependpath]$_" }
+
+    # MSVC toolset version: stable identifier for cache key.
+    $toolsetFile = "$vsPath\VC\Auxiliary\Build\Microsoft.VCToolsVersion.default.txt"
+    $toolset = (Get-Content $toolsetFile -ErrorAction Stop | Select-Object -First 1).Trim()
+    Write-Host "MSVC toolset: $toolset"
+    Write-Host "##vso[task.setvariable variable=MSVC_TOOLSET]$toolset"
+    Write-Host "##vso[task.setvariable variable=CL_PATH]$cl"
+
+    # Bootstrap vcpkg if not pre-installed.
+    $vcpkgRoot = if ($env:VCPKG_INSTALLATION_ROOT) { $env:VCPKG_INSTALLATION_ROOT } else { 'C:\vcpkg' }
+    if (Test-Path "$vcpkgRoot\vcpkg.exe") {
+        Write-Host "vcpkg already available at $vcpkgRoot"
+    } else {
+        Write-Host "vcpkg not found — bootstrapping into $vcpkgRoot"
+        git clone https://github.com/microsoft/vcpkg.git $vcpkgRoot --depth 1
+        & "$vcpkgRoot\bootstrap-vcpkg.bat" -disableMetrics
+        if ($LASTEXITCODE -ne 0) { throw "vcpkg bootstrap failed ($LASTEXITCODE)" }
+        Write-Host "##vso[task.setvariable variable=VCPKG_INSTALLATION_ROOT]$vcpkgRoot"
+    }
+    # vcvarsall sets VCPKG_ROOT to VS's bundled copy; override it to match our
+    # standalone installation so vcpkg.exe doesn't warn about the mismatch.
+    Write-Host "##vso[task.setvariable variable=VCPKG_ROOT]$vcpkgRoot"
+  displayName: Set up MSVC environment
+
+# Hash all files that influence how the C++ dependencies are built.
+# The result is used in the Cache@2 key so the cache is invalidated on any
+# dep-affecting change without listing every file individually in the key.
+- pwsh: |
+    $root = "$(System.DefaultWorkingDirectory)"
+    $files = @(
+        "$root\vcpkg.json",
+        "$root\vcpkg-configuration.json",
+        "$root\cpp\manifest\qdk-chemistry\cgmanifest.json",
+        "$root\external\macis\manifest\cgmanifest.json",
+        "$root\cpp\cmake\third_party.cmake",
+        "$root\cpp\cmake\modules\DependencyManager.cmake",
+        "$root\external\macis\src\lobpcgxx\CMakeLists.txt",
+        "$root\.pipelines\toolchains\windows.cmake"
+    )
+    if (Test-Path "$root\vcpkg-overlay") {
+        $files += Get-ChildItem "$root\vcpkg-overlay" -Recurse -File |
+                  Select-Object -ExpandProperty FullName
+    }
+    if (Test-Path "$root\cpp\cmake\patches") {
+        $files += Get-ChildItem "$root\cpp\cmake\patches" -Recurse -File |
+                  Select-Object -ExpandProperty FullName
+    }
+    $hashes = $files | Where-Object { Test-Path $_ } | Sort-Object |
+              ForEach-Object { (Get-FileHash $_ -Algorithm SHA256).Hash }
+    $combined  = $hashes -join ","
+    $hashBytes = [System.Security.Cryptography.SHA256]::Create().ComputeHash(
+                     [System.Text.Encoding]::UTF8.GetBytes($combined))
+    $hashStr   = ($hashBytes | ForEach-Object { $_.ToString("x2") }) -join ""
+    Write-Host "Dependency files hash: $hashStr"
+    Write-Host "##vso[task.setvariable variable=DEPS_FILES_HASH]$hashStr"
+  displayName: Compute dependency cache key
+
+# Restore the dependency build dirs separately to avoid a known Windows issue
+# with Cache@2 multi-line `path`: the task passes both lines as a single tar
+# argument, causing "could not chdir" at save time. Two tasks work reliably.
+- task: Cache@2
+  displayName: Restore / save vcpkg dependency cache
+  inputs:
+    key: '"windows-vcpkg-x64-windows-static-md-v1" | "$(MSVC_TOOLSET)" | "$(DEPS_FILES_HASH)"'
+    path: $(System.DefaultWorkingDirectory)/vcpkg_installed
+    cacheHitVar: VCPKG_CACHE_RESTORED
+
+- task: Cache@2
+  displayName: Restore / save C++ build cache
+  inputs:
+    key: '"windows-deps-msvc-x64-windows-static-md-v1" | "$(MSVC_TOOLSET)" | "$(DEPS_FILES_HASH)"'
+    path: $(System.DefaultWorkingDirectory)/cpp/build-msvc
+    cacheHitVar: DEPS_CACHE_RESTORED
+
+# Build vcpkg packages, configure CMake, and build the slow FetchContent targets
+# (libint2, ecpint, gauxc, blaspp, lapackpp). Skipped entirely on cache hit.
+- pwsh: |
+    & "$(System.DefaultWorkingDirectory)\.pipelines\pip-scripts\build-pip-wheels-windows-deps.ps1" `
+        -SrcDir    "$(System.DefaultWorkingDirectory)" `
+        -March     "${{ parameters.march }}" `
+        -BuildType "${{ parameters.buildType }}" `
+        -ClPath    "$(CL_PATH)"
+  displayName: Build C++ dependencies (libint2 / gauxc / ecpint / blaspp / lapackpp)
+  condition: or(ne(variables['DEPS_CACHE_RESTORED'], 'true'), ne(variables['VCPKG_CACHE_RESTORED'], 'true'))
+
+# Full qdk build, C++ tests, conda environment setup, and Python wheel build.
+# SYSTEM_ACCESSTOKEN is required by bootstrap-conda for the Azure Artifacts feed.
+- pwsh: |
+    & "$(System.DefaultWorkingDirectory)\.pipelines\pip-scripts\build-pip-wheels-windows.ps1" `
+        -SrcDir        "$(System.DefaultWorkingDirectory)" `
+        -March         "${{ parameters.march }}" `
+        -BuildType     "${{ parameters.buildType }}" `
+        -ClPath        "$(CL_PATH)" `
+        -PythonVersion "${{ parameters.pythonVersion }}" `
+        -DevTag        "${{ parameters.devTag }}"
+  displayName: Build C++ library, run tests, and build Python wheel
+  env:
+    SYSTEM_ACCESSTOKEN: $(System.AccessToken)
+    OMP_NUM_THREADS: '2'
+
+- task: PublishTestResults@2
+  displayName: Publish C++ test results
+  inputs:
+    testResultsFormat: JUnit
+    testResultsFiles: '$(System.DefaultWorkingDirectory)/cpp/build-msvc/ctest_results.xml'
+    testRunTitle: 'C++ tests - Windows x86_64 Python ${{ parameters.pythonVersion }}'
+  condition: always()
diff --git a/.pipelines/templates/test-pip-wheels-windows.yml b/.pipelines/templates/test-pip-wheels-windows.yml
new file mode 100644
index 000000000..50d604158
--- /dev/null
+++ b/.pipelines/templates/test-pip-wheels-windows.yml
@@ -0,0 +1,79 @@
+parameters:
+- name: agentBuildDirectory
+  type: string
+  default: $(Agent.BuildDirectory)
+- name: pythonVersion
+  type: string
+  default: '3.11'
+- name: runSlowTests
+  type: boolean
+  default: true
+- name: condition
+  type: string
+  default: succeeded()
+
+steps:
+# Bootstrap conda and create an isolated test environment, matching the
+# approach used for Linux/macOS via bootstrap-conda.sh.
+# SYSTEM_ACCESSTOKEN (mapped via env: below) authenticates the conda install
+# against the Azure Artifacts feed (public channels blocked in 1ES CFSClean).
+- pwsh: |
+    $ErrorActionPreference = 'Stop'
+    $scriptPath = "$(System.DefaultWorkingDirectory)\.pipelines\pip-scripts\bootstrap-conda.ps1"
+    $condaExe = & $scriptPath -EnvName testenv -PythonVersion '${{ parameters.pythonVersion }}'
+    if ($LASTEXITCODE -ne 0) { throw "Conda bootstrap failed ($LASTEXITCODE)" }
+    # Export conda exe path for subsequent steps.
+    Write-Host "##vso[task.setvariable variable=CONDA_EXE]$condaExe"
+  displayName: Set up conda test environment (Python ${{ parameters.pythonVersion }})
+  condition: ${{ parameters.condition }}
+  env:
+    SYSTEM_ACCESSTOKEN: $(System.AccessToken)
+
+# Install the wheel together with its test extra dependencies.
+- pwsh: |
+    $ErrorActionPreference = 'Stop'
+    $wheels = Get-ChildItem "$(System.DefaultWorkingDirectory)\python\repaired_wheelhouse\qdk_chemistry*.whl"
+    if ($wheels.Count -ne 1) {
+        throw "Expected exactly 1 wheel, found $($wheels.Count): $($wheels.Name -join ', ')"
+    }
+    $wheel = $wheels[0].FullName
+    Write-Host "Installing: $wheel"
+    & "$(CONDA_EXE)" run -n testenv python -m pip install --upgrade pip
+    if ($LASTEXITCODE -ne 0) { throw "pip upgrade failed" }
+    & "$(CONDA_EXE)" run -n testenv python -m pip install "$wheel[test]"
+    if ($LASTEXITCODE -ne 0) { throw "pip install wheel[test] failed ($LASTEXITCODE)" }
+  displayName: Install wheel with test dependencies
+  condition: ${{ parameters.condition }}
+
+# Snapshot the testenv and generate a pip install --report for Component
+# Governance's PipReportDetector (mirrors test-pip-wheels.sh lines 95-102).
+- pwsh: |
+    $manifestDir = "$(System.DefaultWorkingDirectory)\python\build\test-manifest"
+    New-Item -ItemType Directory -Force -Path $manifestDir | Out-Null
+    $reqs = & "$(CONDA_EXE)" run -n testenv python -m pip list --format=freeze --exclude qdk_chemistry
+    if ($LASTEXITCODE -ne 0) { throw "pip list failed ($LASTEXITCODE)" }
+    $reqs | Set-Content -Encoding utf8 "$manifestDir\requirements.txt"
+    $reqs | ForEach-Object { Write-Host $_ }
+    & "$(CONDA_EXE)" run -n testenv python -m pip install `
+        --dry-run --ignore-installed --quiet `
+        --report "$manifestDir\component-detection-pip-report.json" `
+        -r "$manifestDir\requirements.txt"
+  displayName: Generate Component Governance PipReport
+  condition: ${{ parameters.condition }}
+  continueOnError: true
+
+- pwsh: |
+    $ErrorActionPreference = 'Stop'
+    # Set env vars in the current process; conda run inherits them.
+    # conda run --env VAR=VALUE was added only in newer conda versions and is
+    # not universally available on 1ES runners.
+    $env:QSHARP_PYTHON_TELEMETRY      = 'false'
+    $env:QDK_CHEMISTRY_RUN_SLOW_TESTS = '${{ parameters.runSlowTests }}'
+    $env:OMP_NUM_THREADS              = '2'
+    Push-Location "$(System.DefaultWorkingDirectory)\python"
+    & "$(CONDA_EXE)" run -n testenv python -m pytest -v tests/
+    $code = $LASTEXITCODE
+    Pop-Location
+    if ($code -ne 0) { throw "pytest failed ($code)" }
+  displayName: Run Python tests
+  condition: ${{ parameters.condition }}
diff --git a/cpp/cmake/third_party.cmake b/cpp/cmake/third_party.cmake
index e64379918..cc1266128 100644
--- a/cpp/cmake/third_party.cmake
+++ b/cpp/cmake/third_party.cmake
@@ -86,6 +86,13 @@ if(MSVC AND TARGET eritest-libint2)
   endif()
 endif()
 
+# MSVC's /O2 optimizer is pathologically slow on libint2's large CMake Unity
+# translation units (hours vs minutes for clang-cl). Disable Unity for libint2 on
+# MSVC so the small generated TUs compile quickly and parallelize; clang-cl keeps it.
+if(MSVC AND NOT CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND TARGET libint2_obj)
+  set_target_properties(libint2_obj PROPERTIES UNITY_BUILD OFF)
+endif()
+
 # ecpint for ECP-related integral evaluation
 set(LIBECPINT_BUILD_TESTS OFF CACHE BOOL "Enable ECPINT Tests" FORCE)
 set(LIBECPINT_USE_PUGIXML OFF CACHE BOOL "Use pugixml for ECPINT" FORCE)