@@ -0,0 +1,100 @@
+# Temporary iteration workflow for the Windows turbo extension build.
+# Runs alone on pushes to the turbo-windows branch; folded into phar.yml
+# (and this file deleted) once the build and the differential tests are
+# green on windows-latest.
+
+name: "Turbo Windows Spike"
+
+permissions:
+  contents: read
+
+on:
+  push:
+    branches:
+      - "turbo-windows"
+
+jobs:
+  windows:
+    name: "Windows PHP ${{ matrix.php-version }}"
+    runs-on: "windows-latest"
+    timeout-minutes: 40
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php-version: ["8.4", "8.5"]
+
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+          # full history: the extension version is baked from git log over
+          # the watched paths
+          fetch-depth: 0
+
+      - name: "Install PHP"
+        uses: "shivammathur/setup-php@f3e473d116dcccaddc5834248c87452386958240" # v2.37.2
+        with:
+          coverage: "none"
+          php-version: "${{ matrix.php-version }}"
+
+      - name: "Compute extension version and devel-pack URL"
+        id: meta
+        shell: bash
+        run: |
+          MAPPED_PHP=$(php -n -r 'echo implode(" ", array_map(static fn ($e) => $e["php"], array_filter(json_decode(file_get_contents("turbo-ext/shadowed-classes.json"), true), static fn ($e) => !($e["vendored"] ?? false))));')
+          SHA=$(git log -1 --format=%H -- turbo-ext/src $MAPPED_PHP | cut -c1-7)
+          echo "PHPSTANTURBO_VERSION=$SHA" >> "$GITHUB_ENV"
+          FULL=$(php -r 'echo PHP_VERSION;')
+          echo "php full version: $FULL, extension version: $SHA"
+          echo "devel-pack=php-devel-pack-$FULL-nts-Win32-vs17-x64.zip" >> "$GITHUB_OUTPUT"
+
+      - name: "Download PHP devel pack"
+        shell: bash
+        run: |
+          PACK="${{ steps.meta.outputs.devel-pack }}"
+          curl -fsSLo devel-pack.zip "https://windows.php.net/downloads/releases/$PACK" \
+            || curl -fsSLo devel-pack.zip "https://windows.php.net/downloads/releases/archives/$PACK"
+          unzip -q devel-pack.zip -d /c/php-devel
+          ls /c/php-devel
+
+      - name: "Set up MSVC environment"
+        uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
+        with:
+          arch: x64
+
+      - name: "Build the extension"
+        shell: cmd
+        working-directory: turbo-ext
+        run: |
+          for /d %%d in (C:\php-devel\php-*-devel-*) do set DEVEL=%%d
+          set PATH=%DEVEL%;%PATH%
+          call phpize.bat
+          call configure.bat --enable-phpstan-turbo
+          nmake
+
+      - name: "Verify the built extension reports the expected version"
+        shell: bash
+        run: |
+          DLL=$(ls turbo-ext/x64/Release*/php_phpstan_turbo.dll | head -1)
+          echo "built: $DLL"
+          REPORTED="$(php -d extension="$(cygpath -w "$PWD/$DLL")" -r 'echo phpversion("phpstan_turbo");')"
+          EXPECTED="$(sed -n "s/.*EXPECTED_EXTENSION_VERSION = '\([^']*\)'.*/\1/p" src/Turbo/TurboExtensionEnabler.php)"
+          echo "built extension reports: $REPORTED, enabler expects: $EXPECTED"
+          [ "$REPORTED" = "$EXPECTED" ]
+          echo "TURBO_DLL=$(cygpath -w "$PWD/$DLL")" >> "$GITHUB_ENV"
+
+      - uses: "ramsey/composer-install@65e4f84970763564f46a70b8a54b90d033b3bdda" # v4.0.0
+
+      - name: "Smoke test (differential: native vs PHP implementations)"
+        shell: bash
+        run: php -d extension="$TURBO_DLL" turbo-ext/tests/smoke.php
+
+      - name: "Signature parity (reflect native classes against the PHP twins)"
+        shell: bash
+        run: php -d extension="$TURBO_DLL" turbo-ext/tests/signature-parity.php
+
+      - name: "Parser corpus (differential: native vs PHP ASTs must be byte-identical)"
+        shell: bash
+        run: php -d extension="$TURBO_DLL" -d memory_limit=4G turbo-ext/tests/parser-corpus.php
@@ -0,0 +1,25 @@
+// phpstan_turbo — Windows build (php-devel-pack: phpize && configure && nmake).
+// The extension version is baked from the PHPSTANTURBO_VERSION environment
+// variable at configure time (the CI workflow computes it the same way the
+// Makefile does); it defaults to "dev", which the enabler rejects.
+
+ARG_ENABLE("phpstan-turbo", "phpstan turbo extension", "no");
+
+if (PHP_PHPSTAN_TURBO != "no") {
+	var version = WScript.CreateObject("WScript.Shell").Environment("PROCESS")("PHPSTANTURBO_VERSION");
+	if (!version || version == "") {
+		version = "dev";
+	}
+
+	// /EHsc: the C++ standard library assumes unwinding; /bigobj: the
+	// generated parser action files exceed the default section limit.
+	var flags = "/std:c++17 /EHsc /bigobj /DPHPSTANTURBO_VERSION=\\\"" + version + "\\\"";
+
+	EXTENSION("phpstan_turbo",
+		"src/main.cpp src/support.cpp src/CombinationsHelper.cpp src/ConditionalExpressionHolder.cpp src/ExpressionTypeHolder.cpp src/NodeScanner.cpp src/NodeTraverser.cpp src/ScopeOps.cpp src/TrinaryLogic.cpp src/TypeCombinatorCache.cpp",
+		true,
+		flags);
+	ADD_SOURCES(configure_module_dirname + "/src/parser",
+		"ParserRunner.cpp ParserRunnerActions1.cpp ParserRunnerActions2.cpp ParserRunnerActions3.cpp ParserRunnerHelpers.cpp",
+		"phpstan_turbo");
+}