diff --git a/.github/workflows/build-unix.yml b/.github/workflows/build-unix.yml
index ea9fb6ee..3cc8beaf 100644
--- a/.github/workflows/build-unix.yml
+++ b/.github/workflows/build-unix.yml
@@ -331,5 +331,4 @@ jobs:
         with:
           name: build-meta-${{ inputs.php-version }}-${{ inputs.os }}
           path: |
-            buildroot/build-extensions.json
-            buildroot/build-libraries.json
+            buildroot/build-manifest.json
diff --git a/.github/workflows/build-windows-x86_64.yml b/.github/workflows/build-windows-x86_64.yml
index d9cece6a..6eb48d7f 100644
--- a/.github/workflows/build-windows-x86_64.yml
+++ b/.github/workflows/build-windows-x86_64.yml
@@ -115,5 +115,4 @@ jobs:
         with:
           name: build-meta
           path: |
-            buildroot/build-extensions.json
-            buildroot/build-libraries.json
+            buildroot/build-manifest.json
diff --git a/src/Package/Target/php.php b/src/Package/Target/php.php
index 9efd5867..c9d31eaf 100644
--- a/src/Package/Target/php.php
+++ b/src/Package/Target/php.php
@@ -328,6 +328,49 @@ class php extends TargetPackage
         return $info;
     }
 
+    public function getBuildManifestData(PackageInstaller $installer): array
+    {
+        if ($this->getName() !== 'php') {
+            return [];
+        }
+
+        $all_extensions = [];
+        $static_extensions = [];
+        $shared_extensions = [];
+        foreach ($installer->getResolvedPackages(PhpExtensionPackage::class) as $extension) {
+            $extension_name = $extension->getExtensionName();
+            if ($extension->isBuildStatic() || $extension->isBuildShared()) {
+                $all_extensions[] = $extension_name;
+            }
+            if ($extension->isBuildStatic()) {
+                $static_extensions[] = $extension_name;
+            }
+            if ($extension->isBuildShared()) {
+                $shared_extensions[] = $extension_name;
+            }
+        }
+
+        $sapis = array_values(array_filter([
+            $installer->isPackageResolved('php-cli') ? 'cli' : null,
+            $installer->isPackageResolved('php-fpm') ? 'fpm' : null,
+            $installer->isPackageResolved('php-micro') ? 'micro' : null,
+            $installer->isPackageResolved('php-cgi') ? 'cgi' : null,
+            $installer->isPackageResolved('php-embed') ? 'embed' : null,
+            $installer->isPackageResolved('frankenphp') ? 'frankenphp' : null,
+        ]));
+
+        return [
+            'version' => static::getPHPVersion(return_null_if_failed: true),
+            'thread-safety' => $this->getBuildOption('enable-zts', false) ? 'zts' : 'nts',
+            'sapis' => $sapis,
+            'extensions' => [
+                'all' => $all_extensions,
+                'static' => $static_extensions,
+                'shared' => $shared_extensions,
+            ],
+        ];
+    }
+
     #[BeforeStage('php', 'build')]
     public function beforeBuild(PackageBuilder $builder, Package $package): void
     {
diff --git a/src/StaticPHP/Package/PackageInstaller.php b/src/StaticPHP/Package/PackageInstaller.php
index cf93368d..4032d33f 100644
--- a/src/StaticPHP/Package/PackageInstaller.php
+++ b/src/StaticPHP/Package/PackageInstaller.php
@@ -15,6 +15,7 @@ use StaticPHP\Exception\EnvironmentException;
 use StaticPHP\Exception\WrongUsageException;
 use StaticPHP\Registry\PackageLoader;
 use StaticPHP\Runtime\SystemTarget;
+use StaticPHP\Util\BuildManifestDumper;
 use StaticPHP\Util\BuildRootTracker;
 use StaticPHP\Util\DependencyResolver;
 use StaticPHP\Util\DirDiff;
@@ -282,6 +283,11 @@ class PackageInstaller
         // pipeline above (they were merged into $this->packages in resolvePackages()). This only
         // throws if a tool genuinely failed to become available (e.g. no artifact for this platform).
         $this->ensureRequiredTools();
+
+        // Pure install operations must not overwrite the manifest of an existing build.
+        if ($this->build_packages !== []) {
+            new BuildManifestDumper()->dump($this->packages, $this->build_packages, $this->install_packages, $this);
+        }
     }
 
     public function isBuildPackage(Package|string $package): bool
diff --git a/src/StaticPHP/Package/TargetPackage.php b/src/StaticPHP/Package/TargetPackage.php
index 9ff5c7de..18524920 100644
--- a/src/StaticPHP/Package/TargetPackage.php
+++ b/src/StaticPHP/Package/TargetPackage.php
@@ -117,6 +117,19 @@ class TargetPackage extends LibraryPackage
         return null;
     }
 
+    /**
+     * Get target-specific structured data for the build manifest.
+     *
+     * Target implementations may override this method to expose build facts that
+     * cannot be represented by the generic resolved package list.
+     *
+     * @return array<string, mixed>
+     */
+    public function getBuildManifestData(PackageInstaller $installer): array
+    {
+        return [];
+    }
+
     /**
      * Gets all build options for the target package.
      *
diff --git a/src/StaticPHP/Util/BuildManifestDumper.php b/src/StaticPHP/Util/BuildManifestDumper.php
new file mode 100644
index 00000000..c47569b7
--- /dev/null
+++ b/src/StaticPHP/Util/BuildManifestDumper.php
@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+namespace StaticPHP\Util;
+
+use StaticPHP\ConsoleApplication;
+use StaticPHP\Exception\SPCInternalException;
+use StaticPHP\Package\Package;
+use StaticPHP\Package\PackageInstaller;
+use StaticPHP\Package\TargetPackage;
+use StaticPHP\Runtime\SystemTarget;
+
+final class BuildManifestDumper
+{
+    public const int SCHEMA_VERSION = 1;
+
+    /**
+     * @param array<string, Package> $packages        Resolved packages in dependency order
+     * @param array<string, Package> $buildPackages   Packages explicitly scheduled for building
+     * @param array<string, Package> $installPackages Packages explicitly scheduled for installation
+     */
+    public function dump(
+        array $packages,
+        array $buildPackages,
+        array $installPackages,
+        PackageInstaller $installer,
+        string $outputPath = BUILD_ROOT_PATH . '/build-manifest.json',
+    ): void {
+        $targets = [];
+        foreach ($packages as $package) {
+            if (!$package instanceof TargetPackage) {
+                continue;
+            }
+
+            $data = $package->getBuildManifestData($installer);
+            if ($data !== []) {
+                $targets[$package->getName()] = $data;
+            }
+        }
+
+        $manifest = [
+            'schema-version' => self::SCHEMA_VERSION,
+            'spc-version' => ConsoleApplication::VERSION,
+            'target' => [
+                'platform' => SystemTarget::getCurrentPlatformString(),
+                'os' => SystemTarget::getTargetOS(),
+                'architecture' => SystemTarget::getTargetArch(),
+                'libc' => SystemTarget::getLibc(),
+                'libc-version' => SystemTarget::getLibcVersion(),
+                'spc-target' => getenv('SPC_TARGET') ?: null,
+                'toolchain' => getenv('SPC_TOOLCHAIN') ?: null,
+            ],
+            'requested-packages' => [
+                'build' => array_keys($buildPackages),
+                'install' => array_keys($installPackages),
+            ],
+            'packages' => array_values(array_map(
+                static function (Package $package): array {
+                    $artifact = $package->getArtifact();
+                    return [
+                        'name' => $package->getName(),
+                        'type' => $package->getType(),
+                        'artifact' => $artifact?->getName(),
+                    ];
+                },
+                $packages,
+            )),
+            'targets' => $targets,
+        ];
+
+        $json = json_encode(
+            $manifest,
+            JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE | JSON_THROW_ON_ERROR,
+        );
+        if (FileSystem::writeFile($outputPath, $json . PHP_EOL) === false) {
+            throw new SPCInternalException("Failed to write build manifest: {$outputPath}");
+        }
+
+        logger()->info('Generated build manifest with ' . count($packages) . " package(s): {$outputPath}");
+    }
+}
diff --git a/tests/StaticPHP/Util/BuildManifestDumperTest.php b/tests/StaticPHP/Util/BuildManifestDumperTest.php
new file mode 100644
index 00000000..f52a589a
--- /dev/null
+++ b/tests/StaticPHP/Util/BuildManifestDumperTest.php
@@ -0,0 +1,187 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\StaticPHP\Util;
+
+use Package\Target\php as PhpTargetPackage;
+use PHPUnit\Framework\TestCase;
+use StaticPHP\Artifact\Artifact;
+use StaticPHP\ConsoleApplication;
+use StaticPHP\Package\Package;
+use StaticPHP\Package\PackageInstaller;
+use StaticPHP\Package\PhpExtensionPackage;
+use StaticPHP\Package\TargetPackage;
+use StaticPHP\Runtime\SystemTarget;
+use StaticPHP\Util\BuildManifestDumper;
+
+/**
+ * @internal
+ */
+class BuildManifestDumperTest extends TestCase
+{
+    private string $tempDir;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->tempDir = sys_get_temp_dir() . '/build_manifest_dumper_test_' . uniqid();
+        mkdir($this->tempDir, 0755, true);
+    }
+
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+        if (is_dir($this->tempDir)) {
+            $this->removeDirectory($this->tempDir);
+        }
+    }
+
+    public function testDumpWritesResolvedPackagesAndBuildContext(): void
+    {
+        $phpArtifact = new Artifact('php-src', ['source' => ['type' => 'url', 'url' => 'https://example.com/php.tar.gz']]);
+        $phpManifestData = [
+            'thread-safety' => 'nts',
+            'extensions' => ['all' => ['curl'], 'static' => ['curl'], 'shared' => []],
+        ];
+        $php = $this->createTargetPackage('php', $phpArtifact, $phpManifestData);
+        $openssl = $this->createPackage('openssl', 'library');
+        $curl = $this->createPackage('ext-curl', 'php-extension');
+        $cli = $this->createPackage('php-cli', 'target');
+        $installer = $this->createMock(PackageInstaller::class);
+
+        $outputPath = $this->tempDir . '/nested/build-manifest.json';
+        (new BuildManifestDumper())->dump(
+            [
+                'openssl' => $openssl,
+                'ext-curl' => $curl,
+                'php' => $php,
+                'php-cli' => $cli,
+            ],
+            ['php' => $php],
+            ['php-cli' => $cli],
+            $installer,
+            $outputPath,
+        );
+
+        $this->assertFileExists($outputPath);
+        $manifest = json_decode((string) file_get_contents($outputPath), true, flags: JSON_THROW_ON_ERROR);
+
+        $this->assertSame(BuildManifestDumper::SCHEMA_VERSION, $manifest['schema-version']);
+        $this->assertSame(ConsoleApplication::VERSION, $manifest['spc-version']);
+        $this->assertSame(SystemTarget::getCurrentPlatformString(), $manifest['target']['platform']);
+        $this->assertSame(SystemTarget::getTargetOS(), $manifest['target']['os']);
+        $this->assertSame(SystemTarget::getTargetArch(), $manifest['target']['architecture']);
+        $this->assertSame(['php'], $manifest['requested-packages']['build']);
+        $this->assertSame(['php-cli'], $manifest['requested-packages']['install']);
+        $this->assertSame([
+            ['name' => 'openssl', 'type' => 'library', 'artifact' => null],
+            ['name' => 'ext-curl', 'type' => 'php-extension', 'artifact' => null],
+            ['name' => 'php', 'type' => 'target', 'artifact' => 'php-src'],
+            ['name' => 'php-cli', 'type' => 'target', 'artifact' => null],
+        ], $manifest['packages']);
+        $this->assertSame(['php' => $phpManifestData], $manifest['targets']);
+    }
+
+    public function testPhpTargetExportsPhpSpecificBuildFacts(): void
+    {
+        $curl = new PhpExtensionPackage('curl', extension_config: ['arg-type' => 'with']);
+        $curl->setBuildStatic();
+        $pdo = new PhpExtensionPackage('pdo', extension_config: ['arg-type' => 'enable']);
+        $pdo->setBuildStatic();
+        $pdo->setBuildShared();
+        $xdebug = new PhpExtensionPackage('xdebug', extension_config: ['arg-type' => 'enable']);
+        $xdebug->setBuildShared();
+        $unused = new PhpExtensionPackage('unused', extension_config: ['arg-type' => 'enable']);
+
+        $installer = $this->createMock(PackageInstaller::class);
+        $installer->method('getResolvedPackages')->willReturn([$curl, $pdo, $xdebug, $unused]);
+        $installer->method('isPackageResolved')->willReturnCallback(
+            static fn (string $name): bool => in_array($name, ['php-cli', 'php-micro', 'php-embed'], true),
+        );
+
+        $php = new class('php', 'target') extends PhpTargetPackage {
+            public static function getPHPVersion(?string $from_custom_source = null, bool $return_null_if_failed = false): ?string
+            {
+                return '8.4.10';
+            }
+
+            public function getBuildOption(string $key, mixed $default = null): mixed
+            {
+                return $key === 'enable-zts' ? true : $default;
+            }
+        };
+
+        $data = $php->getBuildManifestData($installer);
+
+        $this->assertSame('8.4.10', $data['version']);
+        $this->assertSame('zts', $data['thread-safety']);
+        $this->assertSame(['cli', 'micro', 'embed'], $data['sapis']);
+        $this->assertSame([
+            'all' => ['curl', 'pdo', 'xdebug'],
+            'static' => ['curl', 'pdo'],
+            'shared' => ['pdo', 'xdebug'],
+        ], $data['extensions']);
+    }
+
+    private function createPackage(string $name, string $type, ?Artifact $artifact = null): Package
+    {
+        return new class($name, $type, $artifact) extends Package {
+            public function __construct(string $name, string $type, private readonly ?Artifact $artifact)
+            {
+                parent::__construct($name, $type);
+            }
+
+            public function getArtifact(): ?Artifact
+            {
+                return $this->artifact;
+            }
+        };
+    }
+
+    /** @param array<string, mixed> $manifestData */
+    private function createTargetPackage(string $name, ?Artifact $artifact, array $manifestData): TargetPackage
+    {
+        return new class($name, 'target', $artifact, $manifestData) extends TargetPackage {
+            /** @param array<string, mixed> $manifestData */
+            public function __construct(
+                string $name,
+                string $type,
+                private readonly ?Artifact $artifact,
+                private readonly array $manifestData,
+            ) {
+                parent::__construct($name, $type);
+            }
+
+            public function getArtifact(): ?Artifact
+            {
+                return $this->artifact;
+            }
+
+            public function getBuildManifestData(PackageInstaller $installer): array
+            {
+                return $this->manifestData;
+            }
+        };
+    }
+
+    private function removeDirectory(string $directory): void
+    {
+        $items = scandir($directory);
+        if ($items === false) {
+            return;
+        }
+        foreach ($items as $item) {
+            if ($item === '.' || $item === '..') {
+                continue;
+            }
+            $path = $directory . DIRECTORY_SEPARATOR . $item;
+            if (is_dir($path)) {
+                $this->removeDirectory($path);
+            } else {
+                unlink($path);
+            }
+        }
+        rmdir($directory);
+    }
+}