diff --git a/components/Blueprints/RunnerConfiguration.php b/components/Blueprints/RunnerConfiguration.php
index f02a04ab3..4818834e0 100644
--- a/components/Blueprints/RunnerConfiguration.php
+++ b/components/Blueprints/RunnerConfiguration.php
@@ -32,6 +32,26 @@ class RunnerConfiguration {
 	 * @var string
 	 */
 	private $siteUrl = '';
+	/**
+	 * @var string
+	 */
+	private $installSiteTitle = 'WordPress Site';
+	/**
+	 * @var string
+	 */
+	private $installAdminUser = 'admin';
+	/**
+	 * @var string
+	 */
+	private $installAdminPassword = 'password';
+	/**
+	 * @var string
+	 */
+	private $installAdminEmail = 'admin@example.com';
+	/**
+	 * @var bool
+	 */
+	private $installSkipEmail = false;
 	/**
 	 * @var string
 	 */
@@ -120,6 +140,56 @@ public function getTargetSiteUrl(): string {
 		return $this->siteUrl;
 	}
 
+	public function setInstallSiteTitle( string $t ): self {
+		$this->installSiteTitle = $t;
+
+		return $this;
+	}
+
+	public function getInstallSiteTitle(): string {
+		return $this->installSiteTitle;
+	}
+
+	public function setInstallAdminUser( string $u ): self {
+		$this->installAdminUser = $u;
+
+		return $this;
+	}
+
+	public function getInstallAdminUser(): string {
+		return $this->installAdminUser;
+	}
+
+	public function setInstallAdminPassword( string $p ): self {
+		$this->installAdminPassword = $p;
+
+		return $this;
+	}
+
+	public function getInstallAdminPassword(): string {
+		return $this->installAdminPassword;
+	}
+
+	public function setInstallAdminEmail( string $e ): self {
+		$this->installAdminEmail = $e;
+
+		return $this;
+	}
+
+	public function getInstallAdminEmail(): string {
+		return $this->installAdminEmail;
+	}
+
+	public function setInstallSkipEmail( bool $skip ): self {
+		$this->installSkipEmail = $skip;
+
+		return $this;
+	}
+
+	public function getInstallSkipEmail(): bool {
+		return $this->installSkipEmail;
+	}
+
 	/**
 	 * Sets the database engine.
 	 *
diff --git a/components/Blueprints/Runtime.php b/components/Blueprints/Runtime.php
index cdfa1419c..617b5ada0 100644
--- a/components/Blueprints/Runtime.php
+++ b/components/Blueprints/Runtime.php
@@ -253,7 +253,24 @@ public function createPhpSubProcess(
 			// Still put the script in a temporary file as the path may be refering
 			// to a file inside the currently executed .phar archive.
 			$actual_script_path = wp_join_unix_paths( $tempDir, 'script.php' );
-			$code = '<?php function append_output( $output ) { file_put_contents( getenv("OUTPUT_FILE"), $output, FILE_APPEND ); } $_SERVER["HTTP_HOST"] = "localhost"; ?>';
+			$code = '<?php '
+				. 'function append_output( $output ) { file_put_contents( getenv("OUTPUT_FILE"), $output, FILE_APPEND ); } '
+				. 'if (!isset($_SERVER["HTTP_HOST"])) { $_SERVER["HTTP_HOST"] = "localhost"; } '
+				. 'if (!isset($_SERVER["SERVER_NAME"])) { $_SERVER["SERVER_NAME"] = $_SERVER["HTTP_HOST"]; } '
+				. 'if (!isset($_SERVER["REQUEST_URI"])) { $_SERVER["REQUEST_URI"] = "/"; } '
+				. 'if (!isset($_SERVER["SERVER_PROTOCOL"])) { $_SERVER["SERVER_PROTOCOL"] = "HTTP/1.1"; } '
+				. 'if (!isset($_SERVER["REMOTE_ADDR"])) { $_SERVER["REMOTE_ADDR"] = "127.0.0.1"; } '
+				. 'if (!isset($_SERVER["REQUEST_METHOD"])) { $_SERVER["REQUEST_METHOD"] = "GET"; } '
+				. 'if (!isset($_SERVER["HTTPS"])) { $_SERVER["HTTPS"] = "off"; } '
+				. 'if (!isset($_SERVER["SERVER_PORT"])) { $_SERVER["SERVER_PORT"] = "80"; } '
+				. 'if (!isset($_SERVER["SCRIPT_NAME"])) { $_SERVER["SCRIPT_NAME"] = "/index.php"; } '
+				. '$__docroot = getenv("DOCROOT"); '
+				. 'if ($__docroot) { '
+				. '  if (!isset($_SERVER["DOCUMENT_ROOT"])) { $_SERVER["DOCUMENT_ROOT"] = $__docroot; } '
+				. '  if (!isset($_SERVER["SCRIPT_FILENAME"])) { $_SERVER["SCRIPT_FILENAME"] = $__docroot . "/index.php"; } '
+				. '} '
+				. 'unset($__docroot); '
+				. '?>';
 			$code .= file_get_contents( $script_path );
 			file_put_contents( $actual_script_path, $code );
 
diff --git a/components/Blueprints/SiteResolver/NewSiteResolver.php b/components/Blueprints/SiteResolver/NewSiteResolver.php
index d874ddcef..418bea8c2 100644
--- a/components/Blueprints/SiteResolver/NewSiteResolver.php
+++ b/components/Blueprints/SiteResolver/NewSiteResolver.php
@@ -11,6 +11,7 @@
 use WordPress\HttpClient\Client;
 use WordPress\HttpClient\Request;
 use WordPress\Zip\ZipFilesystem;
+use WordPress\Blueprints\SiteResolver\WordPressInstaller;
 
 use function WordPress\Filesystem\copy_between_filesystems;
 use function WordPress\Filesystem\wp_join_unix_paths;
@@ -110,28 +111,16 @@ static public function resolve( Runtime $runtime, Tracker $progress, ?VersionCon
 				}
 			}
 
-			// Perform installation using WP-CLI
-			// @TODO (low priority): Remove the WP-CLI dependency to lower the download size for blueprints.phar.
-			$progress['install_wordpress']->set( 0.7, 'Installing WordPress' );
-			$wp_cli_path = $runtime->getWpCliPath();
-			$process = $runtime->startShellCommand( [
-				'php',
-				$wp_cli_path,
-				'core',
-				'install',
-				'--path=' . $runtime->getConfiguration()->getTargetSiteRoot(),
-
-				// For Docker compatibility. If we got this far, Blueprint runner was already
-				// allowed to run as root.
-				'--allow-root',
-				'--url=' . $runtime->getConfiguration()->getTargetSiteUrl(),
-				'--title=WordPress Site',
-				'--admin_user=admin',
-				'--admin_password=password',
-				'--admin_email=admin@example.com',
-				'--skip-email',
+			// Perform core installation without WP-CLI by invoking WordPressInternals
+			$installer = new WordPressInstaller();
+			$installer->install( $runtime, $progress['install_wordpress'], [
+				'site_url'       => $runtime->getConfiguration()->getTargetSiteUrl(),
+				'title'          => $runtime->getConfiguration()->getInstallSiteTitle(),
+				'admin_user'     => $runtime->getConfiguration()->getInstallAdminUser(),
+				'admin_password' => $runtime->getConfiguration()->getInstallAdminPassword(),
+				'admin_email'    => $runtime->getConfiguration()->getInstallAdminEmail(),
+				'skip_email'     => $runtime->getConfiguration()->getInstallSkipEmail(),
 			] );
-			$process->mustRun();
 
 			if ( ! self::isWordPressInstalled( $runtime, $progress ) ) {
 				// @TODO: This breaks in Playground CLI
diff --git a/components/Blueprints/SiteResolver/WordPressInstaller.php b/components/Blueprints/SiteResolver/WordPressInstaller.php
new file mode 100644
index 000000000..b490c049a
--- /dev/null
+++ b/components/Blueprints/SiteResolver/WordPressInstaller.php
@@ -0,0 +1,181 @@
+<?php
+
+namespace WordPress\Blueprints\SiteResolver;
+
+use WordPress\Blueprints\Progress\Tracker;
+use WordPress\Blueprints\Runtime;
+use WordPress\Blueprints\Steps\DefineConstantsStep;
+use WordPress\Blueprints\Exception\BlueprintExecutionException;
+
+class WordPressInstaller {
+	/**
+	 * Install WordPress core without relying on WP-CLI.
+	 *
+	 * Supported options (defaults shown):
+	 * - 'site_url'      => $runtime->getConfiguration()->getTargetSiteUrl()
+	 * - 'title'         => 'WordPress Site'
+	 * - 'admin_user'    => 'admin'
+	 * - 'admin_password'=> 'password'
+	 * - 'admin_email'   => 'admin@example.com'
+	 * - 'skip_email'    => true
+	 */
+	public function install( Runtime $runtime, Tracker $tracker, array $options = [] ): void {
+		$targetFs = $runtime->getTargetFilesystem();
+		$tracker->set( 0.65, 'Preparing WordPress installation' );
+
+		// Ensure wp-config.php exists
+		if ( ! $targetFs->exists( '/wp-config.php' ) ) {
+			if ( $targetFs->exists( 'wp-config-sample.php' ) ) {
+				$targetFs->copy( 'wp-config-sample.php', 'wp-config.php' );
+			} else {
+				throw new BlueprintExecutionException( 'Neither wp-config.php, nor wp-config-sample.php was found in the WordPress archive.' );
+			}
+		}
+
+		// Define DB constants according to configuration
+		$dbEngine  = $runtime->getConfiguration()->getDatabaseEngine();
+		$dbCreds   = $runtime->getConfiguration()->getDatabaseCredentials();
+		$constants = [];
+		if ( $dbEngine === 'mysql' ) {
+			$constants = [
+				'DB_NAME'     => $dbCreds['databaseName'] ?? 'wordpress',
+				'DB_USER'     => $dbCreds['username'] ?? 'root',
+				'DB_PASSWORD' => $dbCreds['password'] ?? '',
+				'DB_HOST'     => $dbCreds['host'] ?? '127.0.0.1',
+			];
+		} elseif ( $dbEngine === 'sqlite' ) {
+			// Prefer canonical default used elsewhere in the runner
+			$dbPath = $dbCreds['path'] ?? 'wp-content/.ht.sqlite';
+			if ($dbPath === '' || $dbPath === null) {
+				$dbPath = 'wp-content/.ht.sqlite';
+			}
+			$constants = [ 'DB_NAME' => $dbPath ];
+
+			// Pre-create the database directory to avoid cross‑platform path issues
+			$targetFs = $runtime->getTargetFilesystem();
+			$relativeDbPath = '/' . ltrim( $dbPath, '/' );
+			$dbDir = dirname( $relativeDbPath );
+			if ( ! $targetFs->is_dir( $dbDir ) ) {
+				$targetFs->mkdir( $dbDir, 0755, true );
+			}
+			// Best effort to ensure file exists and is writable (SQLite will create as needed)
+			if ( ! $targetFs->exists( $relativeDbPath ) ) {
+				try { $targetFs->put_contents( $relativeDbPath, '' ); } catch ( \Throwable $e ) { /* ignore */ }
+			}
+
+			// Ensure SQLite extension availability for clearer errors on macOS/Windows
+			if ( ! extension_loaded('sqlite3') && ! extension_loaded('pdo_sqlite') ) {
+				throw new BlueprintExecutionException(
+					'SQLite database engine selected, but neither sqlite3 nor pdo_sqlite PHP extension is loaded. '
+					. 'Enable one of these extensions or switch --db-engine to mysql.'
+				);
+			}
+		}
+		if ( ! empty( $constants ) ) {
+			(new DefineConstantsStep( $constants ))->run( $runtime, $tracker );
+		}
+
+		// Prepare installation options
+		$siteUrl      = $options['site_url'] ?? $runtime->getConfiguration()->getTargetSiteUrl();
+		$title        = $options['title'] ?? 'WordPress Site';
+		$adminUser    = $options['admin_user'] ?? 'admin';
+		$adminPass    = $options['admin_password'] ?? 'password';
+		$adminEmail   = $options['admin_email'] ?? 'admin@example.com';
+		$skipEmail    = (bool) ( $options['skip_email'] ?? true );
+
+		$tracker->set( 0.7, 'Installing WordPress' );
+		$runtime->evalPhpCodeInSubProcess(
+			<<<'PHP'
+<?php
+$docroot     = getenv('DOCROOT');
+$site_url    = getenv('SITE_URL');
+$title       = getenv('TITLE');
+$admin_user  = getenv('ADMIN_USER');
+$admin_pass  = getenv('ADMIN_PASS');
+$admin_email = getenv('ADMIN_EMAIL');
+$skip_email  = getenv('SKIP_EMAIL') === '1';
+$host = null; $port = null; $scheme = null;
+if ($site_url) {
+	$parts = @parse_url($site_url);
+	$host = $parts['host'] ?? null;
+	$port = $parts['port'] ?? null;
+	$scheme = $parts['scheme'] ?? null;
+}
+
+if (!file_exists($docroot . '/wp-load.php')) {
+	fwrite(STDERR, "Blueprint Error: wp-load.php not found in DOCROOT\n");
+	exit(1);
+}
+
+// Ensure WordPress runs in installing context and suppress emails reliably
+if (!defined('WP_INSTALLING')) {
+	define('WP_INSTALLING', true);
+}
+if ($site_url && !defined('WP_HOME')) {
+	define('WP_HOME', rtrim($site_url, '/'));
+}
+if ($site_url && !defined('WP_SITEURL')) {
+	define('WP_SITEURL', rtrim($site_url, '/'));
+}
+// Normalize web server globals to avoid platform-specific behavior
+if ($host) {
+	$_SERVER['HTTP_HOST'] = $host . ($port ? ":$port" : '');
+	$_SERVER['SERVER_NAME'] = $host;
+}
+if ($scheme) {
+	$_SERVER['HTTPS'] = ($scheme === 'https') ? 'on' : 'off';
+	$_SERVER['SERVER_PORT'] = ($scheme === 'https') ? '443' : '80';
+	$_SERVER['REQUEST_SCHEME'] = $scheme;
+}
+if (!isset($_SERVER['REQUEST_URI'])) {
+	$_SERVER['REQUEST_URI'] = '/';
+}
+if (!isset($_SERVER['SERVER_PROTOCOL'])) {
+	$_SERVER['SERVER_PROTOCOL'] = 'HTTP/1.1';
+}
+if (!isset($_SERVER['REMOTE_ADDR'])) {
+	$_SERVER['REMOTE_ADDR'] = '127.0.0.1';
+}
+if (!isset($_SERVER['SCRIPT_NAME'])) {
+	$_SERVER['SCRIPT_NAME'] = '/index.php';
+}
+if (!isset($_SERVER['DOCUMENT_ROOT'])) {
+	$_SERVER['DOCUMENT_ROOT'] = $docroot;
+}
+if (!isset($_SERVER['SCRIPT_FILENAME'])) {
+	$_SERVER['SCRIPT_FILENAME'] = $docroot . '/index.php';
+}
+require $docroot . '/wp-load.php';
+require_once ABSPATH . 'wp-admin/includes/upgrade.php';
+if ($skip_email) {
+	// Short-circuit wp_mail completely (introduced in WP 5.5)
+	if (function_exists('add_filter')) {
+		add_filter('pre_wp_mail', '__return_false');
+		add_filter('send_password_change_email', '__return_false');
+	}
+}
+wp_install($title, $admin_user, $admin_email, /*public*/ true, '', $admin_pass);
+if ($site_url) {
+	$site_url = rtrim($site_url, '/');
+	update_option('siteurl', $site_url);
+	update_option('home', $site_url);
+}
+if (function_exists('flush_rewrite_rules')) {
+	flush_rewrite_rules(false);
+}
+PHP
+			,
+			[
+				'DOCROOT'     => $runtime->getConfiguration()->getTargetSiteRoot(),
+				'SITE_URL'    => $siteUrl,
+				'TITLE'       => $title,
+				'ADMIN_USER'  => $adminUser,
+				'ADMIN_PASS'  => $adminPass,
+				'ADMIN_EMAIL' => $adminEmail,
+				'SKIP_EMAIL'  => $skipEmail ? '1' : '0',
+			]
+		);
+	}
+}
+
+
diff --git a/components/Blueprints/bin/blueprint.php b/components/Blueprints/bin/blueprint.php
index 98a0925a2..d03fe9885 100644
--- a/components/Blueprints/bin/blueprint.php
+++ b/components/Blueprints/bin/blueprint.php
@@ -263,6 +263,12 @@ function createProgressReporter(): ProgressReporter {
 			'db-pass'                     => [ null, true, '', 'MySQL password' ],
 			'db-name'                     => [ null, true, 'wordpress', 'MySQL database' ],
 			'db-path'                     => [ 'p', true, 'wp.db', 'SQLite file path' ],
+			// WordPress install options (used when creating a new site)
+			'wp-title'                    => [ null, true, 'WordPress Site', 'Site title used during installation' ],
+			'wp-admin-user'               => [ null, true, 'admin', 'Administrator username used during installation' ],
+			'wp-admin-pass'               => [ null, true, 'password', 'Administrator password used during installation' ],
+			'wp-admin-email'              => [ null, true, 'admin@example.com', 'Administrator email used during installation' ],
+			'wp-skip-email'               => [ null, false, false, 'Skip sending emails during installation' ],
 			'truncate-new-site-directory' => [ 't', false, false, 'Delete target directory if it exists before execution' ],
 			/**
 			 * @TODO: Reuse this error message removed from the Playground repo:
@@ -451,6 +457,23 @@ function cliArgsToRunnerConfiguration( array $positionalArgs, array $options ):
 	$config->setTargetSiteRoot( $absoluteTargetSiteRoot );
 	$config->setTargetSiteUrl( $options['site-url'] );
 
+	// Install options
+	if ( ! empty( $options['wp-title'] ) ) {
+		$config->setInstallSiteTitle( $options['wp-title'] );
+	}
+	if ( ! empty( $options['wp-admin-user'] ) ) {
+		$config->setInstallAdminUser( $options['wp-admin-user'] );
+	}
+	if ( ! empty( $options['wp-admin-pass'] ) ) {
+		$config->setInstallAdminPassword( $options['wp-admin-pass'] );
+	}
+	if ( ! empty( $options['wp-admin-email'] ) ) {
+		$config->setInstallAdminEmail( $options['wp-admin-email'] );
+	}
+	if ( ! empty( $options['wp-skip-email'] ) ) {
+		$config->setInstallSkipEmail( true );
+	}
+
 	// Set database engine
 	if ( ! empty( $options['db-engine'] ) ) {
 		$config->setDatabaseEngine( $options['db-engine'] );