diff --git a/README.md b/README.md
index cb9c8f77..31987b3d 100644
--- a/README.md
+++ b/README.md
@@ -34,9 +34,12 @@ The Blueprints library is distributed as a .phar library. To build the .phar fil
 vendor/bin/box compile
 ```
 
+Note that in box.json, the `"check-requirements"` option is set to `false`. Somehow, keeping it as `true` results in a
+.phar file
+that breaks HTTP requests in Playground. @TODO: Investigate why this is the case.
+
 To try the built .phar file, run:
 
 ```shell
 rm -rf new-wp/* && USE_PHAR=1 php blueprint_compiling.php
 ```
-
diff --git a/blueprint_compiling.php b/blueprint_compiling.php
index 6e01385e..0fa527ab 100644
--- a/blueprint_compiling.php
+++ b/blueprint_compiling.php
@@ -1,5 +1,6 @@
 <?php
 
+use WordPress\Blueprints\ContainerBuilder;
 use WordPress\Blueprints\Model\BlueprintBuilder;
 use function WordPress\Blueprints\run_blueprint;
 
@@ -21,6 +22,8 @@
 		'WP_CACHE'         => true,
 	] )
 	->withPlugins( [
+		// Required for withContent():
+		'https://downloads.wordpress.org/plugin/wordpress-importer.zip',
 		'https://downloads.wordpress.org/plugin/hello-dolly.zip',
 		'https://downloads.wordpress.org/plugin/gutenberg.17.7.0.zip',
 	] )
@@ -37,6 +40,6 @@
 	->toBlueprint();
 
 
-$results = run_blueprint( $blueprint, __DIR__ . '/new-wp' );
+$results = run_blueprint( $blueprint, ContainerBuilder::ENVIRONMENT_NATIVE, __DIR__ . '/new-wp' );
 
 var_dump( $results );
diff --git a/src/WordPress/Blueprints/ContainerBuilder.php b/src/WordPress/Blueprints/ContainerBuilder.php
index f468466d..ae88c255 100644
--- a/src/WordPress/Blueprints/ContainerBuilder.php
+++ b/src/WordPress/Blueprints/ContainerBuilder.php
@@ -59,21 +59,22 @@
 use WordPress\Blueprints\Runner\Step\UnzipStepRunner;
 use WordPress\Blueprints\Runner\Step\WPCLIStepRunner;
 use WordPress\Blueprints\Runner\Step\WriteFileStepRunner;
-use WordPress\Blueprints\Runtime\NativePHPRuntime;
+use WordPress\Blueprints\Runtime\Runtime;
 use WordPress\Blueprints\Runtime\RuntimeInterface;
 use WordPress\DataSource\FileSource;
+use WordPress\DataSource\PlaygroundFetchSource;
 use WordPress\DataSource\ProgressEvent;
 use WordPress\DataSource\UrlSource;
 
 class ContainerBuilder {
 
-	const RUNTIME_NATIVE = 'native';
-	const RUNTIME_PLAYGROUND = 'playground';
-	const RUNTIME_WP_NOW = 'wp-now';
-	const RUNTIMES = [
-		self::RUNTIME_NATIVE,
-		self::RUNTIME_PLAYGROUND,
-		self::RUNTIME_WP_NOW,
+	const ENVIRONMENT_NATIVE = 'native';
+	const ENVIRONMENT_PLAYGROUND = 'playground';
+	const ENVIRONMENT_WP_NOW = 'wp-now';
+	const ENVIRONMENTS = [
+		self::ENVIRONMENT_NATIVE,
+		self::ENVIRONMENT_PLAYGROUND,
+		self::ENVIRONMENT_WP_NOW,
 	];
 
 	protected $container;
@@ -83,13 +84,13 @@ public function __construct() {
 	}
 
 
-	public function build( RuntimeInterface $runtime ) {
+	public function build( string $environment, RuntimeInterface $runtime ) {
 		$container = $this->container;
 		$container['runtime'] = function () use ( $runtime ) {
 			return $runtime;
 		};
 
-		if ( $runtime instanceof NativePHPRuntime ) {
+		if ( $environment === static::ENVIRONMENT_NATIVE ) {
 			$container['downloads_cache'] = function ( $c ) {
 				return new FileCache();
 			};
@@ -101,6 +102,18 @@ public function build( RuntimeInterface $runtime ) {
 					echo $event->url . ' ' . $event->downloadedBytes . '/' . $event->totalBytes . "                         \r";
 				};
 			};
+			$container[ "resource.resolver." . UrlResource::DISCRIMINATOR ] = function ( $c ) {
+				return new UrlResourceResolver( $c['data_source.url'] );
+			};
+		} elseif ( $environment === static::ENVIRONMENT_PLAYGROUND ) {
+			$container[ "resource.resolver." . UrlResource::DISCRIMINATOR ] = function ( $c ) {
+				return new UrlResourceResolver( $c['data_source.playground_fetch'] );
+			};
+			$container['progress_reporter'] = function ( $c ) {
+				return function ( ProgressEvent $event ) {
+					echo $event->url . ' ' . $event->downloadedBytes . '/' . $event->totalBytes . "                         \r";
+				};
+			};
 		} else {
 			throw new InvalidArgumentException( "Not implemented yet" );
 		}
@@ -218,9 +231,6 @@ function () use ( $c ) {
 			return new RunSQLStepRunner();
 		};
 
-		$container[ "resource.resolver." . UrlResource::DISCRIMINATOR ] = function ( $c ) {
-			return new UrlResourceResolver( $c['data_source.url'] );
-		};
 		$container[ "resource.resolver." . FilesystemResource::DISCRIMINATOR ] = function () {
 			return new FilesystemResourceResolver();
 		};
@@ -262,6 +272,9 @@ function () use ( $c ) {
 		$container['data_source.url'] = function ( $c ) {
 			return new UrlSource( $c['http_client'], $c['downloads_cache'] );
 		};
+		$container['data_source.playground_fetch'] = function ( $c ) {
+			return new PlaygroundFetchSource();
+		};
 
 		// Add a progress listener to all data sources
 		foreach ( $container->keys() as $key ) {
diff --git a/src/WordPress/Blueprints/Model/BlueprintBuilder.php b/src/WordPress/Blueprints/Model/BlueprintBuilder.php
index d7260d1b..0253277d 100644
--- a/src/WordPress/Blueprints/Model/BlueprintBuilder.php
+++ b/src/WordPress/Blueprints/Model/BlueprintBuilder.php
@@ -87,7 +87,7 @@ public function withContent( $wxrs ) {
 		if ( ! is_array( $wxrs ) ) {
 			$wxrs = [ $wxrs ];
 		}
-		$this->withPlugin( 'https://downloads.wordpress.org/plugin/wordpress-importer.zip' );
+		// @TODO: Should this automatically add the importer plugin if it's not already installed?
 		foreach ( $wxrs as $wxr ) {
 			$this->addStep(
 				( new ImportFileStep() )
diff --git a/src/WordPress/Blueprints/Runner/Step/SetSiteOptionsStepRunner.php b/src/WordPress/Blueprints/Runner/Step/SetSiteOptionsStepRunner.php
index 534a141c..ce8d51b3 100644
--- a/src/WordPress/Blueprints/Runner/Step/SetSiteOptionsStepRunner.php
+++ b/src/WordPress/Blueprints/Runner/Step/SetSiteOptionsStepRunner.php
@@ -17,7 +17,7 @@ function run( SetSiteOptionsStep $input, Tracker $tracker ) {
 		// with a separate wp-cli command.
 		return $this->getRuntime()->evalPhpInSubProcess( <<<'CODE'
 <?php
-		require 'wp-load.php';
+		require getenv('DOCROOT'). '/wp-load.php';
 		$site_options = getenv("OPTIONS") ? json_decode(getenv("OPTIONS"), true) : [];
 		foreach($site_options as $name => $value) {
 			update_option($name, $value);
diff --git a/src/WordPress/Blueprints/Runtime/NativePHPRuntime.php b/src/WordPress/Blueprints/Runtime/Runtime.php
similarity index 95%
rename from src/WordPress/Blueprints/Runtime/NativePHPRuntime.php
rename to src/WordPress/Blueprints/Runtime/Runtime.php
index ec8b807d..79240a11 100644
--- a/src/WordPress/Blueprints/Runtime/NativePHPRuntime.php
+++ b/src/WordPress/Blueprints/Runtime/Runtime.php
@@ -7,7 +7,7 @@
 use Symfony\Component\Process\Process;
 use function WordPress\Blueprints\join_paths;
 
-class NativePHPRuntime implements RuntimeInterface {
+class Runtime implements RuntimeInterface {
 
 	public Filesystem $fs;
 
@@ -33,7 +33,7 @@ public function getDocumentRoot(): string {
 	}
 
 	public function resolvePath( string $path ): string {
-        return Path::makeAbsolute($path, $this->getDocumentRoot());
+		return Path::makeAbsolute( $path, $this->getDocumentRoot() );
 	}
 
 	public function withTemporaryDirectory( $callback ) {
diff --git a/src/WordPress/Blueprints/functions.php b/src/WordPress/Blueprints/functions.php
index ae7281ce..9ccbb921 100644
--- a/src/WordPress/Blueprints/functions.php
+++ b/src/WordPress/Blueprints/functions.php
@@ -3,13 +3,12 @@
 namespace WordPress\Blueprints;
 
 use Symfony\Component\Filesystem\Exception\IOException;
-use WordPress\Blueprints\Runtime\NativePHPRuntime;
+use WordPress\Blueprints\Runtime\Runtime;
 
-function run_blueprint( $json, $documentRoot = '/wordpress' ) {
+function run_blueprint( $json, $environment, $documentRoot = '/wordpress' ) {
 	$c = ( new ContainerBuilder() )->build(
-		new NativePHPRuntime(
-			$documentRoot
-		)
+		$environment,
+		new Runtime( $documentRoot )
 	);
 
 	return $c['blueprint.engine']->runBlueprint( $json );
diff --git a/src/WordPress/DataSource/PlaygroundFetchSource.php b/src/WordPress/DataSource/PlaygroundFetchSource.php
new file mode 100644
index 00000000..569cf5d9
--- /dev/null
+++ b/src/WordPress/DataSource/PlaygroundFetchSource.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace WordPress\DataSource;
+
+use Psr\SimpleCache\CacheInterface;
+use Symfony\Component\EventDispatcher\EventDispatcher;
+use Symfony\Component\HttpClient\Response\StreamWrapper;
+use Symfony\Contracts\EventDispatcher\Event;
+use Symfony\Contracts\HttpClient\HttpClientInterface;
+use WordPress\Streams\StreamPeeker;
+use WordPress\Streams\StreamPeekerContext;
+
+class PlaygroundFetchSource extends BaseDataSource {
+
+	public $proc_handles = [];
+
+	public function stream( $resourceIdentifier ) {
+		$url = $resourceIdentifier;
+		$proc_handle = proc_open(
+			[ 'fetch', $url, ],
+			[ 1 => [ 'pipe', 'w' ], 2 => [ 'pipe', 'w' ] ],
+			$pipes
+		);
+		// This prevents the process handle from getting garbage collected and
+		// breaking the stdout pipe. However, how the program never terminates.
+		// Presumably we need to peek() on the resource handle and close the
+		// process handle when it's done.
+		// Without this line, we get the following error:
+		// PHP Fatal error:  Uncaught TypeError: stream_copy_to_stream(): supplied resource is not a valid stream resource i
+		// var_dump()–ing first says
+		//    resource(457) of type (stream)
+		// but then it says
+		//    resource(457) of type (Unknown)
+		$this->proc_handles[] = $proc_handle;
+
+		return $pipes[1];
+	}
+
+}
+
diff --git a/src/WordPress/DataSource/UrlSource.php b/src/WordPress/DataSource/UrlSource.php
index 213d9e8c..fc445636 100644
--- a/src/WordPress/DataSource/UrlSource.php
+++ b/src/WordPress/DataSource/UrlSource.php
@@ -37,7 +37,7 @@ public function stream( $resourceIdentifier ) {
 		if ( $this->cache->has( $url ) ) {
 			// Return a stream resource.
 			// @TODO: Stream directly from the cache
-			$cached    = $this->cache->get( $url );
+			$cached = $this->cache->get( $url );
 			$data_size = strlen( $cached );
 			$this->events->dispatch( new ProgressEvent(
 				$url,
@@ -60,17 +60,17 @@ public function stream( $resourceIdentifier ) {
 				) );
 			},
 		] );
-		$stream   = StreamWrapper::createResource( $response, $this->client );
+		$stream = StreamWrapper::createResource( $response, $this->client );
 		if ( ! $stream ) {
 			throw new \Exception( 'Failed to download file' );
 		}
 		$onChunk = function ( $chunk ) use ( $url, $response, $stream ) {
 			// Handle response caching
-			// @TODO: don't buffer, just keep appending to the cache.
 			static $bufferedChunks = [];
 			$bufferedChunks[] = $chunk;
 			if ( feof( $stream ) ) {
 				$this->cache->set( $url, implode( '', $bufferedChunks ) );
+				$bufferedChunks = [];
 			}
 		};
 		$onClose = function () use ( $response ) {
diff --git a/src/WordPress/Zip/ZipStreamReader.php b/src/WordPress/Zip/ZipStreamReader.php
index a98898e5..409e31f5 100644
--- a/src/WordPress/Zip/ZipStreamReader.php
+++ b/src/WordPress/Zip/ZipStreamReader.php
@@ -57,10 +57,10 @@ static public function readEntry( $fp ) {
 	 * @param resource $stream
 	 */
 	static protected function readFileEntry( $stream ): ZipFileEntry {
-		$data  = self::read_bytes( $stream, 26 );
-		$data  = unpack( 'vversionNeeded/vgeneralPurpose/vcompressionMethod/vlastModifiedTime/vlastModifiedDate/Vcrc/VcompressedSize/VuncompressedSize/vpathLength/vextraLength',
+		$data = self::read_bytes( $stream, 26 );
+		$data = unpack( 'vversionNeeded/vgeneralPurpose/vcompressionMethod/vlastModifiedTime/vlastModifiedDate/Vcrc/VcompressedSize/VuncompressedSize/vpathLength/vextraLength',
 			$data );
-		$path  = self::read_bytes( $stream, $data['pathLength'] );
+		$path = self::read_bytes( $stream, $data['pathLength'] );
 		$extra = self::read_bytes( $stream, $data['extraLength'] );
 		$bytes = self::read_bytes( $stream, $data['compressedSize'] );
 
@@ -119,11 +119,11 @@ static protected function readFileEntry( $stream ): ZipFileEntry {
 	 * @param resource stream
 	 */
 	static protected function readCentralDirectoryEntry( $stream ): ZipCentralDirectoryEntry {
-		$data        = static::read_bytes( $stream, 42 );
-		$data        = unpack( 'vversionCreated/vversionNeeded/vgeneralPurpose/vcompressionMethod/vlastModifiedTime/vlastModifiedDate/Vcrc/VcompressedSize/VuncompressedSize/vpathLength/vextraLength/vfileCommentLength/vdiskNumber/vinternalAttributes/VexternalAttributes/VfirstByteAt',
+		$data = static::read_bytes( $stream, 42 );
+		$data = unpack( 'vversionCreated/vversionNeeded/vgeneralPurpose/vcompressionMethod/vlastModifiedTime/vlastModifiedDate/Vcrc/VcompressedSize/VuncompressedSize/vpathLength/vextraLength/vfileCommentLength/vdiskNumber/vinternalAttributes/VexternalAttributes/VfirstByteAt',
 			$data );
-		$path        = static::read_bytes( $stream, $data['pathLength'] );
-		$extra       = static::read_bytes( $stream, $data['extraLength'] );
+		$path = static::read_bytes( $stream, $data['pathLength'] );
+		$extra = static::read_bytes( $stream, $data['extraLength'] );
 		$fileComment = static::read_bytes( $stream, $data['fileCommentLength'] );
 
 		return new ZipCentralDirectoryEntry(
@@ -204,7 +204,7 @@ static protected function read_bytes( $stream, $length ): string|bool {
 				return false;
 			}
 			$length -= strlen( $chunk );
-			$data   .= $chunk;
+			$data .= $chunk;
 
 			if ( $length === 0 ) {
 				break;
diff --git a/src/WordPress/Zip/functions.php b/src/WordPress/Zip/functions.php
index e836ba3d..3c009533 100644
--- a/src/WordPress/Zip/functions.php
+++ b/src/WordPress/Zip/functions.php
@@ -11,7 +11,7 @@ function zip_extract_to( $fp, $toPath ) {
 		if ( ! $entry->isFileEntry() ) {
 			continue;
 		}
-		$path   = $toPath . '/' . sanitize_path( $entry->path );
+		$path = $toPath . '/' . sanitize_path( $entry->path );
 		$parent = dirname( $path );
 		if ( ! is_dir( $parent ) ) {
 			mkdir( $parent, 0777, true );
diff --git a/tests/Unit/RmStepTest.php b/tests/Unit/RmStepTest.php
index 659cba0d..231935d1 100644
--- a/tests/Unit/RmStepTest.php
+++ b/tests/Unit/RmStepTest.php
@@ -5,112 +5,115 @@
 use WordPress\Blueprints\BlueprintException;
 use WordPress\Blueprints\Model\DataClass\RmStep;
 use WordPress\Blueprints\Runner\Step\RmStepRunner;
-use WordPress\Blueprints\Runtime\NativePHPRuntime;
+use WordPress\Blueprints\Runtime\Runtime;
 
 
-beforeEach(function() {
-    $this->documentRoot = Path::makeAbsolute("test", sys_get_temp_dir());
-    $this->runtime = new NativePHPRuntime($this->documentRoot);
+beforeEach( function () {
+	$this->documentRoot = Path::makeAbsolute( "test", sys_get_temp_dir() );
+	$this->runtime = new Runtime( $this->documentRoot );
 
-    $this->step = new RmStepRunner();
-    $this->step->setRuntime($this->runtime);
+	$this->step = new RmStepRunner();
+	$this->step->setRuntime( $this->runtime );
 
-    $this->fileSystem = new Filesystem();
-});
+	$this->fileSystem = new Filesystem();
+} );
 
-afterEach(function() {
-    $this->fileSystem->remove($this->documentRoot);
-});
+afterEach( function () {
+	$this->fileSystem->remove( $this->documentRoot );
+} );
 
-it('should remove a directory (using an absolute path)', function() {
-    $absolutePath = $this->runtime->resolvePath("dir");
-    $this->fileSystem->mkdir($absolutePath);
+it( 'should remove a directory (using an absolute path)', function () {
+	$absolutePath = $this->runtime->resolvePath( "dir" );
+	$this->fileSystem->mkdir( $absolutePath );
 
-    $input = new RmStep();
-    $input->path = $absolutePath;
+	$input = new RmStep();
+	$input->path = $absolutePath;
 
-    $this->step->run($input);
+	$this->step->run( $input );
 
-    expect($this->fileSystem->exists($absolutePath))->toBeFalse();
-});
+	expect( $this->fileSystem->exists( $absolutePath ) )->toBeFalse();
+} );
 
-it('should remove a directory (using a relative path)', function () {
-    $relativePath = "dir";
-    $absolutePath = $this->runtime->resolvePath($relativePath);
-    $this->fileSystem->mkdir($absolutePath);
+it( 'should remove a directory (using a relative path)', function () {
+	$relativePath = "dir";
+	$absolutePath = $this->runtime->resolvePath( $relativePath );
+	$this->fileSystem->mkdir( $absolutePath );
 
-    $input = new RmStep();
-    $input->path = $relativePath;
+	$input = new RmStep();
+	$input->path = $relativePath;
 
-    $this->step->run($input);
+	$this->step->run( $input );
 
-    expect($this->fileSystem->exists($absolutePath))->toBeFalse();
-});
+	expect( $this->fileSystem->exists( $absolutePath ) )->toBeFalse();
+} );
 
-it ('should remove a directory with a subdirectory', function () {
-    $relativePath = "dir/subdir";
-    $absolutePath = $this->runtime->resolvePath($relativePath);
-    $this->fileSystem->mkdir($absolutePath);
+it( 'should remove a directory with a subdirectory', function () {
+	$relativePath = "dir/subdir";
+	$absolutePath = $this->runtime->resolvePath( $relativePath );
+	$this->fileSystem->mkdir( $absolutePath );
 
-    $input = new RmStep();
-    $input->path = dirname($relativePath);
+	$input = new RmStep();
+	$input->path = dirname( $relativePath );
 
-    $this->step->run($input);
+	$this->step->run( $input );
 
-    expect($this->fileSystem->exists(dirname($absolutePath)))->toBeFalse();
-});
+	expect( $this->fileSystem->exists( dirname( $absolutePath ) ) )->toBeFalse();
+} );
 
-it ('should remove a directory with a file', function () {
-    $relativePath = "dir/file.txt";
-    $absolutePath = $this->runtime->resolvePath($relativePath);
-    $this->fileSystem->dumpFile($absolutePath, "test");
+it( 'should remove a directory with a file', function () {
+	$relativePath = "dir/file.txt";
+	$absolutePath = $this->runtime->resolvePath( $relativePath );
+	$this->fileSystem->dumpFile( $absolutePath, "test" );
 
-    $input = new RmStep();
-    $input->path = dirname($relativePath);
+	$input = new RmStep();
+	$input->path = dirname( $relativePath );
 
-    $this->step->run($input);
+	$this->step->run( $input );
 
-    expect($this->fileSystem->exists(dirname($absolutePath)))->toBeFalse();
-});
+	expect( $this->fileSystem->exists( dirname( $absolutePath ) ) )->toBeFalse();
+} );
 
-it ('should remove a file', function () {
-   $relativePath = "file.txt";
-   $absolutePath = $this->runtime->resolvePath($relativePath);
-   $this->fileSystem->dumpFile($absolutePath, "test");
+it( 'should remove a file', function () {
+	$relativePath = "file.txt";
+	$absolutePath = $this->runtime->resolvePath( $relativePath );
+	$this->fileSystem->dumpFile( $absolutePath, "test" );
 
-   $input = new RmStep();
-   $input->path = $relativePath;
+	$input = new RmStep();
+	$input->path = $relativePath;
 
-   $this->step->run($input);
+	$this->step->run( $input );
 
-   expect($this->fileSystem->exists($absolutePath))->toBeFalse();
-});
+	expect( $this->fileSystem->exists( $absolutePath ) )->toBeFalse();
+} );
 
-it ('should throw an exception when asked to remove a nonexistent directory (using a relative path)', function() {
-    $relativePath = "dir";
+it( 'should throw an exception when asked to remove a nonexistent directory (using a relative path)', function () {
+	$relativePath = "dir";
 
-    $input = new RmStep();
-    $input->path = $relativePath;
+	$input = new RmStep();
+	$input->path = $relativePath;
 
-    $absolutePath = $this->runtime->resolvePath($relativePath);
-    expect(fn() => $this->step->run($input))->toThrow(BlueprintException::class, "Failed to remove \"$absolutePath\": the directory or file does not exist.");
-});
+	$absolutePath = $this->runtime->resolvePath( $relativePath );
+	expect( fn() => $this->step->run( $input ) )->toThrow( BlueprintException::class,
+		"Failed to remove \"$absolutePath\": the directory or file does not exist." );
+} );
 
-it ('should throw an exception when asked to remove a nonexistent directory (using an absolute path)', function () {
-    $absolutePath = "/dir";
+it( 'should throw an exception when asked to remove a nonexistent directory (using an absolute path)', function () {
+	$absolutePath = "/dir";
 
-    $input = new RmStep();
-    $input->path = $absolutePath;
+	$input = new RmStep();
+	$input->path = $absolutePath;
 
-    expect(fn() => $this->step->run($input))->toThrow(BlueprintException::class, "Failed to remove \"$absolutePath\": the directory or file does not exist.");
-});
+	expect( fn() => $this->step->run( $input ) )->toThrow( BlueprintException::class,
+		"Failed to remove \"$absolutePath\": the directory or file does not exist." );
+} );
 
-it ('should throw an exception when asked to remove a nonexistent file', function() {
-    $relativePath = "file.txt";
+it( 'should throw an exception when asked to remove a nonexistent file', function () {
+	$relativePath = "file.txt";
 
-    $input = new RmStep();
-    $input->path = $relativePath;
+	$input = new RmStep();
+	$input->path = $relativePath;
 
-    $absolutePath = $this->runtime->resolvePath($relativePath);
-    expect(fn() => $this->step->run($input))->toThrow(BlueprintException::class, "Failed to remove \"$absolutePath\": the directory or file does not exist.");
-});
+	$absolutePath = $this->runtime->resolvePath( $relativePath );
+	expect( fn() => $this->step->run( $input ) )->toThrow( BlueprintException::class,
+		"Failed to remove \"$absolutePath\": the directory or file does not exist." );
+} );