Use typerocket with root composer.json

composer.json

{
  "require": {
    "typerocket/core": "4.0.*"
  },
  "scripts": {
    "typerocket-migrate": [
      "php ./wp-content/mu-plugins/typerocket/galaxy migrate up"
    ]
  }
}

init.php

<?php
// ** /wp-content/mu-plugins/typerocket/init.php
define( 'TR_APP_NAMESPACE', 'App' );
define( 'TR_PATH', __DIR__ );

new \TypeRocket\Core\Config( __DIR__ . '/config' );

if ( defined( 'WPINC' ) ) {
	( new \TypeRocket\Core\Launcher() )->initCore();
}

loader.php

<?php
// ** /wp-content/mu-plugins/loader.php
/**
 * MU Loader
 *
 * Plugin Name: TypeRocket MU Loader
 * Description: Load TypeRocket
 * Version: 2.0.0
 * License: GPL2
 *
 * @package mu-loader
 */

// Load TypeRocket and TypeRocket centric code.
if ( ! defined( 'TR_APP_NAMESPACE' ) ) {
	require WP_CONTENT_DIR . '/vendor/autoload.php';
	require 'typerocket/init.php';
	add_action(
		'typerocket_loaded',
		function() {
			// Any custom code you need to run after TR is loaded
		}
	);
// In some hosting environments we can't run the galaxy command. This adds galaxy as a WP CLI command.
	if ( defined( 'WP_CLI' ) && WP_CLI ) {
		WP_CLI::add_command(
			'galaxy',
			function () {
				$count = count( $_SERVER['argv'] );
				for ( $i = 0; $i < $count; $i++ ) {
					// strip any preceeding arguments so galaxy isn't confused.
					$arg = array_shift( $_SERVER['argv'] );
					if ( 'galaxy' == $arg ) {
						array_unshift( $_SERVER['argv'], 'galaxy' );
						break;
					}
				}
				new \TypeRocket\Console\Launcher();
			}
		);
	}
}