// public/index.php
use Psr\Http\Message\ServerRequestInterface;
use GuzzleHttp\Psr7;
require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
return function (ServerRequestInterface $request) {
    return new Psr7\Response(200, [], 'PSR-7');
};

// public/index.php
use Psr\Http\Server\RequestHandlerInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Message\ResponseInterface;
use GuzzleHttp\Psr7;
require_once dirname(__DIR__).'/vendor/autoload_runtime.php';
class Application implements RequestHandlerInterface {
    // ...
    public function handle(ServerRequestInterface $request): ResponseInterface
    {
        return new Psr7\Response(200, [], 'PSR-15');
    }
}
return function (array $context) {
    return new Application($context['APP_ENV'] ?? 'dev');
};