What is the best way to allow me to pass data down to my views for all routes via middleware

slim.php

<?php
// Middleware for all requests
$app->add(function ($request, $response, $next) use ($container) {
    if ($request->hasHeader('HTTP_X_PJAX')) {
      // Here is where I would like to define an arg that can
      // be passed down to my views for all requests
    }
    $response = $next($request, $response);
    return $response;
});

$app->get('/{route}', function($request, $response, $args) {
  $template = $args['route'] . '.twig';
  
  // Goal of middleware is to replace done this in each route.
  if ($request->hasHeader('HTTP_X_PJAX')) {
    $args['isPjax'] = true;
  }
  
  return $this->view->render($response, $template, $args);
});