index.php                                          front controller / router
wp-includes/
  functions.php                                    absint / wp_parse_id_list / wp_parse_url
  class-wpdb.php                                    thin $wpdb (prepare / get_results)
  class-wp-query.php                               post query builder
  rest-api/
    class-wp-rest-request.php
    class-wp-rest-server.php                        routing + /batch/v1
    endpoints/class-wp-rest-posts-controller.php    /wp/v2/posts

php -S 127.0.0.1:8080
curl 'http://127.0.0.1:8080/wp-json/wp/v2/posts?author_exclude[]=3'