Escher was a PHP MVC framework developed by Thom Stricklin from 2011-2013. Escher implemented a hybrid of Model2 MVC and PAC architectures and CMS concepts as well as plugins and configuration wizards. Development halted in 2013 in favor of Kohana and later Symfony, which closely aligned to the same design principles as Escher.
A method in the headers helper will be able to have the ability to determine if a request is an AJAX request.