By end user I mean those who install, maintain and use FrontAccounting by themselves with the Slim API, not the FA application operatives using what someone else installs and maintains.
What is wrong with line 6 of index,php? Just a plain include of all php files in the src folder so that any function in any endpoint can use it. I am planning on working on it to make sure that native FA functions are used for the most part. It works for me.
If there is anyone for whom the code does not work, please let me know - I'd like to know why and will do what needs to be done. I am keeping it as backward compatible as is possible so that those on older PHP versions too can still keep their installs whilst leveraging the REST API.
If you put in some test access values in util.php, you can easily browse to say: http://localhost/fa24/modules/api24/category/1
I've been packaging the original submission from Andres Amaya Diaz for FA 2.3 and worked on it while it was being hammered out. You check the wiki history and the original threads too.