Converting a CI3 Project to CI4.5.1

1. You can create any directory for new files. The main thing is to initialize them correctly in the code. 2. 3. Add general parameters to the BaseController or create your own extension based on it. +CSRF protection is already ready in ci4

See example https://github.com/neznaika0/codeigniter-expenses

Thank you for your response.

However, I am still a bit confused by your answer.

I am aware I can add additional directories. However, the heart of my question was how does CI4 work with custom libraries? Is there a specific directory that the framework looks for those files in? Or can I use a "core" directory like before and CI4 work as it natively did in CI3 or do I have to code that link to the resources in for CI4? I am mainly asking if CI4 has any kind of library dependencies built-in for custom libraries, rather than the basic libraries that are built-in like: uri, form, database or etc.

In particular, would a controller library need to be defined as a normal controller or as a library resource?

Thanks again.