This part of the documentation provides in-depth guides for specific features.
You might have seen implicit
Tupler parameters in the type signature of some algebra operations. The Tupler guide explains what it is used for.
When you have application-specific aspects of your communication endpoints that are not covered by endpoints4s you can extend the algebras and their interpreters to include them.
Typically, each application has its own way of dealing with authentication. The custom authentication guide shows how to enrich the algebras with authentication-related vocabulary and how to extend the client and server interpreters to consistently implement the application-specific authentication mechanism.