Currently, the cloudscript sdk on .net has a class called FunctionContext. In the example it is used to parse the request for functions as you can see here.
However, the Create method receives a HttpRequestMessage, which does not work in Azure functions v4 with isolated process (the in process model is considered obsolete).
I request an overload of FunctionContext.Create that receives an HttpRequest object. It would look almost the same.
The documentation currently instructs us to download CS2AFHelperClasses.cs and add it to our functions, but the example you provide does not use it, and it should be built-in functionality.
