Opt-in middleware for one tool, resource, or prompt callback.

A component declares wrap: [MyWrapper, {AnotherWrapper, option: value}]. Each wrapper implements call/4. The first declared wrapper runs first and receives a continuation that calls the next wrapper with a context and arguments. A wrapper may call that continuation, replace the context or arguments, or return a result without invoking the handler.

The options passed to call/4 include the declaration's options plus :component, :kind, :operation, and :slot. Those keys identify the component and wrapper occurrence. Resource and prompt wrappers also run on an explicitly defined complete/2 callback. Middleware runs inside the component callback, after router lookup, authorization, and input validation.