Middleware in design?

I'm really enjoying development with goa. ❤️

I wanted to move some repeating code to a middleware that is used by several methods. I was wondering why the middleware is not part of the design file? Currently the registration in the main.go feels a bit decoupled. Looking at the design or the implementation does not easily reveal which middleware is running for a specific endpoint.

My current workaround is just calling a method at the top of an endpoint, but this feels a bit against the "design first" philosophy.