Someone has to maintain an always-running listener for `/events`. If a server does that, and triggers client calls, we call that webhooks. If a client does that

Someone has to maintain an always-running listener for `/events`. If a server does that, and triggers client calls, we call that webhooks. If a client does that, and triggers internal functions, it's what the op describes. I think that for APIs, `/events` should indeed be the fundamental feature, and "webhooks" should be a nice-to-have service on top of `/events`, for those who don't want to maintain a local subscriber.