Based on my experience working with undici through nxt-undici and building a more advanced client on top undici I have come to a few realizations that have semver major implications:

• onBodySent and onRequestSent are huge footguns. Remove it. (just wrap the body)
• interceptors are weird and overengineered. Remove it. (just wrap dispatchers)
• onConnect is confusing and should be renamed or something to make it more intuitive. Possibly entirely removed.
• body should support a factory method (important for retries and redirects).
• onResponseStarted. Why is onHeaders insufficient?
• maxRedirections and RedirectHandler should not be part of core/dispatcher APi. Move to the api methods.
• Change hooks signature to accept objects instead of params.
• Rename disatpcher param to dispatch which is just a function (opts, handler) => {}