The issue is that the list in headers.lua is finite and cannot accommodate all possible header values. For instance, it does not include the commonly used header "Origin." I understand that keeping this list updated is challenging, especially given the existence of headers like "X-*-*."

Currently, the options are either to ignore this limitation (as most services handle lower-cased headers well) or to manage the headers manually.

My suggestion is to avoid storing headers altogether and instead normalize them on-the-fly. The existing socket.headers table could remain in place and serve as a cache.