“Always” was probably a bit too absolute in my original phrasing. I agree, and would go so far as to say streaming data would probably have a different deliver

“Always” was probably a bit too absolute in my original phrasing. I agree, and would go so far as to say streaming data would probably have a different delivery mechanism all together - SSE/websockets/etc. if you were doing long polling I may still want to put the metadata in the body but I agree it could be kept out of sight quite nicely in the headers.