The “Proper adherence” sentence has always bothered me. Why does “wfile” have to adhere, but not other other APIs (rfile, send_header, etc)? I wonder if the sentence is useful at all. (Of course you have to use HTTP to operate with HTTP clients.)

Perhaps it was intended to say that socket-level HTTP is written to wfile, that it is up to the caller to ensure the encoding, content length, etc is consistent with the HTTP header, and/or the caller has to supply the header (either direct through wfile or via send_header etc). A plausable alternative would be a higher-level file object like the request body in “http.client”, where encoding and content length is handled by the library.