WebSocket over HTTP2

[fengli79]

I'm seeking for using WebSocket over HTTP2 (https://datatracker.ietf.org/doc/html/rfc8441), via httpx or some other python http2 library.
Basically create such a message flow (TLDR), however, I cannot send the :protocol pseudo header via httpx, as it added some other headers ahead, and raise "httpx.LocalProtocolError: Received pseudo-header field out of sequence: b':protocol'"
Is there a way to send out the :protocol header in httpx? If not today, can an API be provided?

[[ From Client ]] [[ From Server ]]

                                    SETTINGS
                                    SETTINGS_ENABLE_CONNECT_[..] = 1

HEADERS + END_HEADERS
:method = CONNECT
:protocol = websocket
:scheme = https
:path = /chat
:authority = server.example.com
sec-websocket-protocol = chat, superchat
sec-websocket-extensions = permessage-deflate
sec-websocket-version = 13
origin = http://www.example.com

                                    HEADERS + END_HEADERS
                                    :status = 200
                                    sec-websocket-protocol = chat

DATA
WebSocket Data

                                    DATA + END_STREAM
                                    WebSocket Data

DATA + END_STREAM
WebSocket Data

[lovelydinosaur]

You'd need to do the investigation here yourself, looking into the interaction between the h2 package and httpcore and reporting back to us on why that pseudo header isn't correctly handled.