Decoded bytes per chunk.
Optionalfrom?: stringExplicit sender JID — required when sending from a component.
Sends the whole body as chunk messages. Pacing comes from awaiting each session.send() (socket backpressure) — the protocol itself has no acks.
Optionaloptions: { signal?: AbortSignal }
The chunkedBase64 mechanism (XEP-0332 §6.4): after the IQ carrying, the body arrives in separate
stanzas holding <chunk xmlns='urn:xmpp:http' streamId nr last?>base64.
nr is 0-based; chunks may arrive out of order and carry no ack mechanism.