Hi, I have not implemented 0-rtt (The Java library I’m using sadly doesn’t support it) but I am sending the entire login+bind command opportunistically as soon as TLS established without waiting for stream features. I believe that functionally this is very similar even though the security properties are notably different. So yes I believe you would include the xml header, the stream start and the auth element in the early data. As soon as the connection is established the server responds with a stream start of it’s own, stream features and the response to auth, and stream features again (as per 0388). If your question boils down to: Do I include the stream start in early data or just the auth element then the fact that the from attribute in the stream start is required for SASL2 should be very strong evidence to support that - even if what I said earlier doesn’t convince you. But yes including a full example would probably help - even though I don’t think we are lacking any information (and in the case we did, a pure example wouldn’t help anyway as examples are not normative) cheers Daniel On Mon, Feb 3, 2025 at 9:41 PM Michael Uvarov <freeakk(a)gmail.com> wrote: