[Lightning-dev] Strawman BOLT11 static "offer" format using probes.

[ZmnSCPxj]

Good morning Rusty,

> I want to propose a method of having reusable BOLT11 "offers" which
> provide almost-spontaneous payments as well as not requiring generating
> a BOLT11 invoice for each potential sale.

Suggest making a new BOLT document.
This would be basically a new BOLT for how to generate a BOLT11 invoice.
I suggest also to use instead the term "BOLT15 advertisement".

>
>     The return lightning message

Will this be a new message that fails the HTLC, or will we reuse `update_fail_htlc` to return the data as an error?

>would contain a new bolt11 invoice (perhaps
>     we optimize some fields by copying from the bolt11 offer if they don't
>     appear?)

Would this require some kind of canonical ordering for tagged fields in the generated bolt11 invoice?
For t-l-v there is proposal for types to have an absolute order (from lowest-numbered to highest-numbered), which would be useful for such cases where we want to only give unique parts of something.
Bolt11 invoices have a signature so the order of the tagged fields matters.

Regards,
ZmnSCPxj