Is Lightning Offers an improvement over Key Send? The draft for BOLT#12 (Offers) introduces a new payment flow where the receiver of funds posts an Offer. The Payer can then request a unique invoice and pay the invoice. There are significant improvements in the flow including payment and payer proofs.
In a Key Send payment, a payer can send funds to a receiver without an invoice by encoding the preimage in the onion payload for the receiver.
Let's say in the context of donations, a receiver can either post an Offer to use the BOLT#12 payment flow OR post their node's public key to use the Key Send payment flow.
Am I correct in thinking that BOLT#12 is an improvement over Key Send payments? Or are these two solutions solving completely different problems?
Yes, offers are a carefully constructed rethinking of use cases like donations that used to be serviced by hacks like keysend.
One specific improvement for this use case is that unlike in keysend, you do receive a receipt for the donation you are giving.
But offers are meant to service many more use cases beyond just donations, and do so in a less ad-hoc fashion.