Draft: dev notes: Draft IPT algorithm: Overhaul for INTRODUCE_NACK fresh descriptor
This is the followup to !1429 (merged) for #966: Clients are supposed to refetch descriptors if they get NAKs from IPTs. So we do not need to publish everywhere where a non-expired IPT was ever published.
But we may not actually want Arti to expect this of clients. See torspec!154. We probably shoudln't merge this until we have nailed down what the spec ought to be, over there.
CC @dgoulet