you can use any relay so long as it listens on 127.0.0.1:4869 in fact, that is just a handy control interface for launching one
as far as protocol goes, nostrudel treats that relay a lot differently to a normal "remote" relay, to the point that it can be perplexing as a relay dev why it works perfectly as a cache but not as a remote
It kinda makes sense that it’d be used differently though, considering it’s just there to prevent remote refetching.
it's not just about avoiding getting data again, because the filter search protocol kinda winds up matching stuff up sometimes, often times, unless the since/until window is decent
what it is more about is keeping a REALLY DAMN BIG database of events that you can go back and back and back and back and back... the web browsers' inbuilt event store can only store 10k events which amounts to about 512mb of data at best, and 2 months ago a reasonable estimate of all published events on nostr was near 200Gb
