https://github.com/dtonon/chronicle

Chronicle is Nostr personal relay, built on the Khatru framework, that stores complete conversations in which the owner has taken part and nothing else: pure signal.

This is possible since writing is limited to the threads in which the owner has partecipated (either as an original poster or with a reply/zap/reaction), and only to his trusted network (WoT), to protect against spam.

Chronicle fits well in the Outbox model, so you can use it as your read/write relay, and it also automatically becomes a space-efficient backup relay.

Try it out, and let me know if you find it useful and how it can be improved!