It would probably be a good idea to implement some sort of rate limiting, (prevent users from spamming, or denial of service by making high IO requests repeatedly (for example spamming messages in a channels, possibly filling the disk quite fast) and in relation to #19 making the server download and store new PGP public keys, again, rapidly filling the disk, maybe also message/public key pruning (very old messages are optionally deleted after a certain amount of time or when the disk gets full.
It would probably be a good idea to implement some sort of rate limiting, (prevent users from spamming, or denial of service by making high IO requests repeatedly (for example spamming messages in a channels, possibly filling the disk quite fast) and in relation to #19 making the server download and store new PGP public keys, again, rapidly filling the disk, maybe also message/public key pruning (very old messages are optionally deleted after a certain amount of time or when the disk gets full.