I think this is a problem with fiatjaf's implementation, not a problem with NIP-29 itself.
Discussion
Can 0xChat’s NIP-29 group work with multiple relays?
By the way, do you prefer group support for a single relay or multiple relays?
Currently, it's not supported. Personally, I prefer using a single relay for group chats. The main advantage is message stability and consistency.
The downside is the single point of failure — but I believe this can be addressed by implementing a backup and migration mechanism to move the chat history to a new relay if needed.
> The main advantage is message stability and consistency.
🤔🤔🤔 Don’t think so.
Unlike notes, group messages rely on group management, and keeping group state in sync across multiple relays is very difficult — if not impossible.
If the user opens the group client, it only needs to fetch messages from multiple relays—specifically, messages from the last timestamp up to the current time. The client then uses the messages from whichever relay responds the fastest.
Pulling group messages from multiple relays is technically fine. But can we really say these relays represent the same group? For example, relay1 might show 3 members, relay2 has 4, and relay3 might already consider the group disbanded. In this case, the group messages you receive are unreliable.
The relay is only responsible for forwarding messages; everything else is outside its concern. The group member list is determined by the group owner.
“ Normally a group will originally belong to one specific relay, but the community may choose to move the group to other relays or even fork the group so it exists in different forms -- still using the same id -- across different relays.”
It seems that NIP-29 was designed specifically to support only a single relay.
The relay implementation is the main problem. But NIP 29 also requires relay support (translating group create/edit into metadata) when it could have been incidental (as it is in NIP 28 as it happens).