Add previous tag

[v0l]

Add a previous tag to replaceable events which prevents updates when the id does not match.

[fiatjaf]

Initially I liked this idea, but isn't this solvable by the client just querying the relay before publishing? The logic for implementing this on the client side will be harder than what it is today and will lead to clients implementing it wrongly and users losing data anyway.

Instead of

"why did the people I followed last week vanished today?"

we'll have

"oh, didn't I follow this person yesterday, why is it not showing up now?"

Because the update that added the new follow was rejected.

[v0l]

Initially I liked this idea, but isn't this solvable by the client just querying the relay before publishing

Yes and this is a way to force clients to implement a query to the relays first, im sick of these issues persisting in my own clients and i want to make it harder for me to replace these events.

Because the update that added the new follow was rejected.

If it was reject this needs to be handled in the client, again i want to make it harder for myself.

[vitorpamplona]

There is a risk that this will make replaceables diverge further away from each other.

Also, clients who are not implementing it will modify the list while keeping the previous intact. Very few clients discard tags they don't recognize from replaceables. They just try to keep as many of them as possible. Which creates a problem for this one. Since the previous won't be updated, these clients will never be able to update replaceables with an existing previous.