Just a quick question in case it's a simple answer before I go digging.
We're running spicedb with a postgres datasource and we've been seeing some unique index constraint violations on the relation_tuple table for uq_relation_tuple_living.
This is caused by a sequence of write relationship -> delete relationship -> write relationship requests.
I've had a look at the buf docs for both and we aren't using any optional preconditions, so I'm not sure why this is occurring? As far as I'm aware the delete transaction should have committed long before the write request comes through.