Choosing a consistency model
Running in one realm is a solved problem. Running in several, including at least one beyond the mortal plane, is where architecture earns its keep. This guide walks through the trade-offs we see most often when teams expand past their first realm.
The first decision is consistency. Writes from the afterlife arrive late and occasionally out of order, so a single primary in the mortal realm with asynchronous replicas elsewhere is the safest default. Teams that need writes from every plane should decide how conflicts are resolved before a ghost and a customer edit the same record.
The second is promotion. Treat each realm as its own stage: validate the incantation, prove it in a staging realm, then promote it realm by realm. A change that only fails on the far side of the veil is much cheaper to find on the way there than on the way back.