Read your own writes, off the primary

Your API accepts the change. It returns 201 Created or 200 OK, the system has saved the user's change, and the moment the user clicks, the change disappears from the app, only to resurface seconds later. That's if you are lucky. There's no error. The change simply ceased to exist for a while. In the era of server-side-rendered applications this was a non-issue: either the state was managed as part of a single request, or the user was too slow to outrun the system. The modern application changed ...