You don't have to predict. Requests just fall into two categories: 1) Nothing bad can happen if we show some optimistic result before server returns, but serve

You don't have to predict. Requests just fall into two categories: 1) Nothing bad can happen if we show some optimistic result before server returns, but server side will end up in different result. 2) Something bad can happen. Accordingly, for (1) we can do optimistic update, for (2) can't