my go to strategy for keeping data consistent in distributed real time apps is prob eventual consistency with conflict

so, im building this new real-time collaboration tool, and honestly, keeping the data the same everywhere for all the nodes and clients is a total pain. we're looking at stuff like eventual consistency and how to handle conflicts when they pop up, but I'm wondering what's actually worked for you all. what tricks or specific tech do you use when you absolutely, positively cannot have old or messed-up data? any horror stories or things you learned the hard way would be awesome