The key, for Google, is that it’s using machine learning in the cloud to optimize the mesh network. Most devices aren’t very good about switching from one access point to a better, closer one on the same network. (iPhones, by the way, are better than most at this, Google tells me). So Google Wifi points keep an eye on what’s connected to them and then force the handoff themselves. Google says it’s targeting transitions that take less than 150 milliseconds, which should be virtually invisible to the user.