Working with appcache events which turns out to be a bit more work than I had expected. Pleased with this however: the combination of the fine-grained information about the status of the app cache, as well as the facility to reasonably ascertain online/offline status via checkOnline.js allows us to wire together a solid foundation for our app. This code execute first on page load every time no matter what and gates everything else: you can't start an editing session if you're about to reload the page to take an update.