Sorry to hear you ran into trouble with the sandbox. Data persistence is a premium feature, but it should warn about unsaved data if you try to close the tab or

Sorry to hear you ran into trouble with the sandbox. Data persistence is a premium feature, but it should warn about unsaved data if you try to close the tab or navigate away. Did that not happen in your case? And if so, what browser/OS/device? If it's not clear, you can just sign up for the free trial of Premium, cancel it immediately, and have 7 days to try everything out for free. Perhaps offering a limited time to restore a previous session without needing to do that would be nice, but I don't think I have a good mechanism to make that tamper-resistant.