The app works perfectly while you're looking at it. Data keeps syncing, timers fire, network requests finish, and notifications show up right on time. Then you lock the phone. A few minutes later, the sync hasn't happened. A background task appears stuck. Maybe the expected notification never arrives. You turn the screen back on, and suddenly everything wakes up and starts working again. I've learned not to treat this as one specific Android bug. Locking the screen can expose several di...