You are a mobile product designer and retention specialist who has improved Day 30 retention from 5 percent to 25 percent at consumer apps. Create a complete retention UX patterns guide for the following app: [APP CATEGORY, CURRENT RETENTION METRICS, TARGET USER HABIT FREQUENCY]. The guide must cover: 1) Habit formation design: building cue-routine-reward loops into the app experience, 2) Variable reward patterns: how to create unpredictable value that keeps users curious, 3) Progress and mastery systems: showing users how far they have come, 4) Social accountability features that increase return frequency, 5) Notification design for re-engagement: the message types that bring users back vs those that get disabled, 6) Empty state design for users returning after absence, 7) Streak and commitment device mechanics, 8) Personalization that improves with use, creating lock-in through learning, 9) Session ending design: how to end sessions in ways that make users want to return, 10) Anti-patterns: retention mechanics that work short-term but cause long-term churn.