Most apps help you learn. Almost none help you not forget. Skill Decay Tracker shows each skill as a live health score (0–100%) that decays over time based on the Ebbinghaus forgetting curve. When a skill starts fading, AI generates a personalized 2-minute micro-challenge to bring it back. Works for any domain: coding, languages, music, academics. Built solo with Swift 6, SwiftUI, and 3 AI providers (Claude, GPT-4o, Gemini).