Know what you're forgetting, before it's due

A due date tells you when a single card needs review. Decay radar looks at the underlying topic, not just the card.

Every flashcard has a live retrievability estimate — the probability you could still recall it right now, not just on its scheduled due date. Decay radar takes that same calculation and connects it across related cards and concepts, so a cluster of connected facts that are all quietly drifting toward "forgotten" shows up before any individual card is technically overdue.

The point isn't to add more urgency to reviews — it's to catch the case a due-date list misses: a topic you haven't touched in a while that's decaying as a whole, not just one card slipping past its date. See how the underlying scheduling works.