Remembers why you got it wrong — and what finally made it click.

• Misconceptions, really fixed — the exact wrong idea, re-checked in disguise. It only counts as fixed once you get it right on two different days.
• Your analogy bank — Russian dolls for recursion, run rates for voltage. What clicked once is reused across new topics.
• Prerequisite tracing — stuck on integration by parts? It checks your product rule first.
• Never goes stale — memories fade unless they show up again, repeats merge into one, and fading topics come back for review.
• Yours to control — see why Doodo believes each thing, then edit it, lock it or forget it.