Building a spaced repetition system that adapts to user pace in real-time (Kotlin/Compose)

I built a flashcard app for interview prep and wanted to share some of the more interesting technical problems I ran into. The app has 1500+ questions across DSA and System Design, and the core challenge was: how do you order cards intelligently without it feeling robotic? Problem 1: Slot Assignment for Spaced Repetition Standard SR (like Anki) just shows the most overdue card next. That works for vocabulary but feels terrible for algorithms because you get 3 Hard questions in a row and want to quit. My app