Your question is Design a Behavior-Based Recommender. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
You are designing a recommendation system for a digital product that personalizes items based on user behavior. The system should learn from clicks, dwell time, saves, and purchases, then adapt as user interests change.
How would you design an algorithm for a recommendation system based on user behavior?