Your question is Design a Real-Time Chat Ranker. 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 the ML system for a real-time chat application. The product needs to surface the most relevant conversations and message suggestions while keeping responses fast and fresh as users send messages continuously.
How would you implement a real-time chat application?