Your question is Online Chess.com System. 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).
Design online Chess.com (High Level Design).
Asked in the HLD + HM stage. Frame the system as a chat application between two people communicating chess moves instead of text messages. Discuss the core architecture, state management, move delivery, correctness, and how you would decide whether machine learning belongs in the system.