Reported interview periodFeb 2026–Sep 2026
Design an Online Chess Service
Design a service that matches two players, maintains authoritative legal game state, supports clocks, and allows games to be reviewed later.
Practice focusRequirements - Define APIs or real-time events for matchmaking, moves, resignations, draw offers, reconnects, and spectators. - The server—not the client—validates turns, legal moves, check, checkmate, stalemate, and special rules. - Make duplicate or reordered client messages idempotent. - Maintain fair clocks despite network delay and disconnects. - Persist an append-only move history and enough state for fast reconnect and review. - State scale assumptions, latency goals, and consistency boundaries.…