Your question is Live Stream Chat UI Replica. 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).
Build a live stream chat UI (like Twitch or YouTube Live) in React, using interviewer-provided mocked functions that simulate incoming user messages; follow-ups require promises, async/await, useEffect/useState, setTimeout/setInterval, debounce and throttle.
Asked in the Onsite: Frontend specialization stage. Functionality over styling. Reported follow-ups: Add debounce/throttle; Handle async message streams.