138Design a real-time dashboard with WebSocket subscriptions, reconnects, and high-volume updates

Design a real-time operations or trading dashboard:

• 20+ widgets (price tickers, order books, charts, alert lists, KPIs) on one screen, each showing live data;
• the server can push thousands of updates per second at peak;
• users customise layouts and add or remove widgets; several dashboards can be open in tabs;
• the connection drops (Wi-Fi, laptop sleep, deploys) and must recover without showing wrong data;
• it runs for hours or days without slowing down or leaking memory.

Cover the transport and subscription protocol, client-side data flow, rendering at high update rates, reconnection and resynchronisation, and long-running stability.