Unified Live Comments

Meta aims to integrate its live streaming services across Instagram, Facebook, Facebook Gaming, and WhatsApp. The goal is to enable simultaneous video viewing across these platforms, while also offering a cohesive experience for live comments.

This unified commenting system requires the capability for comments to be persistent (i.e., they can be reviewed later for analytics) and support interactive features such as reactions (likes, hearts, cares, etc.) from users across all platforms. Additionally, it’s crucial that the reaction counts are updated and displayed in real-time to all viewers.

How would you approach designing a system capable of processing and displaying real-time data across multiple platforms?