actioncable

For a notifications dropdown, I keep the list server-rendered and let Turbo Streams keep it fresh. The dropdown content sits in a turbo_frame_tag (so you can also navigate to a full notifications page), and the unread badge is a separate small target

Presence is often more about “who is here now” than perfect accuracy. Use Redis sets with expiries updated by pings. This keeps the system simple and operationally understandable.

When updates can happen from multiple places, model-level broadcasts keep the UI consistent across tabs without sprinkling stream logic in controllers. Use after-commit hooks so broadcasts only occur once the write is durable.