[P3] Real-time push updates (WebSocket/SSE)

[hazeliscoding]

Problem

Two users in the same watch space can make conflicting updates without knowing. No push mechanism exists.

Requirements

• Evaluate SignalR (natural fit for .NET) vs SSE vs polling
• Implement for key events: anime status changed, episode progress updated, new rating
• Frontend: listen for updates on the active watch space, refresh affected data
• Graceful fallback if WebSocket connection drops

Acceptance Criteria

• When User A updates an anime, User B sees the change within seconds (without refreshing)
• Connection drops are handled gracefully with reconnection
• Only watch space members receive events for their space
• Works behind reverse proxies and CDNs

References

• Roadmap §11 — API & External Integration Robustness