Design Real-Time Comments with Optimistic Updates
CohereFrontend Engineer · Other
Last updated
Design optimistic real-time comments with temporary identities, idempotent posting, response/event reconciliation, visible failure states, and durable history.
Design a real-time comment system with optimistic posting. When a user submits a comment, append it to the visible list immediately so the user can continue interacting while the backend request completes.
Constraints & Assumptions
The source emphasizes optimistic updates. Define ordering and delivery behavior, and include durable history and failure recovery. Do not assume that rendering a pending comment means the server accepted it.
Clarifying Questions
Can comments be edited or deleted? How are comments ordered? What happens after a timeout with an unknown commit outcome? Must another device see the same conversation?
Follow-up questions
- What if a live event arrives before the POST response? How do you avoid duplicate comments on retry? What if the server rejects content or the user navigates away?
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