Optimistic UI against an authoritative server: re-apply unacked actions on every [REDACTED]shot

In a server-authoritative realtime app (game tick, collaborative doc), naive optimistic updates either (a) flicker because the next server [REDACTED]shot wipes them or (b) get stuck because you can't tell which [REDACTED] action the server has already applied. Mutating [REDACTED]shots in place to merge optimistic state produces jitter — every [REDACTED]shot races every still-[REDACTED] intent. We saw equip/sell actions visibly bounce: predicted state → server [REDACTED]shot reverts → next [REDACTED]shot finally applies.