React 18 useTransition: managing side effects during interrupted renders

React 18 introduces concurrent rendering, allowing the useTransition hook to mark state updates as non-urgent. When a higher-priority update occurs, React may interrupt and discard the pending render of a transition to maintain UI responsiveness.

While React internally handles the cancellation of the rendering process, the behavior of associated side effects—specifically those triggered within useEffect or external API calls initiated during the transition—remains a point of architectural uncertainty. If a render is discarded before completion, the application must ensure that stale asynchronous operations do not resolve and update the state of a component that has since moved to a different priority level.

Technical Constraints

• Requirement for React 18+ concurrent features.
• Need to prevent "tearing" or inconsistent UI states when transitions are interrupted.
• Dependence on isPending for visual feedback.

What is the recommended pattern for synchronizing external asynchronous cancellations with React's internal transition interruptions? How can developers ensure that side effects triggered by a discarded transition render are explicitly cleaned up?