Bounding React Fiber work units with useTransition for paginated lists

Goal

Bound React Fiber rendering work for a large paginated list in a React 18 concurrent root so the browser stays responsive while users page through items.

Unresolved constraint

Fiber chooses when to yield using a browser-dependent heuristic such as requestIdleCallback or postMessage. The exact frame deadline is not stable across browsers or React releases, and flushSync can block yielding entirely.

• Is the maximum work duration before a Fiber yield configurable in a concurrent root?
• Should pagination depend on automatic Fiber yields or on explicit chunked updates outside concurrent rendering?
• Does flushSync around a list update override useTransition priority and prevent yielding?