Function prefetch

packages/ui/src/use-chat-scroll.ts:133–137

()

          root.dataset.turnWindow = 'ready';
          arrivalPin.current?.release();
          const prefetch = () => {
            if (root.scrollTop <= Math.max(640, root.clientHeight * 2)) {
              requestEarlierRef.current();
            }
          };
          if (typeof window.requestIdleCallback === 'function') {
            idle = window.requestIdleCallback(prefetch, { timeout: 250 });
          } else {