Function syncStreamScrollFollow

src/hold-stream.ts:117–133

(
  el: HTMLElement,
  state: StreamScrollFollow,
  thresholdPx = DEFAULT_STREAM_SCROLL_THRESHOLD,
)

 * Pauses when the reader scrolls up; resumes when they return near the bottom.
 */
export function syncStreamScrollFollow(
  el: HTMLElement,
  state: StreamScrollFollow,
  thresholdPx = DEFAULT_STREAM_SCROLL_THRESHOLD,
): void {
  if (isNearScrollBottom(el, thresholdPx)) {
    state.paused = false;
    state.lastScrollTop = el.scrollTop;
    return;
  }

  if (el.scrollTop < state.lastScrollTop - 2) {
    state.paused = true;
  }

  state.lastScrollTop = el.scrollTop;
}

/** Poll + follow each animation frame while content streams. */
export function tickStreamScrollFollow(