Function scrollDown

src/components/ScrollKeybindingHandler.tsx:852–865

(s: ScrollBoxHandle, amount: number)

// naturally re-pins (matches typical chat-app behavior). Returns the
// resulting sticky state so callers can propagate it.
function scrollDown(s: ScrollBoxHandle, amount: number): boolean {
  const max = Math.max(0, s.getScrollHeight() - s.getViewportHeight());
  // Include pendingDelta: scrollBy accumulates into pendingScrollDelta
  // without updating scrollTop, so getScrollTop() alone is stale within
  // a batch of wheel events. Without this, wheeling to the bottom never
  // re-enables sticky scroll.
  const effectiveTop = s.getScrollTop() + s.getPendingDelta();
  if (effectiveTop + amount >= max) {
    s.scrollToBottom();
    return true;
  }
  s.scrollBy(amount);
  return false;
}

// Wheel-up past scrollTop=0 clamps via scrollTo(0), clearing
// pendingScrollDelta so aggressive wheel bursts (e.g. MX Master free-spin)