Function targetFor

src/components/VirtualMessageList.tsx:472–475

(i: number)

  // (was a safety net for frac garbage — without frac, est IS the next
  // message's top, spam-n/N converges because message tops are ordered).
  function targetFor(i: number): number {
    const top = jumpState.current.getItemTop(i);
    return Math.max(0, top - HEADROOM);
  }

  // Highlight positions[ord]. Positions are MESSAGE-RELATIVE (row 0 =
  // element top, from scanElement). Compute rowOffset = getItemTop -