Function cellAtIndex

src/ink/screen.ts:643–654

(screen: Screen, index: number)

 * index computation — caller must ensure index is valid.
 */
export function cellAtIndex(screen: Screen, index: number): Cell {
  const ci = index << 1
  const word1 = screen.cells[ci + 1]!
  const hid = (word1 >>> HYPERLINK_SHIFT) & HYPERLINK_MASK
  return {
    // Unwritten cells have charIndex=0 (EMPTY_CHAR_INDEX); charPool.get(0) returns ' '
    char: screen.charPool.get(screen.cells[ci]!),
    styleId: word1 >>> STYLE_SHIFT,
    width: word1 & WIDTH_MASK,
    hyperlink: hid === 0 ? undefined : screen.hyperlinkPool.get(hid),
  }
}

/**
 * Get a Cell at the given index, or undefined if it has no visible content.