Function diffRowAdded

src/ink/screen.ts:1651–1667

* Emit additions for a row that only exists in next (height grew). * Skips empty/unwritten cells.

(
  nextCells: Int32Array,
  next: Screen,
  ci: number,
  y: number,
  startX: number,
  endX: number,
  nextCell: Cell,
  cb: DiffCallback,
)

 * Skips empty/unwritten cells.
 */
function diffRowAdded(
  nextCells: Int32Array,
  next: Screen,
  ci: number,
  y: number,
  startX: number,
  endX: number,
  nextCell: Cell,
  cb: DiffCallback,
): boolean {
  for (let x = startX; x < endX; x++, ci += 2) {
    if (nextCells[ci] === 0 && nextCells[ci | 1] === 0) continue
    cellAtCI(next, ci, nextCell)
    if (cb(x, y, undefined, nextCell)) return true
  }
  return false
}

/**
 * Diff two screens with identical width.