```ts
/**
 * Splits an array into consecutive groups of at most size elements,
 * preserving order; the final group is shorter when the length does not divide evenly.
 * An empty array yields an empty array. The input array must not be mutated.
 *
 * @param items - The array to chunk.
 * @param size - The maximum size of each chunk.
 * @returns An array of chunks, where each chunk is an array of elements.
 */
export function chunk<T>(items: readonly T[], size: number): T[][] {
  if (size <= 0 || !Number.isInteger(size)) {
    throw new Error('Size must be a positive integer');
  }
  if (items.length === 0) {
    return [];
  }

  const result: T[][] = [];
  for (let i = 0; i < items.length; i += size) {
    result.push(items.slice(i, i + size));
  }
  return result;
}
```