```ts
// solution.ts

export function chunk<T>(items: readonly T[], size: number): T[][] {
  if (size < 1) {
    throw new Error("size must be a positive integer");
  }

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