Gemini 2.5 Flash × fizzbuzz

```python
def fizzbuzz(n: int) -> list[str]:
    """
    Generates a list of strings for numbers 1 through n, following the FizzBuzz rules.

    - For multiples of 3, the string is 'Fizz'.
    - For multiples of 5, the string is 'Buzz'.
    - For multiples of both 3 and 5, the string is 'FizzBuzz'.
    - Otherwise, the string is the number itself.

    Args:
        n (int): The upper limit of the range (inclusive). Must be a non-negative integer.

    Returns:
        list[str]: A list of strings representing the FizzBuzz sequence.

    Raises:
        ValueError: If n is a negative integer.
    """
    if n < 0:
        raise ValueError("Input 'n' must be a non-negative integer.")

    results: list[str] = []
    for i in range(1, n + 1):
        if i % 3 == 0 and i % 5 == 0:
            results.append("FizzBuzz")
        elif i % 3 == 0:
            results.append("Fizz")
        elif i % 5 == 0:
            results.append("Buzz")
        else:
            results.append(str(i))
    return results

# --- Usage Examples ---

if __name__ == "__main__":
    # Example 1: Basic FizzBuzz up to 15
    print("FizzBuzz up to 15:")
    print(fizzbuzz(15))
    # Expected output:
    # ['1', '2', 'Fizz', '4', 'Buzz', 'Fizz', '7', '8', 'Fizz', 'Buzz', '11', 'Fizz', '13', '14', 'FizzBuzz']

    print("\n" + "="*30 + "\n")

    # Example 2: FizzBuzz up to 5
    print("FizzBuzz up to 5:")
    print(fizzbuzz(5))
    # Expected output:
    # ['1', '2', 'Fizz', '4', 'Buzz']

    print("\n" + "="*30 + "\n")

    # Example 3: FizzBuzz up to 0 (empty list)
    print("FizzBuzz up to 0:")
    print(fizzbuzz(0))
    # Expected output:
    # []

    print("\n" + "="*30 + "\n")

    # Example 4: Demonstrate error handling for negative input
    print("Attempting FizzBuzz with a negative number:")
    try:
        fizzbuzz(-1)
    except ValueError as e:
        print(f"Caught expected error: {e}")
    # Expected output:
    # Caught expected error: Input 'n' must be a non-negative integer.
```