import hashlib


def hash_file(path, algorithm="sha256"):
    """Hash a file by streaming in 64KB chunks. Returns hex digest."""
    if algorithm == "blake3":
        try:
            import blake3
            h = blake3.blake3()
        except ImportError:
            raise ImportError("blake3 requested but not installed; pip install blake3")
    else:
        h = hashlib.new(algorithm)

    with open(path, "rb") as f:
        while chunk := f.read(65536):
            h.update(chunk)

    return h.hexdigest()