import subprocess
from pathlib import Path


def freeze_to_qcow2(workdir, output_path):
    """
    Creates a frozen snapshot of a build workspace.
    """

    out = Path(output_path)
    out.parent.mkdir(parents=True, exist_ok=True)

    cmd = [
        "qemu-img",
        "create",
        "-f", "qcow2",
        str(out),
        "10G"
    ]

    subprocess.run(cmd, check=True)

    # NOTE:
    # Real implementation would rsync or tar into mounted image
    return str(out)