scripts/download_weights.py

#!/usr/bin/env python3
"""Download and safely extract the published HandEdit LoRA archive."""

from __future__ import annotations

import argparse
import hashlib
import json
import shutil
import zipfile
from pathlib import Path

from huggingface_hub import hf_hub_download

DEFAULT_REPO_ID = "HandEdit/HandEdit-LoRA"
ARCHIVE_NAME = "checkpoints.zip"


def sha256(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as handle:
        for chunk in iter(lambda: handle.read(8 * 1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def safe_extract(archive: Path, destination: Path) -> None:
    root = destination.resolve()
    with zipfile.ZipFile(archive) as bundle:
        for member in bundle.infolist():
            target = (root / member.filename).resolve()
            if target != root and root not in target.parents:
                raise RuntimeError(f"Unsafe archive member: {member.filename}")
        bundle.extractall(root)


def main() -> None:
    parser = argparse.ArgumentParser(
        description="Download the sanitized HandEdit LoRA checkpoints."
    )
    parser.add_argument("--repo-id", default=DEFAULT_REPO_ID)
    parser.add_argument(
        "--output-dir",
        type=Path,
        default=Path("."),
        help="Repository root where checkpoints/ will be extracted.",
    )
    parser.add_argument(
        "--keep-archive",
        action="store_true",
        help="Keep checkpoints.zip after successful extraction.",
    )
    args = parser.parse_args()

    output_dir = args.output_dir.expanduser().resolve()
    output_dir.mkdir(parents=True, exist_ok=True)
    archive = Path(
        hf_hub_download(
            repo_id=args.repo_id,
            filename=ARCHIVE_NAME,
            repo_type="model",
            local_dir=output_dir,
        )
    )

    manifest_path = Path(
        hf_hub_download(
            repo_id=args.repo_id,
            filename="weights_manifest.json",
            repo_type="model",
            local_dir=output_dir,
        )
    )
    manifest = json.loads(manifest_path.read_text(encoding="utf-8"))
    expected = manifest["archive"]["sha256"]
    actual = sha256(archive)
    if actual != expected:
        raise RuntimeError(
            f"Archive checksum mismatch: expected {expected}, received {actual}"
        )

    safe_extract(archive, output_dir)
    print(f"[OK] Extracted sanitized weights to: {output_dir / 'checkpoints'}")
    if not args.keep_archive:
        archive.unlink()
        print(f"[OK] Removed downloaded archive: {archive}")


if __name__ == "__main__":
    main()