Use HuggingFace Hub for checkpoint download

HuggingFace has no bandwidth limits for public models, unlike GitHub
LFS (1 GB/month free). huggingface_hub is already a transitive dep
of transformers so this adds no new dependencies.

Upload checkpoint with:
  huggingface-cli upload ActiveVisionLab/CrossScore ckpt/CrossScore-v1.0.0.ckpt CrossScore-v1.0.0.ckpt

https://claude.ai/code/session_0114iFoswRfTkMai4JTrgMrB

Author: claude

crossscore/_download.py

@@ -1,31 +1,18 @@
 """Utilities for downloading CrossScore model checkpoints."""
 
 import os
-import urllib.request
-import shutil
 from pathlib import Path
 
-# Download directly from GitHub (served via Git LFS)
-CHECKPOINT_URL = (
-    "https://github.com/ActiveVisionLab/CrossScore/raw/main/ckpt/CrossScore-v1.0.0.ckpt"
-)
+HF_REPO_ID = "ActiveVisionLab/CrossScore"
 CHECKPOINT_FILENAME = "CrossScore-v1.0.0.ckpt"
 
 
-def get_cache_dir() -> Path:
-    """Return the cache directory for CrossScore model checkpoints."""
-    cache_dir = Path(os.environ.get("CROSSSCORE_CACHE_DIR", Path.home() / ".cache" / "crossscore"))
-    cache_dir.mkdir(parents=True, exist_ok=True)
-    return cache_dir
-
-
 def get_checkpoint_path() -> str:
     """Get path to the CrossScore checkpoint, downloading it if necessary.
 
-    Downloads from GitHub (Git LFS) on first use and caches locally at
-    ~/.cache/crossscore/. Set environment variables to customize:
+    Downloads from HuggingFace Hub on first use and caches locally.
+    Set environment variables to customize:
         CROSSSCORE_CKPT_PATH - use a specific local checkpoint file
-        CROSSSCORE_CACHE_DIR - custom cache directory
 
     Returns:
         Path to the checkpoint file.
@@ -37,35 +24,10 @@ def get_checkpoint_path() -> str:
             raise FileNotFoundError(f"Checkpoint not found at CROSSSCORE_CKPT_PATH={custom_path}")
         return custom_path
 
-    cache_dir = get_cache_dir()
-    ckpt_path = cache_dir / CHECKPOINT_FILENAME
-
-    if ckpt_path.exists():
-        return str(ckpt_path)
-
-    print(f"Downloading CrossScore checkpoint (~129MB)...")
-    print(f"  From: {CHECKPOINT_URL}")
-    print(f"  To:   {ckpt_path}")
-    print("  (Set CROSSSCORE_CKPT_PATH to skip download and use a local file)")
-
-    tmp_path = str(ckpt_path) + ".tmp"
-    try:
-        urllib.request.urlretrieve(CHECKPOINT_URL, tmp_path, _download_progress)
-        os.rename(tmp_path, str(ckpt_path))
-    except Exception:
-        if os.path.exists(tmp_path):
-            os.remove(tmp_path)
-        raise
-
-    print(f"\n  Download complete.")
-    return str(ckpt_path)
-
+    from huggingface_hub import hf_hub_download
 
-def _download_progress(block_count, block_size, total_size):
-    """Progress callback for urlretrieve."""
-    downloaded = block_count * block_size
-    if total_size > 0:
-        pct = min(100, downloaded * 100 // total_size)
-        mb_done = downloaded / (1024 * 1024)
-        mb_total = total_size / (1024 * 1024)
-        print(f"\r  {mb_done:.1f}/{mb_total:.1f} MB ({pct}%)", end="", flush=True)
+    path = hf_hub_download(
+        repo_id=HF_REPO_ID,
+        filename=CHECKPOINT_FILENAME,
+    )
+    return path