Fix video preview: copy hf downloads to /tmp for Gradio serving

app.py

@@ -2,11 +2,14 @@
 from __future__ import annotations
 
 import json
+import shutil
+import tempfile
 from functools import lru_cache
+from pathlib import Path
 
 import gradio as gr
 import pandas as pd
-from huggingface_hub import hf_hub_download
+from huggingface_hub import hf_hub_download, hf_hub_url
 
 REPO = "WorldArchive/mono-india-workplace-sample"
 LEROBOT_REPO = "WorldArchive/mono-india-workplace-lerobot"
@@ -33,8 +36,22 @@ def load_clips_df() -> pd.DataFrame:
 
 
 def clip_video_path(clip_id: str, layer: str) -> str:
+    """Return a path Gradio can serve on HF Spaces.
+
+    hf_hub_download cache paths are often outside the Space static dir and
+    show as 'Error' in gr.Video. Copy into a temp file under /tmp instead.
+  """
     rel = f"clips_preview/{clip_id}/{layer}.mp4"
-    return hf_hub_download(REPO, rel, repo_type="dataset")
+    try:
+        src = hf_hub_download(REPO, rel, repo_type="dataset")
+        dest = Path(tempfile.gettempdir()) / "wa_explorer" / clip_id / f"{layer}.mp4"
+        dest.parent.mkdir(parents=True, exist_ok=True)
+        if not dest.exists() or dest.stat().st_mtime < Path(src).stat().st_mtime:
+            shutil.copy2(src, dest)
+        return str(dest)
+    except Exception:
+        # Fallback: direct CDN URL (works when copy fails)
+        return hf_hub_url(REPO, rel, repo_type="dataset")
 
 
 def clip_metadata(clip_id: str) -> str:
@@ -64,7 +81,14 @@ def clip_segments(clip_id: str) -> str:
 
 def update(clip_label: str, layer: str):
     clip_id = next(c for c, label in CLIPS if label == clip_label)
-    return clip_video_path(clip_id, layer), clip_metadata(clip_id), clip_segments(clip_id)
+    try:
+        video = clip_video_path(clip_id, layer)
+        meta = clip_metadata(clip_id)
+        segs = clip_segments(clip_id)
+        return video, meta, segs
+    except Exception as e:
+        err = json.dumps({"clip_id": clip_id, "layer": layer, "error": str(e)}, indent=2)
+        return None, err, f"_Preview failed: {e}_"
 
 
 with gr.Blocks(title="World Archive Data Explorer", theme=gr.themes.Soft()) as demo: