Persist feature names back to HF dataset on save

Adds a debounced (2 s) background-thread upload so any manual label
entered in the explorer is pushed to the HF dataset repo after the
user stops typing. Uses the existing HF_TOKEN / HF_DATASET_REPO env
vars that are already configured as Space secrets.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/explorer_app.py

@@ -31,6 +31,7 @@ import os
 import io
 import json
 import base64
+import threading
 from collections import OrderedDict
 
 import cv2
@@ -281,6 +282,45 @@ def _save_names():
     with open(_names_file, 'w') as _f:
         json.dump({str(k): v for k, v in sorted(feature_names.items())}, _f, indent=2)
     print(f"Saved {len(feature_names)} feature names to {_names_file}")
+    _schedule_hf_push(_names_file)
+
+
+_hf_push_pending = [None]   # holds the active debounce timeout handle
+
+def _schedule_hf_push(names_file_path):
+    """Debounce HF dataset upload: waits 2 s after the last save, then pushes in a thread."""
+    hf_token = os.environ.get("HF_TOKEN")
+    hf_repo  = os.environ.get("HF_DATASET_REPO")
+    if not (hf_token and hf_repo):
+        return
+
+    # Cancel any already-pending push for this session.
+    if _hf_push_pending[0] is not None:
+        try:
+            curdoc().remove_timeout_callback(_hf_push_pending[0])
+        except Exception:
+            pass
+
+    def _push_thread():
+        try:
+            from huggingface_hub import upload_file
+            upload_file(
+                path_or_fileobj=names_file_path,
+                path_in_repo=os.path.basename(names_file_path),
+                repo_id=hf_repo,
+                repo_type="dataset",
+                token=hf_token,
+                commit_message="Update feature names",
+            )
+            print(f"  Pushed {os.path.basename(names_file_path)} to HF dataset {hf_repo}")
+        except Exception as e:
+            print(f"  Warning: could not push feature names to HF: {e}")
+
+    def _fire():
+        _hf_push_pending[0] = None
+        threading.Thread(target=_push_thread, daemon=True).start()
+
+    _hf_push_pending[0] = curdoc().add_timeout_callback(_fire, 2000)
 
 
 def _display_name(feat: int) -> str: