Keep models on attached storage when it is available

app.py

@@ -6,6 +6,31 @@ Step 3: MusicGen medium writes a soundtrack and attaches it to the clip.
 Step 4: a small planning model (Qwen2.5 1.5B) writes narration and decides when each line starts;
         Kokoro speaks it, and it is mixed over the music.
 """
+import os
+
+
+def _pick_model_store():
+    """Keep downloaded models on the Space's attached storage, so restarts don't download them again.
+    Uses MODEL_STORE if that variable is set, else the first writable mount it finds."""
+    candidates = [os.environ.get("MODEL_STORE"), "/data", "/bucket", "/storage", "/mnt/bucket", "/mnt/data"]
+    for path in [c for c in candidates if c]:
+        try:
+            os.makedirs(os.path.join(path, "huggingface"), exist_ok=True)
+            probe = os.path.join(path, "huggingface", ".write_test")
+            open(probe, "w").close()
+            os.remove(probe)
+            return os.path.join(path, "huggingface")
+        except OSError:
+            continue
+    return None
+
+
+_store = _pick_model_store()
+if _store:
+    os.environ["HF_HOME"] = _store          # Must be set before the Hugging Face libraries are imported
+print("MODEL STORE:", _store or "none found, using the default temporary cache",
+      "| mounts seen:", [m for m in ("/data", "/bucket", "/storage", "/mnt") if os.path.isdir(m)], flush=True)
+
 import json
 import random
 import re