feat(esm mcp): save predictions to /data/predictions with fallback

esm/mcp_output/mcp_plugin/mcp_service.py

@@ -150,8 +150,20 @@ def predict_structure(sequence: str):
             pdb_io = io.StringIO(response.text)
             structure = parser.get_structure("esmfold_prediction", pdb_io)
 
-            predictions_dir = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "predictions")
-            os.makedirs(predictions_dir, exist_ok=True)
+            # Prefer persistent storage in Space (e.g., /data), fallback to local package dir
+            default_dir = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "predictions")
+            preferred_dir = "/data/predictions"
+            predictions_dir = preferred_dir
+            try:
+                os.makedirs(predictions_dir, exist_ok=True)
+                # Test write permission with a temp touch
+                _probe_path = os.path.join(predictions_dir, ".write_probe")
+                with open(_probe_path, "w") as _probe:
+                    _probe.write("ok")
+                os.remove(_probe_path)
+            except Exception:
+                predictions_dir = default_dir
+                os.makedirs(predictions_dir, exist_ok=True)
 
             timestamp = datetime.datetime.now().strftime("%Y%m%d_%H%M%S")
             pdb_filename = f"prediction_{timestamp}.pdb"