fix: reject unprovenanced ML artifacts

backtesting/engine.py

@@ -8,6 +8,7 @@ from collections import defaultdict
 from datetime import datetime, timedelta
 
 from scoring.policy import SCORE_BRACKETS, SCORE_VERSION, score_in_bracket
+from ml.artifacts import validate_ml_artifact
 
 log = logging.getLogger(__name__)
 
@@ -117,11 +118,15 @@ def _compute_ath_series(price_lookup, dates):
 
 
 def _load_ml_weights():
-    """Load ML weights for ML-optimized scoring mode."""
+    """Load only schema/provenance-valid ML weights."""
     ml_path = _os.path.join(_os.path.dirname(_os.path.dirname(_os.path.abspath(__file__))), "config", "ml_weights.json")
     try:
         with open(ml_path) as f:
             data = _json.load(f)
+        status = validate_ml_artifact(data)
+        if not status["valid"]:
+            log.error("Rejected invalid ML artifact: %s", ", ".join(status["errors"]))
+            return {}
         return data.get("weights", {})
     except Exception:
         return {}