fix(metrics): ignore NaN target/prediction pairs in validation metrics (SIENTIAPDE-2215)

model_manager/utils/repository/data_manager_repository.py

@@ -405,6 +405,23 @@ class DataManagerRepository(SientiaMonitoring):
         y_true_val = y_true_val.loc[common_index]
         y_pred_val = y_pred_val.loc[common_index]
 
+        # NaN target, or NaN prediction for rows with NaN features, carries no error signal
+        # (SIENTIAPDE-2215).
+        valid = y_true_val.notna() & y_pred_val.notna()
+        if not valid.any():
+            raise ValueError(
+                'No validation rows with both target and prediction: all '
+                f'{len(valid)} overlapping rows have NaN'
+            )
+        if not valid.all():
+            self.info(
+                f'Ignoring {int((~valid).sum())} validation row(s) with NaN target or prediction '
+                'in the regression metrics',
+                metadata,
+            )
+        y_true_val = y_true_val[valid]
+        y_pred_val = y_pred_val[valid]
+
         # Metrics helpers already round to 2 decimals.
         tmr.mse_val = mse(y_true_val, y_pred_val)
         tmr.mae_val = mae(y_true_val, y_pred_val)