Fix post-cluster neutral strength ablation

scripts/run_sr_v2_matrix.py

@@ -50,6 +50,12 @@ def _args() -> argparse.Namespace:
         help="Isolate legacy geometry, pivots, and price-traffic grid on training data.",
     )
     _add_common(traffic)
+    traffic.add_argument(
+        "--only-arm",
+        choices=TRAFFIC_ARMS,
+        default=None,
+        help="Rerun one hidden-feature arm without repeating the full matrix.",
+    )
     validate = commands.add_parser(
         "validate",
         help="Run production control and one locked arm from 2024-07-01.",
@@ -135,7 +141,8 @@ def main() -> None:
     if args.command == "train":
         _train(args, TRAINING_ARMS, "backtest-sr-v2-train")
     elif args.command == "traffic":
-        _train(args, TRAFFIC_ARMS, "backtest-sr-traffic-train")
+        arms = (args.only_arm,) if args.only_arm else TRAFFIC_ARMS
+        _train(args, arms, "backtest-sr-traffic-train")
     else:
         _validate(args)