Isolate explicit S/R gate target ladder

scripts/run_backtest_snapshot.py

@@ -60,6 +60,7 @@ def _parse_args() -> argparse.Namespace:
             "rewrite_range504_structural_legacy_primary",
             "rewrite_range504_structural_primary2",
             "production_structural_overlay",
+            "explicit_target_ladder",
         ),
         default=None,
         help="Research-only S/R detector/gate arm.",

scripts/run_sr_v2_matrix.py

@@ -105,6 +105,11 @@ def _args() -> argparse.Namespace:
         help="Test the frozen 5% clean-structure rank overlay on production breadth.",
     )
     _add_common(overlay)
+    ladder = commands.add_parser(
+        "ladder",
+        help="Verify the explicit volume-free gate target ladder against production.",
+    )
+    _add_common(ladder)
     validate = commands.add_parser(
         "validate",
         help="Run production control and one locked arm from 2024-07-01.",
@@ -225,6 +230,36 @@ def _overlay(args: argparse.Namespace) -> None:
     print("Full-period structural ranking overlay complete.")
 
 
+def _ladder(args: argparse.Namespace) -> None:
+    control = ROOT / "reports" / "backtest-sr-full-production_control.json"
+    if not control.exists():
+        raise SystemExit(f"Full-period production control not found: {control}")
+    variant = ROOT / "reports" / "backtest-sr-full-explicit_target_ladder.json"
+    _run_arm(
+        "explicit_target_ladder",
+        args.snapshot,
+        args.workers,
+        output=variant,
+    )
+    subprocess.run(
+        [
+            sys.executable,
+            str(COMPARE),
+            str(control),
+            str(variant),
+            "--out-csv", str(
+                ROOT / "reports" / "sr-explicit-target-ladder-cohorts.csv"
+            ),
+            "--out-json", str(
+                ROOT / "reports" / "sr-explicit-target-ladder-comparison.json"
+            ),
+        ],
+        cwd=ROOT,
+        check=True,
+    )
+    print("Explicit target-ladder production parity comparison complete.")
+
+
 def main() -> None:
     args = _args()
     if args.command == "train":
@@ -242,6 +277,8 @@ def main() -> None:
         _full(args)
     elif args.command == "overlay":
         _overlay(args)
+    elif args.command == "ladder":
+        _ladder(args)
     else:
         _validate(args)