Isolate explicit S/R gate target ladder

tests/unit/test_backtest_service.py

@@ -802,6 +802,7 @@ def test_sr_research_variant_is_explicit_and_validated(monkeypatch):
         "rewrite_range504_structural_legacy_primary",
         "rewrite_range504_structural_primary2",
         "production_structural_overlay",
+        "explicit_target_ladder",
     ):
         monkeypatch.setenv("BACKTEST_SR_VARIANT", variant)
         assert bt._sr_research_variant() == variant
@@ -856,6 +857,10 @@ def test_residual_arms_change_only_the_primary_rr_floor():
         "production_structural_overlay",
         activation,
     ) == 1.5
+    assert bt._primary_min_rr_for_variant(
+        "explicit_target_ladder",
+        activation,
+    ) == 1.5
 
 
 def test_structural_overlay_tags_production_geometry_without_replacing_it(monkeypatch):
@@ -934,6 +939,31 @@ def test_window_setups_routes_explicit_range_grid(
     }
 
 
+def test_window_setups_routes_full_explicit_target_ladder(monkeypatch):
+    captured = {}
+
+    def fake_detector(*args, **kwargs):
+        captured.update(kwargs)
+        return []
+
+    monkeypatch.setenv("BACKTEST_SR_VARIANT", bt.EXPLICIT_TARGET_LADDER_VARIANT)
+    monkeypatch.setattr(bt, "detect_sr_levels_legacy", fake_detector)
+    records = [
+        SimpleNamespace(
+            date=date(2024, 1, 1) + timedelta(days=i),
+            open=100.0,
+            high=101.0,
+            low=99.0,
+            close=100.0,
+            volume=1_000_000,
+        )
+        for i in range(bt.MIN_LOOKBACK)
+    ]
+
+    assert bt._window_setups(records, {}, {}) == []
+    assert captured == {"explicit_range_grid": True}
+
+
 @pytest.mark.parametrize(
     "variant",
     ["legacy_geometry_neutral", "legacy_range_grid_neutral"],

tests/unit/test_detect_sr_levels.py

@@ -277,6 +277,30 @@ class TestDetectSrLevels:
         assert sorted(deployed) == explicit
         assert len(explicit) == 20
 
+    def test_explicit_target_ladder_preserves_full_legacy_mechanics(self):
+        highs, lows, closes, volumes = _make_series(n=500)
+        deployed = detect_sr_levels_legacy(highs, lows, closes, volumes)
+        explicit = detect_sr_levels_legacy(
+            highs,
+            lows,
+            closes,
+            volumes,
+            explicit_range_grid=True,
+        )
+
+        def mechanics(level):
+            return {
+                key: value
+                for key, value in level.items()
+                if key not in {"detection_method", "sources"}
+            }
+
+        assert [mechanics(level) for level in explicit] == [
+            mechanics(level) for level in deployed
+        ]
+        assert any("range_grid" in level["sources"] for level in explicit)
+        assert all("volume_profile" not in level["sources"] for level in explicit)
+
     def test_explicit_range_grid_is_volume_independent(self):
         highs, lows, closes, volumes = _make_series(n=500)
         shifted_volumes = [volume * (i + 1) for i, volume in enumerate(volumes)]