feat(proportion): torso snowman front waist pinch + chest flatten (0065)

src/meshops/proportion/blockout_recipe.py

@@ -19,6 +19,8 @@
 0039: opt-in --join-ready socket overlaps (shoulder/hip/neck/ankle); mutually exclusive with
 --nofuse; setup re-emit via run_blockout_emit_setup; schema stay 1.4.0 + join_ready bool.
 0047: torso oval ry depth taper (anti-snowman chest/waist/hip); schema stay 1.4.0.
+0065: torso front snowman — waist rx pinch + chest ry/front flatten (full3d rear bias);
+schema stay 1.4.0.
 0049: breast_soft center Z hang drop (before 0033 tilt); B1 floor 0.55*rz; schema stay 1.4.0.
 0050: neck column forward tilt (p0/p1) + head/face co-move + radius ceiling vs head.rx;
 schema stay 1.4.0.
@@ -97,12 +99,15 @@
 # 0046 B9: template thigh_tilt adduction (medial-shift cap + knee-cluster co-move).
 THIGH_TILT_DEG_CAP: Final[float] = 15.0
 THIGH_ADDUCTION_MAX_MEDIAL_M: Final[float] = 0.030
-# 0047 B1: torso oval anteroposterior depth taper (anti-snowman); keep 0040 rz law.
-TORSO_OVAL_RY_CHEST_FRAC: Final[float] = 0.95
-TORSO_OVAL_RY_WAIST_FRAC: Final[float] = 0.72
+# 0047 B1 + 0065: torso oval depth + front pinch freezes
+TORSO_OVAL_RY_CHEST_FRAC: Final[float] = 0.85  # was 0.95
+TORSO_OVAL_RY_WAIST_FRAC: Final[float] = 0.58  # was 0.72
 TORSO_OVAL_RY_HIP_FRAC: Final[float] = 0.80  # ≠ PELVIS_OVAL_RY_FRAC_HALF_HIP (0.60)
-TORSO_OVAL_RZ_SPAN_FRAC: Final[float] = 0.22
+TORSO_OVAL_RZ_SPAN_FRAC: Final[float] = 0.22  # fence 0040
 TORSO_OVAL_RZ_FLOOR_M: Final[float] = 0.025
+TORSO_WAIST_RX_MAX_FRAC_CHEST: Final[float] = 0.80
+TORSO_WAIST_PINCH_TAPER_GATE: Final[float] = 0.10
+TORSO_CHEST_Y_REAR_BIAS_FRAC_RY: Final[float] = 0.28
 # 0049 B1: breast_soft vertical hang floor (center Z drop as fraction of rz).
 BREAST_HANG_Z_DROP_FRAC_RZ: Final[float] = 0.55
 # 0049 D2: unit min hang drop vs pre-anchor (softer than B1; waist soft-clamp threshold).
@@ -1668,21 +1673,43 @@ def _build_torso_ovals(
         ("RECIPE_torso_oval_waist", 0.50),
         ("RECIPE_torso_oval_hip", 0.85),
     ]
+    # 0065 two-pass: precompute post-taper rx, then B1 waist cap vs post-taper chest.
+    rx_by: dict[str, float] = {
+        name: _waist_width_at(z_norm, w_s, w_h, taper) for name, z_norm in layers
+    }
+    chest_key = "RECIPE_torso_oval_chest"
+    waist_key = "RECIPE_torso_oval_waist"
+    if taper >= TORSO_WAIST_PINCH_TAPER_GATE:
+        rx_by[waist_key] = min(
+            rx_by[waist_key],
+            TORSO_WAIST_RX_MAX_FRAC_CHEST * rx_by[chest_key],
+        )
+
     ry_chest: float | None = None
     ry_waist: float | None = None
     ry_hip: float | None = None
+    chest_cy: float | None = None
+    rx_chest_emit: float | None = None
+    rx_waist_emit: float | None = None
     for name, z_norm in layers:
         z_m = z_top - z_norm * span
-        hw = _waist_width_at(z_norm, w_s, w_h, taper)
+        hw = rx_by[name]
         # Vertical radius must exceed half layer spacing (0.35*span/2) so chest/waist/hip
         # ovals overlap. 0.12 left a belly gap; 0.18 barely kissed; 0.22 ≈ 4cm overlap.
         rz = max(TORSO_OVAL_RZ_FLOOR_M, span * TORSO_OVAL_RZ_SPAN_FRAC)
+        center_y = y
         if name.endswith("_chest"):
             ry = half_chest * TORSO_OVAL_RY_CHEST_FRAC
             ry_chest = ry
+            # B5: rear bias only when full3d (chest_y known); front_plane stays mid.
+            if placement == "full3d":
+                center_y = y + TORSO_CHEST_Y_REAR_BIAS_FRAC_RY * ry
+            chest_cy = center_y
+            rx_chest_emit = hw
         elif name.endswith("_waist"):
             ry = half_chest * TORSO_OVAL_RY_WAIST_FRAC
             ry_waist = ry
+            rx_waist_emit = hw
         else:  # hip
             ry = half_hip * TORSO_OVAL_RY_HIP_FRAC
             ry_hip = ry
@@ -1691,7 +1718,7 @@ def _build_torso_ovals(
                 name=name,
                 role="torso",
                 kind="ellipsoid",
-                center=[0.0, y, z_m],
+                center=[0.0, center_y, z_m],
                 rx_m=hw,
                 ry_m=ry,
                 rz_m=rz,
@@ -1704,6 +1731,21 @@ def _build_torso_ovals(
             "torso depth taper: chest/waist/hip "
             f"ry={ry_chest:.4f}/{ry_waist:.4f}/{ry_hip:.4f} (anti-snowman)"
         )
+    # 0065 B12: front pinch inventory (waist/chest rx + chest front/rear poles).
+    if (
+        rx_chest_emit is not None
+        and rx_waist_emit is not None
+        and chest_cy is not None
+        and ry_chest is not None
+    ):
+        frac = rx_waist_emit / rx_chest_emit if abs(rx_chest_emit) > 1e-12 else float("nan")
+        front_y = chest_cy - ry_chest
+        rear_y = chest_cy + ry_chest
+        messages.append(
+            "torso front pinch: "
+            f"waist_rx/chest_rx={rx_waist_emit:.4f}/{rx_chest_emit:.4f} "
+            f"({frac:.3f}) chest_front_y={front_y:.4f} chest_rear_y={rear_y:.4f}"
+        )
 
     # 0053 pelvis shelf freezes (was B10: ry = hip_half * 0.85)
     if m.height_m is not None:
@@ -4805,6 +4847,14 @@ def run_blockout_emit_setup(
     "THIGH_ADDUCTION_MAX_MEDIAL_M",
     "THIGH_PROX_SOFT_SCALE",
     "THIGH_TILT_DEG_CAP",
+    "TORSO_CHEST_Y_REAR_BIAS_FRAC_RY",
+    "TORSO_OVAL_RY_CHEST_FRAC",
+    "TORSO_OVAL_RY_HIP_FRAC",
+    "TORSO_OVAL_RY_WAIST_FRAC",
+    "TORSO_OVAL_RZ_FLOOR_M",
+    "TORSO_OVAL_RZ_SPAN_FRAC",
+    "TORSO_WAIST_PINCH_TAPER_GATE",
+    "TORSO_WAIST_RX_MAX_FRAC_CHEST",
     "_BASELINE_ROLES_NO_PROFILE",
     "_MICHELIN_FRAC",
     "BlockoutRecipePackage",

src/meshops/proportion/body_templates/female_adult_athletic.json

@@ -25,7 +25,7 @@
     "cleft_frac": 0.12
   },
   "pelvis_y_m": 0.027,
-  "torso_waist_taper": 0.14,
+  "torso_waist_taper": 0.22,
   "thigh_tilt_deg": 10.0,
   "neck_thickness_scale": 0.72675,
   "neck_thickness_notes": {

tests/test_proportion_blockout_recipe.py

@@ -2103,8 +2103,12 @@ def test_recipe__axial_chest_y_prefers_mid_not_front() -> None:
     """0032 pin: shoulders y null + chest_front=-0.13 + mid=0 → axial Y≈0, not front.
 
     0050: neck tip leans -Y by L*sin(tilt); base p0 stays mid.
+    0065: chest oval alone gets full3d rear bias; waist/hip stay mid.
     """
-    from meshops.proportion.blockout_recipe import NECK_FORWARD_TILT_DEG
+    from meshops.proportion.blockout_recipe import (
+        NECK_FORWARD_TILT_DEG,
+        TORSO_CHEST_Y_REAR_BIAS_FRAC_RY,
+    )
 
     report = _axial_pin_report(chest_front_y=-0.13, chest_mid_y=0.0, shoulder_y=None)
     pkg = build_blockout_recipe(report, limbs=False, torso="ovals")
@@ -2118,7 +2122,13 @@ def test_recipe__axial_chest_y_prefers_mid_not_front() -> None:
     assert ovals
     for o in ovals:
         assert o.center is not None
-        assert o.center[1] == pytest.approx(0.0, abs=1e-6)
+        if o.name == "RECIPE_torso_oval_chest":
+            # 0065 B5: full3d chest rear bias (mid=0 → cy = bias * ry)
+            ry = float(o.ry_m or 0.0)
+            expected_cy = 0.0 + TORSO_CHEST_Y_REAR_BIAS_FRAC_RY * ry
+            assert o.center[1] == pytest.approx(expected_cy, abs=1e-6)
+        else:
+            assert o.center[1] == pytest.approx(0.0, abs=1e-6)
         assert o.center[1] != pytest.approx(-0.13, abs=1e-3)
     bridges = [p for p in pkg.parts if p.role == "shoulder_bridge"]
     assert bridges

tests/test_proportion_body_template.py

@@ -223,7 +223,7 @@ def test_female_seeds__neck_and_breast() -> None:
     assert doc.breast.rz_scale == pytest.approx(2.1)
     assert doc.neck_thickness_scale == pytest.approx(0.72675)
     assert doc.neck_thickness_notes.stages == [0.95, 0.9, 0.85]
-    assert doc.torso_waist_taper == pytest.approx(0.14)
+    assert doc.torso_waist_taper == pytest.approx(0.22)
     assert doc.thigh_tilt_deg == pytest.approx(10.0)
     assert doc.glute.y_frac is not None
     assert doc.glute.y_frac > 0

tests/test_proportion_pelvis_bucket.py

@@ -314,9 +314,9 @@ def test_t8_0052_glute_seat_constants_still_exist() -> None:
 
 
 def test_t9_torso_oval_fracs_unchanged_0047() -> None:
-    """T9: torso chest/waist/hip ry fracs unchanged (0047 magnitudes)."""
-    assert TORSO_OVAL_RY_CHEST_FRAC == 0.95
-    assert TORSO_OVAL_RY_WAIST_FRAC == 0.72
+    """T9: torso chest/waist/hip ry fracs (0047 + 0065 retarget 0.85/0.58/0.80)."""
+    assert TORSO_OVAL_RY_CHEST_FRAC == 0.85
+    assert TORSO_OVAL_RY_WAIST_FRAC == 0.58
     assert TORSO_OVAL_RY_HIP_FRAC == 0.80
     report = _full_torso_report()
     pkg = build_blockout_recipe(report, limbs=False, torso="ovals")