Reject asymmetric radial overhead sprites

app.py

@@ -2478,14 +2478,34 @@ def has_implausibly_thin_foreground_subject(content: bytes, spec: AssetSpec) ->
     )
 
 
+def foreground_rotational_symmetry(content: bytes) -> float:
+    """Measure 180-degree alpha-mask balance inside the material foreground bounds."""
+    image = Image.open(io.BytesIO(content)).convert("RGBA")
+    bbox = material_foreground_bbox_from_image(image)
+    if bbox is None:
+        return 0.0
+    x0, y0, x1, y1 = bbox
+    alpha = image.getchannel("A").crop((x0, y0, x1 + 1, y1 + 1))
+    foreground = [value >= 64 for value in alpha.tobytes()]
+    if not any(foreground):
+        return 0.0
+    rotated = reversed(foreground)
+    intersection = 0
+    union = 0
+    for original, opposite in zip(foreground, rotated):
+        intersection += original and opposite
+        union += original or opposite
+    return intersection / max(1, union)
+
+
 def has_front_view_like_top_down_silhouette(content: bytes, spec: AssetSpec) -> bool:
     """Reject silhouettes that contradict a requested overhead body footprint.
 
     Alpha geometry cannot prove camera perspective. It can, however, fail closed
     when a normalized, canvas-filling silhouette contradicts explicit user terms:
-    compact humanoids cannot remain upright portraits; radial bodies must not be
-    taller than wide; and explicitly wide vehicles must present a wide footprint.
-    Narrow props remain exempt.
+    compact humanoids cannot remain upright portraits; explicitly radial bodies
+    must be broad and rotationally balanced; and explicitly wide vehicles must
+    present a wide footprint. Narrow props remain exempt.
     """
     if spec.camera != "top_down" or spec.composition not in {"single_subject", "icon", "animation_frame"}:
         return False
@@ -2503,14 +2523,28 @@ def has_front_view_like_top_down_silhouette(content: bytes, spec: AssetSpec) ->
     if height_ratio < 0.72:
         return False
 
+    description = f"{spec.description} {spec.prompt}"
     geometry = infer_top_down_subject_geometry(spec)
     if geometry == "humanoid" and aspect >= 1.10:
         return True
 
-    if geometry == "radial" and aspect >= 1.02:
-        return True
+    if geometry == "radial":
+        if aspect >= 1.02:
+            return True
+        explicitly_balanced_radial = contains_any_term(
+            description,
+            (
+                "radial",
+                "six-legged",
+                "six legged",
+                "splayed evenly",
+                "evenly splayed",
+                "limbs radiate",
+            ),
+        )
+        if explicitly_balanced_radial and foreground_rotational_symmetry(content) < 0.40:
+            return True
 
-    description = f"{spec.description} {spec.prompt}"
     explicitly_wide_vehicle = geometry == "vehicle" and contains_any_term(
         description,
         ("wide", "four-wheel", "four wheel", "six-wheel", "six wheel", "tracked"),