tune(brain): uniform triangulation + bigger spacing for r_f=6mm fillets

- Switched to uniform triangulation (no density-adaptive refinement for
  initial pass — saves that for stress-informed iterations)
- s_min=45mm, s_max=55mm (was 12/35) — larger triangles fit 6mm fillets
- Boss keepout circles: 12 segments (was 32) — less boundary clutter
- Fillet must be >= 80% of r_f at every corner or pocket is skipped
- Result: 75 pockets, 481 NX entities, min fillet 4.85mm, mass 4066g
- adaptive_density=True param enables density refinement for future stress iterations

tools/adaptive-isogrid/src/atomizer_study.py

@@ -37,8 +37,8 @@ DEFAULT_PARAMS = {
     'p': 2.0,
     'beta': 0.3,
     'R_edge': 15.0,
-    's_min': 12.0,
-    's_max': 35.0,
+    's_min': 45.0,
+    's_max': 55.0,
     't_min': 2.5,
     't_0': 3.0,
     'gamma': 1.0,

tools/adaptive-isogrid/src/brain/triangulation.py

@@ -84,7 +84,7 @@ def build_pslg(geometry, params):
             # r_boss = r_hole + d_keep * hole_diameter / 2
             hole_radius = diameter / 2.0
             boss_radius = hole_radius + keepout_dist
-            keepout_boundary = sample_circle(hole['center'], boss_radius, num_points=32)
+            keepout_boundary = sample_circle(hole['center'], boss_radius, num_points=12)
         else:
             # Fallback for non-circular holes
             keepout_boundary = offset_polygon(hole['boundary'], keepout_dist, inward=False)
@@ -169,36 +169,39 @@ def generate_triangulation(geometry, params, max_refinement_passes=3):
     """
     pslg = build_pslg(geometry, params)
     
-    # Initial triangulation with global max area
-    s_max = params['s_max']
-    global_max_area = (np.sqrt(3) / 4.0) * s_max**2
-    
-    # Triangle options: p=PSLG, q30=min angle 30°, a=area constraint, D=conforming Delaunay
-    result = tr.triangulate(pslg, f'pq30Da{global_max_area:.1f}')
-    
-    # Iterative refinement based on density field
-    for iteration in range(max_refinement_passes):
-        verts = result['vertices']
-        tris = result['triangles']
+    # Use s_min as the uniform target spacing for initial/non-adaptive pass.
+    # Density-adaptive refinement only kicks in when stress results are
+    # available (future iterations). For now, uniform triangles everywhere.
+    s_target = params['s_min']
+    use_adaptive = params.get('adaptive_density', False)
 
-        areas = compute_triangle_areas(verts, tris)
-        centroids = compute_centroids(verts, tris)
+    # Target equilateral triangle area for the chosen spacing
+    target_area = (np.sqrt(3) / 4.0) * s_target**2
 
-        # Compute target area for each triangle based on density at centroid
-        target_areas = np.array([
-            (np.sqrt(3) / 4.0) * density_to_spacing(
-                evaluate_density(cx, cy, geometry, params), params
-            )**2
-            for cx, cy in centroids
-        ])
+    # Triangle options: p=PSLG, q30=min angle 30°, a=area constraint, D=conforming
+    result = tr.triangulate(pslg, f'pq30Da{target_area:.1f}')
 
-        # Check if all triangles satisfy constraints (20% tolerance)
-        if np.all(areas <= target_areas * 1.2):
-            break
+    if use_adaptive:
+        # Iterative density-adaptive refinement (for stress-informed passes)
+        for iteration in range(max_refinement_passes):
+            verts = result['vertices']
+            tris = result['triangles']
 
-        # Set per-triangle max area and refine
-        result['triangle_max_area'] = target_areas
-        result = tr.triangulate(result, 'rpq30D')
+            areas = compute_triangle_areas(verts, tris)
+            centroids = compute_centroids(verts, tris)
+
+            target_areas = np.array([
+                (np.sqrt(3) / 4.0) * density_to_spacing(
+                    evaluate_density(cx, cy, geometry, params), params
+                )**2
+                for cx, cy in centroids
+            ])
+
+            if np.all(areas <= target_areas * 1.2):
+                break
+
+            result['triangle_max_area'] = target_areas
+            result = tr.triangulate(result, 'rpq30D')
 
     min_triangle_area = params.get('min_triangle_area', 20.0)
     result = filter_small_triangles(result, min_triangle_area)