Kernel rig: 391 graded on its volume (the shelled housing, sharp to rounded at the flange, less the letters' 0.6 mm deboss) and box

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/kernel-cases/shell/391-deboss-text-on-flange-of-filleted-shelled-body/expected.json

@@ -3,7 +3,23 @@
   "tangency-labs/solidcraft#391"
  ],
  "what": "text debossed 0.6 mm into the flat flange top of a filleted and shelled tapered housing, well away from the curved walls",
- "source": "invariants",
- "method": "the flange top (z=6) is planar and the text is clear of the walls, so the deboss must succeed and leave one valid closed body; the letter area is font dependent, so only the outcome and validity are graded",
- "body_count": 1
+ "source": "analytic",
+ "method": "the flange top (z=6) is planar and the text is clear of the walls and of the cavity below (z 2.5..3.5), so the deboss removes exactly 0.6 x the letters' area. Housing: flange 114 x 84 x 6 + the box drafted 2 deg (half-widths 45 - z k, 30 - z k, k = tan2) above it, z 6..35, less its r6 rounds as sloped prisms (section r^2 (tan(psi/2) - psi/2), psi = acos(sin^2 2), times height sqrt(1+2k^2)): 207002.5157. Shell 2.5 open at the top, every kept face moved 2.5 in and extended to meet: the flange's slab 109 x 79 x 1 (z 2.5..3.5) and the drafted box's offset (half-widths less 2.5/cos2, rounds r3.5) from z = 3.5 to 35: cavity 149670.2362, material 57332.2795. Rounding the cavity at the concave loop where the drafted walls meet the flange top (the true offset; under 298.32 mm, the walls 88 deg from the flange) enlarges it by at most 2.5^2 (tan44 - 44 deg) per mm: 368.6982. The letters, Liberation Sans' A and B at a 4 mm capital height (1409 units), are 598584.83 + 781544.83 units^2 (their quadratic outlines integrated exactly), 11.1229 mm^2: the deboss removes 6.6737. V = 56956.9075 .. 57325.6057",
+ "body_count": 1,
+ "volume_mm3": [
+  56956.9,
+  57325.7
+ ],
+ "bbox": {
+  "min": [
+   -57,
+   -42,
+   0
+  ],
+  "max": [
+   57,
+   42,
+   35
+  ]
+ }
 }