Kernel rig: a reversed normal sends a later thicken to the other side, and a solid is refused

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

tests/kernel-cases/surfaces/cov-reverse-normal-l-sheet-swaps-the-thicken-side/expected.json

@@ -0,0 +1,21 @@
+{
+ "sources": [],
+ "what": "the L sheet of two walls (30 and 20, 20 deep) turned over, then thickened +2: the side -2 took before, into the inside corner",
+ "source": "analytic",
+ "method": "kernel-cases/shell/5326: -2 is the inside of this sheet's corner; with every normal reversed +2 is. Each wall offset 2 toward the other, the slabs overlap in 2 x 2: V = (30*2 + 20*2 - 2*2) 20 = 1920, an L prism of 8 faces",
+ "body_count": 1,
+ "faces": 8,
+ "volume_mm3": 1920.0,
+ "bbox": {
+  "min": [
+   0,
+   0,
+   0
+  ],
+  "max": [
+   30,
+   20,
+   20
+  ]
+ }
+}

tests/kernel-cases/surfaces/cov-reverse-normal-l-sheet-swaps-the-thicken-side/recipe.json

@@ -0,0 +1,88 @@
+{
+ "commands": [
+  {
+   "command": "sketch.create",
+   "params": {
+    "plane": {
+     "origin": [
+      0,
+      0,
+      0
+     ],
+     "x_dir": [
+      1,
+      0,
+      0
+     ],
+     "y_dir": [
+      0,
+      1,
+      0
+     ]
+    },
+    "name": "S"
+   }
+  },
+  {
+   "command": "sketch.line",
+   "params": {
+    "points": [
+     [
+      0,
+      0
+     ],
+     [
+      30,
+      0
+     ],
+     [
+      30,
+      20
+     ]
+    ],
+    "infer": false
+   }
+  },
+  {
+   "command": "sketch.finish",
+   "params": {}
+  },
+  {
+   "command": "surface.extrude",
+   "params": {
+    "sketch": "S",
+    "curves": [
+     "l1",
+     "l2"
+    ],
+    "distance": 20,
+    "body_name": "L"
+   }
+  },
+  {
+   "command": "surface.reverse_normal",
+   "params": {
+    "body": "L"
+   }
+  },
+  {
+   "command": "surface.thicken",
+   "params": {
+    "bodies": [
+     "L"
+    ],
+    "thickness": 2,
+    "operation": "new",
+    "body_name": "Wall"
+   }
+  },
+  {
+   "command": "solid.remove",
+   "params": {
+    "bodies": [
+     "L"
+    ]
+   }
+  }
+ ]
+}

tests/kernel-cases/surfaces/cov-reverse-normal-of-a-solid-refused/expected.json

@@ -0,0 +1,8 @@
+{
+ "sources": [],
+ "what": "reverse normal on a solid: refused, its faces face out",
+ "source": "invariants",
+ "method": "a closed solid's orientation is fixed by its material; only a surface may be turned over",
+ "outcome": "refused",
+ "refusal": "a solid's faces face out"
+}

tests/kernel-cases/surfaces/cov-reverse-normal-of-a-solid-refused/recipe.json

@@ -0,0 +1,19 @@
+{
+ "commands": [
+  {
+   "command": "solid.box",
+   "params": {
+    "length": 20,
+    "width": 10,
+    "height": 10,
+    "body_name": "Box"
+   }
+  },
+  {
+   "command": "surface.reverse_normal",
+   "params": {
+    "body": "Box"
+   }
+  }
+ ]
+}

tests/kernel-cases/surfaces/cov-reverse-normal-then-thicken-goes-down/expected.json

@@ -0,0 +1,21 @@
+{
+ "sources": [],
+ "what": "a 10 x 10 sheet patched on XY (normal +z) turned over, then thickened 2 along its normal: the slab lies below it",
+ "source": "analytic",
+ "method": "the patch of an XY sketch faces +z; reversed it faces -z, and a positive thickness goes along the normal: the box 10 x 10 x 2 at z -2..0, V = 200, 6 faces; the sheet is removed so only the slab is graded",
+ "body_count": 1,
+ "faces": 6,
+ "volume_mm3": 200.0,
+ "bbox": {
+  "min": [
+   0,
+   0,
+   -2
+  ],
+  "max": [
+   10,
+   10,
+   0
+  ]
+ }
+}

tests/kernel-cases/surfaces/cov-reverse-normal-then-thicken-goes-down/recipe.json

@@ -0,0 +1,76 @@
+{
+ "commands": [
+  {
+   "command": "sketch.create",
+   "params": {
+    "plane": {
+     "origin": [
+      0,
+      0,
+      0
+     ],
+     "x_dir": [
+      1,
+      0,
+      0
+     ],
+     "y_dir": [
+      0,
+      1,
+      0
+     ]
+    },
+    "name": "Sheet sketch"
+   }
+  },
+  {
+   "command": "sketch.rectangle.two_point",
+   "params": {
+    "p0": [
+     0,
+     0
+    ],
+    "p1": [
+     10,
+     10
+    ]
+   }
+  },
+  {
+   "command": "sketch.finish",
+   "params": {}
+  },
+  {
+   "command": "surface.patch",
+   "params": {
+    "sketch": "Sheet sketch",
+    "body_name": "Sheet"
+   }
+  },
+  {
+   "command": "surface.reverse_normal",
+   "params": {
+    "body": "Sheet"
+   }
+  },
+  {
+   "command": "surface.thicken",
+   "params": {
+    "bodies": [
+     "Sheet"
+    ],
+    "thickness": 2,
+    "operation": "new",
+    "body_name": "Slab"
+   }
+  },
+  {
+   "command": "solid.remove",
+   "params": {
+    "bodies": [
+     "Sheet"
+    ]
+   }
+  }
+ ]
+}