fix: rebuild hay-bale and hitching-post so the joints actually meet

docs/gallery/index.html

@@ -1052,12 +1052,12 @@ <h2><a href="water-trough/">water-trough</a></h2>
       </article>
       <article class="card" data-tags="mesh export showcase">
         <a class="card-media" href="hitching-post/" aria-label="hitching-post example detail page">
-          <img src="assets/hitching-post-hero.webp" alt="hitching-post — A procedural hitching post through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract." loading="lazy" decoding="async" />
+          <img src="assets/hitching-post-hero.webp" alt="hitching-post — A procedural hitching post (corner-aligned cap, stub-and-tenon arm, collar shoe, eye-threaded rings) through UVs, bake, LOD, collider, and Unity glTF…" loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="hitching-post/">hitching-post</a></h2>
-          <p class="teaches">A procedural hitching post through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.</p>
-          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 848 tris, two materials with 262 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.460×0.194×1.260 m, LOD ratios in band (5.2 COLLAPSE more aggressive on LOD2), convex collider 144 tris, non-empty glTF. --skip-decimate exits 9 on the LOD1 ratio budget.</p>
+          <p class="teaches">A procedural hitching post (corner-aligned cap, stub-and-tenon arm, collar shoe, eye-threaded rings) through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 1598 tris, two materials with 269 wood and 532 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.460×0.191×1.258 m, zmin 0, hygiene 0, wood-metal BVH gap 0.45 mm, LOD ratios in band, convex collider 78 tris, non-empty glTF. --skip-decimate exits 9 on LOD1; --lift-z exits 16 on grounded zmin.</p>
           <a class="card-link" href="hitching-post/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>
@@ -1162,12 +1162,12 @@ <h2><a href="wooden-ladder/">wooden-ladder</a></h2>
       </article>
       <article class="card" data-tags="mesh export showcase">
         <a class="card-media" href="hay-bale/" aria-label="hay-bale example detail page">
-          <img src="assets/hay-bale-hero.webp" alt="hay-bale — A procedural bound hay bale with a bevelled loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed…" loading="lazy" decoding="async" />
+          <img src="assets/hay-bale-hero.webp" alt="hay-bale — A procedural bound hay bale with a cinched pillow loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting…" loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="hay-bale/">hay-bale</a></h2>
-          <p class="teaches">A procedural bound hay bale with a bevelled loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.</p>
-          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 252 tris, two materials with 66 hay and 60 twine faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.916×0.520×0.401 m, LOD ratios in band (5.2 COLLAPSE more aggressive), convex collider 68 tris, non-empty glTF. --skip-decimate exits 9 on the LOD1 ratio budget.</p>
+          <p class="teaches">A procedural bound hay bale with a cinched pillow loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 852 tris, two materials with 294 hay and 132 twine faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.920×0.517×0.426 m, zmin 0, hygiene 0, hay-twine BVH gap 0.07 mm, LOD ratios in band, convex collider 78 tris, non-empty glTF. --skip-decimate exits 9 on LOD1; --lift-z exits 16 on grounded zmin.</p>
           <a class="card-link" href="hay-bale/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>

showcase/README.md

@@ -33,7 +33,16 @@ entry in `showcase/gallery.json`, and a rendered still.
   assigned `DECLARED` is not a check).
 - **Falsifier** breaks one pipeline stage so a **named** budget fails and
   the piece exits its documented code. Prove default and falsifier on
-  4.5.11, 5.1.2, and 5.2.1.
+  4.5.11, 5.1.2, and 5.2.1. `--skip-decimate` is the LOD-ratio
+  falsifier (exit 9). `--lift-z` is the grounded-zmin falsifier (exit 16).
+- **Hygiene budgets.** Copied combinatorics from
+  `examples/mesh-hygiene-audit` (do not import the example). Every piece
+  asserts on the generated mesh: non-manifold edges 0, loose verts 0,
+  loose edges 0, doubles at 1e-5 0, zero-area faces 0, n-gons 0, world
+  AABB min Z within 1e-4 of 0. Multi-body props do **not** require Euler
+  characteristic 2 — that is a single-shell contract. Pairs of parts
+  meant to touch assert a BVH surface gap below a named epsilon
+  (vert-vert is the wrong metric for thin straps and collars).
 - **Exit codes** are file-local: `0` success, argparse `2`, `3` and above
   in check order. `9` is legal. FATAL `sys.exit(1)` is a crash, never a
   named check.

showcase/gallery.json

@@ -188,8 +188,8 @@
     {
       "name": "hitching-post",
       "dir": "showcase/hitching-post",
-      "teaches": "A procedural hitching post through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
-      "witnessesFix": "Recomputed: 848 tris, two materials with 262 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.460×0.194×1.260 m, LOD ratios in band (5.2 COLLAPSE more aggressive on LOD2), convex collider 144 tris, non-empty glTF. --skip-decimate exits 9 on the LOD1 ratio budget.",
+      "teaches": "A procedural hitching post (corner-aligned cap, stub-and-tenon arm, collar shoe, eye-threaded rings) through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
+      "witnessesFix": "Recomputed: 1598 tris, two materials with 269 wood and 532 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.460×0.191×1.258 m, zmin 0, hygiene 0, wood-metal BVH gap 0.45 mm, LOD ratios in band, convex collider 78 tris, non-empty glTF. --skip-decimate exits 9 on LOD1; --lift-z exits 16 on grounded zmin.",
       "hero": "docs/gallery/assets/hitching-post-hero.webp",
       "preview": "showcase/hitching-post/preview.webp",
       "tags": [
@@ -308,8 +308,8 @@
     {
       "name": "hay-bale",
       "dir": "showcase/hay-bale",
-      "teaches": "A procedural bound hay bale with a bevelled loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
-      "witnessesFix": "Recomputed: 252 tris, two materials with 66 hay and 60 twine faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.916×0.520×0.401 m, LOD ratios in band (5.2 COLLAPSE more aggressive), convex collider 68 tris, non-empty glTF. --skip-decimate exits 9 on the LOD1 ratio budget.",
+      "teaches": "A procedural bound hay bale with a cinched pillow loaf, end nap, and two sisal twine belts through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
+      "witnessesFix": "Recomputed: 852 tris, two materials with 294 hay and 132 twine faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.920×0.517×0.426 m, zmin 0, hygiene 0, hay-twine BVH gap 0.07 mm, LOD ratios in band, convex collider 78 tris, non-empty glTF. --skip-decimate exits 9 on LOD1; --lift-z exits 16 on grounded zmin.",
       "hero": "docs/gallery/assets/hay-bale-hero.webp",
       "preview": "showcase/hay-bale/preview.webp",
       "tags": [

showcase/hay-bale/README.md

@@ -1,9 +1,9 @@
 # Hay bale
 
-A showcase piece, not an example. Procedural bound straw bale (bevelled
-loaf, end nap, two sisal twine belts) then the shipped pipeline:
-unique-cell UVs, Cycles high-to-low normal bake, LOD chain, convex
-collider, Unity glTF export.
+A showcase piece, not an example. Procedural bound straw bale (cinched
+pillow loaf, end nap, two square-torus sisal belts with hitch loops)
+then the shipped pipeline: unique-cell UVs, Cycles high-to-low normal
+bake, LOD chain, convex collider, Unity glTF export.
 
 It asserts **budget conformance** of the generated result. It does not
 witness an API contract. "It rendered without error" is not a check.
@@ -13,6 +13,11 @@ witness an API contract. "It rendered without error" is not a check.
 `bake_normal_high_to_low.py`, `setup_bake_target_image.py`,
 `lod_chain.py` / `decimate_to_budget.py`, `convex_hull_collider.py`,
 `export_preset_unity.py` (helpers copied, not imported as a package).
+Hygiene combinatorics match `examples/mesh-hygiene-audit` (copied, not
+imported).
+
+Intended size: 0.90 × 0.48 × 0.38 m core loaf; outer AABB includes
+cinch bulge and belts.
 
 ## Budgets
 
@@ -21,34 +26,38 @@ materials, UVs, evaluated LOD, collider, or export file.
 
 | Axis | Declared | Measured (4.5.11 / 5.1.2 / 5.2.1) |
 | --- | --- | --- |
-| Base triangles | 220–290 | 252 / 252 / 252 |
-| LOD1 ratio | 0.32–0.62 of base | 0.5000 / 0.5000 / 0.4683 |
-| LOD2 ratio | 0.10–0.35 of base | 0.2143 / 0.2143 / 0.1429 |
-| Materials | exactly 2 distinct, ≥24 hay, ≥24 twine | 2 slots, 66 hay, 60 twine |
+| Base triangles | 750–1100 | 852 / 852 / 852 |
+| LOD1 ratio | 0.32–0.62 of base | 0.5000 / 0.5000 / 0.5000 |
+| LOD2 ratio | 0.10–0.35 of base | 0.2183 / 0.2183 / 0.2183 |
+| Materials | exactly 2 distinct, ≥24 hay, ≥24 twine | 2 slots, 294 hay, 132 twine |
 | UVs | in `0..1`, AABB overlap ≤ 1e-5 | in range, overlap 0 |
-| Outer AABB | (0.916, 0.520, 0.401) m ± 0.01 | (0.9160, 0.5200, 0.4010), zmin 0 |
-| Collider tris | ≤ 120 | 68 |
-| Export | written, size > 0 | 25944 / 25944 / 25936 bytes |
+| Outer AABB | (0.920, 0.517, 0.426) m ± 0.01 | (0.9199, 0.5170, 0.4257) |
+| Grounded zmin | within 1e-4 of 0 | 0 / 0 / 0 |
+| Hygiene | loose/nonman/zero-area/doubles/ngons = 0 | 0 / 0 / 0 |
+| Hay–twine gap | BVH surface < 0.008 m | 0.00007 / 0.00007 / 0.00007 |
+| Collider tris | ≤ 400 | 78 |
+| Export | written, size > 0 | 70720 / 70720 / 70712 bytes |
 
 DECIMATE COLLAPSE triangle counts are **not** identical across series —
-5.2.1 is more aggressive on both LOD ratios. The gate is a ratio band,
-not an exact count. Bake pixels are stochastic; the gate is `has_data`
-plus operator `FINISHED`, not byte-identity. Construction uses no RNG.
-Export byte counts differ by 8 B on 5.2.1 (glTF serializer), not a
-gated axis.
+the gate is a ratio band, not an exact count. Bake pixels are
+stochastic; the gate is `has_data` plus operator `FINISHED`, not
+byte-identity. Construction uses no RNG. Export byte counts differ by
+8 B on 5.2.1 (glTF serializer), not a gated axis.
 
 `--skip-decimate` skips the LOD DECIMATE stage so LOD1 ratio is 1.0 and
-exit 9 fires. That is the named budget the falsifier violates.
+exit 9 fires. `--lift-z` raises the mesh 5 cm so the grounded-zmin
+hygiene budget fails and exit 16 fires.
 
 ## Run
 
 ```bash
 blender --background --python hay_bale.py --
 blender --background --python hay_bale.py -- --skip-decimate
+blender --background --python hay_bale.py -- --lift-z
 blender --background --python hay_bale.py -- --output bale.png
 ```
 
-Smoke does not pass `--output` or `--skip-decimate`.
+Smoke does not pass `--output`, `--skip-decimate`, or `--lift-z`.
 
 ## Exit codes
 
@@ -72,3 +81,6 @@ File-local. `9` is a valid check code. `10` is reserved for
 | 12 | Bake did not finish or image has no data |
 | 13 | Export file missing or empty |
 | 14 | `--output` produced no file |
+| 15 | Hygiene: loose verts/edges, non-manifold, zero-area, doubles, or n-gons |
+| 16 | Grounded zmin (`--lift-z` lands here) |
+| 17 | Hay–twine BVH gap above 8 mm |