fix(showcase): hitching post visual quality pass

Hang the rings through eyes under one rail and seat the post in a closed shoe, with centerline and cup budgets so a clipped torus cannot pass again.

Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: TMHSDigital

docs/gallery/assets/hitching-post-hero.webp

@@ -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 (corner-aligned cap, stub-and-tenon arm, collar shoe, eye-threaded rings) through UVs, bake, LOD, collider, and Unity glTF…" loading="lazy" decoding="async" />
+          <img src="assets/hitching-post-hero.webp" alt="hitching-post — A procedural hitching post (eaved cap, one rail, cup shoe, rings hung through eyes) through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed…" 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 (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>
+          <p class="teaches">A procedural hitching post (eaved cap, one rail, cup shoe, rings hung through eyes) 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: 1680 tris, two materials with 114 wood and 742 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.500×0.149×1.246 m, zmin 0, hygiene and coplanar pairs 0, post seated at z 0.010, ring centerline error 0, LOD ratios in band, convex collider 80 tris, non-empty glTF. --skip-decimate exits 9; --stray-vert and --twin-sole exit 15; --lift-z exits 16; --clip-ring exits 18; --short-post exits 19.</p>
           <a class="card-link" href="hitching-post/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>
@@ -1151,12 +1151,12 @@ <h2><a href="iron-cauldron/">iron-cauldron</a></h2>
       </article>
       <article class="card" data-tags="mesh export showcase">
         <a class="card-media" href="wooden-ladder/" aria-label="wooden-ladder example detail page">
-          <img src="assets/wooden-ladder-hero.webp" alt="wooden-ladder — A procedural timber ladder with raked stiles, six dowel rungs tenoned into the stiles, and iron shoes and top caps through UVs, bake, LOD, collider, and Unity…" loading="lazy" decoding="async" />
+          <img src="assets/wooden-ladder-hero.webp" alt="wooden-ladder — A procedural timber ladder with raked tapered stiles, six turned rungs, ferrule caps, and level shoe plates through UVs, bake, LOD, collider, and Unity glTF…" loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="wooden-ladder/">wooden-ladder</a></h2>
-          <p class="teaches">A procedural timber ladder with raked stiles, six dowel rungs tenoned into the stiles, and iron shoes and top caps 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: 936 tris, two materials with 324 wood and 216 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.472×0.365×1.460 m, grounded at zmin 0, mesh hygiene all zero, 12 shells with every rung clearing the stile chamfer by 3.61 mm, convex collider 24 tris, non-empty glTF. Four falsifiers exit 9, 15, 16, and 17 on the LOD, hygiene, grounded, and joint-fit budgets.</p>
+          <p class="teaches">A procedural timber ladder with raked tapered stiles, six turned rungs, ferrule caps, and level shoe plates 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: 2536 tris, two materials with 612 wood and 736 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.490×0.376×1.487 m, zmin 0, hygiene and coplanar pairs 0, tenon clearance 8 mm, shoe bite 20 mm, LOD ratios in band, convex collider 24 tris, non-empty glTF. --skip-decimate exits 9; --stray-vert and --twin-sole exit 15; --lift-z exits 16; --fat-rungs exits 17; --short-stile exits 18.</p>
           <a class="card-link" href="wooden-ladder/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>

docs/gallery/hitching-post/index.html

@@ -188,8 +188,8 @@
     {
       "name": "hitching-post",
       "dir": "showcase/hitching-post",
-      "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.",
+      "teaches": "A procedural hitching post (eaved cap, one rail, cup shoe, rings hung through eyes) through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
+      "witnessesFix": "Recomputed: 1680 tris, two materials with 114 wood and 742 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.500×0.149×1.246 m, zmin 0, hygiene and coplanar pairs 0, post seated at z 0.010, ring centerline error 0, LOD ratios in band, convex collider 80 tris, non-empty glTF. --skip-decimate exits 9; --stray-vert and --twin-sole exit 15; --lift-z exits 16; --clip-ring exits 18; --short-post exits 19.",
       "hero": "docs/gallery/assets/hitching-post-hero.webp",
       "preview": "showcase/hitching-post/preview.webp",
       "tags": [
@@ -296,8 +296,8 @@
     {
       "name": "wooden-ladder",
       "dir": "showcase/wooden-ladder",
-      "teaches": "A procedural timber ladder with raked stiles, six dowel rungs tenoned into the stiles, and iron shoes and top caps through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
-      "witnessesFix": "Recomputed: 936 tris, two materials with 324 wood and 216 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.472×0.365×1.460 m, grounded at zmin 0, mesh hygiene all zero, 12 shells with every rung clearing the stile chamfer by 3.61 mm, convex collider 24 tris, non-empty glTF. Four falsifiers exit 9, 15, 16, and 17 on the LOD, hygiene, grounded, and joint-fit budgets.",
+      "teaches": "A procedural timber ladder with raked tapered stiles, six turned rungs, ferrule caps, and level shoe plates through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets rather than an API contract.",
+      "witnessesFix": "Recomputed: 2536 tris, two materials with 612 wood and 736 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.490×0.376×1.487 m, zmin 0, hygiene and coplanar pairs 0, tenon clearance 8 mm, shoe bite 20 mm, LOD ratios in band, convex collider 24 tris, non-empty glTF. --skip-decimate exits 9; --stray-vert and --twin-sole exit 15; --lift-z exits 16; --fat-rungs exits 17; --short-stile exits 18.",
       "hero": "docs/gallery/assets/wooden-ladder-hero.webp",
       "preview": "showcase/wooden-ladder/preview.webp",
       "tags": [

docs/gallery/index.html

@@ -1,24 +1,24 @@
 # Hitching post
 
-A showcase piece, not an example. Procedural timber hitching post
-(square post, pyramid cap on the post corners, stub-and-tenon
-cross-arm, iron collar shoe and bands, eye-threaded hitching rings)
-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 timber hitching post: a
+125 mm square post seated in a closed iron shoe, one cross-rail through
+the post, a pyramidal cap with eaves, and two rings hung through eyes
+under the rail. 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.
 
+Intended size: post 0.125 m square and 1.16 m of timber, cap 0.096 m,
+cross-rail 0.50 m. Outer AABB 0.500 × 0.149 × 1.246 m.
+
 **Composes** skills `mesh-editing-and-bmesh`, `bake-high-to-low`,
 `depsgraph-and-evaluated-data`, `engine-export-presets`, and snippets
 `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: 0.125 m square post, 1.16 m timber plus 0.10 m cap;
-cross-arm 0.46 m; outer AABB 0.460 × 0.191 × 1.258 m.
+imported). Coplanar-pair counting matches `showcase/signpost`.
 
 ## Budgets
 
@@ -27,39 +27,62 @@ materials, UVs, evaluated LOD, collider, or export file.
 
 | Axis | Declared | Measured (4.5.11 / 5.1.2 / 5.2.1) |
 | --- | --- | --- |
-| Base triangles | 900–1800 | 1598 / 1598 / 1598 |
-| LOD1 ratio | 0.32–0.62 of base | 0.4994 / 0.4994 / 0.4994 |
+| Base triangles | 1400–2400 | 1680 / 1680 / 1680 |
+| LOD1 ratio | 0.32–0.62 of base | 0.5000 / 0.5000 / 0.5000 |
 | LOD2 ratio | 0.10–0.35 of base | 0.2190 / 0.2190 / 0.2190 |
-| Materials | exactly 2 distinct, ≥12 wood, ≥24 metal | 2 slots, 269 wood, 532 metal |
+| Materials | exactly 2 distinct, ≥70 wood, ≥560 metal | 2 slots, 114 wood, 742 metal |
 | UVs | in `0..1`, AABB overlap ≤ 1e-5 | in range, overlap 0 |
-| Outer AABB | (0.460, 0.191, 1.258) m ± 0.01 | (0.4600, 0.1912, 1.2580) |
+| Outer AABB | (0.500, 0.149, 1.246) m ± 0.01 | (0.5000, 0.1490, 1.2460) |
 | Grounded zmin | within 1e-4 of 0 | 0 / 0 / 0 |
-| Hygiene | loose/nonman/zero-area/doubles/ngons = 0 | 0 / 0 / 0 |
-| Wood–metal gap | BVH surface < 0.008 m | 0.00045 / 0.00045 / 0.00045 |
-| Collider tris | ≤ 280 | 78 |
-| Export | written, size > 0 | 121496 / 121496 / 121480 bytes |
+| Hygiene | loose/nonman/zero-area/doubles/n-gons/coplanar pairs = 0 | all 0 |
+| Post seat | world zmin in (0.004, 0.014), XY centroid within 0.010 of origin, arm axis cos ≥ cos(0.5°) | 0.01000, 0, 1.000 |
+| Hung ring | centerline error ≤ 0.008 m, ring–wood overlap 0, eye–wood overlap 0, shank–ring overlap 0, shank bites the eye | 0, 0, 0, 0, 40 |
+| Shoe | each band overlaps the post, shoe overlaps the sole | band gap 0, sole–shoe 8 |
+| Wood–metal gap | BVH surface < 0.008 m | 0.00075 |
+| Collider tris | ≤ 280 | 80 |
+| Export | written, size > 0 | 127428 / 127428 / 127412 bytes |
+
+Base triangles rose from **1598 to 1680**. The old rings were faceted
+tori clipped into the arm; the new eyes, shanks, and 24-segment hung
+rings replace that mesh. Cylinder caps are triangulated so the n-gon
+budget stays at 0.
 
 DECIMATE COLLAPSE triangle counts are **not** identical across series —
-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
-16 B on 5.2.1 (glTF serializer), not a gated axis. Euler characteristic
-is 10 (multi-body: timber, collars, eyes, rings) — not gated to 2.
+the gate is a ratio band, not an exact count. On this mesh the three
+binaries agreed. Bake pixels are stochastic; the gate is `has_data`
+plus operator `FINISHED`, not byte-identity. Construction uses no RNG.
+Export byte counts differ by 16 B on 5.2.1 (glTF serializer), not a
+gated axis. Euler is 12 (six balls and seven tori) and is not gated to 2.
+
+Each falsifier violates exactly one named budget. Proven on Blender
+4.5.11 LTS, 5.1.2, and 5.2.1 LTS (the binaries' own `--version`):
+
+| Falsifier | Budget violated | Exit | Measured failure |
+| --- | --- | --- | --- |
+| `--skip-decimate` | LOD1 ratio band | 9 | ratio 1.0000 |
+| `--stray-vert` | Mesh hygiene, loose verts | 15 | `loose_v=1` |
+| `--twin-sole` | Coplanar face pairs | 15 | `zfight=6` |
+| `--lift-z` | Grounded zmin | 16 | zmin 0.050000 |
+| `--clip-ring` | Hung-ring centerline | 18 | ring_err 0.024, ring–wood overlap 32 |
+| `--short-post` | Seated post | 19 | post zmin 0.030 |
 
-`--skip-decimate` skips the LOD DECIMATE stage so LOD1 ratio is 1.0 and
-exit 9 fires. `--lift-z` raises the mesh 5 cm so the grounded-zmin
-hygiene budget fails and exit 16 fires.
+Default exit is 0 on all three. `--clip-ring` also overlaps the rail;
+the centerline gate is the one that fires.
 
 ## Run
 
 ```bash
 blender --background --python hitching_post.py --
 blender --background --python hitching_post.py -- --skip-decimate
+blender --background --python hitching_post.py -- --stray-vert
+blender --background --python hitching_post.py -- --twin-sole
 blender --background --python hitching_post.py -- --lift-z
-blender --background --python hitching_post.py -- --output hitching-post.png
+blender --background --python hitching_post.py -- --clip-ring
+blender --background --python hitching_post.py -- --short-post
+blender --background --python hitching_post.py -- --output preview.webp --engine cycles
 ```
 
-Smoke does not pass `--output`, `--skip-decimate`, or `--lift-z`.
+Smoke does not pass `--output` or a falsifier.
 
 ## Exit codes
 
@@ -83,6 +106,8 @@ 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) |
+| 15 | Hygiene, including coplanar pairs (`--stray-vert`, `--twin-sole`) |
+| 16 | Grounded zmin (`--lift-z`) |
 | 17 | Wood–metal BVH gap above 8 mm |
+| 18 | Hung ring or shoe seat (`--clip-ring`) |
+| 19 | Post plumb, origin, and cup seat (`--short-post`) |