fix(showcase): anvil and campfire visual quality pass (#178)

* fix(showcase): rebuild anvil as London-pattern iron on a coopered stump

The old piece stacked beveled boxes with glued nubs as holes and a
twisted horn. One slotted face, oval rings, and stave-chord hoops are
durable; per-coordinate nudges are not.

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

* fix(showcase): rebuild campfire with seated courses and a kissing teepee

The old ring floated a mortar gap between identical boxes and ended
the tripod at one point. Shared-Z courses and an overshooting apex
ring are durable; per-log coordinate nudges are not.

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

---------

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

Author: TMHSDigital

docs/gallery/anvil/index.html

@@ -925,7 +925,7 @@ <h2><a href="wooden-barrel/">wooden-barrel</a></h2>
         <div class="card-body">
           <h2><a href="campfire/">campfire</a></h2>
           <p class="teaches">A procedural campfire 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: 3616 tris, three materials with 100 wood and 48 ash faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.789×0.789×0.410 m, LOD ratios in band, convex collider 254 tris, non-empty glTF. --skip-decimate exits 9 on the LOD1 ratio budget.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 2200 tris, three materials with 216 wood, 48 ash and 1304 stone faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.807×0.808×0.404 m, LOD ratios in band, convex collider 198 tris, hygiene 0, 14 grounded bottom stones, teepee kiss 0.00001 m, course seat 0, non-empty glTF. --skip-decimate exits 9; --stray-vert 15; --lift-z/--short-stones 16; --float-logs 17; --gap-courses 18.</p>
           <a class="card-link" href="campfire/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>
@@ -1035,7 +1035,7 @@ <h2><a href="wheelbarrow/">wheelbarrow</a></h2>
         <div class="card-body">
           <h2><a href="anvil/">anvil</a></h2>
           <p class="teaches">A procedural blacksmith anvil on a timber stump 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: 6616 tris, two materials with 2616 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.772×0.419×0.662 m, LOD ratios in band, convex collider 190 tris, non-empty glTF. --skip-decimate exits 9 on the LOD1 ratio budget.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Recomputed: 2988 tris, two materials with 1040 wood and 822 metal faces, UVs in 0..1 with zero AABB overlap, outer AABB 0.621×0.414×0.489 m, LOD ratios in band, convex collider 134 tris, hygiene 0, 16 grounded staves, hoop bite 0.003 m, foot-on-head gap 0.003 m, non-empty glTF. --skip-decimate exits 9; --stray-vert 15; --lift-z/--short-staves 16; --float-anvil 17; --round-band 18.</p>
           <a class="card-link" href="anvil/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>

docs/gallery/assets/anvil-hero.webp

@@ -1,10 +1,17 @@
 # Anvil
 
 A showcase piece, not an example. Procedural London-pattern anvil on a
-timber stump (horn, face, heel, waist, iron hoops) then the shipped
+coopered timber stump (16 jittered staves, chord-lofted iron hoops, a
+sawn head, spreading foot, pinched waist, one slotted face with hardy
+and pritchel through-holes, oval-lofted horn) then the shipped
 pipeline: unique-cell UVs, Cycles high-to-low normal bake, LOD chain,
 convex collider, Unity glTF export.
 
+The face is one `add_slotted_slab` so hardy/pritchel are real holes in
+a single shell, not nubs glued onto stacked boxes. Hoops evaluate the
+same `host_outer_r` chord as the stave flats. `--round-band` is the
+falsifier: a circle of `radius_at(z)` instead of the chord.
+
 It asserts **budget conformance** of the generated result. It does not
 witness an API contract. "It rendered without error" is not a check.
 
@@ -21,39 +28,83 @@ materials, UVs, evaluated LOD, collider, or export file.
 
 | Axis | Declared | Measured (4.5.11 / 5.1.2 / 5.2.1) |
 | --- | --- | --- |
-| Base triangles | 6450–6800 | 6616 / 6616 / 6616 |
+| Base triangles | 2500–4500 | 2988 / 2988 / 2988 |
 | LOD1 ratio | 0.32–0.62 of base | 0.5000 / 0.5000 / 0.5000 |
-| LOD2 ratio | 0.10–0.35 of base | 0.2198 / 0.2198 / 0.2198 |
-| Materials | exactly 2 distinct, ≥24 metal faces | 2 slots, 628 wood, 2616 metal |
+| LOD2 ratio | 0.10–0.35 of base | 0.2195 / 0.2195 / 0.2195 |
+| Materials | exactly 2 distinct; ≥400 wood, ≥400 metal faces | 2 slots; 1040 / 822 |
 | UVs | in `0..1`, AABB overlap ≤ 1e-5 | in range, overlap 0 |
-| Outer AABB | (0.772, 0.419, 0.662) m ± 0.01 | (0.7720, 0.4183, 0.6618), zmin 0 |
-| Collider tris | ≤ 220 | 190 |
-| Export | written, size > 0 | 474984 / 474984 / 474972 bytes |
+| Outer AABB | (0.621, 0.414, 0.489) m ± 0.015 | (0.6210, 0.4137, 0.4890), zmin 0 |
+| Collider tris | ≤ 280 | 134 |
+| Export | written, size > 0 | 244052 / 244052 / 244036 bytes |
+
+Base triangles dropped from **6616 to 2988** in the quality pass:
+overlapping face boxes and a beveled superellipse horn became one
+slotted slab plus a circular oval loft. Hidden coincident faces were
+the waste.
+
+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. Stave-width jitter uses fixed seed 17. Export byte counts
+differ by 16 B on 5.2.1 (glTF serializer), not a gated axis.
+
+### Hygiene
+
+Recomputed from the generated mesh, not asserted about the script.
+
+| Axis | Declared | Measured (all three) |
+| --- | --- | --- |
+| Non-manifold edges | 0 | 0 |
+| Loose verts / edges | 0 / 0 | 0 / 0 |
+| Doubles merged at 1e-5 | 0 | 0 |
+| Zero-area faces | 0 | 0 |
+| N-gons | 0 | 0 |
+| Coplanar disjoint face pairs | 0 | 0 |
+| Grounded: `zmin` | within 1e-4 of 0 | 0.0000 |
+| Named supports: 16 staves | each `zmin` ≤ 0.001 | 16, stave_z 0.00000 |
+| Body plan | 0.621 m long × 0.180 m high ± 0.05 | 0.6210 × 0.1800 |
+
+### Joint fit and seat
+
+| Axis | Declared | Measured (all three) |
+| --- | --- | --- |
+| Foot-on-head BVH gap | ≤ 0.006 m | 0.00300 |
+| Hoop bite (host r − inner hoop r) | 0.0012–0.008 m | 0.00300 |
+
+### Falsifiers
 
-DECIMATE COLLAPSE triangle counts are **not** identical across series in
-general — the gate is a ratio band, not an exact count. On this mesh LOD
-ratios matched across 4.5.11 / 5.1.2 / 5.2.1. Bake pixels are stochastic;
-the gate is `has_data` plus operator `FINISHED`, not byte-identity.
-Construction uses no RNG. Export byte counts differ by 12 B on 5.2.1
-(glTF serializer), not a gated axis.
+Each violates one named budget. All six were run on 4.5.11, 5.1.2 and
+5.2.1 and returned the same code on each.
 
-`--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.
+| Flag | Budget violated | Exit |
+| --- | --- | --- |
+| `--skip-decimate` | LOD1 ratio band | 9 |
+| `--stray-vert` | loose vertex count is 0 | 15 |
+| `--lift-z` | bounding box `zmin` is 0 | 16 |
+| `--short-staves` | named stave supports at Z=0 | 16 |
+| `--float-anvil` | foot-on-head gap | 17 |
+| `--round-band` | hoop bite band | 18 |
 
 ## Run
 
 ```bash
 blender --background --python anvil.py --
 blender --background --python anvil.py -- --skip-decimate
+blender --background --python anvil.py -- --stray-vert
+blender --background --python anvil.py -- --lift-z
+blender --background --python anvil.py -- --short-staves
+blender --background --python anvil.py -- --float-anvil
+blender --background --python anvil.py -- --round-band
 blender --background --python anvil.py -- --output anvil.png
 ```
 
-Smoke does not pass `--output` or `--skip-decimate`.
+Smoke passes no flags.
 
 ## Exit codes
 
 File-local. `9` is a valid check code. `10` is reserved for
-`gallery_framing.check_framing` on the `--output` path.
+`gallery_framing.check_framing` on the `--output` path. `15`–`19` are the
+hygiene and joint-fit family.
 
 | Code | Meaning |
 | --- | --- |
@@ -62,7 +113,7 @@ File-local. `9` is a valid check code. `10` is reserved for
 | 2 | argparse / usage |
 | 3 | Mesh did not build / no UV layer |
 | 4 | Base triangle count outside range |
-| 5 | Material count ≠ 2 distinct slots, or wood/metal faces missing |
+| 5 | Material count ≠ 2 distinct slots, or a face-count floor missed |
 | 6 | UVs outside 0..1 |
 | 7 | UV AABB overlap above tolerance |
 | 8 | World AABB off declared outer size |
@@ -72,3 +123,8 @@ 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 | Mesh hygiene: loose, non-manifold, zero-area, doubles, n-gons, z-fight |
+| 16 | Not grounded: bounding box `zmin` off 0, or a named stave floats |
+| 17 | Joint fit: foot-on-head gap (`--float-anvil`) |
+| 18 | Seat: hoop bite band (`--round-band`) |
+| 19 | Body length or height off the stated real-world size |