feat: add crate-stack and stone-archway showcase pieces (#199)

* feat: add crate-stack showcase piece

Three shipping crates stacked, built by one generator called three times
with a per-instance seed. The subject is reuse with variation: the seed
drives yaw and plank widths so the crates read as three of the same design
rather than one model pasted three times, and the README says plainly that
true instancing and per-instance geometry variation are mutually exclusive.

Budgets recomputed from the finished mesh, measured before they were
written: 4380 tris, 2 materials with 216 iron and 2436 timber faces, UVs in
0..1 with zero overlap, outer AABB 0.658x0.524x0.704 m, each crate's own
footprint 0.585x0.425 m in its own frame, three ground runners at z=0, both
crate-to-crate seats overlapping, LOD ratios in band, 202-tri collider,
non-empty glTF, and hygiene zero across loose/non-manifold/zero-area/
doubles/n-gons/coplanar-disjoint.

Six falsifiers, each breaking one named budget, all proven on 4.5.11,
5.1.2 and 5.2.1 with identical exit codes: --skip-decimate 9, --stray-vert
15, --lift-z 16, --short-skids 16, --float-stack 18, --same-seed 20.

Three findings the budgets forced, all documented in the README:

- Shape filters had to move to principal axes. Every part is axis-aligned
  in its crate's frame then rotated about Z, so a world-AABB filter
  measures the rotated box: a 0.554 m board yawed 0.09 rad reports 0.061 m
  of depth instead of 0.013 m, and every thickness-keyed filter matched
  nothing.
- Stack levels had to be clustered from the runners the mesh actually has.
  Binning against the declared pitch put a lid on the wrong level as soon
  as a falsifier shifted a crate, and the seat budget then compared a crate
  against itself.
- find_doubles caught two real joints, not false positives: the corner
  straps sat flush with the post corner, and the lid rested exactly on the
  rail top. Both now bite into their host.

Falsifiers were also retuned so each fails on its own budget rather than on
an earlier check: the stray vertex sits inside the silhouette, --short-skids
floats one of three runners so the AABB still grounds, and --same-seed
collapses only the design stream while placement stays per-instance so the
footprint is unchanged.

LOD2 is the one value that differs across versions (878 tris on 5.2, 934 on
4.5 and 5.1) — DECIMATE COLLAPSE, which is why the gate is a ratio band.

Adds ~1.0 s to smoke on 4.5/5.1 and ~1.2 s on 5.2.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* fix: warm the crate-stack wedge pool

Building the contact sheet against the pinned calibration set
(armature-bend, damped-track-aim, bmesh-gear) showed the wedge reading as a
cool grey band rather than the warm pool the house style calls for. Move it
closer to the backdrop, raise it to 560 W, and shift its colour to
(1.0, 0.72, 0.40).

Lighting only — no geometry, no budget, no assertion, no exit code changes.
Mean luminance 0.2185, inside the calibration band [0.1722, 0.3048]. Hero
and preview re-rendered; contact sheet committed under
docs/gallery/contact-sheets/.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* feat: add stone-archway showcase piece

A freestanding masonry arch: two coursed piers, projecting imposts, nine
voussoirs turning a semicircle, and a keystone standing proud at the crown.

The headline budget is the one an arch can fail invisibly. Nine wedge
blocks laid in a row are still nine wedge blocks; what makes them an arch
is that their intrados vertices sit on a circle. The piece recomputes that
circle from vertex positions rather than from the angles the generator
used, and asserts every intrados vertex lands within 4 mm of the declared
0.60 m radius over an arc of at least 168 degrees. Measured: 0.97 mm over
178.0 degrees.

Other budgets, all recomputed: 924 tris, two materials with 182 dressed and
364 ashlar faces, UVs in 0..1 with zero overlap, outer AABB
1.644x0.510x2.057 m, clear opening 1.203 m, both piers grounded, the
springing joint an overlap, all eight mortar joints at 9.70 mm inside a
6-17 mm band, 168-tri collider, non-empty glTF, and hygiene zero across
loose/non-manifold/zero-area/doubles/n-gons/coplanar-disjoint.

Seven falsifiers, each breaking one named budget, all proven on 4.5.11,
5.1.2 and 5.2.1 with identical exit codes: --skip-decimate 9, --stray-vert
15, --lift-z 16, --float-pier 16, --sink-keystone 17, --wide-mortar 18,
--off-circle 19.

Four findings the budgets forced, all documented in the README:

- bmesh.ops.bevel gives every face it creates material_index 0. Chamfering
  nineteen blocks left 30 faces on the dressed slot and moved 464 to
  ashlar; the slot count and the distinct-material check both still
  passed. Only the per-material face floor caught it. Materials are now
  re-stamped per block after the bevel.
- The impost landed exactly on the top course — same footprint, same
  plane, coincident face centres. It now sits on its own mortar bed.
- BVHTree.find_nearest is unsigned, so a voussoir seated inside the pier
  head reported a 5.4 mm gap where there was none. Joint gaps now test
  overlap first.
- Joint gaps need measuring both ways: the keystone's radial faces are
  wider in Y than its neighbours', so every keystone vertex on the joint
  lies outside the neighbour and read 33 mm instead of 9.7 mm.

Three falsifiers needed the model changed rather than the budget loosened.
--sink-keystone originally shrank the Y bounding box and tripped the AABB
gate, so imposts were added to own the envelope — correct masonry the arch
was missing. --off-circle began as --flat-arch, which is 0.62 m shorter and
also fails on the bounding box, proving nothing about the circle fit.
--float-pier tripped the z-fight budget because the impost was pinned to an
absolute height while its courses rose into it.

LOD2 is the one value that differs across versions (196 tris on 5.2, 202 on
4.5 and 5.1) — DECIMATE COLLAPSE, which is why the gate is a ratio band.

Adds ~0.82 s to smoke on 4.5, ~0.85 s on 5.1, ~0.98 s on 5.2. All 28
showcase pieces together run in 20.9 s on 5.2.1.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

* docs: sync the showcase candidate pool

Mark crate-stack and stone-archway shipped, and restock the pool with four
subjects identified while building them: rope bridge, grain sacks, brazier,
apothecary shelf.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>

---------

Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -163,6 +163,8 @@
     "showcase/tavern-stool",
     "showcase/iron-cauldron",
     "showcase/wooden-ladder",
-    "showcase/hay-bale"
+    "showcase/hay-bale",
+    "showcase/crate-stack",
+    "showcase/stone-archway"
   ]
 }

CLAUDE.md

@@ -22,7 +22,7 @@ rules/<rule-name>.mdc          - Anti-pattern rules, 9 total
 templates/<template-name>/     - Starter projects, 3 total
 snippets/<snippet-name>.py     - Standalone code patterns, 27 total
 examples/<name>/               - Runnable smoke-gated examples, 59 total (+ gallery.json)
-showcase/<name>/               - Budget-conformance props, 26 pieces (sibling of examples/; see showcase/README.md)
+showcase/<name>/               - Budget-conformance props, 28 pieces (sibling of examples/; see showcase/README.md)
 scripts/build_gallery.py       - Regenerates docs/gallery/ from examples/gallery.json + showcase/gallery.json
 scripts/site/                  - Vendored landing-page build (Jinja2)
 docs/gallery/                  - Committed generated gallery pages + hero renders

README.md

@@ -18,7 +18,7 @@
 </p>
 
 <p align="center">
-  <strong>16 skills</strong> &nbsp;&bull;&nbsp; <strong>9 rules</strong> &nbsp;&bull;&nbsp; <strong>3 templates</strong> &nbsp;&bull;&nbsp; <strong>27 snippets</strong> &nbsp;&bull;&nbsp; <strong>59 examples</strong> &nbsp;&bull;&nbsp; <strong>26 showcase pieces</strong>
+  <strong>16 skills</strong> &nbsp;&bull;&nbsp; <strong>9 rules</strong> &nbsp;&bull;&nbsp; <strong>3 templates</strong> &nbsp;&bull;&nbsp; <strong>27 snippets</strong> &nbsp;&bull;&nbsp; <strong>59 examples</strong> &nbsp;&bull;&nbsp; <strong>28 showcase pieces</strong>
 </p>
 
 <p align="center">
@@ -37,7 +37,7 @@
 
 ## Overview
 
-This repository ships **16 skills, 9 rules, 3 templates, 27 snippets, 59 examples, and 26 showcase pieces** for Blender Python development targeting Blender 5.2 LTS (current stable) with Blender 4.5 LTS fallback support. Blender 5.1 is prior stable.
+This repository ships **16 skills, 9 rules, 3 templates, 27 snippets, 59 examples, and 28 showcase pieces** for Blender Python development targeting Blender 5.2 LTS (current stable) with Blender 4.5 LTS fallback support. Blender 5.1 is prior stable.
 
 The content is consumed by AI coding agents reading these files directly from a checkout — **there is no MCP server in this repository, and none is required**. Cursor applies `rules/*.mdc` automatically wherever their scope globs match and takes skills by name in chat; Claude Code reads `skills/` and `rules/` from the project workspace, or from this repo kept as a referenced checkout. Any agent that can read files in a workspace can use it the same way. There is no build step for the content — edit the Markdown and Python files directly.
 
@@ -106,7 +106,7 @@ per-script exit-code model, are in
 Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](showcase/README.md).
 
 <details>
-<summary><strong>26 showcase pieces</strong> — click to expand the preview grid</summary>
+<summary><strong>28 showcase pieces</strong> — click to expand the preview grid</summary>
 
 <p align="center">
   <a href="showcase/shipping-crate/"><img src="showcase/shipping-crate/preview.webp" width="24%" alt="Shipping crate: a wooden slat crate with iron corner brackets on a dark studio floor, warm wedge on the back wall" /></a>
@@ -135,6 +135,8 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/iron-cauldron/"><img src="showcase/iron-cauldron/preview.webp" width="24%" alt="Iron cauldron: a bulged iron pot hanging from a timber tripod on a dark studio floor" /></a>
   <a href="showcase/wooden-ladder/"><img src="showcase/wooden-ladder/preview.webp" width="24%" alt="Wooden ladder: a raked timber ladder with six rungs and iron shoes on a dark studio floor" /></a>
   <a href="showcase/hay-bale/"><img src="showcase/hay-bale/preview.webp" width="24%" alt="Hay bale: a bound straw bale with two sisal twine belts on a dark studio floor" /></a>
+  <a href="showcase/crate-stack/"><img src="showcase/crate-stack/preview.webp" width="24%" alt="Crate stack: three slatted shipping crates stacked and yawed, each with iron corner straps and runners, on a dark studio floor" /></a>
+  <a href="showcase/stone-archway/"><img src="showcase/stone-archway/preview.webp" width="24%" alt="Stone archway: a semicircular masonry arch with coursed piers, projecting imposts, nine voussoirs and a proud keystone, on a dark studio floor" /></a>
 </p>
 
 [`shipping-crate`](showcase/shipping-crate/) — procedural crate through UVs, bake, LOD, collider, and Unity glTF, asserting recomputed budgets. Falsifier `--skip-decimate` exits 9.

ROADMAP.md

@@ -131,6 +131,12 @@ Not committed; target list for the next content version. (v0.3.0 shipped the smo
 - ~~Cast-iron cooking cauldron on a tripod as a game-prop showcase piece~~ **SHIPPED** as `showcase/iron-cauldron/` — bulged open pot, bail, timber tripod, hook; `--skip-decimate` exits 9 on the LOD1 ratio band
 - ~~Wooden ladder (rungs, stiles, iron shoes) as a game-prop showcase piece~~ **SHIPPED** as `showcase/wooden-ladder/` — raked stiles, six rungs, iron shoes and straps; `--skip-decimate` exits 9 on the LOD1 ratio band
 - ~~Bound hay bale as a game-prop showcase piece~~ **SHIPPED** as `showcase/hay-bale/` — bevelled loaf, end nap, two sisal twine belts; `--skip-decimate` exits 9 on the LOD1 ratio band
+- ~~Stack of shipping crates as a game-prop showcase piece~~ **SHIPPED** as `showcase/crate-stack/` — one generator called three times with a per-instance seed driving yaw and plank widths, crates seated on the lid below; `--same-seed` exits 20 on the per-instance variation budget, `--float-stack` exits 18 on the seat
+- ~~Keystone archway with voussoirs as a game-prop showcase piece~~ **SHIPPED** as `showcase/stone-archway/` — coursed piers, projecting imposts, nine voussoirs, proud keystone; the intrados circle fit is recomputed from vertex positions and `--off-circle` exits 19 on it while leaving every other budget passing
+- Rope bridge (planks, rope rails, sag between anchors) as a game-prop showcase piece
+- Grain sacks (cloth sacks, some slumped, tied necks) as a game-prop showcase piece
+- Brazier (iron bowl on legs, coals, ash) as a game-prop showcase piece
+- Apothecary shelf (shelf unit, bottles and jars of varied form) as a game-prop showcase piece
 - Wooden yoke (oxbow, iron rings) as a game-prop showcase piece
 - Butter churn (staved tub, lid, dasher) as a game-prop showcase piece
 - ~~Small modular kit showcase on recognizable geometry (`modular-kit-snap` contract)~~ **SHIPPED** as `showcase/fence-kit/` — tiling post-and-rail section (AABB X is the tile width; does not re-witness the snap contract); `--skip-decimate` exits 9 on the LOD1 ratio band