feat(showcase): add book-trolley (#284)

The library book trolley was the first unclaimed candidate in the ROADMAP
pool. What a sloped shelf adds over the bookshelf's flat ones is a second
support: a book in a trough stands on the shelf and rests against the
backrest. A book seated on the shelf but standing off the backrest passes
every seat, the bounding box, the triangle count and the overlap budget
(which must exempt both designed contacts). The piece pairs each tilted
shelf with the backrest biting into it, reads the backrest face plane off
the mesh and asserts every trough book's fore-edge sits 0.3-2.0 mm behind
it; --off-back and --deep-back exit 21 on it.

Also asserts four wheels on the floor, ten cross members housed in both
end panels, caster plates seated in the skids, X/Y mirror symmetry of
carcass and casters, page blocks, gilt bands, book seats along the shelf
normal, size spread, zero unplanned book overlaps and no right-angle wood
edges, each with a falsifier proven on 4.5.11, 5.1.2 and 5.2.1.

Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -172,6 +172,7 @@
     "showcase/apothecary-shelf",
     "showcase/wooden-yoke",
     "showcase/butter-churn",
-    "showcase/bookshelf"
+    "showcase/bookshelf",
+    "showcase/book-trolley"
   ]
 }

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, 35 pieces (sibling of examples/; see showcase/README.md)
+showcase/<name>/               - Budget-conformance props, 36 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>35 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>36 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 35 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 36 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>35 showcase pieces</strong> — click to expand the preview grid</summary>
+<summary><strong>36 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>
@@ -144,6 +144,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/wooden-yoke/"><img src="showcase/wooden-yoke/preview.webp" width="24%" alt="Wooden yoke: a carved oak ox yoke with upturned ends standing on two bent hickory oxbows pinned above the beam, with an iron ring hung under its centre, on a dark studio floor" /></a>
   <a href="showcase/butter-churn/"><img src="showcase/butter-churn/preview.webp" width="24%" alt="Butter churn: a tall staved oak churn narrowing toward the top, bound by three iron hoops, with a two-board lid and a maple dasher handle rising through it, on a dark studio floor" /></a>
   <a href="showcase/bookshelf/"><img src="showcase/bookshelf/preview.webp" width="24%" alt="Bookshelf: a stained wooden bookcase of cloth and leather hardbacks, some standing, some stacked flat and two leaning on their neighbours, on a dark studio floor" /></a>
+  <a href="showcase/book-trolley/"><img src="showcase/book-trolley/preview.webp" width="24%" alt="Book trolley: a double-sided wooden library book truck on four casters, two sloped troughs of hardbacks leaning back spines out and loose books stacked on its deck, 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.
@@ -212,6 +213,8 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
 
 [`bookshelf`](showcase/bookshelf/) — procedural bookcase of thirty-eight rounded-spine hardbacks, standing, stacked and leaning, whose leaning books' contact with their neighbour's head edge is recomputed as a band, through the same pipeline. Falsifiers `--air-lean` and `--deep-lean` exit 22, `--crowd-books` exits 23.
 
+[`book-trolley`](showcase/book-trolley/) — procedural double-sided library book truck on four casters, forty-seven hardbacks in four sloped troughs, whose every book's fore-edge depth in its backrest is recomputed as a band beside its shelf seat, through the same pipeline. Falsifiers `--off-back` and `--deep-back` exit 21, `--skew-caster` exits 19.
+
 </details>
 
 ## Examples

ROADMAP.md

@@ -140,7 +140,8 @@ Not committed; target list for the next content version. (v0.3.0 shipped the smo
 - ~~Wooden yoke (oxbow, iron rings) as a game-prop showcase piece~~ **SHIPPED** as `showcase/wooden-yoke/` — lofted oak beam with neck saddles and upturned ends, two bent-hickory bows through it and pinned above it, a staple and a threaded hung ring; each neck opening measured between the bow legs and up to the saddle, `--pinch-bows` exits 19 on it while the bows still ground and the envelope is unchanged
 - ~~Butter churn (staved tub, lid, dasher) as a game-prop showcase piece~~ **SHIPPED** as `showcase/butter-churn/` — sixteen tapered staves with canted ends, three hoops seated vertex-for-vertex on them, a three-board bottom in a croze, a two-board lid and a cross dasher; the plunge stroke is recomputed from the inner wall and the plunger's reach, `--wide-dasher` exits 20 on it while the plunger still clears the staves at rest
 - ~~Bookshelf with leaning books (upright and toppled volumes of varied size, one leaning on its neighbour) as a game-prop showcase piece~~ **SHIPPED** as `showcase/bookshelf/` — housed shelves on a recessed plinth, lapped back boards and a stepped cornice, thirty-eight rounded-spine hardbacks with glued page blocks and gilt bands, standing, stacked and leaning; each leaning board's contact with its neighbour's head edge is read off the mesh as a plane depth, `--air-lean` and `--deep-lean` exit 22 on it while every seat and the envelope still pass
-- Library ladder or book trolley with loose books as a game-prop showcase piece — books resting across two rails (a ledge, a trolley shelf) exercise a two-point support the bookshelf's flat shelves never do
+- ~~Library ladder or book trolley with loose books as a game-prop showcase piece~~ **SHIPPED** (the trolley half) as `showcase/book-trolley/` — a double-sided library book truck on four swivel casters: arched end panels standing in skids, four sloped troughs each a tilted shelf and a backrest square to it, forty-seven spines-out hardbacks and two loose stacks on the deck; each trough book's fore-edge depth in its backrest is read off the mesh beside its shelf seat, `--off-back` and `--deep-back` exit 21 on it while every seat and the envelope still pass
+- Library rolling ladder (hooked top rollers riding a round rail, raked stiles, treads, floor wheels) as a game-prop showcase piece — the unbuilt half of the item above: a hook riding a round rail is a curved-on-curved contact that neither the trolley's flat backrests nor the yoke's hung ring exercise
 - Ox cart tongue or plough beam that hitches to the yoke's ring as a game-prop showcase piece — a hitch is a ring-on-hook contact the yoke's hung ring only tests against a fixed bar
 - ~~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