feat(showcase): add fern-mossy-rock (nature)

The ninth piece in the nature category: a shaded woodland corner, 2.29 x
2.22 m and 0.86 m high, on a soil bank that rises 190 mm per metre toward
the back. A gritstone boulder (1.2 x 1.0 m in plan, 0.5 m out of the bank)
is an ellipsoid cut by ten cleavage planes through weathering bevels, with
seven chipped facets, and split across its top by a crack: a V 124 mm wide
and 220 mm deep along a plane through the field's origin, closing on the
low flanks. Its cube-sphere lattice is turned so one family of lines runs
along the crack and drawn in toward it, so the narrow V and its lip are
resolved. It is bedded sector by sector until each of eight sectors' most
buried flank vertex is 40 mm under the soil, its underside cut flat 40 mm
over Z = 0. Four moss cushions are conforming lens shells snapped to the
stone as built: the main one over the larger block's crown, draped down its
shaded front, hummocks up to 58 mm deep along the stone's normal, a
scalloped rim tucked 5 mm into the stone, stopping short of the soil and,
on a ragged line, of the crack's lip. At the downhill foot a male fern's
scaly rootstock, bedded in the soil with seven old stipe bases, carries a
shuttlecock crown of eleven bipinnate fronds (0.96-1.14 m): one tapering
tube each, scaly stipe then green rachis, with 15 alternate pinnae a side,
longest a third of the way up and tapering to the tip, each a closed thin
shell cut almost to its costa into up to five alternate pinnules a side.
Three fiddleheads unroll as logarithmic spirals (1.65 turns). A four-frond
fern grows from a rootstock wedged down the crack. 56 beech leaves drift
against the boulder among 16 pebbles, a twig and eight clumps of wood
sorrel. Ten materials; fronds and sorrel carry a translucent lobe.

Budgets (measured, 5.2.1): 77176 tris (76800-77600), LOD 0.5000/0.2200,
10 materials with face floors, UVs 0..1 no overlap, AABB 2.2896x2.2209x
0.8601 (+-0.01), collider 128 (<=200), hygiene 0 incl. 0 coplanar
cross-shell pairs, zmin 0; 25 stalks >=0.0085 m inside their rootstock
(>=0.004), 434 pinnae >=0.0013 m inside their rachis (>=0.0004), rootstock
sealed 8/8 (worst 0.0322, >=0.010); moss top 0.0111-0.0568 m over the stone
(0.006-0.080), rim and underside >=0.0040 inside it; boulder sealed 8/8
(worst 0.0400, >=0.020); moss facing 0.8982 (>=0.85); crack fern bite
0.0192, in the cleft, walls 0.0100 (<=0.060); 15 fronds alternate, gaps
0.442-0.575 (0.25-0.75), peak 0.223-0.468 (0.10-0.60), tip <=0.326
(<=0.40), base <=0.647 (<=0.88); fiddleheads 1.697-1.722 turns (>=1.20),
curvature ratio >=2.901 (>=1.80); 102 cover pieces bedded, 186 shells
joined. Two default runs identical; 4.5.11 and 5.1.2 print the same
measurements (export differs by 8 bytes).

Heavier than broadleaf-oak (77176 vs 68350 tris): 65% is pinnae, and the
point of the piece is geometric pinnule detail at hero size.

Fixes found on the way: 216 coplanar cross-shell pairs on the first build,
211 within one frond - pinnae along a rachis are translated copies in one
blade plane. Pinnae are now flat (costa 0.12% of the pinna's length proud,
floored so tiny tip pinnae do not weld top to bottom: that gave 6 doubles),
twisted in a +-0.20 rad three-step cycle, and the plan turns each in 0.04
rad steps until its plane is 8 deg off every pinna whose faces can come
within the coplanar range; all 434 clear. Sorrel leaflets sharing a petiole
point are turned apart the same way (14 deg); beech leaves are rolled
0.20-0.32 rad so none lies in a soil face's plane. The boulder first sank
0.28 m through the disc's base (zmin -0.277); its underside is now cut flat.
The moss seat audit caught spokes aimed at the crack floored at a quarter
length, putting top vertices down the V 27 mm inside the far block; every
ring on a spoke now clears the lip. The moss and then the crack fern tied
for the top of the envelope, so --float-moss and --perch-rock exited 8; the
crack fern now stands 81 mm over the moss. --perch-rock first passed: the
boulder was bedded on a coarser lattice than the audit reads; it is now
bedded on the shipped lattice. --stray-vert first exited 8 (vertex above
the box). A first --sunny-moss turned every cushion rigidly and overlapped
two (exit 15); it now moves the main cushion alone.

Falsifiers (flag -> measured -> exit), 5.2.1 and 4.5.11 identical; tris
77176 and envelope unchanged in all:
  --skip-decimate     LOD1 1.0000                                 9
  --stray-vert        loose_v 1                                  15
  --lift-z            zmin 0.05000                               16
  --float-fronds      shallowest stalk base -0.0484 m            17
  --lift-crown        rootstock worst sector -0.0178 m           17
  --float-moss        top to 0.0967 m, rim -0.0360 m             18
  --perch-rock        worst sector -0.0166 m, 7/8                20
  --sunny-moss        facing 0.4250                              21
  --perch-crack-fern  centre not in cleft, walls 0.1557 m        22
  --flat-taper        tip ratio 0.996                            23
  --opposite-pinnae   gaps 0.0026-0.9976, not alternate          23
  --open-crozier      0.932 turns, curvature ratio 1.128         24
  --float-cover       -0.046 m, 186 shells loose                 25
tests/check_falsifier_targets.py --run --only fern-mossy-rock passes.

Blender: E:\Blender-Developer-Tools\.scratch\5.2\blender-5.2.1-windows-x64\blender.exe,
reports "Blender 5.2.1 LTS"; default and every falsifier also run on
.scratch\blender-4.5.11-windows-x64 ("Blender 4.5.11 LTS"); default on
.scratch\blender-5.1.2-windows-x64 ("Blender 5.1.2").

Render: render_hero.py wrote hero and preview; framing fill x 0.766, y
0.728, margins left 0.131 right 0.103 bottom 0.094 top 0.178; asset-quality
floors pass (10 materials, edge90 0.007). Default stage, hero yaw -50 deg
about Z so the fern stands in front of the mossy, cracked face.

Asset sheet (docs/gallery/asset-sheets/fern-mossy-rock.webp): not the
least-designed object; the hydrant is plainer. Isolated, it reads as a
mossy cleft boulder with a lush fern clump at its foot. Weak point: the
piece is wide and low (frond tips set the box), so it sits small in its
panel and pinnule detail is lost at sheet scale; the disc was pulled in
toward the subject to limit that.

Contact sheet (docs/gallery/contact-sheets/fern-mossy-rock-contact-sheet.webp):
luma 0.2401 against 0.2369-0.2428 (in band, after relighting from 0.3509,
0.2487 and 0.2431); stage 0.2425 against 0.1919-0.2517; wedge warmth
+0.0546 (calibration -0.144..+0.105); saturation 0.2116 against
0.1525-0.2367; subject fill 0.766 horizontal. Thumbnail legible: a fern
clump in front of a moss-covered boulder reads at a glance.

Also updated: README, CLAUDE.md, AGENTS.md counts (65 -> 66), ROADMAP
Nature list (fern & mossy rock shipped), asset_sheet.py SELECT row,
catalog.json, plugin.json and the regenerated gallery. build_gallery,
check_site_links (121 pages, 0 failures), check_falsifier_targets (static
and --run), check_exit_code_readme, check_engine_id, check_gallery_images
and check_import_export_rules pass.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -203,6 +203,7 @@
     "showcase/mushroom-stump",
     "showcase/go-kart",
     "showcase/broadleaf-oak",
-    "showcase/farm-tractor"
+    "showcase/farm-tractor",
+    "showcase/fern-mossy-rock"
   ]
 }

AGENTS.md

@@ -21,7 +21,7 @@ classifies it as a `cursor-plugin`. This is content the AI loads when the user
 asks Blender questions or works on Blender add-ons in Cursor or Claude Code.
 
 The content base is 16 skills, 9 rules, 3 templates, 27 snippets, 60
-examples, and 65 showcase pieces (counts are CI-enforced against README.md)
+examples, and 66 showcase pieces (counts are CI-enforced against README.md)
 and the manifest). The full inventory tables and per-item purposes live in
 `CLAUDE.md`. Example anatomy and authoring rules: copy `examples/bmesh-gear/`;
 showcase conventions: `showcase/README.md`. The render look is specified

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, 60 total (+ gallery.json)
-showcase/<name>/               - Budget-conformance props, 65 pieces, each with a gallery `category` (sibling of examples/; see showcase/README.md § Categories)
+showcase/<name>/               - Budget-conformance props, 66 pieces, each with a gallery `category` (sibling of examples/; see showcase/README.md § Categories)
 scripts/build_gallery.py       - Regenerates docs/gallery/ from examples/gallery.json + showcase/gallery.json
 scripts/site/                  - Vendored landing-page build (Jinja2); tokens.css is the shared palette
 tests/check_site_links.py      - Internal link/anchor/alt gate over the built site (docs/)

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>60 examples</strong> &nbsp;&bull;&nbsp; <strong>65 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>60 examples</strong> &nbsp;&bull;&nbsp; <strong>66 showcase pieces</strong>
 </p>
 
 <p align="center">
@@ -37,7 +37,7 @@
 
 ## Overview
 
-This repository ships **16 skills, 9 rules, 3 templates, 27 snippets, 60 examples, and 65 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, 60 examples, and 66 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>65 showcase pieces</strong> — click to expand the preview grid</summary>
+<summary><strong>66 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 stencilled PORT ROYAL and NO 17, with iron corner brackets and an end handle, on a dark studio floor, warm wedge on the back wall" /></a>
@@ -174,6 +174,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/go-kart/"><img src="showcase/go-kart/preview.webp" width="24%" alt="Go-kart: yellow go-kart on a patch of track asphalt before a red and white kerb: bent red tube chassis, black seat, finned engine with chain to the rear axle, slick tyres on silver rims." /></a>
   <a href="showcase/broadleaf-oak/"><img src="showcase/broadleaf-oak/preview.webp" width="24%" alt="Broadleaf oak: a broad oak with a short fluted trunk and crooked spreading limbs under a domed crown of lobed green leaves, on a grassy soil disc with surface roots, tufts, fallen leaves and acorns" /></a>
   <a href="showcase/farm-tractor/"><img src="showcase/farm-tractor/preview.webp" width="24%" alt="Farm tractor: green farm tractor in muddy ruts beside a puddle: long bonnet, barred grille, rusty exhaust stack, big lugged rear tyres on cream rims with weights, small ribbed fronts." /></a>
+  <a href="showcase/fern-mossy-rock/"><img src="showcase/fern-mossy-rock/preview.webp" width="24%" alt="Fern and mossy rock: a male fern's arching crown of finely cut fronds, with curled fiddleheads, in front of a cleft boulder cushioned in moss on a soil bank with fallen beech leaves, pebbles and wood sorrel" /></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.
@@ -302,6 +303,8 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
 
 [`farm-tractor`](showcase/farm-tractor/) — the ninth `vehicles` piece: procedural mid-century utility tractor standing in the ruts of a muddy farmyard with a puddle between its wheels (a cast-iron backbone of engine, bell housing, gearbox and rear axle housing with trumpets; a front axle oscillating on a pivot pin through the front support's lugs and two bushings, kingpins, spindles and a tie rod; 1.240 m rear tyres with 44 chevron bars rooted in the carcass and handed for forward travel, on dished rims with welded clamp lugs and cast-iron half-moon weights; ribbed front tyres; a grille shell with radiator and headlamps, a louvred bonnet, fuel tank and dash; a vertical exhaust stack with a hinged rain cap and an oil-bath pre-cleaner bowl; a raked steering column, a pan seat on a leaf spring, pedals and footplates; mudguards with a tail lamp and a work lamp; a three-point linkage with lift arms, lift rods, lower links, a stowed top link and the drawbar, and a PTO stub under its shield; paint chipped to primer at its edges, rust-streaked, sun-faded and mud-splashed). Asserts 122272 tris, twelve materials with face floors, zero coplanar cross-shell pairs, every tyre sunk 18–45 mm into the mud, hubs and the pivot pin coaxial, 14 link eyes on their pins, beads seated, 88 bars rooted and evenly pitched with their apex leading, body and wheels mirrored, wheelbase, tracks and rear-tyre diameter at their stated size, the mass centre inside the support triangle of the rear contacts and the front pivot by a quarter of the track, and one connected assembly; `--float-tyre` exits 16, `--cock-hub`, `--cant-pin` and `--unpin-link` 17, `--sink-tyre` and `--float-lugs` 18, `--skew-wheel`, `--wide-track`, `--tall-lugs` and `--odd-fender` 19, `--bunch-lugs` 20, `--reverse-lugs` 21, `--offset-pivot` 22, `--loose-lamp` 23, while the envelope holds.
 
+[`fern-mossy-rock`](showcase/fern-mossy-rock/) — the ninth `nature` piece: procedural shaded woodland corner on a sloping soil bank (a gritstone boulder cleaved into broken, weathered faces and split by a deep crack, sunk into the bank all round, a thick moss cushion over its crown draped down its shaded front as a conforming shell with a lumpy rim tucked into the stone, a male fern's shuttlecock crown of eleven bipinnate fronds whose 434 alternate pinnae are cut into pinnules and taper to the tip, three fiddleheads unrolling as logarithmic spirals from a scaly rootstock bedded in the soil, a smaller fern growing out of the crack, and beech litter, pebbles, a twig and wood sorrel at the foot), whose rooted fronds and rootstock, moss thickness over the stone, boulder sealed in the bank, moss facing up or into the shade, crack fern wedged in the cleft, pinna alternation and taper, true spirals and ground cover are recomputed from the mesh, through the same pipeline. `--float-fronds` and `--lift-crown` exit 17 on every frond rooted in its crown and the crown sealed in the soil, `--float-moss` 18 on the moss cushion's thickness band on the stone, `--perch-rock` 20 on the boulder sealed all round, `--sunny-moss` 21 on moss facing up or into the shade, `--perch-crack-fern` 22 on the crack fern rooted in the cleft, `--flat-taper` and `--opposite-pinnae` 23 on pinnae alternating and tapering along the rachis, `--open-crozier` 24 on every fiddlehead a real spiral, `--float-cover` 25 on the ground cover joined to the soil, while the envelope holds.
+
 </details>
 
 ## Examples