feat(showcase): add mushroom-stump (nature)

The seventh piece in the nature category: a felled-tree stump on a
forest-floor soil disc that rises toward the back. The stump is one lathe
about a plumb axis, sawn off 0.50 m above the soil and 0.62 m across the
bark, widening toward the ground and flaring through five buttresses into
it. Its foot follows the soil: the four lowest rings sit a fixed offset
above the soil read back by raycast under each vertex, the lowest 45 mm
under it. Plated bark cut by sixteen wandering V furrows, peeled in two
patches to the sapwood with a dark torn rim (Peel point attribute). The saw
cut carries uneven growth rings drawn as thin latewood lines round a dark
heartwood, grey weathering from the rim in, faint chainsaw streaks, and
five radial drying checks, each a V groove deepening toward the rim that
notches the bark (Check point attribute darkens only the groove floor). A
strip of torn holding wood stands on the hinge chord, leaning toward the
fall, with three long splinters. Five surface roots, one per buttress, lie
in the soil along their run and dive into it; near the disc's rolled rim
they are held inside the thinning soil. Four moss cushions on the shaded
north flank; two tiers of thin, lobed, banded turkey-tail brackets set into
the bark; three fly agarics (mature, domed, button) with Voronoi warts on a
red cap, pleated gills, a bulbous volva and a hanging skirt on a folded
lathe profile; two clusters of ringed honey fungus out of a root (7) and
the stump's foot (6), neighbours alternating tall-and-close with
short-and-leaning so the caps shingle. 101 leaves in drifts, two fern
clumps, three forked twigs, four cleaved pebbles. Twelve materials.

Budgets (measured, 5.2.1): 35250 tris (34700-35800), LOD 0.5000/0.2200,
12 materials with face floors, UVs 0..1 no overlap, AABB 1.9961x1.8965x
0.7807 (+-0.01), collider 66 (<=75), hygiene 0 incl. 0 coplanar
cross-shell pairs, zmin 0; stump sealed in 8/8 sectors (5 mm); 16 caps on
16 stipes, bite 0.0057-0.0137 m (0.003-0.030); cut tilt 0.1167 deg (<=1.0),
0.6207 m across and 0.5002 m tall (0.62/0.50 +-0.015); 5 roots, shallowest
of 19 stations 0.0227 m under (>=0.006); 16 stipes rooted 0.0237-0.0425 m
in soil, root or stump (0.008-0.070); 6 shelves 0.0182-0.0212 m in the
bark (0.006-0.050); moss 0.9529 up/north (>=0.85); 343 cover shells all
joined to the soil. Two default runs identical; 4.5.11 and 5.1.2 print the
same measurements (export differs by 8 bytes).

The coplanar budget caught cap-cap pairs in the honey clusters (members at
one height and reach), a leaf pair (leaves closer than their length) and a
fern pinna pair; fixed by alternating members, half-length spacing plus a
per-leaf roll, and a per-frond twist phase. The root bed audit first binned
at 0.05 m with rings 0.075 m apart, so bins held part rings and read
negative; roots now carry 24 rings and bins where a root leaves the
buttress (sealed by the stump) are skipped. A soil heap round the foot made
--perch-stump seal 8/8 anyway; the heap went and the slope steepened.

Falsifiers (flag -> measured -> exit), 5.2.1 and 4.5.11 identical; tris
35250 and envelope unchanged in all:
  --skip-decimate    LOD1 1.0000                                 9
  --stray-vert       loose_v 1                                  15
  --lift-z           zmin 0.05000                               16
  --perch-stump      sealed 7/8 sectors                         17
  --float-caps       stipe bite -0.0156..-0.0100 m              18
  --tilt-cut         cut tilt 4.8884 deg                        19
  --fat-stump        0.6703 m across                            19
  --arch-roots       shallowest station -0.0273 m               20
  --float-mushrooms  host depth -0.0260..-0.0052 m              21
  --float-brackets   bark bite -0.0166..-0.0130 m               22
  --sunny-moss       0.4448 up/north                            23
  --float-cover      101 of 343 cover shells loose              24
--float-caps at 30 mm put a honey crown on a neighbour's gill plane and
exited 15; 24 mm keeps it on 18. --perch-stump first moved a honey cap onto
a bracket underside (15); the lower tier went up the bole. --fat-stump
first re-grounded the piece 6.4 mm (the foot fan's centre went below the
disc); the centre now sits under the ring's mean. The upper lathe ring
count is fixed so a falsifier that moves the foot keeps the topology.
tests/check_falsifier_targets.py --run --only mushroom-stump 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 (46360 B) and preview (41952 B); framing
fill x 0.675, y 0.856, margins left 0.206 right 0.119 bottom 0.039 top
0.106; asset-quality floors pass (12 materials, edge90 0.018). Default
stage, hero yaw 180 deg about Z, no deviation.

Asset sheet (docs/gallery/asset-sheets/mushroom-stump.webp): not the
least-designed object; the hydrant is plainer. Isolated, it reads at once
as a sawn stump with a ringed, checked top and splinters, buttress roots,
moss, banded brackets, honey clusters and fly agarics among leaves and
ferns. Weak point: at panel size the small parts are small against a wide
soil disc, and the ferns are the stylised fronds shared with fallen-log.

Contact sheet (docs/gallery/contact-sheets/mushroom-stump-contact-sheet.webp):
luma 0.2377 against 0.2369-0.2428 (in band, after relighting from 0.2753);
stage 0.2456 against 0.1919-0.2517 (in range, dark); wedge warmth +0.1456,
a warm pool on the wall (calibration -0.144..+0.105, warmest of the set);
saturation 0.2298 against 0.1525-0.2367; subject fill 0.856 vertical.
Thumbnail legible: stump, red caps and ferns read at a glance.

Also updated: README, CLAUDE.md, AGENTS.md counts (61 -> 62), ROADMAP
Nature list (tree stump with mushrooms struck as shipped), asset_sheet.py
SELECT row, catalog.json, plugin.json and the regenerated gallery.
build_gallery, check_site_links (117 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

@@ -199,6 +199,7 @@
     "showcase/palm-tree",
     "showcase/wingback-armchair",
     "showcase/planet-rover",
-    "showcase/traffic-cones"
+    "showcase/traffic-cones",
+    "showcase/mushroom-stump"
   ]
 }

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 61 showcase pieces (counts are CI-enforced against README.md)
+examples, and 62 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, 61 pieces, each with a gallery `category` (sibling of examples/; see showcase/README.md § Categories)
+showcase/<name>/               - Budget-conformance props, 62 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>61 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>62 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 61 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 62 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>61 showcase pieces</strong> — click to expand the preview grid</summary>
+<summary><strong>62 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>
@@ -170,6 +170,7 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
   <a href="showcase/wingback-armchair/"><img src="showcase/wingback-armchair/preview.webp" width="24%" alt="Wingback armchair: an oxblood leather wingback with a deep-button tufted back, rolled arms trimmed with brass nailheads and a piped seat cushion, beside a side table with a brass reading lamp and books on a fringed rug" /></a>
   <a href="showcase/planet-rover/"><img src="showcase/planet-rover/preview.webp" width="24%" alt="Planet rover: a six-wheeled rocker-bogie rover with gold-foil sides, a camera mast, a dish antenna and a finned power unit, its arm drilling a boulder on red-grey regolith" /></a>
   <a href="showcase/traffic-cones/"><img src="showcase/traffic-cones/preview.webp" width="24%" alt="Traffic cones: orange cones with white reflective collars on a patch of asphalt with a worn white line, three standing in a row, three nested in a stack and one knocked over showing its open base, before a striped A-frame barricade with an amber warning lamp" /></a>
+  <a href="showcase/mushroom-stump/"><img src="showcase/mushroom-stump/preview.webp" width="24%" alt="Mushroom stump: a sawn tree stump with ringed, cracked end grain and torn splinters on a sloping soil disc, buttress roots in the soil, moss, banded shelf fungi, honey mushroom clusters, red fly agarics, ferns and fallen leaves" /></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.
@@ -290,6 +291,8 @@ Budget-conformance props. Not examples. Conventions: [`showcase/README.md`](show
 
 [`traffic-cones`](showcase/traffic-cones/) — the seventh `vehicles` piece: procedural roadworks set on a cut-out patch of asphalt (a broken edge, a worn white road line and two sealed tar cracks; seven 720 mm PVC cones, each a hollow lathed body with a moulded bead and a rolled lip round an open tip, bonded into a square rubber base with chamfered corners, a raked top, a collar, four lugs and a recess underneath, and hooped with two retroreflective collars; three standing in a taper line, three nested in a stack and one knocked over onto the edge of its base and its lip; a folding A-frame barricade of four square steel legs hinged in pairs on pivot bolts, spread by pinned straps, footed in rubber pads, with two striped boards bolted to each face and a warning lamp with amber fresnel lenses on a bracket), the cone wall sized so each cone in the stack bears 1 mm on the one below at a 36 mm pitch. `--float-cone` exits 16 on every support bedded in the slab, `--gap-board` 17 on the boards biting their legs, `--float-band` 18 on the collars seated on their bodies, `--lean-cone` and `--skew-leg` 19 on the cones plumb at real size and the legs mirror-symmetric, `--loose-stack` 20 on the nesting pitch and wall bite, `--loose-lamp` 21 on one connected assembly, while the envelope holds.
 
+[`mushroom-stump`](showcase/mushroom-stump/) — the seventh `nature` piece: procedural felled-tree stump on a sloping forest-floor soil disc (one furrowed lathe about a plumb axis flaring through five buttresses into the ground, plated bark peeled to sapwood in two patches, a level saw cut with weathered growth rings round a dark heartwood, radial drying checks notching the rim and a strip of torn holding wood with long splinters, five surface roots lying in the soil and diving into it, moss on the shaded flank, two tiers of turkey-tail brackets, three fly agarics with warted caps, pleated gills, a volva and a hanging skirt, two clusters of ringed honey fungus out of a root and the stump's foot, fallen leaves, ferns, twigs and pebbles), whose foot sealed in the soil all round, caps seated on their stipes, level cut and stated size, roots bedded along their run, stipes rooted in their soil or wood, brackets rooted in the bark, moss on up- and shade-facing surfaces and ground cover joined to the soil are recomputed from the mesh, through the same pipeline. `--perch-stump` exits 17 on the stump sealed all round, `--float-caps` 18 on every cap seated on its stipe, `--tilt-cut` and `--fat-stump` 19 on the level cut and stated size, `--arch-roots` 20 on the roots bedded, `--float-mushrooms` 21 on every stipe rooted in its host, `--float-brackets` 22 on the brackets rooted in the bark, `--sunny-moss` 23 on moss facing up or into the shade, `--float-cover` 24 on the ground cover joined to the soil, while the envelope holds.
+
 </details>
 
 ## Examples