feat: add modular-kit-snap example

A tiling corridor kit where the snap is the contract: 16 boundary verts
on x in {0, 4} within 1e-6 m, end rings coincident under the tile offset
(nearest-key match), a linked duplicate's joint positions deviating 0.0,
shell bbox equal to the declared tile, manifold except the two open ends,
and 12 detail parts contained inside the tile. Built for reuse: pivot at
the start-edge connection point, identity transforms, Kit.CorridorSeg.*
datablocks. Falsification: an unsnapped variant (3 mm skew, 2 mm nudge)
fails at exits 3/4 with measured errors; a --falsify render exaggerates
the same failure class to visible floor gaps and broken trim rails.
Byte-identical check output on 4.5.11 LTS and 5.1.2.

Also takes the featured_rank 8 slot on the landing page from
color-attribute-wheel: the corridor is the only interior/envelope
composition in the set and the stronger card.

Authoring hazard recorded in ROADMAP: sorted-zip ring matching mispairs
displaced verts and reports bogus cascade errors - match by nearest key.

Signed-off-by: fOuttaMyPaint <TMhospitalitystrategies@gmail.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -82,6 +82,7 @@
     "examples/light-link-studio",
     "examples/lod-decimate-chain",
     "examples/mesh-hygiene-audit",
+    "examples/modular-kit-snap",
     "examples/parent-inverse-orrery",
     "examples/png-exr-alpha",
     "examples/prop-origin-transform",

.github/workflows/blender-smoke.yml

@@ -566,3 +566,16 @@ jobs:
           # Exits non-zero on failure.
           xvfb-run -a "$BLENDER" --background \
             --python examples/degenerate-bevel-weld/degenerate_bevel_weld.py --
+
+      - name: Shipped example - modular kit snap (tile boundary contract)
+        run: |
+          set -euo pipefail
+          # Check only (no render): a 4x3x3 corridor segment; asserts 16
+          # boundary verts on x in {0, TILE} within 1e-6, end-ring coincidence
+          # within 1e-6, a linked duplicate's joint positions matching within
+          # 1e-6, shell bbox == declared tile (dev 0), manifold shell except
+          # the 16 open-end edges, watertight detail parts contained inside
+          # the tile, and reuse hygiene (identity scales, kit names, pivot
+          # origins). Exits non-zero on failure.
+          xvfb-run -a "$BLENDER" --background \
+            --python examples/modular-kit-snap/modular_kit_snap.py --

README.md

@@ -18,7 +18,7 @@
 </p>
 
 <p align="center">
-  <strong>12 skills</strong> &nbsp;&bull;&nbsp; <strong>6 rules</strong> &nbsp;&bull;&nbsp; <strong>2 templates</strong> &nbsp;&bull;&nbsp; <strong>17 snippets</strong> &nbsp;&bull;&nbsp; <strong>40 examples</strong>
+  <strong>12 skills</strong> &nbsp;&bull;&nbsp; <strong>6 rules</strong> &nbsp;&bull;&nbsp; <strong>2 templates</strong> &nbsp;&bull;&nbsp; <strong>17 snippets</strong> &nbsp;&bull;&nbsp; <strong>41 examples</strong>
 </p>
 
 <p align="center">
@@ -780,6 +780,26 @@ welds their loops. Companion to
 check first caught the weld) and [`mesh-hygiene-audit`](examples/mesh-hygiene-audit/)
 (topology gates). Seam markers are placed from live mesh data.
 
+</td>
+</tr>
+<tr>
+<td width="46%" valign="middle">
+<a href="examples/modular-kit-snap/"><img src="examples/modular-kit-snap/preview.webp" alt="Modular kit snap: a corridor run of four tiling segments — dark steel walls with blue-gray panels, orange trim rails, and ceiling light strips converging on a glowing amber doorway, with every joint seamless because the boundary verts snap exactly to the tile grid" /></a>
+</td>
+<td valign="middle">
+
+### [modular-kit-snap](examples/modular-kit-snap/)
+
+A tiling corridor kit where the snap is the contract. **16 boundary verts**
+on `x ∈ {0, 4}` within **1e-6 m**, opposing end loops coincident under the
+tile offset, and a linked duplicate's joint positions matching within 1e-6 —
+zero gap, zero overlap. Shell bbox equals the declared tile exactly, the
+tube is manifold except its two open ends, and all twelve detail parts are
+contained inside the tile. The unsnapped probe (3 mm skew) fails with the
+measured error printed. Companion to
+[`prop-origin-transform`](examples/prop-origin-transform/) (pivot discipline)
+and [`mesh-hygiene-audit`](examples/mesh-hygiene-audit/) (topology gates).
+
 </td>
 </tr>
 </table>

ROADMAP.md

@@ -109,6 +109,7 @@ Not committed; target list for the next content version. (v0.3.0 shipped the smo
 - UV-handle lifetime snippet: re-fetch attribute/UV layers by name after any CustomData-reallocating call (`calc_tangents`, `VertexGroup.add`, modifier edits) — held handles dangle silently on 4.5, survive by luck on 5.1 (found authoring `triangulate-tangents`)
 - ~~glTF skinned-mesh export witness: follow-up to `gltf-export-roundtrip` + `vertex-weight-limit`~~ **SHIPPED** as `examples/gltf-skin-roundtrip/` — `skins[0].joints` names every bone, JOINTS_0/WEIGHTS_0 with unit sums (3e-8), weights bit-exact, rest matrices to 2.4e-07, deformation to 4.8e-07; exporter welds duplicate loops (sorted-multiset comparisons mispair — compare by rest-key); unparented skinned meshes make the exporter bind an armature by name
 - ~~Degenerate-bevel weld hazard~~ **SHIPPED** as `examples/degenerate-bevel-weld/` — at `offset == min_dim/2` the bevel band collapses to exactly 12 zero-area faces (4 min-axis edges × 3 segments) with 16 coincident verts (4 × (segments+1)) and min_area down 3.2e5×; a stdlib GLB re-parse counts **32 degenerate triangles crossing the export boundary** (MEASURED regression constant) versus 0 for the safe mesh — the loops an engine merge-by-distance welds; byte-identical on 4.5.11 and 5.1.2
+- ~~Modular kit snap witness~~ **SHIPPED** as `examples/modular-kit-snap/` — tiling corridor segment: 16 boundary verts on `x ∈ {0, TILE}` within 1e-6 m, end rings coincident under the tile offset (nearest-key match), linked-duplicate joint deviation 0.0, shell bbox == declared tile (dev 0.0), manifold except the 16 open-end edges, 12 detail parts contained inside the tile; unsnapped probe (3 mm skew, 2 mm nudge) fails at exits 3/4 with measured errors; sorted-zip ring matching mispairs displaced verts — match by nearest key (authoring hazard, fixed); byte-identical on 4.5.11 and 5.1.2
 - ~~GAMMA_CROSS blend-curve witness~~ **SHIPPED** as `examples/vse-gamma-cross/` — the cross blends in a gamma-0.5 space: `((1-t)·√A + t·√B)²` with `t = (frame − start)/duration`, never 1 inside the effect; mid-cross dips 0.115 below the sRGB lerp from crimson/teal (closed form (0.341, 0.349, 0.463) confirmed per frame); AgX-default sampling poisons the fit (0.146 red-channel error, `view_transform='Standard'` mandatory); deleting a consumed input orphans-and-deletes the effect — follow-up to `vse-cut-list`
 - Falsy `bpy_prop_collection` trap snippet: an empty collection is falsy, so `editor.strips or editor.sequences` silently falls through to the legacy accessor on an empty timeline — always branch on `hasattr`; likely generalizes across the API (found authoring `vse-cut-list`)
 - ~~Collision compound witness~~ **SHIPPED** as `examples/collision-hull-proxy/` — game-prop collision as a compound of convex pieces, each a `bmesh.ops.convex_hull` of a coarse `sec(π/n)`-inflated cage (containment 4.4e-08, watertight, positive signed volume, Euler 2, per-piece 255-face budget: body 70, caps 60×3, compound 250); a hull of the dense render mesh measures 380 faces — over budget — which is why pipelines hull cages; proud details cost cage rows, concave grooves are free; byte-identical on 4.5.11 and 5.1.2

docs/gallery/assets/modular-kit-snap-hero.webp

@@ -272,7 +272,7 @@ <h1>Examples Gallery</h1>
             autocomplete="off" spellcheck="false" aria-label="Search examples" />
           <button class="q-clear" id="qClear" type="button" aria-label="Clear search" hidden>&times;</button>
         </div>
-        <span class="count" id="count" role="status" aria-live="polite">40 examples</span>
+        <span class="count" id="count" role="status" aria-live="polite">41 examples</span>
         <div class="density" role="group" aria-label="Card density">
           <button class="density-btn" data-density="compact" type="button" aria-pressed="false">Compact</button>
           <button class="density-btn" data-density="detailed" type="button" aria-pressed="false">Detailed</button>
@@ -762,6 +762,17 @@ <h2><a href="degenerate-bevel-weld/">degenerate-bevel-weld</a></h2>
           <a class="card-link" href="degenerate-bevel-weld/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>
+      <article class="card" data-tags="mesh bmesh game-pipeline instancing">
+        <a class="card-media" href="modular-kit-snap/" aria-label="modular-kit-snap example detail page">
+          <img src="assets/modular-kit-snap-hero.webp" alt="modular-kit-snap — A tiling corridor kit whose open-end boundary verts snap to the tile grid, so instances at 4 m multiples join with zero gap or overlap." loading="lazy" decoding="async" />
+        </a>
+        <div class="card-body">
+          <h2><a href="modular-kit-snap/">modular-kit-snap</a></h2>
+          <p class="teaches">A tiling corridor kit whose open-end boundary verts snap to the tile grid, so instances at 4 m multiples join with zero gap or overlap.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> 16 boundary verts on x∈{0,4} within 1e-6 m, linked-duplicate joint deviation 0.0, bbox == declared tile; unsnapped probe fails at 3e-3 m.</p>
+          <a class="card-link" href="modular-kit-snap/">View example <span aria-hidden="true">&rarr;</span></a>
+        </div>
+      </article>
     </div>
     <p class="noresults" id="noResults" hidden>No examples match the current filters.
       <button class="chip" id="resetFilters" type="button">Clear search and tags</button></p>