fix(examples): redesign gn-instance-grid as a 3x3 macropad key field

The gallery review judged the hero programmer art: nine bare lime cubes on
a 3x3 grid joined by thin lattice lines.

The tree now instances a modeled DSA-profile keycap (six rounded-rectangle
rings, a dished top, sharp foot ring) read in through Object Info, so the
realized grid is the key field of a cobalt macropad: recessed well, switch
housings, knurled brass knob and an OLED meter (render-only staging). A
second Set Material, selected by a per-face position field, puts an orange
accent on the front-right key. No floor labels.

The check stays exactly as strict and gains a gate. Topology expectations
are derived from the keycap's construction parameters (9 x 121 = 1089
verts, 1089 faces). The count gate now runs first (exit 4, where
--one-cell still lands); the corner-cell gate (exit 5) asserts one whole
keycap in the corner cell; the corner position gate (exit 7) checks bbox
centre and the Transform lift; new exit 9 asserts the accent selection
covers exactly one keycap at the front-right grid point. The render path
adds the framing (10) and asset-quality (11) gates.

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

Author: TMHSDigital

README.md

@@ -566,15 +566,16 @@ and that a `Set Material` node carries the material through the remesh.
 </tr>
 <tr>
 <td width="46%" valign="middle">
-<a href="examples/gn-instance-grid/"><img src="examples/gn-instance-grid/preview.webp" alt="GN instance grid: nine lime-green cubes in a 3x3 grid on a dark studio floor, instanced via Geometry Nodes Instance on Points" /></a>
+<a href="examples/gn-instance-grid/"><img src="examples/gn-instance-grid/preview.webp" alt="GN instance grid: a cobalt-blue 3x3 macropad whose nine cream keycaps are instanced onto a Geometry Nodes Mesh Grid, one orange accent key picked out by a position-field Set Material" /></a>
 </td>
 <td valign="middle">
 
 ### [gn-instance-grid](examples/gn-instance-grid/)
 
-A generative Geometry Nodes tree — Mesh Grid → Instance on Points → Realize Instances —
-attached as a `NODES` modifier with no Group Input. Asserts evaluated topology is
-verts = 72, faces = 54, and `Set Material` carries the lime accent.
+A generative Geometry Nodes tree — Mesh Grid → Instance on Points (a modeled keycap via
+`Object Info`) → Realize Instances — attached as a `NODES` modifier with no Group Input.
+Asserts evaluated topology is verts = faces = 1089 (9 keycaps × 121), and a position-field
+`Set Material` lands the orange accent on exactly one keycap.
 
 </td>
 </tr>

docs/gallery/asset-sheets/gn-instance-grid.webp

@@ -442,12 +442,12 @@ <h2><a href="temp-override-join/">temp-override-join</a></h2>
       </article>
       <article class="card" data-tags="geometry-nodes instancing">
         <a class="card-media" href="gn-instance-grid/" tabindex="-1" aria-hidden="true">
-          <img src="assets/gn-instance-grid-hero.webp" alt="A three-by-three grid of green instanced cubes, each sitting on a node of a faint source-grid lattice on a dark floor." loading="lazy" decoding="async" />
+          <img src="assets/gn-instance-grid-hero.webp" alt="A cobalt-blue macropad with a brass knob and a glowing OLED meter, its three-by-three key field of cream keycaps instanced by Geometry Nodes, with one orange accent key at the front right." loading="lazy" decoding="async" />
         </a>
         <div class="card-body">
           <h2><a href="gn-instance-grid/">gn-instance-grid</a></h2>
-          <p class="teaches">A generative Geometry Nodes tree — Mesh Grid → Instance on Points → Realize Instances → Set Shade Smooth — attached as a NODES modifier with no Group Input geometry.</p>
-          <p class="witnesses"><span class="tag">witnesses</span> Realized instances produce closed-form topology (72 verts, 54 faces), Set Material carries Lime, and the corner instance center sits at its closed-form grid coordinate.</p>
+          <p class="teaches">A generative Geometry Nodes tree — Mesh Grid → Instance on Points (a modeled keycap via Object Info) → Realize Instances → Set Shade Smooth → Set Material — attached as a NODES modifier with no Group Input geometry.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> Realized instances produce closed-form topology (9 keycaps × 121 = 1089 verts, 1089 faces), Set Material carries the keycap plastic, a position-field Set Material lands the accent on exactly one keycap, and the corner keycap sits at its closed-form grid coordinate.</p>
           <a class="card-link" href="gn-instance-grid/">View example<span class="sr-only"> gn-instance-grid</span> <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>

docs/gallery/assets/gn-instance-grid-hero.webp

@@ -125,9 +125,9 @@
     {
       "name": "gn-instance-grid",
       "dir": "examples/gn-instance-grid",
-      "teaches": "A generative Geometry Nodes tree — Mesh Grid → Instance on Points → Realize Instances → Set Shade Smooth — attached as a NODES modifier with no Group Input geometry.",
-      "alt": "A three-by-three grid of green instanced cubes, each sitting on a node of a faint source-grid lattice on a dark floor.",
-      "witnessesFix": "Realized instances produce closed-form topology (72 verts, 54 faces), Set Material carries Lime, and the corner instance center sits at its closed-form grid coordinate.",
+      "teaches": "A generative Geometry Nodes tree — Mesh Grid → Instance on Points (a modeled keycap via Object Info) → Realize Instances → Set Shade Smooth → Set Material — attached as a NODES modifier with no Group Input geometry.",
+      "alt": "A cobalt-blue macropad with a brass knob and a glowing OLED meter, its three-by-three key field of cream keycaps instanced by Geometry Nodes, with one orange accent key at the front right.",
+      "witnessesFix": "Realized instances produce closed-form topology (9 keycaps × 121 = 1089 verts, 1089 faces), Set Material carries the keycap plastic, a position-field Set Material lands the accent on exactly one keycap, and the corner keycap sits at its closed-form grid coordinate.",
       "hero": "docs/gallery/assets/gn-instance-grid-hero.webp",
       "preview": "examples/gn-instance-grid/preview.webp",
       "tags": [

docs/gallery/contact-sheets/gn-instance-grid-contact-sheet.webp

@@ -1,25 +1,42 @@
 # GN Instance Grid
 
 A runnable example that builds a generative Geometry Nodes tree — Mesh Grid →
-Instance on Points → Realize Instances → Transform → Set Shade Smooth — and
-attaches it as a `NODES` modifier, following the
+Instance on Points → Realize Instances → Transform → Set Shade Smooth → Set
+Material — and attaches it as a `NODES` modifier, following the
 [`geometry-nodes-python`](../../skills/geometry-nodes-python/SKILL.md) skill. The
-tree has no Group Input: the grid and cube primitives live inside the node group.
+tree has no Group Input: the grid lives inside the node group, and the instance
+is a modeled DSA-profile keycap read in through an `Object Info` node (original
+transform space). The realized grid is the key field of a 3x3 macropad.
 
 **What it witnesses:** instancing is not free geometry until you realize it. The
-check asserts the closed-form evaluated topology — verts = grid points × cube
-verts (3 × 3 × 8 = 72), faces = 9 × 6 — that a `Set Material` node carries the
-lime accent, and that the corner instance center sits at its closed-form grid
-coordinate. If Realize Instances is omitted, the evaluated mesh is empty and the
-counts fail.
+check asserts the closed-form evaluated topology — verts = grid points × keycap
+verts (9 × 121 = 1089), faces = 9 × 121 = 1089 — where the keycap counts come
+from its construction parameters (six rounded-rectangle rings of
+4 × (4 + 1) = 20 verts, plus the dish centre; five ring-to-ring quad bands, a
+20-triangle dish fan and one bottom n-gon), not from measuring the mesh. It
+also asserts that the (+x, +y) corner cell holds exactly one keycap, centred on
+its closed-form grid point with its foot at the Transform lift, that `Set
+Material` carries `Keycap.PBT`, and that a second `Set Material`, selected by a
+per-face position field, puts `Keycap.Accent` on exactly one keycap at the
+front-right grid point. If Realize Instances is bypassed, the evaluated mesh is
+empty and the count gate fails.
+
+**What the render shows:** nine identical keycaps, one per grid point, seated on
+switch housings in the recessed well of an anodized case, and the one orange
+"enter" key the position-field selection picked out. The count gate is numeric:
+an unrealized grid renders the same keycaps, because the renderer draws
+instances either way. What does show is the grid itself — `--one-cell` renders
+a single keycap in the centre of an empty well — and where the accent
+selection landed. The knob, OLED, case and switch housings are render-only
+staging built in bmesh; only the key field comes from the tree.
 
 ## Run
 
 ```bash
 # Cheap correctness check (no render) — the CI check:
 blender --background --python gn_instance_grid.py --
 
-# Falsifier: 1×1 grid. Must exit non-zero (corner instance missing).
+# Falsifier: 1×1 grid. Must exit non-zero (4: eight keycaps missing).
 blender --background --python gn_instance_grid.py -- --one-cell
 
 # Also render a still (EEVEE on a GPU host; use --engine cycles on GPU-less hosts):
@@ -38,11 +55,14 @@ against it.
 | 1 | Uncaught exception (FATAL wrapper) |
 | 2 | argparse / usage |
 | 3 | Carrier vertex count ≠ 1 |
-| 4 | Corner instance vert count ≠ 8 (`--one-cell` lands here) |
-| 5 | Evaluated topology ≠ 72 verts / 54 faces |
-| 6 | Set Material did not carry Lime |
-| 7 | Corner instance center off the closed-form grid point |
+| 4 | Evaluated topology ≠ 1089 verts / 1089 faces (`--one-cell` lands here) |
+| 5 | Corner grid cell does not hold exactly one keycap (121 verts) |
+| 6 | Set Material did not carry `Keycap.PBT` and `Keycap.Accent` |
+| 7 | Corner keycap off its closed-form grid point or lift |
 | 8 | `--output` produced no file |
+| 9 | Accent selection did not cover exactly one keycap at the front-right point |
+| 10 | Render path: Layer 1 framing violation (`gallery_framing`) |
+| 11 | Render path: asset-quality floor violation (`gallery_asset_quality`) |
 
 The `blender-smoke` workflow runs the check on Blender 5.2 LTS and 4.5 LTS
 (5.1 on the weekly cron, the `needs-5.1` PR label, or manual dispatch).