feat: add prop-origin-transform example (#102)

Ship base-center origin bake, data-API scale apply, and MPI accessory
parenting as a dual-panel gallery example so prop pipelines can prove
ingest transforms without teleporting children.

Signed-off-by: fOuttaMyPaint <TMhospitalitystrategies@gmail.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -81,6 +81,7 @@
     "examples/mesh-hygiene-audit",
     "examples/parent-inverse-orrery",
     "examples/png-exr-alpha",
+    "examples/prop-origin-transform",
     "examples/shader-node-group",
     "examples/shape-key-blend",
     "examples/sky-texture-sun-elevation",

.github/workflows/blender-smoke.yml

@@ -505,3 +505,14 @@ jobs:
           # positive signed volume, Euler V-E+F == 2. Exits non-zero on failure.
           xvfb-run -a "$BLENDER" --background \
             --python examples/mesh-hygiene-audit/mesh_hygiene_audit.py --
+
+      - name: Shipped example - prop origin transform (base origin + scale + MPI)
+        run: |
+          set -euo pipefail
+          # Check only (no render): street pedestal; asserts scale (1,1,1) after
+          # data-API apply, local bbox min.z == 0, world AABB unchanged, bare
+          # parent jumps accessory, matrix_parent_inverse restores world location,
+          # and matrix_world stays stale until view_layer.update(). Exits non-zero
+          # on failure.
+          xvfb-run -a "$BLENDER" --background \
+            --python examples/prop-origin-transform/prop_origin_transform.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>35 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>36 examples</strong>
 </p>
 
 <p align="center">
@@ -36,7 +36,7 @@
 
 ## Overview
 
-This repository ships **12 skills, 6 rules, 2 templates, 17 snippets, and 35 runnable examples** for Blender Python development targeting Blender 5.1 (current stable) with Blender 4.5 LTS fallback support.
+This repository ships **12 skills, 6 rules, 2 templates, 17 snippets, and 36 runnable examples** for Blender Python development targeting Blender 5.1 (current stable) with Blender 4.5 LTS fallback support.
 
 The content is consumed by AI coding agents (Cursor, Claude Code, any MCP-capable client) when working on Blender add-ons, geometry nodes scripts, batch pipelines, or animation tooling. There is no build step. Edit the markdown and Python files directly.
 
@@ -537,7 +537,7 @@ portable path is `radius`.
 </details>
 
 <details>
-<summary><strong>Game asset pipeline</strong> — 8 examples</summary>
+<summary><strong>Game asset pipeline</strong> — 9 examples</summary>
 
 <table>
 <tr>
@@ -682,6 +682,23 @@ closed solid (measured 24/44/22, volume 0.989248). Companion to
 and [`bmesh-gear`](examples/bmesh-gear/) (parametric closed solids). Dual-panel
 still: DIRTY (injected boundary + loose vert) vs CLEAN.
 
+</td>
+</tr>
+<tr>
+<td width="46%" valign="middle">
+<a href="examples/prop-origin-transform/"><img src="examples/prop-origin-transform/preview.webp" alt="Prop origin transform: dual-panel TRAP vs MPI KEEP street pedestals — left bare-parent accessory teleports with expected-seat ghost, right accessory stays put, emissive origin markers at base — proving scale apply, base origin, and matrix_parent_inverse" /></a>
+</td>
+<td valign="middle">
+
+### [prop-origin-transform](examples/prop-origin-transform/)
+
+The origin / scale-apply / MPI contract a prop pipeline relies on before
+engine ingest: data-API scale bake to exactly `(1,1,1)`, local bbox
+`min.z == 0` (origin at base), world AABB unchanged across the bake, and
+`matrix_parent_inverse` so a bolted accessory does not teleport. Extends
+[`parent-inverse-orrery`](examples/parent-inverse-orrery/) without retreading
+orbits. Dual-panel still: TRAP (bare parent) vs MPI KEEP.
+
 </td>
 </tr>
 </table>

ROADMAP.md

@@ -119,9 +119,10 @@ Not committed; target list for the next content version. (v0.3.0 shipped the smo
 - Camera DOF + focus_distance witness: `cam.dof.use_dof`, focus plane vs defocus variance on high-freq cards (Stage deviation — depth needs background content)
 - Volumetric scatter optical-depth witness: Volume Scatter density → Beer–Lambert transmittance along a known path (Cycles; Stage deviation)
 - Freestyle SVG / line-set witness: Freestyle line set on a silhouette (full render pass; prefer Line Art first)
-- prop-origin-transform witness — origin to base center, `transform_apply` through the data API, delta transforms, `matrix_parent_inverse` so parented children do not teleport; closed forms: post-apply scale exactly (1,1,1), local bbox min Z == 0, world bbox unchanged (builds on `parent-inverse-orrery`, does not duplicate it)
+- ~~prop-origin-transform witness~~ **SHIPPED** as `examples/prop-origin-transform/` — origin to base center + data-API scale apply + `matrix_parent_inverse` for a bolted accessory; scale `(1,1,1)`, local `min.z==0`, world AABB delta 0, bare jump ~0.43 m, MPI err ~3e-8; stale `matrix_world` until `view_layer.update()`; byte-identical on 4.5.11 and 5.1.2
 - ~~mesh-hygiene-audit witness~~ **SHIPPED** as `examples/mesh-hygiene-audit/` — engine-ingest topology checklist on a stepped street electrical pedestal: no ngons, no loose verts, manifold edges (exactly 2 faces), no zero-area faces (`min_area` printed), positive signed volume, Euler `V−E+F==2` (24/44/22, volume 0.989248); byte-identical on 4.5.11 and 5.1.2; dual-panel dirty vs clean still
 - UV atlas pack witness — lightmap/unique UV island packing with non-overlap + utilization closed forms (deferred behind hygiene/origin; overlaps `uv-layer-grid` / `triangulate-tangents` / `gltf-export-roundtrip` UV arc)
+- Attribute domain witness: writing a POINT-domain color attribute and reading it as if it were CORNER (or vice versa) silently shears colors across shared verts — companion to `color-attribute-wheel`
 
 ## Future (uncommitted)
 

docs/gallery/assets/prop-origin-transform-hero.webp

@@ -199,12 +199,14 @@ <h1>Examples Gallery</h1>
     <button class="chip" data-tag="node-groups" type="button">node-groups</button>
     <button class="chip" data-tag="objects" type="button">objects</button>
     <button class="chip" data-tag="operators" type="button">operators</button>
+    <button class="chip" data-tag="parenting" type="button">parenting</button>
     <button class="chip" data-tag="performance" type="button">performance</button>
     <button class="chip" data-tag="render" type="button">render</button>
     <button class="chip" data-tag="rendering" type="button">rendering</button>
     <button class="chip" data-tag="sequencer" type="button">sequencer</button>
     <button class="chip" data-tag="shape-keys" type="button">shape-keys</button>
     <button class="chip" data-tag="sky" type="button">sky</button>
+    <button class="chip" data-tag="transform" type="button">transform</button>
     <button class="chip" data-tag="transforms" type="button">transforms</button>
     <button class="chip" data-tag="uv" type="button">uv</button>
     <button class="chip" data-tag="world" type="button">world</button>
@@ -596,6 +598,17 @@ <h2><a href="mesh-hygiene-audit/">mesh-hygiene-audit</a></h2>
           <a class="card-link" href="mesh-hygiene-audit/">View example <span aria-hidden="true">&rarr;</span></a>
         </div>
       </article>
+      <article class="card" data-tags="transform parenting game-pipeline">
+        <a class="card-media" href="prop-origin-transform/" aria-label="prop-origin-transform example detail page">
+          <img src="assets/prop-origin-transform-hero.webp" alt="prop-origin-transform — Street pedestal origin-to-base-center + data-API scale apply + matrix_parent_inverse for a bolted accessory." loading="lazy" decoding="async" />
+        </a>
+        <div class="card-body">
+          <h2><a href="prop-origin-transform/">prop-origin-transform</a></h2>
+          <p class="teaches">Street pedestal origin-to-base-center + data-API scale apply + matrix_parent_inverse for a bolted accessory. After bake: scale exactly (1,1,1), local min.z==0, world AABB delta 0. Bare parent jumps the accessory (~0.43 m); MPI restores world location (~3e-8). view_layer.update() before reading matrix_world.</p>
+          <p class="witnesses"><span class="tag">witnesses</span> AI code parents with child.parent = parent alone (accessory teleports), skips view_layer.update() before matrix_world, or leaves non-uniform scale / centered origin for engine ingest. Skipping apply, origin bake, or MPI each fails a closed-form gate.</p>
+          <a class="card-link" href="prop-origin-transform/">View example <span aria-hidden="true">&rarr;</span></a>
+        </div>
+      </article>
     </div>
   </main>
   <footer>