feat: add grease-pencil-rosette example (GPv3 attribute API drift witness) (#57)

Grease Pencil v3 is the largest bpy API break in the 4.x-to-5.x window and
nothing in the gallery touched it. This example draws five nested neon rose
curves through the attribute-based GPv3 surface and asserts the divergence
each version actually exposes: on 4.5 LTS GPv3 lives at grease_pencils_v3
while bpy.data.grease_pencils is still legacy GPencil (frame.strokes, no
.drawing); on 5.x legacy is deleted and GPv3 owns the grease_pencils name.
It also witnesses that stroke points are views over lazily materialized
attribute layers, round-tripping every closed-form position through the raw
POINT buffer.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -68,6 +68,7 @@
     "examples/driver-wave",
     "examples/gn-instance-grid",
     "examples/gn-sdf-remesh",
+    "examples/grease-pencil-rosette",
     "examples/parent-inverse-orrery",
     "examples/shader-node-group",
     "examples/shape-key-blend",

.github/workflows/blender-smoke.yml

@@ -274,3 +274,15 @@ jobs:
           # on its closed form. Exits non-zero on failure.
           xvfb-run -a "$BLENDER" --background \
             --python examples/parent-inverse-orrery/parent_inverse_orrery.py --
+
+      - name: Shipped example - grease pencil rosette (GPv3 attribute API)
+        run: |
+          set -euo pipefail
+          # Frame-independent check only (no render): five nested rose curves drawn
+          # as GPv3 strokes; asserts the version-gated datablock address (4.5:
+          # grease_pencils_v3 with grease_pencils still legacy; 5.x: grease_pencils
+          # is GPv3, legacy names gone), lazy attribute-layer materialization from
+          # point writes, and a closed-form round-trip of every position through
+          # the raw POINT attribute buffer. Exits non-zero on failure.
+          xvfb-run -a "$BLENDER" --background \
+            --python examples/grease-pencil-rosette/grease_pencil_rosette.py --

AGENTS.md

@@ -27,7 +27,7 @@ The content base (counts are CI-enforced against README.md and the manifest):
 - 2 templates: `extension-addon-template` for Extensions Platform add-ons,
   and `headless-batch-script-template` for unattended batch jobs.
 - 17 snippets covering canonical patterns.
-- 16 examples under `examples/<name>/`: runnable scripts that assert a real
+- 17 examples under `examples/<name>/`: runnable scripts that assert a real
   API contract with deterministic checks, exit non-zero on failure, and
   optionally render a still via `--output`. Each is executed headless on
   Blender 4.5 LTS and 5.1 by `blender-smoke.yml`; its render ships in the
@@ -41,7 +41,7 @@ Blender-Developer-Tools/
   rules/<rule-name>.mdc          # 6 rule files
   templates/<template-name>/     # 2 starter templates
   snippets/<snippet-name>.py     # 17 standalone Python snippets
-  examples/<name>/               # 16 runnable smoke-gated examples (+ gallery.json)
+  examples/<name>/               # 17 runnable smoke-gated examples (+ gallery.json)
   scripts/build_gallery.py       # generates docs/gallery/ (stdlib only)
   scripts/site/                  # vendored landing-page build (build_site.py + template)
   docs/gallery/                  # committed generated gallery pages + hero assets

CLAUDE.md

@@ -19,7 +19,7 @@ skills/<skill-name>/SKILL.md   - AI workflow definitions, 12 total
 rules/<rule-name>.mdc          - Anti-pattern rules, 6 total
 templates/<template-name>/     - Starter projects, 2 total
 snippets/<snippet-name>.py     - Standalone code patterns, 17 total
-examples/<name>/               - Runnable smoke-gated examples, 16 total (+ gallery.json)
+examples/<name>/               - Runnable smoke-gated examples, 17 total (+ gallery.json)
 scripts/build_gallery.py       - Regenerates docs/gallery/ from gallery.json (stdlib only)
 scripts/site/                  - Vendored landing-page build (Jinja2)
 docs/gallery/                  - Committed generated gallery pages + hero renders
@@ -80,11 +80,11 @@ v0.1.0: canonical object creation and deletion, depsgraph evaluated mesh, bmesh
 
 v0.2.0: Principled BSDF material, driver-with-custom-function via `driver_namespace`, application handler registration, shader node group with cross-version `interface` API, `foreach_get` bulk vertex read, version-branch skeleton, and USD export with `evaluation_mode='RENDER'`.
 
-## Examples (16)
+## Examples (17)
 
 Runnable scripts at `examples/<name>/`, each asserting a real API contract with
 deterministic checks (exit non-zero on failure) and optionally rendering a still via
-`--output`. All sixteen run headless on Blender 4.5 LTS and 5.1 in `blender-smoke.yml`;
+`--output`. All seventeen run headless on Blender 4.5 LTS and 5.1 in `blender-smoke.yml`;
 their renders ship in the site gallery at `docs/gallery/`. `examples/gallery.json` is the
 gallery's source of truth. When authoring a new one, copy the anatomy of
 `examples/bmesh-gear/` (script structure, README shape, dark-studio render recipe) and

README.md

@@ -17,14 +17,14 @@
 </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>16 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>17 examples</strong>
 </p>
 
 ---
 
 ## Overview
 
-This repository ships **12 skills, 6 rules, 2 templates, 17 snippets, and 16 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 17 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.
 
@@ -280,6 +280,23 @@ carries arms, planets, and a two-level moon through spinning pivots. Asserts bar
 `.parent =` really teleports, `matrix_world` is stale until `view_layer.update()`,
 and every orbit lands on its closed form.
 
+</td>
+</tr>
+<tr>
+<td width="46%" valign="middle">
+<a href="examples/grease-pencil-rosette/"><img src="examples/grease-pencil-rosette/preview.webp" alt="Grease pencil rosette: five nested neon rose curves drawn as tapered Grease Pencil v3 strokes, cyan through magenta to red, glowing against a dark studio wall with a soft blue halo" /></a>
+</td>
+<td valign="middle">
+
+### [grease-pencil-rosette](examples/grease-pencil-rosette/)
+
+Five nested rose curves drawn with the Grease Pencil v3 attribute API — layer →
+`frames.new().drawing` → `add_strokes` → per-point position, radius, opacity, and
+vertex color. Asserts the GPv3 address break: on 4.5 GPv3 is `grease_pencils_v3`
+while `grease_pencils` is still legacy; on 5.x legacy is gone and GPv3 owns the
+name. Point writes lazily materialize attribute layers, and every position
+round-trips through the raw `POINT` buffer.
+
 </td>
 </tr>
 </table>

ROADMAP.md

@@ -97,6 +97,7 @@ Not committed; target list for the next content version. (v0.3.0 shipped the smo
 - Refresh the `slotted-actions-animation` skill against any 5.2 changes
 - Bump `blender_version_min` in the templates if 5.2 APIs are used
 - Additional snippets for asset library scripting, EXR baking, multi-file extensions
+- Gallery coverage follow-ups from the GPv3 review: `armature-bend` (edit_bones + vertex groups + pose evaluation) and `text-version-stamp` (TextCurve self-labeling renders); lower priority: light-linking, bulk `pixels.foreach_set`, VSE sequences-to-strips witness (`grease-pencil-rosette` shipped first as the strongest 4.x-to-5.x drift witness)
 
 ## Future (uncommitted)