feat: uv-and-mesh-attributes skill for the UV, tangent and attribute examples

Six examples (uv-layer-grid, lightmap-uv-channel, triangulate-tangents,
color-attribute-wheel, shape-key-blend, vertex-weight-limit) were credited to
mesh-editing-and-bmesh, whose prose had no section on any of their
contracts, so an agent had to infer them from example scripts. The new skill
states each contract those examples measured: the calc_uvs=True no-op, the
lightmap channel's active/active_render flags, re-fetching layers by name
after calc_tangents (the 4.5 dangling-handle read and segfault), tangents
and n-gons, CORNER vs POINT color domains, shape keys and four-influence
weights with renormalizing. The six examples now map to it as well.

Its high-level block is smoke-run (ratchet floor 14 -> 15). Live-run proven:
it PASSES on Blender 5.2.1 LTS and 4.5.14 LTS via run_content.py.

Closes #533

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LpkeXRvikhJZSVGBFM91Dv
Signed-off-by: TM Hospitality Strategies <TMHospitalityStrategies@gmail.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -44,7 +44,8 @@
     "skills/constraints-and-parenting/SKILL.md",
     "skills/images-and-pixels/SKILL.md",
     "skills/curves-and-text/SKILL.md",
-    "skills/compositor-nodes/SKILL.md"
+    "skills/compositor-nodes/SKILL.md",
+    "skills/uv-and-mesh-attributes/SKILL.md"
   ],
   "rules": [
     "rules/prefer-data-over-ops-in-loops.mdc",

AGENTS.md

@@ -20,7 +20,7 @@ a `.cursor-plugin/plugin.json` manifest so the ecosystem drift checker
 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 25 skills, 16 rules, 3 templates, 31 snippets, 66
+The content base is 26 skills, 16 rules, 3 templates, 31 snippets, 66
 examples, and 80 showcase pieces (counts are CI-enforced across README.md, the agent docs, ROADMAP.md,
 `site.json` and the site templates). The full inventory tables and per-item purposes live in
 `CLAUDE.md`. Example anatomy and authoring rules: copy `examples/bmesh-gear/`;
@@ -32,7 +32,7 @@ in `docs/VISUAL-STYLE.md`; the canonical run prompt is
 
 ```
 Blender-Developer-Tools/
-  skills/<skill-name>/SKILL.md   # 25 skill files
+  skills/<skill-name>/SKILL.md   # 26 skill files
   rules/<rule-name>.mdc          # 16 rule files
   templates/<template-name>/     # 3 starter templates
   snippets/<snippet-name>.py     # 31 standalone Python snippets

CLAUDE.md

@@ -17,7 +17,7 @@ The **Blender Developer Tools** repository is at **v0.158.0**. It packages skill
 ## Repository Architecture
 
 ```
-skills/<skill-name>/SKILL.md   - AI workflow definitions, 25 total
+skills/<skill-name>/SKILL.md   - AI workflow definitions, 26 total
 rules/<rule-name>.mdc          - Anti-pattern rules, 16 total
 templates/<template-name>/     - Starter projects, 3 total
 snippets/<snippet-name>.py     - Standalone code patterns, 31 total
@@ -30,7 +30,7 @@ docs/gallery/                  - Committed generated gallery pages + hero render
 VERSION                        - Source of truth for the repo version
 ```
 
-## Skills (25)
+## Skills (26)
 
 | Skill | Purpose |
 | --- | --- |
@@ -59,6 +59,7 @@ VERSION                        - Source of truth for the repo version
 | images-and-pixels | `Image.pixels` layout and bulk `foreach_*`, byte vs float buffers, colorspace, `save()` vs `save_render()`, PNG vs EXR alpha |
 | curves-and-text | Curve and TextCurve datablocks: splines, bevel/extrude closed forms, `body`, Bfont, evaluated mesh read-back |
 | compositor-nodes | 4.5 `scene.node_tree` vs 5.x `scene.compositing_node_group`, Glare node enum-to-menu-socket change, `use_compositing` |
+| uv-and-mesh-attributes | UV layers (`calc_uvs=True` no-op without a layer), lightmap channel `active` / `active_render`, re-fetch layers by name after `calc_tangents`, color-attribute domains, shape keys, four-influence skin weights |
 
 ## Rules (16)
 

CONTRIBUTING.md

@@ -329,7 +329,7 @@ The drift-check workflow enforces these on every push and PR.
 
 ## Aggregate Counts
 
-`README.md` declares aggregate counts (e.g. "25 skills, 16 rules, 3 templates, 31 snippets, 69 examples, and 80 showcase pieces"). The `validate-counts` job in `.github/workflows/validate.yml` enforces these substrings against the filesystem on every push and PR. Showcase pieces are counted separately from examples. When you add or remove content, update the README counts in the same commit.
+`README.md` declares aggregate counts (e.g. "26 skills, 16 rules, 3 templates, 31 snippets, 69 examples, and 80 showcase pieces"). The `validate-counts` job in `.github/workflows/validate.yml` enforces these substrings against the filesystem on every push and PR. Showcase pieces are counted separately from examples. When you add or remove content, update the README counts in the same commit.
 
 ## Pull Request Process
 

README.md

@@ -25,7 +25,7 @@
 </p>
 
 <p align="center">
-  <strong>25 skills</strong> &nbsp;&bull;&nbsp; <strong>16 rules</strong> &nbsp;&bull;&nbsp; <strong>3 templates</strong> &nbsp;&bull;&nbsp; <strong>31 snippets</strong> &nbsp;&bull;&nbsp; <strong>69 examples</strong> &nbsp;&bull;&nbsp; <strong>80 showcase pieces</strong>
+  <strong>26 skills</strong> &nbsp;&bull;&nbsp; <strong>16 rules</strong> &nbsp;&bull;&nbsp; <strong>3 templates</strong> &nbsp;&bull;&nbsp; <strong>31 snippets</strong> &nbsp;&bull;&nbsp; <strong>69 examples</strong> &nbsp;&bull;&nbsp; <strong>80 showcase pieces</strong>
 </p>
 
 <p align="center">
@@ -44,13 +44,13 @@
 
 ## Overview
 
-This repository ships **25 skills, 16 rules, 3 templates, 31 snippets, 69 examples, and 80 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 **26 skills, 16 rules, 3 templates, 31 snippets, 69 examples, and 80 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, installed as a plugin or read from a checkout. An optional second plugin registers the official [Blender Lab MCP server](https://www.blender.org/lab/mcp-server/) for live sessions (see [Live Blender session](#live-blender-session-mcp)); the server is referenced from upstream, not part of this repository, and nothing else depends on it. Cursor and Claude Code both install it as a plugin (see [Quick start](#quick-start)): Cursor loads the skills and applies `rules/*.mdc` wherever their scope globs match; Claude Code loads the skills and gets the rules through a generated `blender-rules` skill, since it does not read Cursor `.mdc` files. An agent picks a skill up when its description matches the task. 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.
 
 | Layer | Role |
 | --- | --- |
-| **Skills** | Guided workflows: scaffolding, operators, panels, properties, mesh and bmesh, headless batch, slotted actions, geometry nodes, procedural materials, depsgraph queries, drivers and handlers, `bl_info` migration, video sequencer, imported-mesh cleanup, high-to-low baking, engine export presets, extension runtime and packaging, timers, modal operators and threading, GPU drawing and viewport overlays, porting add-ons to Blender 5, Grease Pencil v3, constraints and parenting, images and pixels, curves and text, compositor nodes |
+| **Skills** | Guided workflows: scaffolding, operators, panels, properties, mesh and bmesh, headless batch, slotted actions, geometry nodes, procedural materials, depsgraph queries, drivers and handlers, `bl_info` migration, video sequencer, imported-mesh cleanup, high-to-low baking, engine export presets, extension runtime and packaging, timers, modal operators and threading, GPU drawing and viewport overlays, porting add-ons to Blender 5, Grease Pencil v3, constraints and parenting, images and pixels, curves and text, compositor nodes, UV layers and mesh attributes |
 | **Rules** | Guardrails for the most common AI mistakes: ops-in-loops, bmesh leaks, legacy `bl_info` only, prop assignments, deprecated context-copy override, per-element loops over bulk mesh data, import without scale check, export without evaluated geometry, mixed glTF/FBX axis RNA, and the 5.x breaks: `bgl`, the pre-4.1 normals API, `sequence_editor.sequences`, `action.fcurves`, 3.x Principled socket names, NodesModifier ID-property inputs, the EEVEE engine id |
 | **Templates** | A working Extensions Platform add-on starter, a headless batch script starter, and a GLB-in engine-ready asset pipeline |
 | **Snippets** | 31 small standalone Python files demonstrating canonical patterns, 5 to 75 lines each |
@@ -61,14 +61,14 @@ The content is consumed by AI coding agents, installed as a plugin or read from
 
 Neither agent needs a clone of `main`: both install the slim `plugin-dist` build. Clone the full repository only to [run the examples or contribute](#run-the-examples-or-contribute).
 
-- **Cursor** — install it as a local plugin from the slim `plugin-dist` branch, then run **Developer: Reload Window**. **Customize** lists the 25 skills and 16 rules; the rules apply by glob scope and the agent loads a skill when its description matches the task.
+- **Cursor** — install it as a local plugin from the slim `plugin-dist` branch, then run **Developer: Reload Window**. **Customize** lists the 26 skills and 16 rules; the rules apply by glob scope and the agent loads a skill when its description matches the task.
 
   ```bash
   git clone --branch plugin-dist --single-branch https://github.com/TMHSDigital/Blender-Developer-Tools.git ~/.cursor/plugins/local/blender-developer-tools
   ```
 
   (On Windows the folder is `%USERPROFILE%\.cursor\plugins\local\`. Cursor skips symlinks that point outside that folder, so clone or copy rather than link.) Teams can import the repository as a team marketplace instead; it carries `.cursor-plugin/marketplace.json`. The plugin already applies the rules, so there is nothing to copy. Only to scope the pack to one project without the plugin, copy `skills/*` into that project's `.cursor/skills/` and `rules/*.mdc` into `.cursor/rules/` from a checkout; copying only the rules gives you no skills.
-- **Claude Code** — install as a plugin, then run `/skills` to see all 25 skills plus `blender-rules`:
+- **Claude Code** — install as a plugin, then run `/skills` to see all 26 skills plus `blender-rules`:
 
   ```text
   /plugin marketplace add TMHSDigital/Blender-Developer-Tools@plugin-dist
@@ -197,7 +197,7 @@ Browse both, with filters, full-size renders and each script's README, in the **
 ## How content is organized
 
 ```
-skills/<name>/SKILL.md   - 25 skill files, YAML frontmatter, one canonical pattern each
+skills/<name>/SKILL.md   - 26 skill files, YAML frontmatter, one canonical pattern each
 rules/<name>.mdc         - 16 rule files, anti-pattern + correction
 templates/<name>/        - 3 template directories (extension-addon-template, headless-batch-script-template, ai-asset-pipeline-template)
 snippets/<name>.py       - 31 standalone Python snippets, 5 to 75 lines each

ROADMAP.md

@@ -40,6 +40,7 @@ derives the actual version from conventional-commit types.
 | Skills for stranded examples: Grease Pencil v3, constraints and parenting, images and pixels, curves and text, compositor nodes | 25 | 12 | 3 | 31 | Shipped |
 | Live-session bridge (opt-in `blender-live-session` plugin, upstream Blender Lab MCP) | - | - | - | - | Shipped |
 | Rules for the headline 5.x breaks: `action.fcurves`, Principled v2 socket names, NodesModifier ID-property inputs, the EEVEE engine id | 25 | 16 | 3 | 31 | Shipped |
+| UV layers and mesh attributes skill (lightmap channel, tangents, color attributes, shape keys, skin weights) | 26 | 16 | 3 | 31 | Shipped |
 | Stable (1.0) | — | — | — | — | Upcoming; criteria below |
 
 ## What "Stable (1.0)" means

examples/index.json

@@ -331,6 +331,7 @@
     "path": "examples/color-attribute-wheel/",
     "script": "examples/color-attribute-wheel/color_attribute_wheel.py",
     "skills": [
+      "uv-and-mesh-attributes",
       "mesh-editing-and-bmesh"
     ],
     "render": true,
@@ -1428,6 +1429,7 @@
     "path": "examples/lightmap-uv-channel/",
     "script": "examples/lightmap-uv-channel/lightmap_uv_channel.py",
     "skills": [
+      "uv-and-mesh-attributes",
       "mesh-editing-and-bmesh"
     ],
     "render": true,
@@ -1853,6 +1855,7 @@
     "path": "examples/shape-key-blend/",
     "script": "examples/shape-key-blend/shape_key_blend.py",
     "skills": [
+      "uv-and-mesh-attributes",
       "mesh-editing-and-bmesh"
     ],
     "render": true,
@@ -2241,6 +2244,7 @@
     "path": "examples/triangulate-tangents/",
     "script": "examples/triangulate-tangents/triangulate_tangents.py",
     "skills": [
+      "uv-and-mesh-attributes",
       "mesh-editing-and-bmesh"
     ],
     "render": true,
@@ -2380,6 +2384,7 @@
     "path": "examples/uv-layer-grid/",
     "script": "examples/uv-layer-grid/uv_layer_grid.py",
     "skills": [
+      "uv-and-mesh-attributes",
       "mesh-editing-and-bmesh"
     ],
     "render": true,
@@ -2452,6 +2457,7 @@
     "path": "examples/vertex-weight-limit/",
     "script": "examples/vertex-weight-limit/vertex_weight_limit.py",
     "skills": [
+      "uv-and-mesh-attributes",
       "mesh-editing-and-bmesh"
     ],
     "render": true,

examples/skills.json

@@ -9,7 +9,7 @@
   "car-mirror-symmetry": ["depsgraph-and-evaluated-data"],
   "coincident-vert-weld": ["ai-mesh-cleanup"],
   "collision-hull-proxy": ["ai-mesh-cleanup", "mesh-editing-and-bmesh"],
-  "color-attribute-wheel": ["mesh-editing-and-bmesh"],
+  "color-attribute-wheel": ["uv-and-mesh-attributes", "mesh-editing-and-bmesh"],
   "compositor-glare": ["compositor-nodes", "porting-to-blender-5"],
   "cross-version-property-delete": ["custom-properties", "porting-to-blender-5"],
   "curve-bevel-arc": ["curves-and-text"],
@@ -37,7 +37,7 @@
   "image-pixels-testcard": ["images-and-pixels"],
   "lattice-deform": ["depsgraph-and-evaluated-data", "mesh-editing-and-bmesh"],
   "light-link-studio": ["procedural-materials-and-shaders"],
-  "lightmap-uv-channel": ["mesh-editing-and-bmesh"],
+  "lightmap-uv-channel": ["uv-and-mesh-attributes", "mesh-editing-and-bmesh"],
   "lod-decimate-chain": ["ai-mesh-cleanup", "depsgraph-and-evaluated-data", "mesh-editing-and-bmesh"],
   "mesh-automasking-settings": ["mesh-editing-and-bmesh"],
   "mesh-normals-after-41": ["mesh-editing-and-bmesh", "porting-to-blender-5"],
@@ -49,7 +49,7 @@
   "prop-origin-transform": ["ai-mesh-cleanup", "operators"],
   "ray-cast-space": ["depsgraph-and-evaluated-data"],
   "shader-node-group": ["procedural-materials-and-shaders"],
-  "shape-key-blend": ["mesh-editing-and-bmesh"],
+  "shape-key-blend": ["uv-and-mesh-attributes", "mesh-editing-and-bmesh"],
   "sky-texture-sun-elevation": ["procedural-materials-and-shaders"],
   "soccer-ball-goldberg": ["depsgraph-and-evaluated-data", "mesh-editing-and-bmesh"],
   "socket-attach-points": ["constraints-and-parenting"],
@@ -58,13 +58,13 @@
   "temp-override-join": ["headless-batch-scripting", "operators"],
   "timers-modal-threading": ["operators", "timers-modal-and-threading"],
   "text-version-stamp": ["curves-and-text"],
-  "triangulate-tangents": ["mesh-editing-and-bmesh"],
+  "triangulate-tangents": ["uv-and-mesh-attributes", "mesh-editing-and-bmesh"],
   "turntable": ["slotted-actions-animation"],
   "unapplied-scale-gltf": ["ai-mesh-cleanup", "engine-export-presets"],
   "usd-export-evaluation-mode": ["depsgraph-and-evaluated-data", "headless-batch-scripting"],
-  "uv-layer-grid": ["mesh-editing-and-bmesh"],
+  "uv-layer-grid": ["uv-and-mesh-attributes", "mesh-editing-and-bmesh"],
   "vertex-color-ao": ["mesh-editing-and-bmesh"],
-  "vertex-weight-limit": ["mesh-editing-and-bmesh"],
+  "vertex-weight-limit": ["uv-and-mesh-attributes", "mesh-editing-and-bmesh"],
   "vse-cut-list": ["vse-python"],
   "vse-gamma-cross": ["vse-python"],
   "vse-linear-modifiers": ["vse-python"],

scripts/build_plugin_dist.py

@@ -76,7 +76,7 @@
 ```
 
 Cursor: clone this branch into `~/.cursor/plugins/local/blender-developer-tools`
-and reload the window (Customize then lists the 25 skills and 16 rules).
+and reload the window (Customize then lists the 26 skills and 16 rules).
 
 Skills reference bundled files as `${CLAUDE_PLUGIN_ROOT}/snippets/...`, which
 Claude Code expands to this plugin's install directory. In Cursor, read it as

site.json

@@ -18,8 +18,8 @@
     "github": "https://github.com/TMHSDigital/Blender-Developer-Tools"
   },
   "installSteps": [
-    "<strong>Claude Code:</strong> <code>/plugin marketplace add TMHSDigital/Blender-Developer-Tools@plugin-dist</code> then <code>/plugin install blender-developer-tools@blender-developer-tools</code>. The 25 skills load when a task matches; the rules come along as the <code>blender-rules</code> skill",
-    "<strong>Cursor:</strong> <code>git clone --branch plugin-dist --single-branch https://github.com/TMHSDigital/Blender-Developer-Tools.git ~/.cursor/plugins/local/blender-developer-tools</code>, then reload the window; Customize lists the 25 skills and 16 rules, and the plugin applies the rules for you. This clones only the 0.3 MB plugin build, not <code>main</code>",
+    "<strong>Claude Code:</strong> <code>/plugin marketplace add TMHSDigital/Blender-Developer-Tools@plugin-dist</code> then <code>/plugin install blender-developer-tools@blender-developer-tools</code>. The 26 skills load when a task matches; the rules come along as the <code>blender-rules</code> skill",
+    "<strong>Cursor:</strong> <code>git clone --branch plugin-dist --single-branch https://github.com/TMHSDigital/Blender-Developer-Tools.git ~/.cursor/plugins/local/blender-developer-tools</code>, then reload the window; Customize lists the 26 skills and 16 rules, and the plugin applies the rules for you. This clones only the 0.3 MB plugin build, not <code>main</code>",
     "<strong>Other agents (Codex, Copilot, Windsurf):</strong> clone the same slim build (<code>git clone --branch plugin-dist --single-branch https://github.com/TMHSDigital/Blender-Developer-Tools.git</code>) and copy its <code>skills/*</code> into <code>.agents/skills/</code>, append <code>exports/AGENTS.md</code> to your project's <code>AGENTS.md</code> for the rules, and for Copilot copy <code>exports/copilot/blender-python.instructions.md</code> into <code>.github/instructions/</code>",
     "<strong>Optional, live session:</strong> <code>/plugin install blender-live-session@blender-developer-tools</code> adds the official Blender Lab MCP server (needs <code>uv</code> and Blender 5.1+ with its add-on) so the agent can inspect and drive your open scene, plus a skill that has it read before it mutates and prove changes headless. See the README's <a href=\"https://github.com/TMHSDigital/Blender-Developer-Tools#live-blender-session-mcp\">Live Blender session</a>",
     "Grab <code>snippets/</code> and <code>templates/</code> as starting points for add-ons and headless batch jobs"