feat: witness Unity vs Godot glTF axis conversion on reimport

The same beacon under export_yup True vs False produces different disk POSITION and different reimported orientation.
Inventory, gallery, catalog, and the engine-export-presets roadmap row ship with the example.

Signed-off-by: TMHSDigital <154358121+TMHSDigital@users.noreply.github.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: TMHSDigital

.cursor-plugin/plugin.json

@@ -16,6 +16,7 @@
   "skills": [
     "skills/addon-scaffolding/SKILL.md",
     "skills/ai-mesh-cleanup/SKILL.md",
+    "skills/engine-export-presets/SKILL.md",
     "skills/operators/SKILL.md",
     "skills/ui-panels/SKILL.md",
     "skills/custom-properties/SKILL.md",
@@ -37,7 +38,8 @@
     "rules/prefer-temp-override-over-context-copy.mdc",
     "rules/use-foreach-set-for-bulk-data.mdc",
     "rules/validate-imported-mesh-scale.mdc",
-    "rules/no-unapplied-modifiers-on-export.mdc"
+    "rules/no-unapplied-modifiers-on-export.mdc",
+    "rules/use-correct-axis-rna-per-exporter.mdc"
   ],
   "snippets": [
     "snippets/action-ensure-channelbag-for-slot.py",
@@ -50,6 +52,9 @@
     "snippets/decimate_to_budget.py",
     "snippets/depsgraph-evaluated-mesh.py",
     "snippets/driver-with-custom-function.py",
+    "snippets/export_preset_godot.py",
+    "snippets/export_preset_unity.py",
+    "snippets/export_preset_unreal.py",
     "snippets/foreach-get-vertices.py",
     "snippets/foreach-set-vertices.py",
     "snippets/gltf_draco_export.py",
@@ -83,6 +88,7 @@
     "examples/depsgraph-export",
     "examples/driver-wave",
     "examples/exit-pre-sidecar",
+    "examples/export-preset-axis",
     "examples/gltf-export-roundtrip",
     "examples/gltf-skin-roundtrip",
     "examples/gn-bundle-roundtrip",

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 14 skills, 8 rules, 2 templates, 21 snippets, and 53
+The content base is 15 skills, 9 rules, 2 templates, 24 snippets, and 54
 examples (counts are CI-enforced against README.md and the manifest). The full
 inventory tables and per-item purposes live in `CLAUDE.md`. Example anatomy
 and authoring rules: copy `examples/bmesh-gear/`; the render look is specified
@@ -31,11 +31,11 @@ in `docs/VISUAL-STYLE.md`; the canonical run prompt is
 
 ```
 Blender-Developer-Tools/
-  skills/<skill-name>/SKILL.md   # 14 skill files
-  rules/<rule-name>.mdc          # 8 rule files
+  skills/<skill-name>/SKILL.md   # 15 skill files
+  rules/<rule-name>.mdc          # 9 rule files
   templates/<template-name>/     # 2 starter templates
-  snippets/<snippet-name>.py     # 21 standalone Python snippets
-  examples/<name>/               # 53 runnable smoke-gated examples (+ gallery.json)
+  snippets/<snippet-name>.py     # 24 standalone Python snippets
+  examples/<name>/               # 54 runnable smoke-gated examples (+ gallery.json)
   examples/gallery_framing.py    # shared Layer 1 framing measurement (render path only)
   scripts/build_gallery.py       # generates docs/gallery/ (stdlib only)
   scripts/site/                  # vendored landing-page build (build_site.py + template)

CLAUDE.md

@@ -17,23 +17,24 @@ The **Blender Developer Tools** repository is at **v0.54.0**. It packages skills
 ## Repository Architecture
 
 ```
-skills/<skill-name>/SKILL.md   - AI workflow definitions, 14 total
-rules/<rule-name>.mdc          - Anti-pattern rules, 8 total
+skills/<skill-name>/SKILL.md   - AI workflow definitions, 15 total
+rules/<rule-name>.mdc          - Anti-pattern rules, 9 total
 templates/<template-name>/     - Starter projects, 2 total
-snippets/<snippet-name>.py     - Standalone code patterns, 21 total
-examples/<name>/               - Runnable smoke-gated examples, 53 total (+ gallery.json)
+snippets/<snippet-name>.py     - Standalone code patterns, 24 total
+examples/<name>/               - Runnable smoke-gated examples, 54 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
 VERSION                        - Source of truth for the repo version
 ```
 
-## Skills (14)
+## Skills (15)
 
 | Skill | Purpose |
 | --- | --- |
 | addon-scaffolding | Extensions Platform manifest, file layout, register/unregister symmetry |
 | ai-mesh-cleanup | Ordered cleanup for imported generated meshes: units, transform apply, origin, normals, budget, collider |
+| engine-export-presets | Unity Y-up, Godot Z-up, and Unreal centimeter glTF/FBX presets; glTF uses export_yup, FBX uses axis_forward/axis_up |
 | operators | `bpy.types.Operator` lifecycle, `bl_idname`, redo, defensive context handling |
 | ui-panels | `bpy.types.Panel` declarative `draw()`, layout primitives, conditional UI |
 | custom-properties | `bpy.props` annotations, PropertyGroup, PointerProperty, storage tradeoffs |
@@ -47,7 +48,7 @@ VERSION                        - Source of truth for the repo version
 | bl-info-migration | Three-step migration from legacy `bl_info` to Extensions Platform, dual-format pattern |
 | vse-python | VSE timeline from Python: `.strips` vs `.sequences`, `new_effect` kwargs, 5.2 COLOR `width`/`height` bake |
 
-## Rules (8)
+## Rules (9)
 
 | Rule | Scope | What it flags |
 | --- | --- | --- |
@@ -59,6 +60,7 @@ VERSION                        - Source of truth for the repo version
 | use-foreach-set-for-bulk-data | `*.py` | Python loops over `mesh.vertices` setting bulk attributes one at a time |
 | validate-imported-mesh-scale | `*.py` | glTF/FBX import then mesh work with no `transform_apply` and no unit-scale check |
 | no-unapplied-modifiers-on-export | `*.py` | Export with live modifiers when the export does not request evaluated geometry |
+| use-correct-axis-rna-per-exporter | `*.py` | `export_scene.gltf` with FBX `axis_forward`/`axis_up`, or `export_scene.fbx` with glTF `export_yup` |
 
 ## Templates (2)
 
@@ -78,17 +80,17 @@ VERSION                        - Source of truth for the repo version
 - glTF export via `bpy.ops.export_scene.gltf`
 - Explicit exit codes for CI integration
 
-## Snippets (21)
+## Snippets (24)
 
 Small standalone `.py` files at `snippets/<name>.py`, each 5 to 50 lines.
 
 v0.1.0: canonical object creation and deletion, depsgraph evaluated mesh, bmesh load-edit-free, temp_override context, foreach_set vertex bulk write, register_classes_factory, PointerProperty binding, cross-version property delete, and the `action_ensure_channelbag_for_slot` slotted-actions bridge.
 
 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'`.
 
-AI asset pipeline track: `decimate_to_budget.py`, `convex_hull_collider.py`, `lod_chain.py` (helper duplicated, not imported), `gltf_draco_export.py`.
+AI asset pipeline track: `decimate_to_budget.py`, `convex_hull_collider.py`, `lod_chain.py` (helper duplicated, not imported), `gltf_draco_export.py`, `export_preset_unity.py`, `export_preset_godot.py`, `export_preset_unreal.py`.
 
-## Examples (53)
+## Examples (54)
 
 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

README.md

@@ -18,7 +18,7 @@
 </p>
 
 <p align="center">
-  <strong>14 skills</strong> &nbsp;&bull;&nbsp; <strong>8 rules</strong> &nbsp;&bull;&nbsp; <strong>2 templates</strong> &nbsp;&bull;&nbsp; <strong>21 snippets</strong> &nbsp;&bull;&nbsp; <strong>53 examples</strong>
+  <strong>15 skills</strong> &nbsp;&bull;&nbsp; <strong>9 rules</strong> &nbsp;&bull;&nbsp; <strong>2 templates</strong> &nbsp;&bull;&nbsp; <strong>24 snippets</strong> &nbsp;&bull;&nbsp; <strong>54 examples</strong>
 </p>
 
 <p align="center">
@@ -36,16 +36,16 @@
 
 ## Overview
 
-This repository ships **14 skills, 8 rules, 2 templates, 21 snippets, and 53 examples** 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 **15 skills, 9 rules, 2 templates, 24 snippets, and 54 examples** 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 (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.
 
 | 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 |
-| **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 |
+| **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, engine export presets |
+| **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 |
 | **Templates** | A working Extensions Platform add-on starter and a headless batch script starter |
-| **Snippets** | 21 small standalone Python files demonstrating canonical patterns |
+| **Snippets** | 24 small standalone Python files demonstrating canonical patterns |
 
 ## Quick start
 
@@ -627,7 +627,7 @@ portable path is `radius`.
 </details>
 
 <details>
-<summary><strong>Game asset pipeline</strong> — 20 examples</summary>
+<summary><strong>Game asset pipeline</strong> — 21 examples</summary>
 
 <table>
 <tr>
@@ -646,6 +646,22 @@ loop), V-flipped UVs, and per-triangle material bindings — all against the
 depsgraph-evaluated mesh. The exporter/importer RNA signatures are probed
 byte-identical on 4.5.11 and 5.1.2 and guarded against future renames.
 
+</td>
+</tr>
+<tr>
+<td width="46%" valign="middle">
+<a href="examples/export-preset-axis/"><img src="examples/export-preset-axis/preview.webp" alt="Export preset axis: a radio beacon exported under Unity and Godot glTF presets and re-imported side by side on a dark studio floor - Unity standing with a glowing cap, Godot lying on its base - proving the two files have different vertex orientation" /></a>
+</td>
+<td valign="middle">
+
+### [export-preset-axis](examples/export-preset-axis/)
+
+The same beacon mesh under the Unity (`export_yup=True`) and Godot
+(`export_yup=False`) glTF presets. Re-importing each file proves the axis
+conversion: Unity stands, Godot lies along `-Y`. `--same-axis` exports both
+Y-up and the differ check exits 9. Neighbor of
+[`gltf-export-roundtrip`](examples/gltf-export-roundtrip/).
+
 </td>
 </tr>
 <tr>
@@ -1008,15 +1024,15 @@ the duplicates, then glTF ships 24 tris / 48 positions / 8 unique.
 ## How content is organized
 
 ```
-skills/<name>/SKILL.md   - 14 skill files, YAML frontmatter, one canonical pattern each
-rules/<name>.mdc         - 8 rule files, anti-pattern + correction
+skills/<name>/SKILL.md   - 15 skill files, YAML frontmatter, one canonical pattern each
+rules/<name>.mdc         - 9 rule files, anti-pattern + correction
 templates/<name>/        - 2 template directories (extension-addon-template, headless-batch-script-template)
-snippets/<name>.py       - 21 standalone Python snippets, 5 to 50 lines each
+snippets/<name>.py       - 24 standalone Python snippets, 5 to 50 lines each
 ```
 
 ## Using rules in Cursor
 
-The `.mdc` files in `rules/` apply automatically when Cursor opens a Blender Python project, scoped by the `globs` in each rule's frontmatter. The eight rules are:
+The `.mdc` files in `rules/` apply automatically when Cursor opens a Blender Python project, scoped by the `globs` in each rule's frontmatter. The nine rules are:
 
 - `prefer-data-over-ops-in-loops`: flags `bpy.ops.*` calls inside object iteration
 - `always-free-bmesh`: flags `bmesh.new()` without paired `bm.free()` in `try`/`finally`
@@ -1026,6 +1042,7 @@ The `.mdc` files in `rules/` apply automatically when Cursor opens a Blender Pyt
 - `use-foreach-set-for-bulk-data`: flags Python loops over `mesh.vertices` setting `co`, normals, or other per-element bulk data
 - `validate-imported-mesh-scale`: flags glTF/FBX import then mesh work with no `transform_apply` and no unit-scale check
 - `no-unapplied-modifiers-on-export`: flags export of objects with live modifiers when the export does not request evaluated geometry
+- `use-correct-axis-rna-per-exporter`: flags `export_scene.gltf` calls that pass FBX `axis_forward` / `axis_up`, and `export_scene.fbx` calls that pass glTF `export_yup`
 
 Symlink or clone this repo, then point Cursor at it as a skills/rules source.
 

ROADMAP.md

@@ -18,8 +18,8 @@ derives the actual version from conventional-commit types.
 | 5.2 LTS targeting, GN modifier inputs | 12 | 6 | 2 | 17 | Shipped |
 | VSE COLOR strip intrinsic size (undocumented 5.2) | 13 | 6 | 2 | 17 | Shipped |
 | Modal operators, USD, mathutils | — | — | — | — | Upcoming |
-| AI asset pipeline: post-generation cleanup | - | - | - | - | Upcoming |
-| AI asset pipeline: engine export presets | - | - | - | - | Upcoming |
+| AI asset pipeline: post-generation cleanup | 14 | 8 | 2 | 21 | Shipped (v0.54.0) |
+| AI asset pipeline: engine export presets | 15 | 9 | 2 | 24 | Shipped |
 | AI asset pipeline: headless template | - | - | - | - | Upcoming |
 | AI asset pipeline: live-session bridge (spike) | - | - | - | - | Upcoming |
 | Stable | — | — | — | — | Upcoming |
@@ -95,10 +95,10 @@ Audit pass on v0.1.0 content: standards-version markers bumped from `1.9.1` to `
 
 Provider-agnostic GLB-in / engine-ready-out. This repo does not generate meshes.
 
-- **Post-generation cleanup skills** (this phase starts the family; bake/UV/atlas follow on): import and unit-scale normalization, transform apply and origin, poly-budget decimate, LOD chain, collision mesh, high-to-low bake, UV transfer and atlas packing. Phase 1: `ai-mesh-cleanup`, four snippets, two rules.
-- **Engine export presets.** Unity (Y-up), Godot, and Unreal (centimeter scale) glTF and FBX paths with Draco. One skill, one snippet set.
-- **`ai-asset-pipeline-template/`.** Third template. Headless: GLB path in; LOD set, convex collider, engine-preset export; explicit CI exit codes. Pattern: `templates/headless-batch-script-template/`. Phase 2.
-- **Live-session agent bridge.** Research spike, not a committed deliverable. MCP server or socket listener so an agent can execute against a running Blender instance instead of blind `--background` scripts. Built on `templates/extension-addon-template/`. Needs its own design pass.
+- **Post-generation cleanup skills.** Import and unit-scale normalization, transform apply and origin, poly-budget decimate, LOD chain, collision mesh. Phase 1 shipped in v0.54.0 as `ai-mesh-cleanup`, four snippets, two rules. Bake/UV/atlas follow on.
+- **Engine export presets.** **Delivered.** Unity (Y-up glTF), Godot (Z-up glTF, meters), Unreal (centimeter glTF bake and FBX `global_scale`). Skill `engine-export-presets`, three snippets, rule `use-correct-axis-rna-per-exporter`, witness `examples/export-preset-axis/`. Draco remains opt-in via `gltf_draco_export.py`.
+- **`ai-asset-pipeline-template/`.** Third template. Headless: GLB path in; LOD set, convex collider, engine-preset export; explicit CI exit codes. Pattern: `templates/headless-batch-script-template/`. Phase 3. Unpinned.
+- **Live-session agent bridge.** Research spike, not a committed deliverable. MCP server or socket listener so an agent can execute against a running Blender instance instead of blind `--background` scripts. Built on `templates/extension-addon-template/`. Needs its own design pass. Unpinned.
 
 ## Candidate pool (next content)