fix: correct version-accuracy defects across skills and snippets

Re-verified empirically on Blender 4.5.10 LTS and 5.1.1 plus the 4.4/4.5/5.0
release notes. Four confirmed defects corrected:

1. EEVEE engine id was inverted. Correct mapping: 4.2-4.5 use
   'BLENDER_EEVEE_NEXT'; 5.0+ reclaimed 'BLENDER_EEVEE' (5.0 release notes,
   confirmed by introspection: 5.1.1 rejects _NEXT, 4.5.10 rejects plain).
   Fixed version-branch-skeleton.py get_eevee_engine_id(), the
   headless-batch-scripting detect snippet/choices/prose, and the
   procedural-materials version table.

2. Slotted Actions framing and fabricated 4.5 shim. The slotted data model
   shipped in 4.4 (not 5.0); legacy action.fcurves was removed in 5.0;
   action_ensure_channelbag_for_slot is new in 5.0 and absent on 4.4/4.5
   (no auto-detecting shim). Rewrote slotted-actions-animation: real
   version-branching helper (ensure-fn on 5.0+, strip.channelbag(ensure=True)
   on 4.4/4.5), removed the hasattr(action,'slots') "5.x sniff", corrected the
   compatibility matrix and the snippet header comment.

3. save_pre/save handler signature. Arg0 is the file path string, not a Scene
   (4.5 docs + introspection on both versions). Fixed the handler table and
   worked examples in drivers-and-app-handlers and app-handler-registration.py
   so handlers reach scenes via bpy.data, never treating arg0 as a Scene.

4. Geometry Nodes node version tags. For Each Element (4.3) and Mesh to SDF
   Grid (4.3) were mis-tagged "5.0+"; fixed labels and changed
   has_for_each_element() to gate on >= (4,3,0). NodeSocketBundle/has_bundles
   left at 5.0 (confirmed: interface socket works in 5.1, TypeError in 4.5).

No content added or removed; counts unchanged (12/6/2/17). All snippets and
templates py_compile. Corrected snippets verified to run on 4.5.10 and 5.1.1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: fOuttaMyPaint <TMhospitalitystrategies@gmail.com>

Author: TMHSDigital

skills/drivers-and-app-handlers/SKILL.md

@@ -145,15 +145,17 @@ The handlers live as lists at `bpy.app.handlers.<event>`. To register, append; t
 
 | Handler | Signature | Fires when |
 | --- | --- | --- |
-| `save_pre` | `(scene)` (some 4.x), `(scene, filepath)` (5.x) | Before the .blend is written. Use to clean up data you don't want serialized. |
-| `save_post` | Same | After the .blend is written. Use for post-save bookkeeping. |
-| `load_pre` | `(scene)` | Before a .blend is loaded. The current scene is still the old one. |
-| `load_post` | `(scene)` | After a .blend is loaded. Use to validate or migrate add-on data. |
+| `save_pre` | `(filepath: str)` | Before the .blend is written. The argument is the file being saved (empty string for the startup file), **not** a Scene. Use to clean up data you don't want serialized. |
+| `save_post` | `(filepath: str)` | After the .blend is written. Same single filepath argument. |
+| `load_pre` | `(filepath: str)` | Before a .blend is loaded. The argument is the file being loaded. |
+| `load_post` | `(filepath: str)` | After a .blend is loaded. Use to validate or migrate add-on data. |
 | `depsgraph_update_pre` | `(scene, depsgraph)` | Before a depsgraph evaluation pass. |
 | `depsgraph_update_post` | `(scene, depsgraph)` | After a depsgraph evaluation pass. Fires very frequently; must be O(1) or near-O(1). |
 | `frame_change_pre` | `(scene, depsgraph)` | Before frame is set. |
 | `frame_change_post` | `(scene, depsgraph)` | After frame is set. |
-| `exit_pre` (new in 5.1) | `(scene)` | Before Blender shuts down. Use for resource cleanup, telemetry flush, etc. |
+| `exit_pre` (new in 5.1) | `(*args)` | Before Blender shuts down. Use for resource cleanup, telemetry flush, etc. The argument is not a Scene; accept `*args`. |
+
+The save/load handlers (`save_pre`, `save_post`, `load_pre`, `load_post`) all receive the **file path as a string** as their single argument, **not** a Scene. (Verified empirically on 4.5.10 LTS and 5.1.1, and against `bpy.app.handlers` docs: "Accepts one argument: the file being saved/loaded.") Only the depsgraph/frame-change handlers receive `(scene, depsgraph)`.
 
 The `exit_pre` handler in 5.1 is particularly useful for add-ons that need to release external resources (sockets, log files, child processes) deterministically before the process terminates.
 
@@ -165,10 +167,15 @@ from bpy.app.handlers import persistent
 
 
 @persistent
-def on_save_pre(scene, filepath):
-    """Clear temporary cache data before save so it doesn't bloat the .blend."""
-    if 'my_addon_cache' in scene:
-        del scene['my_addon_cache']
+def on_save_pre(filepath):
+    """Clear temporary cache data before save so it doesn't bloat the .blend.
+
+    The handler argument is the path being saved (a string), not a Scene, so
+    reach the scene(s) through bpy.data.
+    """
+    for scene in bpy.data.scenes:
+        if 'my_addon_cache' in scene:
+            del scene['my_addon_cache']
 
 
 def register():
@@ -201,7 +208,10 @@ from bpy.app.handlers import persistent
 
 
 @persistent
-def increment_save_count(scene, filepath):
+def increment_save_count(filepath):
+    # save_post passes the saved file path (a string) as its only argument.
+    # Store the running count on the current scene.
+    scene = bpy.context.scene
     counts = scene.get('save_counts', {})
     counts[filepath] = counts.get(filepath, 0) + 1
     scene['save_counts'] = counts
@@ -224,8 +234,11 @@ from bpy.app.handlers import persistent
 
 
 @persistent
-def cleanup_on_exit(scene):
-    """Release the external log file handle before the process terminates."""
+def cleanup_on_exit(*args):
+    """Release the external log file handle before the process terminates.
+
+    exit_pre's argument is unused here; accept *args to stay signature-proof.
+    """
     global _log_handle
     if _log_handle is not None:
         _log_handle.close()
@@ -250,14 +263,14 @@ The `exit_pre` handler list is new in Blender 5.1. On 4.5 LTS, fall back to OS-l
 - **Doing real work inside `depsgraph_update_post`.** This handler fires on every depsgraph evaluation, which is many times per second during playback or interaction. Anything more than O(1) bookkeeping causes user-visible slowdown.
 - **Recursively modifying the scene from a depsgraph handler.** The modification triggers another depsgraph evaluation, which calls the handler, which modifies the scene. Infinite loop, often manifesting as a hang.
 - **Asymmetric register/unregister.** The handler is appended on register but not removed on unregister. Disabling the add-on leaves the callback in place. After enable/disable cycles, the callback runs N times per event.
-- **Assuming the `save_pre` signature.** It changed across the 4.x to 5.x window. Use `(scene, filepath=None)` defensively, or `*args` if you don't need the values.
+- **Treating the `save_pre` argument as a Scene.** The save/load handlers receive the **file path string** (empty for the startup file), not a Scene. Name the parameter `filepath` (or take `*args`), and reach scenes via `bpy.context.scene` / `bpy.data.scenes`. A membership test like `'key' in arg0` against the path string is silently wrong, and `del arg0['key']` raises `TypeError`.
 
 ## Version correctness
 
 | Topic | 4.5 LTS | 5.1 stable |
 | --- | --- | --- |
 | `exit_pre` handler | Not available | New in 5.1; use `atexit` fallback for 4.x |
-| `save_pre` signature | `(scene)` in 4.0, varies | `(scene, filepath)` in 5.x |
+| `save_pre` / `save_post` signature | `(filepath)` — a string | `(filepath)` — a string (unchanged) |
 | `driver_namespace` | Available | Same |
 | Driver security | Already restrictive | Same |
 

skills/geometry-nodes-python/SKILL.md

@@ -154,10 +154,10 @@ The argument is the exact RNA `bl_idname` of the node class. A few you'll reach
 | Vector Math | `ShaderNodeVectorMath` |
 | Mix | `ShaderNodeMix` |
 | Noise Texture | `ShaderNodeTexNoise` |
-| Mesh to SDF Grid (5.0+) | `GeometryNodeMeshToSDFGrid` |
+| Mesh to SDF Grid (4.3+) | `GeometryNodeMeshToSDFGrid` |
 | SDF Grid to Mesh / Volume to Mesh | `GeometryNodeVolumeToMesh` |
 | Repeat Input / Output | `GeometryNodeRepeatInput`, `GeometryNodeRepeatOutput` |
-| For Each Element Input / Output (5.0+) | `GeometryNodeForeachGeometryElementInput`, `GeometryNodeForeachGeometryElementOutput` |
+| For Each Element Input / Output (4.3+) | `GeometryNodeForeachGeometryElementInput`, `GeometryNodeForeachGeometryElementOutput` |
 
 To list all available Geometry node types in your Blender version:
 
@@ -243,8 +243,9 @@ def has_bundles():
     return major >= 5
 
 def has_for_each_element():
-    major, _minor, _patch = bpy.app.version
-    return major >= 5
+    # The For Each Element zone shipped in Blender 4.3, so it is available on
+    # the whole 4.5 LTS / 5.x supported range. (Bundles, by contrast, are 5.0+.)
+    return bpy.app.version >= (4, 3, 0)
 ```
 
 ## Common AI mistakes

skills/headless-batch-scripting/SKILL.md

@@ -161,11 +161,15 @@ def main():
     parser = argparse.ArgumentParser()
     parser.add_argument("--output", required=True)
     parser.add_argument("--frames", default="1")
-    parser.add_argument("--engine", default="CYCLES", choices=["CYCLES", "BLENDER_EEVEE_NEXT"])
+    parser.add_argument("--engine", default="CYCLES", choices=["CYCLES", "EEVEE"])
     args = parser.parse_args(argv)
 
     scene = bpy.context.scene
-    scene.render.engine = args.engine
+    if args.engine == "EEVEE":
+        # EEVEE's engine id is 'BLENDER_EEVEE' on 5.0+, 'BLENDER_EEVEE_NEXT' on 4.2-4.5.
+        scene.render.engine = 'BLENDER_EEVEE' if bpy.app.version >= (5, 0, 0) else 'BLENDER_EEVEE_NEXT'
+    else:
+        scene.render.engine = args.engine
     scene.render.image_settings.file_format = 'PNG'
 
     output_dir = os.path.dirname(args.output) or "."
@@ -185,7 +189,7 @@ if __name__ == "__main__":
 Notes:
 
 - `bpy.ops.render.render(write_still=True)` is one of the few `bpy.ops` calls that work in `--background`.
-- `BLENDER_EEVEE_NEXT` is the 5.x EEVEE engine identifier. On 4.5 LTS, use `BLENDER_EEVEE`. Detect via `bpy.app.version`.
+- EEVEE's engine identifier is `BLENDER_EEVEE` on Blender 5.0+ and `BLENDER_EEVEE_NEXT` on 4.2-4.5 LTS (the id was reclaimed in 5.0 after legacy EEVEE was removed in 4.2). Detect via `bpy.app.version`.
 
 ## Detecting Blender version in scripts
 
@@ -195,9 +199,9 @@ import bpy
 major, minor, _patch = bpy.app.version
 
 if (major, minor) >= (5, 0):
-    eevee_engine = 'BLENDER_EEVEE_NEXT'
-else:
     eevee_engine = 'BLENDER_EEVEE'
+else:
+    eevee_engine = 'BLENDER_EEVEE_NEXT'
 ```
 
 `bpy.app.version` is a `(major, minor, patch)` tuple, always reliable.

skills/procedural-materials-and-shaders/SKILL.md

@@ -162,7 +162,7 @@ When the same subgraph appears across multiple materials, factor it into a `Shad
 | --- | --- | --- | --- |
 | Principled BSDF | `ShaderNodeBsdfPrincipled` | Same | Some inputs renamed in 5.0; `Specular` -> `Specular IOR Level`. Use string lookup with the 5.x name. |
 | Node group socket interface | `group.inputs.new` / `group.outputs.new` | `group.interface.new_socket` | Different APIs, see snippet `shader-node-group.py`. |
-| EEVEE engine string | `'BLENDER_EEVEE'` | `'BLENDER_EEVEE_NEXT'` | EEVEE Next is the default in 5.x; legacy EEVEE was retired. |
+| EEVEE engine string | `'BLENDER_EEVEE_NEXT'` | `'BLENDER_EEVEE'` | Legacy EEVEE was removed in 4.2. EEVEE Next used the id `'BLENDER_EEVEE_NEXT'` on 4.2-4.5, then reclaimed the plain `'BLENDER_EEVEE'` id in 5.0. |
 | Layered Textures | Not present | Not present in 5.1 | Roadmap pushed to 2027. Do not generate code referencing it. |
 
 EEVEE Next stabilized in Blender 5.1 with material caching and feature parity improvements; most Principled BSDF graphs render identically across EEVEE Next and Cycles.