fix(cnn_v3): blender_export.py Blender 5 File Output node slots + file_name

- Prefer file_output_items over file_slots; use explicit is-None checks
  so empty collections do not fall through to the legacy attribute.
- Clear out_node.file_name so multilayer EXR frames are named 0001.exr
  instead of file_name0001.exr.

handoff(Gemini): blender_export.py now produces frames/0001.exr on Blender 5.0.1.

1 files changed, 5 insertions, 1 deletions

diff --git a/cnn_v3/training/blender_export.py b/cnn_v3/training/blender_export.py
index bb0d3d9..345f395 100644
--- a/cnn_v3/training/blender_export.py
+++ b/cnn_v3/training/blender_export.py
@@ -161,9 +161,13 @@ def configure_compositor(args):
     out_node.format.file_format = "OPEN_EXR_MULTILAYER"
     out_node.format.exr_codec = "ZIP"
     _set_output_path(out_node, args.output)
+    if hasattr(out_node, "file_name"):
+        out_node.file_name = ""  # Blender 5: clear prefix so output is just ####.exr
 
     # The node starts with one default slot; rename it first, then add the rest.
-    slots = getattr(out_node, "file_slots", None) or getattr(out_node, "file_output_items", None)
+    slots = getattr(out_node, "file_output_items", None)
+    if slots is None:
+        slots = getattr(out_node, "file_slots", None)
     if slots is None:
         candidates = [a for a in dir(out_node) if not a.startswith("__")]
         _die("cannot find slots attribute on CompositorNodeOutputFile.", candidates)