Allow generic Vector2 face-corner attributes that aren’t treated as UV layers

Description

Currently, any mesh attribute with domain='CORNER' and data_type='FLOAT2' is automatically recognized as a UV layer in Blender 4.3 and later.

This makes it impossible to store non-UV per-corner Vector2 data (for example, procedural coordinates, mapping data, or custom geometry information) without cluttering the UV Layers panel or being interpreted by exporters as TEXCOORD data.

Proposed Solution

Add a simple property to bpy.types.Attribute , for example:

bpy.types.Attribute.role = Enum(('AUTO', 'UV', 'GENERIC'))

Only attributes with role='UV' would be listed as UV layers. Attributes with role='GENERIC' would remain accessible through mesh.attributes but stay hidden from the UV UI and ignored by exporters that only handle UV data.

Existing UV maps would default to role='UV' , preserving full backward compatibility.

Example

import bpy

mesh = bpy.data.meshes.new("Example")
mesh.from_pydata([(0,0,0),(1,0,0),(0,1,0)], [], [(0,1,2)])

# Create a per-corner 2D attribute for generic data
attr = mesh.attributes.new("CornerData", 'FLOAT2', 'CORNER')

print(mesh.uv_layers.keys())
# Current: includes "CornerData" as a UV layer (unwanted)
# Proposed: only visible if attr.role == 'UV'

Benefits

• Prevents non-UV attributes from cluttering UV layers and the UV Editor
• Keeps exporters and add-ons from misinterpreting custom Vector2 attributes
• Fully backward compatible with existing files and workflows
• Minimal implementation change with long-term flexibility