CNN v2: Add TODO for flexible feature layout in binary format v3

Document future enhancement for arbitrary feature vector layouts.

Proposed feature descriptor in binary format v3:
- Specify feature types, sources, and ordering
- Enable runtime experimentation without shader recompilation
- Examples: [R,G,B,dx,dy,uv_x,bias] or [mip1.r,mip2.g,laplacian,uv_x,sin20_x,bias]

Added TODOs in:
- CNN_V2_BINARY_FORMAT.md: Detailed proposal with struct layout
- CNN_V2.md: Future extensions section
- train_cnn_v2.py: compute_static_features() docstring
- cnn_v2_static.wgsl: Shader header comment
- cnn_v2_effect.cc: Version check comment

Current limitation: Hardcoded [p0,p1,p2,p3,uv_x,uv_y,sin10_x,bias] layout.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/gpu/effects/cnn_v2_effect.cc b/src/gpu/effects/cnn_v2_effect.cc
index 97e4790..566686e 100644
--- a/src/gpu/effects/cnn_v2_effect.cc
+++ b/src/gpu/effects/cnn_v2_effect.cc
@@ -88,6 +88,7 @@ void CNNv2Effect::load_weights() {
   FATAL_CHECK(magic != 0x324e4e43, "Invalid CNN v2 weights magic\n");  // 'CNN2'
 
   // Support both version 1 (16-byte header) and version 2 (20-byte header with mip_level)
+  // TODO: Version 3 should include feature descriptor for arbitrary layout/ordering
   if (version == 1) {
     mip_level_ = 0;  // Default for v1
   } else if (version == 2) {