CNN v2: parametric static features - design doc

Design document for CNN v2 with enhanced feature inputs:
- 7D static features: RGBD + UV + sin encoding + bias
- Per-layer configurable kernels (1×1, 3×3, 5×5)
- Float16 weight storage (~6.4 KB vs 3.2 KB)
- Multi-pass architecture with static feature compute

Implementation plan:
1. Static features compute shader (RGBD + UV + sin + bias)
2. C++ effect class (CNNv2Effect)
3. Training pipeline (train_cnn_v2.py, export_cnn_v2_shader.py)
4. Validation tooling (validate_cnn_v2.sh)

Files:
- doc/CNN_V2.md: Complete technical design (architecture, training, export)
- scripts/validate_cnn_v2.sh: End-to-end validation script
- TODO.md: Add CNN v2 as Priority 2 task
- doc/HOWTO.md: Add CNN v2 validation usage

Target: <10 KB for 64k demo constraint

handoff(Claude): CNN v2 design ready for implementation

1 files changed, 16 insertions, 0 deletions

diff --git a/doc/HOWTO.md b/doc/HOWTO.md
index d02fdb4..2b896ab 100644
--- a/doc/HOWTO.md
+++ b/doc/HOWTO.md
@@ -130,6 +130,22 @@ Processes entire image with sliding window (matches WGSL):
 
 **Kernel sizes:** 3×3 (36 weights), 5×5 (100 weights), 7×7 (196 weights)
 
+### CNN v2 Validation
+
+End-to-end testing: checkpoint → shaders → build → test images → results
+
+```bash
+./scripts/validate_cnn_v2.sh checkpoints/checkpoint_epoch_5000.pth
+
+# Options:
+#   -i DIR     Test images directory (default: training/validation)
+#   -o DIR     Output directory (default: validation_results)
+#   --skip-build   Use existing cnn_test binary
+#   -h         Show all options
+```
+
+See `scripts/validate_cnn_v2.sh --help` for full usage. See `doc/CNN_V2.md` for design details.
+
 ---
 
 ## Timeline