feat(cnn_v3): Phase 3 complete — WGSL U-Net inference shaders

5 compute shaders + cnn_v3/common snippet:
  enc0: Conv(20→4,3×3) + FiLM + ReLU             full-res
  enc1: AvgPool + Conv(4→8,3×3) + FiLM + ReLU    half-res
  bottleneck: AvgPool + Conv(8→8,1×1) + ReLU     quarter-res
  dec1: NearestUp + cat(enc1) + Conv(16→4) + FiLM half-res
  dec0: NearestUp + cat(enc0) + Conv(8→4) + FiLM + Sigmoid full-res

Parity rules: zero-pad conv, AvgPool down, NearestUp, FiLM after
conv+bias, skip=concat, OIHW weights+bias layout. Matches PyTorch
train_cnn_v3.py forward() exactly.

Registered in workspaces/main/assets.txt + src/effects/shaders.cc.
Weight layout + Params struct documented in cnn_v3/docs/HOWTO.md §7.

Next: Phase 4 — C++ CNNv3Effect + FiLM uniform upload.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/PROJECT_CONTEXT.md b/PROJECT_CONTEXT.md
index cadd514..f42ccf4 100644
--- a/PROJECT_CONTEXT.md
+++ b/PROJECT_CONTEXT.md
@@ -36,7 +36,7 @@
 - **Audio:** Sample-accurate sync. Zero heap allocations per frame. Variable tempo. OLA-IDCT synthesis (v2 .spec): Hann analysis window, rectangular synthesis, 50% overlap, click-free. V1 (raw DCT-512) preserved for generated notes. .spec files regenerated as v2.
 - **Shaders:** Parameterized effects (UniformHelper, .seq syntax). Beat-synchronized animation support (`beat_time`, `beat_phase`). Modular WGSL composition with ShaderComposer. 27 shared common shaders (math, render, compute). Reusable snippets: `render/scratch_lines`, `render/ntsc_common` (NTSC signal processing, RGB and YIQ input variants via `sample_ntsc_signal` hook), `math/color` (YIQ/NTSC), `math/color_c64` (C64 palette, Bayer dither, border animation).
 - **3D:** Hybrid SDF/rasterization with BVH. Binary scene loader. Blender pipeline.
-- **Effects:** CNN post-processing: CNNEffect (v1) and CNNv2Effect operational. CNN v2: sigmoid activation, storage buffer weights (~3.2 KB), 7D static features, dynamic layers. Training stable, convergence validated. **CNN v3 Phase 1 complete:** `GBufferEffect` integrated (MRT raster + pack compute, 20-channel feature textures). See `cnn_v3/docs/HOWTO.md`.
+- **Effects:** CNN post-processing: CNNEffect (v1) and CNNv2Effect operational. CNN v2: sigmoid activation, storage buffer weights (~3.2 KB), 7D static features, dynamic layers. Training stable, convergence validated. **CNN v3 Phase 3 complete:** 5 WGSL inference shaders (enc0/enc1/bottleneck/dec1/dec0) + `cnn_v3/common` snippet. Zero-pad convs, AvgPool down, NearestUp, FiLM, skip-concat, sigmoid output. Registered in assets + shaders.cc. See `cnn_v3/docs/HOWTO.md` §7.
 - **Tools:** CNN test tool operational. Texture readback utility functional. Timeline editor (web-based, beat-aligned, audio playback).
 - **Build:** Asset dependency tracking. Size measurement. Hot-reload (debug-only). WSL (Windows 10) supported: native Linux build and cross-compile to `.exe` via `mingw-w64`.
 - **Sequence:** DAG-based effect routing with explicit node system. Python compiler with topological sort and ping-pong optimization. 12 effects operational (Passthrough, Placeholder, GaussianBlur, Heptagon, Particles, RotatingCube, Hybrid3D, Flash, PeakMeter, Scene1, Scene2, Scratch). Effect times are absolute (seq_compiler adds sequence start offset). See `doc/SEQUENCE.md`.
@@ -46,7 +46,7 @@
 
 ## Next Up
 
-**Active:** CNN v3 Phase 3 (WGSL U-Net shaders), Spectral Brush Editor
+**Active:** CNN v3 Phase 4 (C++ CNNv3Effect + FiLM uniform), Spectral Brush Editor
 **Ongoing:** Test infrastructure maintenance (35/35 passing)
 **Future:** Size optimization (64k target), 3D enhancements