docs: update temporal feedback docs — wire_dag auto-wiring, F16X8 formatHEADmain

- HOWTO.md: replace manual set_cnn_output_node() instructions with
  wire_dag() auto-wiring explanation; add timeline.seq snippet as canonical
  wiring example; document F16X8/GBUF_ALBEDO format requirement
- CNN_V3.md: fix prev_tex format (rgba16float, not rgba8unorm);
  mark timeline.seq CNNv3Effect TODO as done
- SEQUENCE.md: already updated in previous commit (wire_dag pattern,
  format-matching rule, sink guard)

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

1 files changed, 6 insertions, 2 deletions

diff --git a/doc/SEQUENCE.md b/doc/SEQUENCE.md
index ca45756..3d7a6ce 100644
--- a/doc/SEQUENCE.md
+++ b/doc/SEQUENCE.md
@@ -132,7 +132,8 @@ class MyEffect : public Effect {
   void set_source_node(const std::string& n) { source_node_ = n; }
 
   void declare_nodes(NodeRegistry& reg) override {
-    reg.declare_node(node_prev_, NodeType::U8X4_NORM, -1, -1);
+    // Use a NodeType whose format matches source_node_ and has CopyDst.
+    reg.declare_node(node_prev_, NodeType::F16X8, -1, -1);
   }
 
   void render(...) override {
@@ -221,7 +222,10 @@ if (!src_tex) return;  // external view — no owned texture to copy
 - `GBUF_RGBA32UINT`: RGBA32Uint — packed feature textures (CNN v3 feat_tex0/1); `STORAGE_BINDING|TEXTURE_BINDING`
 
 **`COPY_SRC|COPY_DST`** is required on any node used with `wgpuCommandEncoderCopyTextureToTexture`.
-`U8X4_NORM` has both; use it for temporal feedback dest nodes.
+The `node_prev_` format **must match** the source texture format exactly —
+`CopyTextureToTexture` requires identical formats.  `F16X8` (Rgba16Float,
+`CopySrc|CopyDst`) matches `GBUF_ALBEDO` (CNNv3Effect output).  Use `U8X4_NORM`
+only when the source is also Rgba8Unorm.
 
 **Aliasing**: Compiler detects ping-pong patterns (Effect i writes A reads B, Effect i+1 writes B reads A) and aliases nodes to same backing texture.