feat(sequence): complete v2 migration with DAG-based routing

Phase 4 complete: V1 system removed, v2 fully operational.

Architecture Changes:
- Explicit Node system with typed buffers (u8x4_norm, f32x4, depth24)
- DAG effect routing with multi-input/multi-output support
- Python compiler (seq_compiler_v2.py) with topological sort and ping-pong optimization
- Compile-time node aliasing for framebuffer reuse

V1 Removal (~4KB):
- Deleted effect.h/cc base classes (1.4KB)
- Deleted 19 v1 effect pairs: heptagon, particles, passthrough, gaussian_blur,
  solarize, scene1, chroma_aberration, vignette, hybrid_3d, flash_cube,
  theme_modulation, fade, flash, circle_mask, rotating_cube, sdf_test,
  distort, moving_ellipse, particle_spray (2.7KB)

V2 Effects Ported:
- PassthroughEffectV2, PlaceholderEffectV2
- GaussianBlurEffectV2 (multi-pass with temp nodes)
- HeptagonEffectV2 (scene effect with dummy texture)
- ParticlesEffectV2 (compute + render, format fixed)
- RotatingCubeEffectV2 (3D with depth node)
- Hybrid3DEffectV2 (Renderer3D integration, dummy textures for noise/sky)

Compiler Features:
- DAG validation (cycle detection, connectivity checks)
- Topological sort for execution order
- Ping-pong optimization (aliased node detection)
- Surface-based and encoder-based RenderV2Timeline generation
- init_effect_nodes() automatic generation

Fixes Applied:
- WebGPU binding layout validation (standard v2 post-process layout)
- Surface format mismatch (ctx.format for blit, RGBA8Unorm for framebuffers)
- Depth attachment compatibility (removed forced depth from gpu_create_render_pass)
- Renderer3D texture initialization (created dummy 1x1 white textures)
- ParticlesEffectV2 format (changed from ctx.format to RGBA8Unorm)
- Encoder-based RenderV2Timeline (added missing preprocess() call)

Testing:
- 34/36 tests passing (2 v1-dependent tests disabled)
- demo64k runs successfully (no crashes)
- All seek positions work (--seek 12, --seek 15 validated)

Documentation:
- Updated PROJECT_CONTEXT.md (v2 status, reference to SEQUENCE_v2.md)
- Added completion entry to COMPLETED.md

TODO (Future):
- Port CNN effects to v2
- Implement flatten mode (--flatten code generation)
- Port remaining 10+ effects
- Update HTML timeline editor for v2 (deferred)

handoff(Claude): Sequence v2 migration complete, v1 removed, system operational.
Phase 5 (editor) deferred per user preference.

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

1 files changed, 0 insertions, 147 deletions

diff --git a/src/effects/hybrid_3d_effect.cc b/src/effects/hybrid_3d_effect.cc
deleted file mode 100644
index 61f3165..0000000
--- a/src/effects/hybrid_3d_effect.cc
+++ /dev/null
@@ -1,147 +0,0 @@
-// This file is part of the 64k demo project.
-// It implements the Hybrid3DEffect.
-
-#include "effects/hybrid_3d_effect.h"
-#include "generated/assets.h"
-#include "util/asset_manager_utils.h"
-#include <cassert>
-#include <cmath>
-#include <iostream>
-
-Hybrid3DEffect::Hybrid3DEffect(const GpuContext& ctx) : Effect(ctx) {
-}
-
-void Hybrid3DEffect::resize(int width, int height) {
-  if (width == width_ && height == height_)
-    return;
-
-  Effect::resize(width, height);
-
-  if (!initialized_)
-    return;
-
-  renderer_.resize(width_, height_);
-}
-
-void Hybrid3DEffect::init(MainSequence* demo) {
-  (void)demo;
-  WGPUTextureFormat format =
-      demo->gpu_ctx.format; // Get current format from MainSequence (might be
-                            // different than constructor if resized)
-
-  renderer_.init(ctx_.device, ctx_.queue, ctx_.format);
-  renderer_.resize(width_, height_);
-  initialized_ = true;
-
-  // Texture Manager
-  texture_manager_.init(ctx_.device, ctx_.queue);
-
-  // Load Noise Asset
-  TextureAsset noise_tex = GetTextureAsset(AssetId::ASSET_NOISE_TEX);
-  if (noise_tex.pixels && noise_tex.width == 256 && noise_tex.height == 256) {
-    texture_manager_.create_texture("noise", noise_tex.width, noise_tex.height,
-                                    noise_tex.pixels);
-    renderer_.set_noise_texture(texture_manager_.get_texture_view("noise"));
-  } else {
-    std::cerr << "Failed to load NOISE_TEX asset." << std::endl;
-  }
-
-  // Setup Scene
-  scene_.clear();
-  Object3D center(ObjectType::BOX); // Use BOX for bumps
-  center.position = vec3(0, 0, 0);
-  center.color = vec4(1, 0, 0, 1);
-  scene_.add_object(center);
-
-  for (int i = 0; i < 8; ++i) {
-    ObjectType type = ObjectType::SPHERE;
-    if (i % 3 == 1)
-      type = ObjectType::TORUS;
-    if (i % 3 == 2)
-      type = ObjectType::BOX;
-
-    Object3D obj(type);
-
-    float angle = (i / 8.0f) * 6.28318f;
-
-    obj.position = vec3(std::cos(angle) * 4.0f, 0, std::sin(angle) * 4.0f);
-
-    obj.scale = vec3(0.7f, 0.7f, 0.7f); // Increased scale by 40%
-
-    if (type == ObjectType::SPHERE)
-      obj.color = vec4(0, 1, 0, 1);
-
-    else if (type == ObjectType::TORUS)
-      obj.color = vec4(0, 0.5, 1, 1);
-    else
-      obj.color = vec4(1, 1, 0, 1);
-
-    scene_.add_object(obj);
-  }
-}
-
-// Cubic ease-in/out function for non-linear motion
-
-static float ease_in_out_cubic(float t) {
-  t *= 2.0f;
-
-  if (t < 1.0f) {
-    return 0.5f * t * t * t;
-  }
-
-  t -= 2.0f;
-
-  return 0.5f * (t * t * t + 2.0f);
-}
-
-void Hybrid3DEffect::render(WGPURenderPassEncoder pass,
-                            const CommonPostProcessUniforms& uniforms) {
-  // Animate Objects
-
-  for (size_t i = 1; i < scene_.objects.size(); ++i) {
-    scene_.objects[i].rotation =
-        quat::from_axis(vec3(0, 1, 0), uniforms.time * 2.0f + i);
-
-    scene_.objects[i].position.y = std::sin(uniforms.time * 3.0f + i) * 1.5f;
-  }
-
-  // Camera jumps every other pattern (2 seconds) for dramatic effect
-  int pattern_num = (int)(uniforms.time / 2.0f);
-  int camera_preset = pattern_num % 4; // Cycle through 4 different angles
-
-  vec3 cam_pos, cam_target;
-
-  switch (camera_preset) {
-  case 0: // High angle, orbiting
-  {
-    float angle = uniforms.time * 0.5f;
-    cam_pos = vec3(std::sin(angle) * 12.0f, 8.0f, std::cos(angle) * 12.0f);
-    cam_target = vec3(0, 0, 0);
-  } break;
-  case 1: // Low angle, close-up
-  {
-    float angle = uniforms.time * 0.3f + 1.57f; // Offset angle
-    cam_pos = vec3(std::sin(angle) * 6.0f, 2.0f, std::cos(angle) * 6.0f);
-    cam_target = vec3(0, 1, 0);
-  } break;
-  case 2: // Side view, sweeping
-  {
-    float sweep = std::sin(uniforms.time * 0.4f) * 10.0f;
-    cam_pos = vec3(sweep, 5.0f, 8.0f);
-    cam_target = vec3(0, 0, 0);
-  } break;
-  case 3: // Top-down, rotating
-  {
-    float angle = uniforms.time * 0.6f;
-    cam_pos = vec3(std::sin(angle) * 5.0f, 12.0f, std::cos(angle) * 5.0f);
-    cam_target = vec3(0, 0, 0);
-  } break;
-  }
-
-  camera_.set_look_at(cam_pos, cam_target, vec3(0, 1, 0));
-  camera_.aspect_ratio = uniforms.aspect_ratio;
-
-  // Draw
-
-  renderer_.draw(pass, scene_, camera_, uniforms.time);
-}