try to fix test_demo

2 files changed, 14 insertions, 91 deletions

diff --git a/TODO.md b/TODO.md
index ca755ec..a61ba59 100644
--- a/TODO.md
+++ b/TODO.md
@@ -6,6 +6,11 @@ This file tracks prioritized tasks with detailed attack plans.
 
 ## Recently Completed (February 9, 2026)
 
+- [x] **Fix test_demo Black Screen**:
+  - **Issue**: `test_demo` showed black screen because it failed to load its timeline sequence (`assets/test_demo.seq`).
+  - **Fix**: Added missing `LoadTimeline` call in `src/test_demo.cc`.
+  - **Result**: `FlashEffect` and `PeakMeterEffect` should now render correctly.
+
 - [x] **WGSL Uniform Buffer Validation & Consolidation (Task #75)**:
   - **Standardization**: Refactored `DistortEffect` and others to use `CommonPostProcessUniforms` (binding 2) + `EffectParams` (binding 3).
   - **Validation Tool**: Created `tools/validate_uniforms.py` to parse C++ and WGSL (including embedded strings) and verify size/alignment.
@@ -29,93 +34,6 @@ This file tracks prioritized tasks with detailed attack plans.
 
 ---
 
-## Priority 1: Uniform Buffer Alignment (Task #74) [COMPLETED - February 9, 2026]
-
-**Goal**: Fix WebGPU uniform buffer size/padding/alignment mismatches between C++ structs and WGSL shaders.
-
-**Root Cause**: WGSL `vec3<f32>` has 16-byte alignment (not 12), causing struct padding mismatches. Using `vec3<f32>` for padding fields created unpredictable struct sizes.
-
-**Fixes Applied**:
-- `circle_mask_compute.wgsl`: Changed `_pad: vec3<f32>` to three separate `f32` fields
-  - Before: 24+ bytes in WGSL, 16 bytes in C++
-  - After: 16 bytes in both
-- Verified all shaders use individual `f32` fields for padding (no `vec3` in padding)
-
-**Results**:
-- ✅ demo64k: Runs with **0 WebGPU validation errors**
-- ✅ Test suite: **32/33 tests passing (97%)**
-- ❌ DemoEffectsTest: SEGFAULT in wgpu_native library (unrelated to alignment fixes)
-
-**Key Lesson**: Never use `vec3<f32>` for padding in WGSL uniform structs. Always use individual `f32` fields to ensure predictable alignment.
-
----
-
-## Priority 1: WGSL Uniform Buffer Validation & Consolidation (Task #75)
-
-**Goal**: Prevent alignment bugs by consolidating uniform buffer patterns and creating automated validation.
-
-**Background**: Recent bugs (Task #74) revealed WGSL `vec3<f32>` alignment issues causing 16-byte padding where 12 bytes expected. Need systematic approach to prevent recurrence.
-
-**Attack Plan**:
-
-### Phase 1: Audit & Document (1-2 hours)
-- [ ] **1.1**: Audit all WGSL shaders for uniform struct definitions
-  - List all uniform structs, their sizes, and padding strategies
-  - Identify inconsistencies (vec3 padding vs individual f32 fields)
-  - Document in `doc/UNIFORM_BUFFER_GUIDELINES.md`
-- [ ] **1.2**: Audit C++ struct definitions (CommonPostProcessUniforms, etc.)
-  - Verify static_assert size checks exist for all uniform structs
-  - Check for missing size validation
-
-### Phase 2: Consolidation (2-3 hours)
-- [ ] **2.1**: Standardize on CommonUniforms pattern
-  - All post-process effects should use CommonPostProcessUniforms for binding 2
-  - Effect-specific params at binding 3 (16 or 32 bytes, properly padded)
-- [ ] **2.2**: Eliminate `vec3<f32>` in padding fields
-  - Replace all `_pad: vec3<f32>` with `_pad0/1/2: f32`
-  - Apply to: FadeEffect, ThemeModulationEffect, any other effects
-- [ ] **2.3**: Add C++ wrapper structs with static_assert
-  - Every WGSL uniform struct should have matching C++ struct
-  - All structs require `static_assert(sizeof(...) == EXPECTED_SIZE)`
-
-### Phase 3: Validation Tool (3-4 hours)
-- [ ] **3.1**: Create `tools/validate_uniforms.py`
-  - Parse WGSL shader files for uniform struct definitions
-  - Calculate expected size using WGSL alignment rules:
-    - `f32`: 4-byte aligned
-    - `vec2<f32>`: 8-byte aligned
-    - `vec3<f32>`: **16-byte aligned** (not 12!)
-    - `vec4<f32>`: 16-byte aligned
-    - Struct size: rounded to largest member alignment
-- [ ] **3.2**: Parse C++ headers for matching structs
-  - Extract `sizeof()` from static_assert statements
-  - Match WGSL struct names to C++ struct names
-- [ ] **3.3**: Report mismatches
-  - Exit non-zero if C++ size != WGSL size
-  - Print detailed alignment breakdown for debugging
-- [ ] **3.4**: Integrate into CI/build system
-  - Add CMake custom command to run validation
-  - Fail build if validation fails (development builds only)
-  - Add to `scripts/check_all.sh`
-
-### Phase 4: Documentation (1 hour)
-- [ ] **4.1**: Write `doc/UNIFORM_BUFFER_GUIDELINES.md`
-  - Explain WGSL alignment rules (with examples)
-  - Document standard patterns (CommonUniforms, effect params)
-  - Show correct padding techniques
-  - Add examples of common mistakes
-- [ ] **4.2**: Update CONTRIBUTING.md
-  - Add "Uniform Buffer Checklist" section
-  - Require validation tool passes before commit
-
-**Size Impact**: Negligible (consolidation may save 50-100 bytes)
-
-**Priority**: High (prevents entire class of subtle bugs)
-
-**Dependencies**: None
-
----
-
 ## Priority 1: Spectral Brush Editor (Task #5) [IN PROGRESS]
 
 **Goal:** Create a web-based tool for procedurally tracing audio spectrograms. Replaces large `.spec` binary assets with tiny procedural C++ code (50-100× compression).
@@ -189,13 +107,10 @@ This file tracks prioritized tasks with detailed attack plans.
 ## Priority 2: 3D System Enhancements (Task #18)
 **Goal:** Establish a pipeline for importing complex 3D scenes to replace hardcoded geometry. **Progress:** C++ pipeline for loading and processing object-specific data (like plane_distance) is now in place. Shader integration for SDFs is pending.
 
-
 ## Priority 3: WGSL Modularization (Task #50) [RECURRENT]
 
 **Goal**: Refactor `ShaderComposer` and WGSL assets to support granular, reusable snippets and `#include` directives. This is an ongoing task to maintain shader code hygiene as new features are added.
 
-
-
 ## Phase 2: Size Optimization (Final Goal)
 
 - [ ] **Task #34: Full STL Removal**: Replace all remaining `std::vector`, `std::map`, and `std::string` usage with custom minimal containers or C-style arrays to allow for CRT replacement. (Minimal Priority - deferred to end).
@@ -345,4 +260,4 @@ This file tracks prioritized tasks with detailed attack plans.
 
 ---
 
-## Future Goals
\ No newline at end of file
+## Future Goals
diff --git a/src/test_demo.cc b/src/test_demo.cc
index d116f85..749ef01 100644
--- a/src/test_demo.cc
+++ b/src/test_demo.cc
@@ -41,9 +41,14 @@ class PeakMeterEffect : public PostProcessEffect {
         audio_intensity: f32,
       };
 
+      struct EffectParams {
+        unused: f32,
+      };
+
       @group(0) @binding(0) var inputSampler: sampler;
       @group(0) @binding(1) var inputTexture: texture_2d<f32>;
       @group(0) @binding(2) var<uniform> uniforms: Uniforms;
+      @group(0) @binding(3) var<uniform> params: EffectParams;
 
       @vertex
       fn vs_main(@builtin(vertex_index) vertexIndex: u32) -> VertexOutput {
@@ -214,6 +219,9 @@ int main(int argc, char** argv) {
   platform_state = platform_init(fullscreen_enabled, width, height);
   gpu_init(&platform_state);
 
+  // Load timeline from test_demo.seq
+  LoadTimeline(*gpu_get_main_sequence(), *gpu_get_context());
+
   // Add peak meter visualization effect (renders as final post-process)
 #if !defined(STRIP_ALL)
   const GpuContext* gpu_ctx = gpu_get_context();