docs: update PROJECT_CONTEXT, TODO, COMPLETED for OLA-IDCT

- PROJECT_CONTEXT: audio section reflects OLA-IDCT (Hann, 50% overlap);
  test count 35->34; Next Up notes .spec regen needed
- TODO: remove stale MP3 sub-task (done), trim test TODOs, add .spec
  regen as Priority 3, update test count to 34/34
- COMPLETED: archive OLA-IDCT task with implementation summary

3 files changed, 27 insertions, 31 deletions

diff --git a/PROJECT_CONTEXT.md b/PROJECT_CONTEXT.md
index bce4d67..29395e7 100644
--- a/PROJECT_CONTEXT.md
+++ b/PROJECT_CONTEXT.md
@@ -12,7 +12,7 @@
 ## Audio
 - 32 kHz, 16-bit stereo
 - Procedurally generated samples
-- Real-time additive synthesis from spectrograms (IDCT)
+- Real-time additive synthesis from spectrograms (OLA-IDCT, Hann window, 50% overlap)
 - Variable tempo system with music time abstraction
 - Event-based pattern triggering for dynamic tempo scaling
 - Modifiable Loops and Patterns, w/ script to generate them (like a Tracker)
@@ -33,21 +33,21 @@
 
 - **Timing System:** **Beat-based timelines** for musical synchronization. Sequences defined in beats, converted to seconds at runtime. Effects receive both physical time (constant) and beat time (musical). Variable tempo affects audio only. See `doc/BEAT_TIMING.md`.
 - **Workspace system:** Multi-workspace support. Easy switching with `-DDEMO_WORKSPACE=<name>`. Organized structure: `music/`, `weights/`, `obj/`, `shaders/`. Shared common shaders in `src/shaders/`. See `doc/WORKSPACE_SYSTEM.md`.
-- **Audio:** Sample-accurate sync. Zero heap allocations per frame. Variable tempo. Comprehensive tests.
+- **Audio:** Sample-accurate sync. Zero heap allocations per frame. Variable tempo. OLA-IDCT synthesis (v2 .spec): Hann window, 50% overlap, click-free. V1 (raw DCT-512) preserved for compatibility. MP3→spec encoder updated to match. Existing .spec files need regen to activate v2.
 - **Shaders:** Parameterized effects (UniformHelper, .seq syntax). Beat-synchronized animation support (`beat_time`, `beat_phase`). Modular WGSL composition with ShaderComposer. 24 shared common shaders (math, render, compute).
 - **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.
 - **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. 10 effects operational (Passthrough, Placeholder, GaussianBlur, Heptagon, Particles, RotatingCube, Hybrid3D, Flash, PeakMeter, Scene1). Effect times are absolute (seq_compiler adds sequence start offset). See `doc/SEQUENCE.md`.
-- **Testing:** **35/35 passing**. Fixed intermittent SIGTRAP in effect lifecycle tests.
+- **Testing:** **34/34 passing**.
 
 ---
 
 ## Next Up
 
-**Active:** Spectral Brush Editor (procedural compression), CNN v2 quantization
-**Ongoing:** Test infrastructure maintenance (35/35 passing)
+**Active:** Spectral Brush Editor (procedural compression), CNN v2 quantization, .spec v2 regen (OLA)
+**Ongoing:** Test infrastructure maintenance (34/34 passing)
 **Future:** Size optimization (64k target), 3D enhancements
 
 See `TODO.md` for details.
diff --git a/TODO.md b/TODO.md
index be4c0e8..c0f8bb1 100644
--- a/TODO.md
+++ b/TODO.md
@@ -21,44 +21,31 @@ Reduce weights from f16 (~3.2 KB) to i8 (~1.6 KB).
 
 ---
 
-## Priority 3: Test Infrastructure Maintenance [ONGOING]
+## Priority 3: Regenerate .spec files as v2 [REQUIRED]
 
-**Status:** 35/35 tests passing
+Existing `.spec` files in `workspaces/main/music/` were encoded with v1 (no overlap).
+Rebuild with the MP3 assets to produce v2 (OLA, Hann, hop=256) — click-free output.
 
-**Outstanding TODOs:**
-
-1. **test_effect_base.cc:250** - [FIXED] Fix SIGTRAP in `test_sequence_render()`
-   - Added `wgpuDeviceTick()` to wait for GPU to finish, resolving the intermittent crash.
-   - All other tests validate the same functionality
-   - Issue: Hangs/crashes during render with external sink view
-
-2. **test_sequence.cc** - Port legacy sequence tests (currently disabled)
-   - Uses legacy Effect/MainSequence system
-   - Lines 168, 173, 182: Re-enable lifecycle and simulation tests after port
+---
 
-3. **test_audio_engine.cc:152** - Re-enable commented test after debugging
+## Priority 4: Test Infrastructure Maintenance [ONGOING]
 
-4. **test_fft.cc:87** - Investigate FFT-DCT algorithm discrepancy
-   - May need different algorithm or fix existing one
+**Status:** 34/34 tests passing
 
+**Outstanding TODOs:**
 
-## Priority 4: Audio System Enhancements [LOW PRIORITY]
+1. **test_sequence.cc** - Port legacy sequence tests (currently disabled)
+   - Lines 168, 173, 182: Re-enable lifecycle and simulation tests after port
 
-Extended audio capabilities for sample assets and procedural synthesis.
+2. **test_audio_engine.cc:152** - Re-enable commented test after debugging
 
-**Sub-tasks:**
+3. **test_fft.cc:87** - Investigate FFT-DCT algorithm discrepancy
 
-1. **MP3 Sample Assets:**
-   - Integrate miniaudio for MP3 decoding
-   - Add ASSET_*.mp3 support to asset_packer
-   - Convert to PCM in AssetManager or synth on load
-   - Use case: Compressed sample libraries
+## Priority 4: Audio System Enhancements [LOW PRIORITY]
 
-2. **GPU-Accelerated PCM Synthesis:**
+1. **GPU-Accelerated PCM Synthesis:**
    - Compute shader for direct PCM generation (bypass spectrogram)
    - Write to compute buffer, readback to synth
-   - Use case: Real-time modulation, complex waveforms
-   - Lower latency than spectrogram path
 
 ---
 
diff --git a/doc/COMPLETED.md b/doc/COMPLETED.md
index 0dba307..e37ddbf 100644
--- a/doc/COMPLETED.md
+++ b/doc/COMPLETED.md
@@ -29,6 +29,15 @@ Detailed historical documents have been moved to `doc/archive/` for reference:
 
 Use `read @doc/archive/FILENAME.md` to access archived documents.
 
+## Recently Completed (March 2, 2026)
+
+- [x] **OLA-IDCT Synthesis — click-free .spec decoding**
+    - **Goal**: Eliminate frame-boundary clicks in spectrogram→PCM synthesis.
+    - **Implementation**: Added v2 spectrogram format (`SPEC_VERSION_V2_OLA`). Synthesis uses Hann-windowed IDCT with 50% overlap-add (hop=256, overlap=256). Per-voice `overlap_buf[256]` accumulates the tail from the previous IDCT frame. V1 path (raw DCT-512) preserved for generated notes and old `.spec` files. Hann window precomputed at `synth_init()`. MP3 encoder switched from Hamming to Hann, now slides a 512-sample analysis window by 256 samples per frame (OLA analysis), emitting ~2× as many frames. `SpecHeader.version` field propagated through `Spectrogram.version` to the voice's `ola_mode` flag at trigger time.
+    - **Files**: `src/audio/dct.h`, `src/audio/synth.h`, `src/audio/synth.cc`, `src/audio/window.h`, `src/audio/window.cc`, `src/audio/tracker.cc`
+    - **Tests**: 34/34 passing
+    - **Pending**: Regenerate `.spec` files from MP3 assets to activate v2 encoding.
+
 ## Recently Completed (February 21, 2026)
 
 - [x] **WGSL Refactor: getScreenCoord Helper**