Doc: Add tracker humanization and sample offset features

Specifies sample offset (shift trigger left) and humanization (per-note timing/volume variation) for realistic playback.

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

1 files changed, 18 insertions, 1 deletions

diff --git a/TODO.md b/TODO.md
index 3734ec6..072efe2 100644
--- a/TODO.md
+++ b/TODO.md
@@ -46,7 +46,24 @@ Enhanced CNN post-processing with multi-dimensional feature inputs.
 
 ---
 
-## Priority 3: 3D System Enhancements (Task #18)
+## Priority 3: Tracker Humanization & Sample Offset
+
+Enhance tracker with sample offset and humanization for realistic playback.
+
+**Features:**
+1. **Sample Offset:** Intrinsic offset value per sample (shifts trigger left, preserves beat sync)
+   - Add `offset_sec` to `NoteParams` (gen.h) and `Sample` struct
+   - Extend `.track` SAMPLE syntax: `SAMPLE <name> [OFFSET <sec>] [VOL <vol>]`
+   - Apply negative `start_offset_samples` in `trigger_note_event()`
+
+2. **Humanization:** Per-note random timing/volume variation (baked into WAV export)
+   - Add to `TrackerScore`: `humanize_seed`, `timing_variation_pct`, `volume_variation_pct`
+   - `.track` syntax: `HUMANIZE SEED <int> TIMING <pct> VOLUME <pct>`
+   - Apply per-event RNG modulation in `tracker_update()`
+
+---
+
+## Priority 4: 3D System Enhancements (Task #18)
 
 Pipeline for importing complex 3D scenes to replace hardcoded geometry.