reaper-control/.sdd/changes/sidechain/tasks.md

Tasks: 808 Bass Sidechain Ducking

Phase 1: Schema — Foundation

• 1.1 Add CCEvent dataclass (controller: int, time: float, value: int) to src/core/schema.py
• 1.2 Add midi_cc: list[CCEvent] = field(default_factory=list) to ClipDef in src/core/schema.py
• 1.3 Update asdict if used; verify song.validate() passes with empty midi_cc

Phase 2: Kick Cache + CC Generation

• 2.1 Add constants _KICK_CONFIDENCE_THRESHOLD=0.6, _CC11_DIP=50, _CC11_HOLD=0.02, _CC11_RELEASE=0.18 to scripts/compose.py
• 2.2 Add _get_kick_cache(drumloop_paths: list[str], bpm: float) -> dict[str, list[float]] to scripts/compose.py
• 2.3 Modify build_bass_track() to accept kick_cache: dict[str, list[float]] parameter; generate CC events for kicks in range
• 2.4 Update main() to build kick cache from drumloop paths and pass to build_bass_track()

Phase 3: Builder CC Emission

• 3.1 Modify _build_midi_source() in src/reaper_builder/__init__.py to merge notes + cc events and emit E B0 0B {value:02x} lines
• 3.2 Verify delta cursor correctly advances across CC events (CC events contribute zero ticks)

Phase 4: Testing

• 4.1 Unit test CCEvent dataclass round-trip in tests/test_schema.py
• 4.2 Unit test _build_midi_source() emits B0 0B lines for clips with midi_cc
• 4.3 Integration test build_bass_track() populates midi_cc when kick cache present
• 4.4 Regression: run existing 261 tests, verify all pass unchanged