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renato97 014e636889 feat: professional reggaeton production engine — 7 SDD changes, 302 tests

- section-energy: track activity matrix + volume/velocity multipliers per section
- smart-chords: ChordEngine with voice leading, inversions, 4 emotion modes
- hook-melody: melody engine with hook/stabs/smooth styles, call-and-response
- mix-calibration: Calibrator module (LUFS volumes, HPF/LPF, stereo, sends, master)
- transitions-fx: FX track with risers/impacts/sweeps at section boundaries
- sidechain: MIDI CC11 bass ducking on kick hits via DrumLoopAnalyzer
- presets-pack: role-aware plugin presets (Serum/Decapitator/Omnisphere per role)

Full SDD pipeline (propose→spec→design→tasks→apply→verify) for all 7 changes.
302/302 tests passing.

2026-05-03 23:54:29 -03:00

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Proposal: Smart Chord Engine

Intent

Current chord generation (build_chords_track) produces static root-position block chords with zero voice leading — every chord jump resets all 3 voices, producing audible jumps and amateur-sounding progressions. Add a ChordEngine class with voice leading, inversion selection, emotion modes, and genre-specific reggaeton progressions.

Scope

In Scope

New src/composer/chords.py with ChordEngine class
Voice leading: minimize semitone movement, max 4 semitone jump per voice
Inversion selection: root, first, second inversion
4 emotion modes: romantic, dark, club, classic
Genre-specific reggaeton chord progressions per emotion
Deterministic: seed-based reproducibility
Modify build_chords_track() in scripts/compose.py to use ChordEngine

Out of Scope

Seventh/suspended/diminished chord types (use existing CHORD_TYPES)
Real-time chord generation (only batch/offline)
Other genres beyond reggaeton
Chord rhythm/pattern generation (only chord selection + voicing)

Capabilities

New Capabilities

chord-engine: ChordEngine class with seed-based deterministic progression generation, voice leading, and inversion selection

Modified Capabilities

chords-track-generation: build_chords_track() delegates to ChordEngine instead of hardcoded i-VI-III-VII

Approach

Pure Python, zero new dependencies — all chord logic runs on MIDI note numbers using existing NOTE_NAMES, SCALE_INTERVALS, and CHORD_TYPES from composer/__init__.py.

Voice leading: score candidate voicings by total semitone distance from previous chord; select lowest-score candidate within the 4-semitone max-jump constraint.

Emotions → progression profiles:

Emotion	Degrees	Quality flavor
romantic	i-VI-III-VII	softer, wider voicings
dark	i-iv-V-v	minor-focused
club	i-VII-VI-V	driving, ascending
classic	i-VI-III-VII	tight block chords

Affected Areas

Area	Impact	Description
`src/composer/chords.py`	New	`ChordEngine` class
`scripts/compose.py`	Modify	`build_chords_track()` uses `ChordEngine`
`tests/test_chords.py`	New	Unit tests for voice leading, emotion modes, inversions

Risks

Risk	Likelihood	Mitigation
Voice leading sounds worse than static	Low	4-semitone cap prevents unnatural jumps; inversions smooth transitions
Emotion modes too similar	Med	Each has distinct degree set and quality bias

Rollback Plan

Revert build_chords_track() to hardcoded progression. Delete src/composer/chords.py. One commit.

Dependencies

None. Uses existing composer/__init__.py constants only.

Success Criteria

ChordEngine(seed=42).progression(8) returns identical output on repeated calls
No voice leap exceeds 4 semitones
All 4 emotion modes produce distinct chord sequences
build_chords_track() produces MIDI notes with <4 semitone jumps between consecutive chords
Existing tests pass unchanged

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