Files
reaper-control/.sdd/changes/presets-pack/spec.md
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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Markdown

# presets-pack Specification
## Purpose
Role-aware plugin preset system. Different track roles (bass/lead/chords/pad) get distinct preset data for the same plugin, replacing the current flat `{plugin: [chunks]}` lookup.
## Requirements
### Requirement: Role-Aware Preset Structure
`PLUGIN_PRESETS` MUST be restructured from `dict[str, list[str]]` (plugin → chunks) to `dict[str, dict[str, list[str]]]` (plugin → {role → chunks}). The `"default"` role key SHALL contain the original unmodified preset. Lookup SHALL fall back to `"default"` when a role has no specific variant.
#### Scenario: Role-specific preset found
- GIVEN `PLUGIN_PRESETS["Serum_2"]["bass"]` and `["lead"]` exist
- WHEN resolving serum preset with `role="bass"`
- THEN bass-specific chunks are returned
- WHEN resolving with `role="lead"`
- THEN lead-specific chunks are returned
#### Scenario: Fallback to default
- GIVEN `PLUGIN_PRESETS["Decapitator"]["default"]` exists but `["pad"]` does not
- WHEN resolving Decapitator preset with `role="pad"`
- THEN the `"default"` preset data is returned
### Requirement: Preset Transformation Pipeline
The system SHALL provide a `PresetTransformer` that base64-decodes preset data, modifies role-specific parameters, and re-encodes. Each supported plugin MUST have its own decoder function keyed by plugin name.
| Plugin | Format | Modifications per role |
|--------|--------|----------------------|
| Serum_2 | base64 → JSON | Osc type (sine=0→bass, saw=1→lead), filter cutoff, FX bypass |
| Decapitator | base64 → key=value | Drive high→drums, Drive low→bass, Tone bright→drums, Tone dark→bass |
| Omnisphere | base64 → SynthMaster | Attack slow→pad, filter mod→pad, LFO rate up→pad |
#### Scenario: Serum bass variant
- GIVEN Serum_2 default preset decoded as JSON
- WHEN transformed for `role="bass"`
- THEN oscillator type set to sine (0), filter cutoff ≤ 200Hz
#### Scenario: Decapitator drums variant
- GIVEN Decapitator default preset decoded as key=value text
- WHEN transformed for `role="drums"`
- THEN `Drive=0.8`, `Tone=0.7`, `Style=A`
### Requirement: Round-Trip Integrity
Each preset transform MUST produce valid base64 output that decodes back to equivalent content. A round-trip test per (plugin, role) combination SHALL verify: `encode(decode(chunks)) == original_chunks`.
#### Scenario: Serum round-trip
- GIVEN Serum_2 preset chunks `[header, json_body, ...]`
- WHEN decoded, modified, re-encoded
- THEN all chunks maintain original length and base64 character set
- AND JSON body is valid JSON
#### Scenario: Decapitator round-trip
- GIVEN Decapitator preset chunks `[header, body, ...]`
- WHEN decoded, modified, re-encoded
- THEN chunk count matches, first chunk (header) unchanged
### Requirement: Role Propagation Through Pipeline
`make_plugin()` in `compose.py` and `_build_plugin()` in `__init__.py` MUST accept an optional `role: str | None` parameter. When role is provided, preset lookup SHALL use role-aware structure. `FX_CHAINS` layout is unchanged — role is the FX_CHAINS key (e.g., "bass", "lead").
#### Scenario: Bass track gets bass preset
- GIVEN `FX_CHAINS["bass"] = ["Serum_2", "Decapitator", ...]`
- WHEN `make_plugin("Serum_2", 0, role="bass")` is called
- THEN preset_data resolved from `PLUGIN_PRESETS["Serum_2"]["bass"]`
#### Scenario: Unknown plugin with role
- GIVEN plugin not in PLUGIN_PRESETS
- WHEN called with any role
- THEN returns PluginDef with `preset_data=None` (no crash)