feat: SDD workflow — test sync, song generation + validation, ReaScript hybrid pipeline

- compose-test-sync: fix 3 failing tests (NOTE_TO_MIDI, DrumLoopAnalyzer mock, section name)
- generate-song: CLI wrapper + RPP validator (6 structural checks) + 4 e2e tests
- reascript-hybrid: ReaScriptGenerator + command protocol + CLI + 16 unit tests
- 110/110 tests passing
- Full SDD cycle (propose→spec→design→tasks→apply→verify) for all 3 changes

.sdd/changes/archive/2026-05-03-compose-test-sync/proposal.md

@@ -0,0 +1,59 @@
+# Proposal: compose-test-sync
+
+## Intent
+
+Sync 3 failing tests to the new compose.py API. The compose.py rewrite removed `root_to_midi` and `DrumLoopAnalyzer`, and changed `build_melody_track` signature. Tests are calling old APIs that no longer exist.
+
+## Scope
+
+### In Scope
+- Fix `test_melody_uses_pentatonic` — remove stale `analysis` arg and ensure single-section test works
+- Fix `test_main_without_render_produces_rpp` — remove obsolete `DrumLoopAnalyzer` mock
+- Fix `test_root_to_midi` — replace removed `root_to_midi` with `NOTE_TO_MIDI` dict lookup
+- Run full suite to confirm all 90 pass
+
+### Out of Scope
+- No new features
+- No compose.py changes — only test fixes
+
+## Capabilities
+
+> No spec-level capabilities change. Tests are sync fixes only.
+
+- None — test-only change, no capability modification
+
+## Approach
+
+1. **`test_root_to_midi`**: Replace `from scripts.compose import root_to_midi` with direct `NOTE_TO_MIDI` dict access. `root_to_midi` was removed; the constant `NOTE_TO_MIDI` ({"A": 69, "C": 60, ...}) is the correct replacement.
+
+2. **`test_main_without_render_produces_rpp`**: Remove both `patch("scripts.compose.SampleSelector")` and `patch("scripts.compose.DrumLoopAnalyzer")`. The rewrite moved drumloop logic to `build_drumloop_track` which uses `Path(ABLETON_DRUMLOOP_DIR)` directly — no class-based analyzer. Keep only `SampleSelector` patch if still needed for other path.
+
+3. **`test_melody_uses_pentatonic`**: The call signature is now `build_melody_track(sections, offsets, "A", True, seed=42)` — `analysis` arg removed. However `build_lead_track` (called by `build_melody_track`) only generates clips for sections named `chorus`, `chorus2`, or `final`. The test uses `"verse"` which produces zero clips. Fix: change section name to `"chorus"` OR add a second section named `"final"`.
+
+## Affected Areas
+
+| Area | Impact | Description |
+|------|--------|-------------|
+| `tests/test_section_builder.py` | Modified | Replace `root_to_midi` with `NOTE_TO_MIDI` |
+| `tests/test_render_cli.py` | Modified | Remove `DrumLoopAnalyzer` mock, adjust patches |
+| `tests/test_compose_integration.py` | Modified | Fix call signature, use chorus section |
+
+## Risks
+
+| Risk | Likelihood | Mitigation |
+|------|------------|------------|
+| Test fix breaks another test | Low | Run full suite after each change |
+| compose.py behavior changed unexpectedly | Low | 87/90 tests already pass |
+
+## Rollback Plan
+
+Revert test files to prior commit. `git checkout HEAD~1 -- tests/` restores all three to original state.
+
+## Dependencies
+
+- None — test-only fix, no external deps
+
+## Success Criteria
+
+- [ ] All 90 tests pass (`pytest tests/ -q`)
+- [ ] No compose.py files modified (only test files changed)