# minimal viable song engine
required domain generators

timbre layer: minimal sound requires a spectral shape (amplitudes), spectral layout (frequencies), and amplitude envelope (envelope).
onset layer: onset structure is necessary to generate multiple sounds in time, not just a static texture.
pitch layer: without pitch domains, all notes would be spectrally shaped noise at fixed frequencies. tonal + tuning give musical identity.
structure layer: essential to escape the loop - these allow for evolution, form, and larger-scale behavior.

## minimal viable song engine includes:
* `timbre.amplitudes`
* `timbre.frequencies`
* `timbre.envelope`
* `onset.grid`
* `onset.density`
* `onset.voicing`
* `pitch.tonal`
* `pitch.tuning`
* `structure.segmentation`
* `structure.ordering`

## what is not critical path
these add expressivity, realism, or complexity, but are not strictly required:
* `decorators`, `dynamics`, `envelopes` - enhance timbre expressivity
* `offset`, `pattern` - improve rhythm, but not required to place notes
* `generative`, `atonal` - expand pitch sources
* `hierarchy` - adds complex structure
* `interplay.` - defines voice interactions, not needed for solo behavior
* `spatial.` - purely perceptual spatialization; optional for musical structure

## summary
a complete parametric song can be generated using 10 core domains across 5 layers. these provide static structure, rhythm, pitch, spectrum, and form - everything needed to produce standalone music. all other domains can be added incrementally to expand the expressivity space.