create-midi

Compose MIDI arrangements and convert between JSON spec and MIDI files. Two modes: 'compose' uses an LLM (via /prompt-lab prompt) to create a full arrangement from annotated lyrics + reference MIDI fragments + heart tags. 'from-spec' and 'to-spec' are mechanical JSON↔MIDI conversion via pretty_midi. The arrangement is the creative heart of the music pipeline — it decides what every instrument plays at every beat.