Lacuna is an AI music studio with two craft agents. Music agent: hum or describe — composes vocals + arrangement, no music theory needed. Lyrics agent: a real workspace with real-time syllable counter, automatic end-rhyme detection (color-coded pairs), AI rhyme suggestions, and verse/chorus/bridge templates. Thinks with you, doesn't write for you. MIDI tools: text/image/PDF to MIDI, sheet music scanner, in-browser MIDI editor — take the output into your DAW. 9 languages. Free tier, no card.