Orfeo

The party decides, the app executes#

Orfeo — after Monteverdi's L'Orfeo — is a participative auto-DJ. Guests at a party propose and vote on tracks from their phones, without installing any app, and an autonomous brain decides what to play and when, mixing on its own when the stream of suggestions dries up.

The constraint that defines the project: the app is the DJ. It schedules and drives playback in real time, while the curation logic stays entirely platform-agnostic.

Three layers, one golden rule#

On the guest side, a web app (Next.js) serves catalog search, voting and dedications. On the host side, a native macOS app (SwiftUI + MusicKit) subscribes to live state and drives ApplicationMusicPlayer. Between them, Supabase is the source of truth — every track is keyed by its ISRC, never a native URI.

The golden rule: the brain (CurationEngine) never knows the playback platform. It receives a snapshot of live state and emits an ordered plan of tracks. Only the adapters touch Apple Music. All business logic lives in pure, testable units — never in a SwiftUI View or a React component.

The brain#

The CurationEngine scores each candidate — log-normalized votes, energy/mood fit, party-phase fit, dedication bonus, anti-repetition penalties on artist and genre — and produces an ordered queue, deterministic aside from injected jitter. When proposals run dry, auto-continue navigates a real catalog from what the room is listening to — each track leads to its artist, that artist's radio and related artists — and falls back on reference tracks chosen by the organiser. The local LLM never proposes a title: it only supplies genres and tags, so a filler can never be a track that doesn't exist.

Why#

Orfeo started from a concrete need: run the music for a real party without anyone glued to the speakers all night. v1 did it on August 14, 2026: a 45-guest birthday, from noon to 3 a.m.; what follows explores a self-serve service so anyone can do the same.