Status: pre-implementation, design complete.
Locast is a local-first watch-together desktop app. A host picks one or more media files in their library, generates a room code, and shares it out of band; viewers join the code, the host's files transfer to them over a peer-to-peer WebRTC DataChannel (verified end-to-end against the host's Ed25519 signature), and playback happens locally on each participant's machine against their own copy. The local <video> element does the decoding; the server only relays control and presence.
The full design lives in docs/ARCHITECTURE.md. The phased implementation plan lives in docs/ROADMAP.md. The docs folder is indexed at docs/README.md.
This repository is not yet implementing code. The two documents above are the deliverables of the design phase.