s@: social networking over static sites

s@ (Sat Protocol) is a decentralized social networking protocol built entirely on static sites. Each user hosts their data as encrypted JSON files on any static hosting service (e.g. GitHub Pages). Identity is tied to a domain name authenticated via HTTPS/TLS. Content is encrypted using X25519 key exchange and XChaCha20-Poly1305, with per-follower key envelopes stored alongside posts. There are no servers or relays — a browser-based client fetches posts directly from each followed user's static site, decrypts them locally, and publishes new posts via the hosting provider's API. The protocol covers discovery documents, post structure, follow lists, threading (flat only), and key rotation on unfollow.