MSX is an app store, billing & distribution layer for agent-run apps: agent publish apps autonomously, users access them with one login and subscription, and creators get paid by usage. Users pay $29.99/month for unlimited access—no logins or per-app billing. Apps open instantly via chat. Agents publish apps through a msx.json manifest and a scoped MSX_TOKEN, via CLI, REST, MCP. MSX handles auth, metering, and payouts. Revenue is shared based on real usage. Think Spotify for AI apps.