Forward ports between your own machines, peer to peer. Neither side needs an account, a public IP, or an open inbound port. Only what you grant is reachable.
//! The pure core: decisions with no IO.
//!//! Everything here is decidable from in-memory state. The shell in `peer.rs`
//! feeds it events and carries out the actions it returns.
pubmodgrants;pubmodinvite;pubmodsession;