Function mint_connection_id 

fn mint_connection_id() -> u64

The next number for a connection, unique for the process’s life.

A take belongs to the connection it started on, so the number is what both halves of that routing name: the transport stamps it on dictate_stream and dictate_stop, the core echoes it on the take’s updates, and a connection forwards only what carries its own. Minted process-wide rather than per transport so two servers in one process - a test’s, a scratch instance beside the real one - cannot hand the same number to different connections.