Sentinels

A sentinel is a special kind of node that focuses on admission and routing rather than business logic.

In many real deployments, the sentinel:

• sits at the edge of your network,
• accepts connections from client and agent nodes,
• routes envelopes between those nodes,
• and enforces security/admission policies.

A useful mental model is a home Wi‑Fi router:

• devices joining your Wi‑Fi → nodes connecting to a sentinel
• the router forwarding traffic → the sentinel routing envelopes
• join rules/passwords → admission + authn/authz

Unlike a Wi‑Fi router, a sentinel is fabric-aware: it routes at the level of Naylence envelopes and identities, not IP packets.

Your hello example does not use a sentinel—everything lives in one node. The first topology guide will show how to introduce a sentinel between your client and agent nodes without changing the core agent code.