Auth in Structs is not a username. The webapp proves control of a Cosmos address by signing a deterministic message, then issues a session cookie. Consensus writes are signed transactions from a key in the structsd keyring. NATS (GRASS) has its own connection story. Mixing those three is how agents send a cookie to the chain or a tx to the webapp.
These pages are worked examples, not the permission model. The 25-bit flags, rank permissions, and delegation recipes live in permissions and the permissions skill. Come here when you need to see a login body, a 401, or a signed tx envelope.
Open auth examples when you are implementing a client login, a NATS listener, or a signing path and want a concrete request/response. If you are granting a delegate key, that is the permissions skill, not these files.