The responder re-read its secret on any non-2xx introspection answer.
With the re-read backoff added in the previous commit, an IdP outage
(503s, 502s from nginx, 429s) made each re-read find the unchanged
secret, so the delay grew to minutes. A real 401 after the rotation
then landed inside that window, and the responder denied every new
NATS connect until it ran out.
`Answer::Refused` now carries the status. `OidcSecret::introspect`
re-reads only when `stored_secret::is_credential_refusal` says the
status is 400 or 401, the same predicate `ClientSecret::refused` uses on
the client path. Every other non-2xx is a denial with no re-read.
The client-path test for a 429 now runs the mint against a loopback
endpoint answering 429 and 503, instead of calling `refused()` directly.
swarm-queue-client's README no longer names `ClientSecret::Value`.
Part of #5017 (slice Q).
hive-c0re (`hive-<name>`), swarm-controller and swarm-review-classifier
read their queue client secret from the store once and held it as
`ClientSecret::Value` for the life of the process. After authelia
re-minted a secret and swarm-secret-publish stored the new one, every
later token mint presented the old value and was refused until the
daemon restarted.
`ClientSecret::Stored` replaces `Value`: a `StoredSecret` holds the
secret in memory with a caller-supplied read callback, so the crate
takes no store dependency. When the token endpoint answers 400 or 401,
`mint_token` (and its blocking sibling, used by the controller's OTLP
exporters) re-reads it and, if the store holds a different secret,
mints once more with it. One re-read runs at a time and is spawned so
it outlives a caller that gives up. A re-read that fails or finds the
refused value delays the next one, 5 s doubling to 5 min, so a secret
that stays wrong costs one store read per delay. Logs name the client
id and never the secret.
swarm-nats-auth's `oidc_secret` was the template; its re-read machinery
now sits on `StoredSecret`, so the tree has one copy. The responder
gains the same re-read backoff.
The controller keeps its `IDENTITY` OnceLock: it now holds a
`QueueConfig` whose secret is re-read, and the lazily built vcs-metrics
exporter reads the identity from it.
agent_renewal.rs's module doc said a re-minted agent queue secret only
reaches the agent at its next start; hive-agent reads the store on every
connection attempt after its first, so the doc now says that.
Part of #5017 (slice Q).
