An agent's harness connects to the swarm queue with the agent's own
credential or not at all. The first connect retries after 5s, doubling
(7 attempts, about five minutes), with a warning per failed attempt;
when every attempt fails the harness logs an error and exits 1. Missing
coordinates (HIVE_AGENT_NATS_URL, or the secret store's BAO_ADDR /
HIVE_AGENT_NAME / certificate) fail the boot outright.
Previously the first connect's outcome was memoized for the life of the
process: a store 403 or queue refusal at boot left the agent on the
hive's shared client, or disconnected, until someone restarted it, and
an agent with no queue coordinates ran on without one. Both paths are
gone, with the hive-scoped subjects that only the shared client used.
The harness unit now restarts after 30s instead of 2s, so a swarm-wide
outage doesn't restart every agent every 2s, and has no start limit, so
it keeps coming back however long the outage lasts.
The hive's shared client credential is still imported into the harness
unit for swarm-logs; the two HIVE_AGENT_OIDC_*_FILE variables that
pointed the harness at it are dropped, as is the unset
HIVE_AGENT_OIDC_CA_FILE override.
With the fallback gone, the pieces #4944 added only for it go too:
swarm_input's skip-on-shared-client branch and swarm-queue-client's
connect_with_inbox_prefix. swarm-nats-auth's grant for the hive's shared
agent client is unchanged.
Closes#4909
The auth callout grants an agent that presents its own queue credential
one more subject, `$KV.agent-icons.<agent>`: its own key in the
agent-icons bucket and no other. The hive's shared agent client is
granted none of the bucket, since every agent on a hive presents it.
hive-agent writes `/etc/hyperhive/icon.svg`, the file its `GET /icon`
serves, to that key once per start, as a JetStream publish straight to
the subject (what `kv::Store::put` sends, minus the bucket lookup), so
the one subject is the whole grant. No icon deletes the key. A failed
write, including one that arrives before the bucket exists, is retried
with backoff until acked. An agent connected with the hive's shared
client publishes nothing.
swarm-controller creates the bucket as soon as its queue connection is
up, instead of on the first icon read, so an agent's write does not
wait for someone to look.
Measured against a local nats-server with a user allowed publish on
`$KV.agent-icons.atlas` only: the write to its own key is stored and
readable, a write to `$KV.agent-icons.argus` is refused (the ack times
out), the DEL marker makes the key read as absent, and a write before
the bucket exists fails with "no responders".
