The retry loop treated everything but a cert-pin mismatch as transient,
so a refused login (revoked/mis-sealed credential) or a malformed broker
URL retried for ever logging 'not reachable yet' — the silent
non-progress the fix set out to remove, and a contradiction of its own
docstring. fatalBrokerReason now classifies those three as fatal and
everything else (connection refused, timeout, DNS) as retryable, with a
unit test covering the split — the honest proof the bed cannot give,
since it only ever starts the consumer after the broker is up.
The pin case is now a typed PinMismatchError caught by instanceof, not a
prose substring a reword could silently downgrade to an infinite retry
against an impostor. Added a little jitter so modules do not stampede a
recovering broker in lockstep.
jschoubben