Replace Task.Delay(100) subscriber-attachment races with WaitForSubscriberCountAsync,
a polling gate on GatewaySession.ActiveEventSubscriberCount so Advise and event fan-out
cannot proceed until all subscribers are confirmed registered.
Fix WaitForMessageCountAsync to honor a single CancellationTokenSource deadline across
the poll loop rather than resetting the timeout on each intermediate wakeup.
Add ordering comment in the cancellation test explaining why stream1Task must be awaited
before AllowNextEvent to guarantee sub1 is unregistered before the 2nd event is fanned.
Assert capException.Status.Detail contains "maximum" in the cap test to distinguish
EventSubscriberLimitReached (AllowMultiple=true cap) from EventSubscriberAlreadyActive
(single-subscriber rejection) — both map to ResourceExhausted.
Extract shared ConfigureCommandReply helper and move FakeWorkerProcess to TestSupport/
so both fake-worker test classes reference one definition.
Joseph Doherty
056bb39a4d