Resolves StoreAndForward-001, ExternalSystemGateway-001, NotificationService-001
— one systemic gap where buffered messages were persisted but never delivered,
and the active node never replicated its buffer to the standby.
Delivery handlers (ExternalSystemGateway-001 / NotificationService-001):
- AkkaHostedService registers delivery handlers for the ExternalSystem,
CachedDbWrite and Notification categories after StoreAndForwardService starts;
each resolves its scoped consumer in a fresh DI scope.
- ExternalSystemClient, DatabaseGateway and NotificationDeliveryService each
gain a DeliverBufferedAsync method: re-resolve the target and re-attempt
delivery, returning true/false/throwing per the transient-vs-permanent contract.
- EnqueueAsync gains an attemptImmediateDelivery flag; CachedCallAsync and
NotificationDeliveryService.SendAsync pass false (they already attempted
delivery themselves) so registering a handler does not dispatch twice.
Replication (StoreAndForward-001):
- ReplicationService is injected into StoreAndForwardService; a new BufferAsync
helper replicates every enqueue, and successful-retry removes and parks are
replicated too. Fire-and-forget, no-op when replication is disabled.
Tests: StoreAndForwardReplicationTests (Add/Remove/Park observed),
attemptImmediateDelivery behaviour, and DeliverBufferedAsync paths for each
consumer. Full solution builds; StoreAndForward/ExternalSystemGateway/
NotificationService suites green.
