M4 Bundle B (B1) — add the central-only ICentralAuditWriter implementation
and inject it into NotificationOutboxActor so subsequent tasks (B2/B3) can
route attempt + terminal lifecycle events through the direct-write audit path.
- CentralAuditWriter: thin wrapper around IAuditLogRepository.InsertIfNotExistsAsync;
scope-per-call (matches AuditLogIngestActor / NotificationOutboxActor pattern);
stamps IngestedAtUtc; swallows all internal failures (alog.md §13).
- Registered as a singleton in AddAuditLog.
- NotificationOutboxActor ctor takes ICentralAuditWriter (validated non-null).
- Host wiring resolves the writer once from the root provider and passes it
into the singleton's Props.Create call.
- Existing TestKit fixtures updated with a NoOpCentralAuditWriter helper so
tests that don't exercise audit emission still compile and pass.
FU1 of the Notification Outbox follow-ups. EmailNotificationDeliveryAdapter
carried verbatim private copies of credential redaction, SMTP error
classification, and address validation because the NotificationService
helpers were internal. This eliminates the divergence risk by promoting the
helpers to public and deleting the adapter's copies.
- CredentialRedactor: internal -> public.
- Extract SmtpErrorClassifier + SmtpErrorClass enum into a new public static
class; NotificationDeliveryService now routes classification through it
(behavior unchanged). Adds focused SmtpErrorClassifierTests.
- NotificationDeliveryService.ValidateAddresses: internal -> public; the
adapter calls it directly.
- EmailNotificationDeliveryAdapter: deleted ScrubCredentials, ClassifySmtpError,
SmtpErrorClass, IsTransientSmtpError and ValidateAddresses copies.
No InternalsVisibleTo hack — specific helpers promoted to public. Both test
suites green; full solution builds clean.
