Durable queue boundary

Durable queue boundary

DurableQueue is optional and only for workflow/background/batch jobs. Realtime and interactive admission never acquire durable-broker latency or semantics. All adapters enforce a bounded encoded job size and provide at-least-once delivery around a stable UUID; consumers must make downstream effects idempotent by that ID.

The built-in adapters are:

• InMemoryDurableQueue, for deterministic development, with explicit in-flight tracking.
• NatsJetStreamQueue, using a work-queue stream, durable pull consumer, publish acknowledgements, explicit double acknowledgement, a stable NATS message ID, and a ten-delivery ceiling. Supply NATS TLS, NKey, JWT, or credentials through connect_with_options.
• AzureServiceBusQueue, using the HTTPS REST peek-lock and settlement protocol. Authentication is a short-lived bearer-token provider; the azure-auth feature supplies managed-identity and workload-identity implementations. Settlement redirects are disabled and a returned settlement URL must remain on the configured namespace host.

The Service Bus adapter does not accept connection strings or embedded SAS keys. The environment token provider exists for isolated contract tests only. Lock renewal and dead-letter policy remain broker configuration concerns; an expired/unsettled delivery is intentionally eligible for redelivery.