[jeremydmiller]

Closes #5126

Every Wolverine transport can now be configured by connection-string name, the way Aspire passes resources to a project (builder.AddProject(...).WithReference(resource) puts the value at ConnectionStrings:<name>). Every broker that supports named brokers gets a matching named-broker form. This is additive only: new overloads, and no change to how existing ones behave.

Naming

The issue spells the API as UseX(string connectionStringName). What shipped follows the existing UseRabbitMqUsingNamedConnection / UseKafkaUsingNamedConnection convention, Use<X>UsingNamedConnection(name, ...), plus AddNamed<X>BrokerUsingNamedConnection(broker, name, ...). A bare UseX(string) would collide with the existing UseX(string connectionString) overloads.

Core: one hook for every transport

options.ApplyNamedConnectionString(kind, name, aspireMethod, value => ...) in NamedConnectionStringExtensions:

• Startup check: it adds the name to the existing Named connection strings: validate every named dependency up front in one aggregated startup check, register JasperFx environment checks, and name the Aspire remedy in the message #4527 check, so every missing name fails startup together in one MissingNamedConnectionStringsException, and the message names the Aspire builder.AddX("name") fix.
• When the value is applied: once the container exists, it reads the value from IConfiguration and passes it to the callback. The callback captures the transport instance, which is why this works for named brokers; the earlier Kafka/RabbitMQ per-transport DI singletons don't. WolverineRuntime.ApplyNamedConnectionStrings() does this, and it runs once at each of these points:
  • at the top of host startup, right after the async extensions run, before the message store initializes and before any transport connects;
  • in WolverineSystemPart.FindResources(), so resources setup/check/... also see the value without the host starting.
• Earlier startup check: the aggregated Named connection strings: validate every named dependency up front in one aggregated startup check, register JasperFx environment checks, and name the Aspire remedy in the message #4527 check now runs at that earlier point instead of after handler compilation. It still fires before storage migration, and now also before the message store initializes.
• No check-env registration, for the AOT reason documented in NamedConnectionStringExtensions.

Per transport

Transport	Named-connection value (what Aspire supplies)	Container-client overload
Azure Service Bus	The emulator's full connection string, or a namespace endpoint (https://ns.servicebus.windows.net:443/) secured with a TokenCredential (default DefaultAzureCredential). EntityPath is dropped.	Not feasible. Aspire registers only ServiceBusClient, the transport also needs an admin client built from the same credentials, and it disposes its client.
Amazon SQS / SNS	The emulator service URL (http://localhost:4566) from LocalStack's AddLocalStack or the CommunityToolkit's AddFlociAws. Placeholder credentials are used unless set explicitly. Aspire.Hosting.AWS supplies no connection string, so real AWS uses the plain overloads or:	Added: UseAmazonSqsTransportWithClientFromContainer / UseAmazonSnsTransportWithClientsFromContainer (+ named-broker forms) take the IAmazonSQS / IAmazonSimpleNotificationService registered by AddAWSService<T>(). Wolverine does not dispose container-owned clients.
NATS	nats://[user:pass@]host:port (AddNats). Optional configure for auth/TLS/JetStream.	Not added. NatsTransport owns its connection: it disposes it, recreates closed connections on retry, and applies its own options. Possible follow-up.
Redis	A StackExchange.Redis configuration string (AddRedis)	Already covered by UseRedisTransport(Func<IServiceProvider, IConnectionMultiplexer>)
Pulsar	pulsar://, pulsar+ssl:// or host:port. Neither official Aspire nor the CommunityToolkit has a Pulsar integration, so the error names no Aspire method.	No client integration exists
MQTT 3 / 5 (shared source)	mqtt://host:port from the CommunityToolkit's AddMosquitto, plus mqtts://, ws(s)://, host:port and user:pass@ credentials	No client integration exists
GCP Pub/Sub	The emulator endpoint from the CommunityToolkit's AddFlociGcp (http://host:port). The project id remains an explicit argument, because endpoint URIs include it at configuration time. Emulator only; production uses UsePubsub.	No client integration exists

Each transport's existing configure lambdas still apply immediately. I checked each transport, and none reads its connection settings before ConnectAsync/InitializeAsync (or the lazy client builders); details are in the commit messages.

Tests

Each transport test project has a new named_connection_5126 class. Each covers:

• a missing name failing startup (default and named broker);
• the value applied to the default and named broker for every supported format (with StubAllExternalTransports(), so no broker is needed);
• an end-to-end send/receive against a local broker (ASB emulator, LocalStack, NATS and Redis testcontainers, Pulsar, an in-process MQTT broker, the Pub/Sub emulator).

The happy-path snippets are wrapped in #region sample_<transport>_using_named_connection / ..._named_broker_using_named_connection for the docs (#5156).

Local results:

• CoreTests named_connection_string_binding_5126 + named_connection_string_validation_4527: 10/10
• ASB 13/13, SQS 10/10, SNS 11/11, NATS 6/6 + 1/1 end-to-end, Redis 7/7, Pulsar 8/8, MQTT 16/16, MQTT5 16/16, Pub/Sub 8/8
• Existing named-broker / per-tenant regression classes in SQS, SNS, NATS, Redis, Pulsar, MQTT and Pub/Sub: all green
• dotnet build wolverine.slnx -c Release -f net9.0: 0 errors, and the only warnings are the existing MessagePack NU1902 advisory
• Full CoreTests: 3808 total, 0 failed, 3800 succeeded, 8 skipped

Not in this PR

• Message stores (Message storage registration by connection-string name or DI data source for every provider (PersistMessagesWithX(connectionStringName), DbDataSource from the container) #5127), docs (Docs: lead every transport and persistence page with the named-connection form #5156).
• Unrelated, noticed in passing: AddNamedAzureServiceBusBroker(WolverineOptions, BrokerName, string, AzureNamedKeyCredential, ...) is missing this, so it isn't an extension method. Adding this is source-compatible.

🤖 Generated with Claude Code