Map Wolverine TenantId from incoming MassTransit messages (supersedes #3167)

[jeremydmiller]

Supersedes #3167 by @outofrange-consulting (Geoffrey MARC), whose original commits are retained here with authorship intact. This adds the requested feature and then reworks the public surface per maintainer review.

Feature (from #3167)

IMassTransitInterop.MapTenantIdFrom<T>(...) lets you derive Wolverine's Envelope.TenantId for incoming MassTransit messages from either the deserialized message body or the surrounding MassTransit metadata (headers, addresses, ids). It affects only the inbound/deserialization path, supports multiple message types (each mapper fires only for its own T), and works on every MassTransit-interop listener (RabbitMQ, Azure Service Bus, Amazon SQS). The UseMassTransitInterop(configure) lambda is now threaded through to the serializer on the RabbitMQ and SQS listeners so the mapping actually takes effect.

What changed vs #3167 (public API rework)

#3167 exposed a new public interface IMassTransitEnvelope<T> as the MapTenantIdFrom hook type. Per review, this instead exposes the concrete MassTransitEnvelope type publicly and removes the interface abstraction:

• MassTransitEnvelope is now a public abstract base (MassTransit transport metadata + TransferData); MassTransitEnvelope<T> is the public generic subclass adding the typed Message. (The non-generic type is now the base of the generic one — previously inverted — so it can serve as the non-generic handle the serializer needs.)
• Removed both the internal non-generic IMassTransitEnvelope and the IMassTransitEnvelope<T> interface that Map Wolverine TenantId from incoming MassTransit messages #3167 introduced.
• MapTenantIdFrom<T> now takes Func<MassTransitEnvelope<T>, string?>.
• BusHostInfo is made public so the public MassTransitEnvelope.Host property has consistent accessibility.

Breaking-change assessment

• IMassTransitInterop.MapTenantIdFrom<T> is a new member on a public interface → technically a source/binary break for any external implementer of IMassTransitInterop. In practice the only implementer is the internal MassTransitJsonSerializer (it's a config seam, not a user-implemented interface), and main is on the 6.0 line where deliberate breaks are acceptable. Low real-world impact.
• Making MassTransitEnvelope/MassTransitEnvelope<T>/BusHostInfo public is additive (they were internal).
• IMassTransitEnvelope<T> only ever existed in the unmerged Map Wolverine TenantId from incoming MassTransit messages #3167, so removing it is not a break to any shipped API.

Tests

All MassTransit interop tests pass locally: CoreTests (24, incl. the new MassTransitTenantMappingTests and the updated MassTransitEnvelopeTests), the RabbitMQ stubbed masstransit_interop_map_tenant_id, and the AWS SQS masstransit_mapper_tenant_mapping.

🤖 Generated with Claude Code