consumer

Create a class implementing IConsumer<TEvent> in Infrastructure/Consumers, inject the service UnitOfWork, and implement Consume with your business logic. Wrap mutations in BeginTransactionAsync/CommitTransactionAsync and rethrow on failure so MassTransit auto-retries.

Define the event as a C# record (not a class) implementing IntegrationEvent, placed in SharedContracts/Events/{EventName}.cs. Use the {Action}Event naming pattern, for example BatteryAnomalyDetectedEvent, with init-style properties.

Services without an Outbox publish after CommitTransactionAsync to avoid emitting events for rolled-back work. Services with an Outbox publish before SaveChangesAsync so the event and state change persist atomically.

MassTransit automatically retries when the Consume method throws. The pattern is to catch exceptions, call RollbackTransactionAsync on the UnitOfWork, then rethrow so the bus handles retry and eventual error queues.

Call services.AddMessageBus(configuration, typeof(YourConsumer).Assembly) during startup. Passing the consumer's assembly lets the registration scan and wire up all consumers in that service automatically.