Messaging Gateway Generator

[GenerateMessagingGateway] creates a typed MessagingGateway<TRequest, TResponse> factory.

[GenerateMessagingGateway(typeof(PaymentAuthorizationRequest), typeof(PaymentAuthorizationDecision), FactoryName = "Create", GatewayName = "payment-authorization-gateway")]
public static partial class PaymentGateway
{
    [MessagingGatewayHandler]
    private static Message<PaymentAuthorizationDecision> Authorize(Message<PaymentAuthorizationRequest> request, MessageContext context)
        => Message<PaymentAuthorizationDecision>.Create(new("AUTH-100", true));
}

The generated factory accepts a MessageChannel<TRequest> so the gateway can be composed through IServiceCollection.

Diagnostics:

• PKGWY001: host type must be partial.
• PKGWY002: exactly one messaging gateway handler is required.
• PKGWY003: messaging gateway handler signature is invalid.