The Melt Saga in Coco is probably the most interesting piece of software I have written in a while.
First of all sagas by themselves are also really cool, and I had a lot of fun writing the first one for the Send API. Now melt adds more complexity by needing to support different methods, that will have different behaviour. While the SendOperationService owned all behaviour the melt one does not. This is where I added the MeltHandlerProvider, a little piece of code that provides handlers based on the method used to the Saga. The saga will get the required behaviour from the provider when it needs to advance.
This way each method can implement its own behaviour, and consumers can even add their own methods via plugins or at runtime.