The apple diagram doesn’t look too far off what quietbritishjim described though, assuming that the “updates” arrow from controller to model is the model asking

The apple diagram doesn’t look too far off what quietbritishjim described though, assuming that the “updates” arrow from controller to model is the model asking for an update, but the model actually implementing the logic. Personally, I hate the name controller because its really unclear to me what they actually do. What do they control? The actual update logic is part of the domain knowledge, so that should live in the model itself, as quietbritishjim said. Router is a better name imho (even if itself not a perfect name).