Some further thoughts on APIs for social systems
It will help quite a bit to establish exactly what will be needed from the various systems involved. It is clear that a knowledge system will allow characters to have reflective models of the world, of themselves, and so on, but it is less clear exactly how this information will be accessed or modified. What are the entry and exit points? What are the procedures? What is the greatest, clearest layer of abstraction that can be drawn here?
Similar questions can be raised for the other components as well. There are lots of resources on how to write modular and robust APIs, but these presuppose understanding what they are going to be used for precisely. Answering this question seems like the next logical step.