[growingconcern]

Regarding the question about whether it's fair to call this an AI library...well it's kind of a valid question. But really this is game AI which is isn't trying to be Artificial Intelligence, it's just the subject of making game agents perform behaviours and look intelligent - or even just functional. But is your question really even an important question? Much of classical AI can just be reduced to search (which is why prolog is so popular in university AI courses). Is search AI? Is it any more AI than putting together control flow statements? There is a lot of stuff that can happen in those condition and behaviour nodes. And yes in trivial examples the control flow is fixed, but the "learning" is done by hand by the coder/designer (is it any more "AI" to have it done by a evolutionary algorithms?). And more advanced versions of behaviour trees can incorporate much more sophisticated selectors than just "pick the first that works".