[Lombra]

You should try CHAT_MSG_LOOT. I don't know that it will fire for every conceivable situation, but I don't think BAG_UPDATE will work very well. First of all you'd need to keep track of what's actually changed between every update, and not just store everything in your bags. BAG_UPDATE also fires when items are removed, stacks are split, etc. Anything that requires the bag UI to update. What if you swap two items with each other, or put an equipped item in your bags?