I don't like how ACTIVE does not have available notification callbacks like HOT and CRITICAL do. Perhaps I fail to grasp why they aren't there but besides just applying a cooling device, one might want to do something else as well upon hitting these trip points. So that said, it might be nice to add a notification to STATE_ACTIVE as well.
Well I added ACTIVE_STATE trip type as just some additional features over trip type ACTIVE. Also each thermal zone can have more then one trip types so HOT notifications can still be used. But I like your suggestion of putting notfications in all the trip types. Lets see if the maintainers agree to this idea.
Thinking about it a bit more, I didn't consider HOT because it only notifies when you cross above this trip point and not below and the use case I had in mind would ideally want to be notified in both cases. Also, if ACTIVE/ACTIVE_STATE trip types will always have cooling devices bound to them, then the notification could be put in the cooling device code if desired. I think these features are separate from your main effort and can be addressed in separate future patch.