hi! after looking for quite a while i never found a mod that tweaked mending in a way so that it will not invaliate repairing, i don't know if it's easy or not to implement, but if you are interested about a possible idea:

• add an option to set a chance for repairing or do nothing when picking up xp
• when an item with mening is broken, it regain a percentage of durability and loses mending
• an item with mending cost 0 exp to repair at an anvil

edit: clarification about the exp cost