As described in the title; the XP Tank mending feature is not functioning properly with things equipped in Curios API slots. For reference, these same accessories in Curios API slots repair fine when I pick up an XP orb but not with the backpack mending function.

Steps to reproduce the behaviour:

1. Equip accessory that has durability and a mending enchant on it in a Curios API slot
2. Enable mending feature in XP Pump tab of backpack
3. Nothing happens to accessories enchanted with mending equipped in Curios API

Expected behaviour
Accessories are repaired by backpack.

Versions
1.16.5 - 3.15.1.503

Well, this is more a feature request as it works the same way that vanilla mending does. I am guess curios may be adding support for mending in its slots and that's why you would see it working there. The enhancement definitely makes sense to me and I will add it in the future.

Shadows-of-Fire/Apotheosis#786 accidentally went to say something about this in apotheosis's github before realizing it was the wrong mod, but maybe this could help you implement it in SophBackpacks?