As the title says. Unsure whether it's a fix needed on the Cold Sweat side of things or the TC side of things, so I'm opening an issue on both githubs to try and figure that out. It is an alpha TC release though, so it may just be that no real fix can be implemented at the moment.

What is interesting is that the TC item preview shows the insulation during the repair, but the moment materials are spent the insulation disappears. So that might narrow down where the incompatibility lies.

SlimeKnights/TinkersConstruct#5310 Crosslinking the Tinker's Construct issue.

If I'm not mistaken, this is a TConstruct issue. Capability data ("capabilities" are what mods use to store data on Vanilla objects) should be preserved when repairing the item.

Cool cool, I'll mark this as closed for the moment then. Thank you for the help! Hopefully the TConstruct devs will have a solution.

Item stack capabilities are completely overkill on item stacks for storage. Item stacks have a freely editable compound tag already that gives you way more compatibility with other mod. This is the first mod I've seen use item stack caps for item storage on another mods items.

I can look into supporting it, but odds are its not going to be practical as we just don't work with ItemStack the majority of the time for tools as raw NBT manipulation is just bad practice. I'll see if there is a way to keep the cap data but knowing forge its going to be a pain to access.

I used NBT in previous versions, but insulation is really too dynamic for NBT to be practical. There are types of insulation that adapt to the environment, and insulation can also carry item/entity predicates that determine whether it will apply to the player. Serializing/deserializing this data every time it needs to be accessed is simply too unruly. It also degrades performance.