Why is this mod incompatible with infinite quality tiers? Is it a performance thing? If so, you may want to just add a disclaimer on the information page warning users about the issue instead of just outright banning it for use.

notices first compatibility point

I'm assuming this is because you hard-coded recipes for certain qualities. And re-reading the description again, yeah, that makes sense. OK, nevermind, forget I asked. Would be interesting if the recipes were instead of per quality be per item, changing the requirements based off of that instead, which would make it compatible with quality adding mods, I think.

Yes, the upgrade machines and upgrade material chains are all designed and hard-coded for the vanilla qualities.

I'm looking over the mods that add more quality tiers, and they should be compatible in the sense that nothing breaks. But my mod would only add the upgrade machines for the quality tiers that have the original internal names. So for infinite quality tiers you could only upgrade up to legendary using this mod, for higher tiers you would need to use the vanilla mechanics. For mods that insert "+" tiers between original ones you would have to alternate between the mod and vanilla.

But I'll remove the hard incompatibilites for these mods so people can play around with that if they want.