Enchant & Repair

Enchanting tables exist to enchant and anvils exist to repair, but they both suck at their respective jobs, therefore most players prefer to enchant with books bought from villagers and repair with Mending instead, both of which are rather overpowered. This mod attempts to make the original mechanics relevant again, while at the same time nerfing book/tool trading and Mending to balance things back. It's based around the following principles:

• You should be able to repair items indefinitely, but reparing them should always involve some of the material the item was made with.
• XP should represent the progress in the game instead of being an expendable resource, and should in particular represent your ability to enchant and repair items, rather than its cost.
• Anvils should be used to repair items, not enchant them.
• High end equipment should be expensive to obtain and cheap to repair. 
• Enchanted books should be rare and reusable to some degree.

Nearly everything is configurable. In multiplayer, installing the mod on the client is not mandatory but recommended to prevent issues with inventory desync.

Changes

• Anvil repairing doesn't cost XP and consumes less resources at high levels.
• When repairing, there's a chance that each repair item (ingot/gem) is not consumed. The chance grows with the level of the player (40% at level 30, 83% at level 70). At level 70, you can repair two nearly broken items using only one ingot/gem, on average.
• When repairing, there's a chance that the operation fails and the item's durability becomes 1. The chance is 15% at level 30 and 4% at level 70.
• When repairing, there's a chance that the tool loses one level from one non-treasure enchantment, or lose the enchantment altogether if it's level 1. The chance is 15% at level 30 and 4% at level 70.
• Tools without repair items can be made repairable through the configuration. By default, the mod adds iron ingots for shields and prismarine crystals for tridents.
• Renaming items also doesn't cost XP and doesn't damage the anvil either.
• Enchanting doesn't cost XP and is affected by nearby enchanted books.
  
• The enchanting table searches for nearby chiseled bookselves (barrels in 1.19) and enchanted books inside of them, and randomly adds a number of those books to the item before generating the random enchantments. The number of books applied depends on the level of the books (relative to the maximum) and the experience level of the player. On average, two full-level books are used at level 30 and four at level 70. Books are not consumed in the process, unless they contain Curse of Vanishing or treasure enchantments (the latter can be recovered with a grindstone). The slot selected in the UI is irrelevant, as only the level of the player matters for this step, not the one displayed in the slot.
• Once the book enchantments have been added, the enchanting table generates some random enchantments to add as usual, which must be compatible with the ones in the books that have been used. The enchantments are normally weaker than they would be in vanilla, unless the player reached a very high level. The reason is that reaching those levels is easier now that XP is not consumed and also because books are now reusable and the primary mean to get powerful enchantments at lower levels (<70).
• Books can't be enchanted. Items with 0 enchantability (e.g. shears) can be enchanted, but only through books.
• Cursed tools can be enchanted as long as they don't have any other enchantment. They must not have the Curse of Vanishing either.
• There's a chance that enchanting an item will also damage it, but not to the point of destroying it. The chance is 10% at level 30 and 4% at level 70.
• Anvils cannot merge tools or books, or add books to tools.
  
• Crafting tools together in the crafting table still works as usual.
• Villagers sell disposable items that can't be repaired or enchanted, and disposable enchanted books that turn normal items into unrepairable ones.
• Enchanted books and enchanted gear sold by the villagers always have the Curse of Vanishing among their enchantments
• Items with the Curse of Vanishing cannot be repaired or enchanted and cannot have their treasure enchantments extracted.
• Experience orbs cannot repair items with Mending.
• The Mending enchantment instead decreases the chance of consuming the repair item and the chance of damaging or disenchanting the tool when repairing it.
• Only one experience level is lost on death.
• Half of that level is dropped as XP orbs, the other half is lost altogether.
• The grindstone can extract treasure enchantments from non-vanishing tools to a regular book in the bottom slot.
• By default, it also keeps the treasure enchantments when disenchanting an item that has both treasure and non-treasure enchantments, so that you can't accidentally lose the treasure ones by forgetting to insert the book.
• It doesn't give XP when disenchanting tools.
• Specific enchanted books can now be found in various structures:
  

This list is not definitive and I'm open to suggestions. Report issues on GitHub providing logs and mod list, and experiment with enabling/disabling the other mods before reporting incompatibilities.