Spoilers

"recipes/golden_axe.json"
{
  "type": "crafting_shaped",
  "pattern": [
    "XX",
    "X#",
    " #"
  ],
  "key": {
    "#": {
      "item": "minecraft:stick"
    },
    "X": {
      "item": "minecraft:gold_ingot"
    }
  },
  "result": {
    "item": "minecraft:golden_axe"
  }
}
"recipes/book.json"
{
  "type": "crafting_shapeless",
  "ingredients": [
    {
      "item": "minecraft:paper"
    },
    {
      "item": "minecraft:paper"
    },
    {
      "item": "minecraft:paper"
    },
    {
      "item": "minecraft:leather"
    }
  ],
  "result": {
    "item": "minecraft:book"
  }
}
"advancements/upgrade_tools.json"
{
    "display": {
        "icon": "minecraft:stone_pickaxe",
        "title": "Upgrade tools"
    },
    "parent": "minecraft:story/mine_stone",
    "criteria": {
        "stone_pickaxe": {
            "trigger": "minecraft:inventory_changed",
            "conditions": {
                "items": [
                    {
                        "item": "minecraft:stone_pickaxe"
                    }
                ]
            }
        }
    }
}
"advancements/chest_recipe.json"
{
    "rewards": {
        "recipes": ["minecraft:chest"]
    },
    "criteria": {
        "slightly_full_inventory": {
            "trigger": "minecraft:inventory_changed",
            "conditions": {
                "slots": {
                    "occupied": 9
                }
            }
        },
        "already_has_recipe": {
            "trigger": "minecraft:recipe_unlocked",
            "conditions": {
                "recipe": "minecraft:chest"
            }
        }
    },
    "requirements": [["slightly_full_inventory"], ["already_has_recipe"]]
}