1.19.2 -> 1.19.3 (1.20) [part 2]

src/main/java/com/minelittlepony/unicopia/Race.java

@@ -9,7 +9,7 @@ import org.spongepowered.include.com.google.common.base.Objects;
 
 import com.google.common.base.Strings;
 import com.minelittlepony.unicopia.ability.magic.Affine;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 import com.mojang.brigadier.context.CommandContext;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import com.mojang.brigadier.exceptions.DynamicCommandExceptionType;
@@ -24,7 +24,7 @@ import net.minecraft.registry.RegistryKey;
 
 public final class Race implements Affine {
     public static final String DEFAULT_ID = "unicopia:human";
-    public static final Registry<Race> REGISTRY = Registries.createDefaulted(Unicopia.id("race"), DEFAULT_ID);
+    public static final Registry<Race> REGISTRY = RegistryUtils.createDefaulted(Unicopia.id("race"), DEFAULT_ID);
     public static final RegistryKey<? extends Registry<Race>> REGISTRY_KEY = REGISTRY.getKey();
     private static final DynamicCommandExceptionType UNKNOWN_RACE_EXCEPTION = new DynamicCommandExceptionType(id -> Text.translatable("race.unknown", id));
 

src/main/java/com/minelittlepony/unicopia/ability/Abilities.java

@@ -9,13 +9,13 @@ import java.util.function.BiFunction;
 
 import com.minelittlepony.unicopia.Race;
 import com.minelittlepony.unicopia.Unicopia;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.minecraft.util.*;
 import net.minecraft.registry.Registry;
 
 public interface Abilities {
-    Registry<Ability<?>> REGISTRY = Registries.createSimple(Unicopia.id("abilities"));
+    Registry<Ability<?>> REGISTRY = RegistryUtils.createSimple(Unicopia.id("abilities"));
     Map<AbilitySlot, Set<Ability<?>>> BY_SLOT = new EnumMap<>(AbilitySlot.class);
     BiFunction<AbilitySlot, Race.Composite, List<Ability<?>>> BY_SLOT_AND_COMPOSITE_RACE = Util.memoize((slot, race) -> {
         return BY_SLOT.computeIfAbsent(slot, s -> new LinkedHashSet<>())

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/effect/SpellType.java

@@ -19,7 +19,7 @@ import com.minelittlepony.unicopia.ability.magic.spell.ThrowableSpell;
 import com.minelittlepony.unicopia.ability.magic.spell.trait.SpellTraits;
 import com.minelittlepony.unicopia.item.GemstoneItem;
 import com.minelittlepony.unicopia.item.UItems;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.NbtCompound;
@@ -33,8 +33,8 @@ public final class SpellType<T extends Spell> implements Affine, SpellPredicate<
     public static final Identifier EMPTY_ID = Unicopia.id("none");
     public static final SpellType<?> EMPTY_KEY = new SpellType<>(EMPTY_ID, Affinity.NEUTRAL, 0xFFFFFF, false, SpellTraits.EMPTY, t -> null);
 
-    public static final Registry<SpellType<?>> REGISTRY = Registries.createSimple(Unicopia.id("spells"));
+    public static final Registry<SpellType<?>> REGISTRY = RegistryUtils.createSimple(Unicopia.id("spells"));
-    private static final Map<Affinity, Set<SpellType<?>>> BY_AFFINITY = new EnumMap<>(Affinity.class);
+    public static final Map<Affinity, Set<SpellType<?>>> BY_AFFINITY = new EnumMap<>(Affinity.class);
 
     public static final SpellType<PlaceableSpell> PLACED_SPELL = register("placed", Affinity.NEUTRAL, 0, false, SpellTraits.EMPTY, PlaceableSpell::new);
     public static final SpellType<ThrowableSpell> THROWN_SPELL = register("thrown", Affinity.NEUTRAL, 0, false, SpellTraits.EMPTY, ThrowableSpell::new);

src/main/java/com/minelittlepony/unicopia/ability/magic/spell/effect/TransformationSpell.java

@@ -13,7 +13,7 @@ import com.minelittlepony.unicopia.entity.UEntities;
 import com.minelittlepony.unicopia.particle.ParticleUtils;
 import com.minelittlepony.unicopia.projectile.MagicProjectileEntity;
 import com.minelittlepony.unicopia.projectile.ProjectileDelegate;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.EntityType;
@@ -66,7 +66,7 @@ public class TransformationSpell extends AbstractSpell implements ProjectileDele
 
     @SuppressWarnings("unchecked")
     private <T extends MobEntity> Optional<EntityType<T>> pickType(EntityType<?> except, World world) {
-        Set<EntityType<?>> options = Registries.valuesForTag(world, UTags.TRANSFORMABLE_ENTITIES).collect(Collectors.toSet());
+        Set<EntityType<?>> options = RegistryUtils.valuesForTag(world, UTags.TRANSFORMABLE_ENTITIES).collect(Collectors.toSet());
         if (except.getSpawnGroup() == SpawnGroup.MONSTER) {
             options.removeIf(t -> t.getSpawnGroup() == SpawnGroup.MONSTER);
         } else {

src/main/java/com/minelittlepony/unicopia/block/Tree.java

@@ -5,6 +5,7 @@ import java.util.function.Predicate;
 import java.util.function.Supplier;
 
 import net.fabricmc.fabric.api.biome.v1.*;
+import net.fabricmc.fabric.api.event.registry.DynamicRegistrySetupCallback;
 import net.fabricmc.fabric.api.object.builder.v1.block.FabricBlockSettings;
 import net.minecraft.block.*;
 import net.minecraft.block.sapling.SaplingGenerator;
@@ -13,7 +14,6 @@ import net.minecraft.util.Identifier;
 import net.minecraft.util.math.random.Random;
 import net.minecraft.registry.*;
 import net.minecraft.registry.tag.BiomeTags;
-import net.minecraft.registry.entry.*;
 import net.minecraft.world.gen.GenerationStep;
 import net.minecraft.world.gen.feature.*;
 import net.minecraft.world.gen.feature.size.TwoLayersFeatureSize;
@@ -23,12 +23,36 @@ import net.minecraft.world.gen.stateprovider.BlockStateProvider;
 import net.minecraft.world.gen.trunk.TrunkPlacer;
 
 public record Tree (
-        RegistryEntry<ConfiguredFeature<TreeFeatureConfig, ?>> configuredFeature,
+        Identifier id,
-        Optional<RegistryEntry<PlacedFeature>> placedFeature,
+        TreeFeatureConfig.Builder config,
-        Optional<Block> sapling
+        RegistryKey<ConfiguredFeature<?, ?>> configuredFeatureId,
+        Optional<RegistryKey<PlacedFeature>> placedFeatureId,
+        Optional<Block> sapling,
+        Optional<PlacementModifier> placement
     ) {
     public static final List<Tree> REGISTRY = new ArrayList<>();
 
+    private static void bootstrap() {
+        DynamicRegistrySetupCallback.EVENT.register(registries -> {
+            registries.getOptional(RegistryKeys.CONFIGURED_FEATURE).ifPresent(registry -> {
+                REGISTRY.forEach(tree -> {
+                    Registry.register(registry, tree.id(), new ConfiguredFeature<>(Feature.TREE, tree.config.build()));
+                });
+            });
+            registries.getOptional(RegistryKeys.PLACED_FEATURE).ifPresent(registry -> {
+                var reg = registries.asDynamicRegistryManager().createRegistryLookup().getOrThrow(RegistryKeys.CONFIGURED_FEATURE);
+                REGISTRY.stream().filter(tree -> tree.placedFeatureId().isPresent()).forEach(tree -> {
+                    var placedFeature = new PlacedFeature(reg.getOrThrow(tree.configuredFeatureId()),
+                            VegetationPlacedFeatures.modifiersWithWouldSurvive(tree.placement().orElseThrow(), tree.sapling().orElse(Blocks.OAK_SAPLING))
+                    );
+
+                    Registry.register(registry, tree.id, placedFeature);
+                });
+            });
+        });
+
+    }
+
     public static class Builder {
         public static final Predicate<BiomeSelectionContext> IS_FOREST = BiomeSelectors.foundInOverworld().and(BiomeSelectors.tag(BiomeTags.IS_FOREST));
 
@@ -92,31 +116,28 @@ public record Tree (
         }
 
         public Tree build() {
-            RegistryEntry<ConfiguredFeature<TreeFeatureConfig, ?>> configuredFeature = ConfiguredFeatures.register(id.toString(), Feature.TREE, configSupplier.map(Supplier::get)
+            RegistryKey<ConfiguredFeature<?, ?>> configuredFeatureId = RegistryKey.of(RegistryKeys.CONFIGURED_FEATURE, id);
+            Tree tree = new Tree(id, configSupplier.map(Supplier::get)
                     .orElseGet(() -> new TreeFeatureConfig.Builder(
                             BlockStateProvider.of(logType),
                             trunkPlacer,
                             BlockStateProvider.of(leavesType),
                             foliagePlacer,
                             size.get()
-                    ).forceDirt()).build());
+                        ).forceDirt()), configuredFeatureId, selector.map(selector -> {
-
+                RegistryKey<PlacedFeature> i = RegistryKey.of(RegistryKeys.PLACED_FEATURE, id);
-            Optional<Block> sapling = saplingId.map(id -> UBlocks.register(id, new SaplingBlock(new SaplingGenerator() {
+                BiomeModifications.addFeature(selector, GenerationStep.Feature.VEGETAL_DECORATION, i);
+                return i;
+            }), saplingId.map(id -> UBlocks.register(id, new SaplingBlock(new SaplingGenerator() {
                 @Override
-                protected RegistryEntry<? extends ConfiguredFeature<?, ?>> getTreeFeature(Random rng, boolean flowersNearby) {
+                protected RegistryKey<ConfiguredFeature<?, ?>> getTreeFeature(Random rng, boolean flowersNearby) {
-                    return configuredFeature;
+                    return configuredFeatureId;
                 }
-            }, FabricBlockSettings.copy(Blocks.OAK_SAPLING)), ItemGroup.DECORATIONS));
+            }, FabricBlockSettings.copy(Blocks.OAK_SAPLING)), ItemGroups.NATURAL)), countModifier);
 
-            Optional<RegistryEntry<PlacedFeature>> placedFeature = selector.map(selector -> {
+            if (REGISTRY.isEmpty()) {
-                var pf = PlacedFeatures.register(id.toString() + "_checked", configuredFeature,
+                bootstrap();
-                    VegetationPlacedFeatures.modifiersWithWouldSurvive(countModifier.orElseThrow(), sapling.orElse(Blocks.OAK_SAPLING))
+            }
-                );
-                BiomeModifications.addFeature(selector, GenerationStep.Feature.VEGETAL_DECORATION, pf.getKey().get());
-                return pf;
-            });
-
-            Tree tree = new Tree(configuredFeature, placedFeature, sapling);
 
             REGISTRY.add(tree);
             return tree;

src/main/java/com/minelittlepony/unicopia/block/UBlocks.java

@@ -5,6 +5,7 @@ import java.util.List;
 
 import com.minelittlepony.unicopia.Unicopia;
 import com.minelittlepony.unicopia.item.UItems;
+import com.minelittlepony.unicopia.item.group.ItemGroupRegistry;
 
 import net.fabricmc.fabric.api.object.builder.v1.block.FabricBlockSettings;
 import net.fabricmc.fabric.api.object.builder.v1.block.FabricMaterialBuilder;
@@ -33,23 +34,23 @@ public interface UBlocks {
 
     Block FROSTED_OBSIDIAN = register("frosted_obsidian", new FrostedObsidianBlock(FabricBlockSettings.copy(Blocks.OBSIDIAN).ticksRandomly()));
 
-    Block ZAP_LOG = register("zap_log", new ZapAppleLogBlock(Blocks.OAK_LOG, MapColor.GRAY, MapColor.DEEPSLATE_GRAY), ItemGroup.MATERIALS);
+    Block ZAP_LOG = register("zap_log", new ZapAppleLogBlock(Blocks.OAK_LOG, MapColor.GRAY, MapColor.DEEPSLATE_GRAY), ItemGroups.BUILDING_BLOCKS);
-    Block ZAP_WOOD = register("zap_wood", new ZapAppleLogBlock(Blocks.OAK_WOOD, MapColor.DEEPSLATE_GRAY, MapColor.DEEPSLATE_GRAY), ItemGroup.MATERIALS);
+    Block ZAP_WOOD = register("zap_wood", new ZapAppleLogBlock(Blocks.OAK_WOOD, MapColor.DEEPSLATE_GRAY, MapColor.DEEPSLATE_GRAY), ItemGroups.BUILDING_BLOCKS);
 
-    Block STRIPPED_ZAP_LOG = register("stripped_zap_log", new ZapAppleLogBlock(Blocks.STRIPPED_OAK_LOG, MapColor.LIGHT_GRAY, MapColor.GRAY), ItemGroup.MATERIALS);
+    Block STRIPPED_ZAP_LOG = register("stripped_zap_log", new ZapAppleLogBlock(Blocks.STRIPPED_OAK_LOG, MapColor.LIGHT_GRAY, MapColor.GRAY), ItemGroups.BUILDING_BLOCKS);
-    Block STRIPPED_ZAP_WOOD = register("stripped_zap_wood", new ZapAppleLogBlock(Blocks.STRIPPED_OAK_WOOD, MapColor.GRAY, MapColor.GRAY), ItemGroup.MATERIALS);
+    Block STRIPPED_ZAP_WOOD = register("stripped_zap_wood", new ZapAppleLogBlock(Blocks.STRIPPED_OAK_WOOD, MapColor.GRAY, MapColor.GRAY), ItemGroups.BUILDING_BLOCKS);
 
-    Block ZAP_LEAVES = register("zap_leaves", new ZapAppleLeavesBlock(), ItemGroup.DECORATIONS);
+    Block ZAP_LEAVES = register("zap_leaves", new ZapAppleLeavesBlock(), ItemGroups.NATURAL);
     Block ZAP_BULB = register("zap_bulb", new FruitBlock(FabricBlockSettings.of(Material.GOURD, MapColor.GRAY).strength(500, 1200).sounds(BlockSoundGroup.AZALEA_LEAVES), Direction.DOWN, ZAP_LEAVES, FruitBlock.DEFAULT_SHAPE, false));
     Block ZAP_APPLE = register("zap_apple", new FruitBlock(FabricBlockSettings.of(Material.GOURD, MapColor.GRAY).sounds(BlockSoundGroup.AZALEA_LEAVES), Direction.DOWN, ZAP_LEAVES, FruitBlock.DEFAULT_SHAPE, false));
 
-    Block WEATHER_VANE = register("weather_vane", new WeatherVaneBlock(FabricBlockSettings.of(Material.METAL, MapColor.BLACK).requiresTool().strength(3.0f, 6.0f).sounds(BlockSoundGroup.METAL).nonOpaque()), ItemGroup.DECORATIONS);
+    Block WEATHER_VANE = register("weather_vane", new WeatherVaneBlock(FabricBlockSettings.of(Material.METAL, MapColor.BLACK).requiresTool().strength(3.0f, 6.0f).sounds(BlockSoundGroup.METAL).nonOpaque()), ItemGroups.TOOLS);
 
     Block GREEN_APPLE_LEAVES = register("green_apple_leaves", new FruitBearingBlock(FabricBlockSettings.copy(Blocks.OAK_LEAVES),
             0xE5FFFF88,
             () -> UBlocks.GREEN_APPLE,
             () -> UItems.GREEN_APPLE.getDefaultStack()
-    ), ItemGroup.DECORATIONS);
+    ), ItemGroups.NATURAL);
     Block GREEN_APPLE = register("green_apple", new FruitBlock(FabricBlockSettings.of(Material.GOURD, MapColor.GREEN).sounds(BlockSoundGroup.WOOD), Direction.DOWN, GREEN_APPLE_LEAVES, FruitBlock.DEFAULT_SHAPE));
     Block GREEN_APPLE_SPROUT = register("green_apple_sprout", new SproutBlock(0xE5FFFF88, () -> UItems.GREEN_APPLE_SEEDS, () -> UTreeGen.GREEN_APPLE_TREE.sapling().map(Block::getDefaultState).get()));
 
@@ -57,7 +58,7 @@ public interface UBlocks {
             0xE5FFCC88,
             () -> UBlocks.SWEET_APPLE,
             () -> UItems.SWEET_APPLE.getDefaultStack()
-    ), ItemGroup.DECORATIONS);
+    ), ItemGroups.NATURAL);
     Block SWEET_APPLE = register("sweet_apple", new FruitBlock(FabricBlockSettings.of(Material.GOURD, MapColor.GREEN).sounds(BlockSoundGroup.WOOD), Direction.DOWN, SWEET_APPLE_LEAVES, FruitBlock.DEFAULT_SHAPE));
     Block SWEET_APPLE_SPROUT = register("sweet_apple_sprout", new SproutBlock(0xE5FFCC88, () -> UItems.SWEET_APPLE_SEEDS, () -> UTreeGen.SWEET_APPLE_TREE.sapling().map(Block::getDefaultState).get()));
 
@@ -65,7 +66,7 @@ public interface UBlocks {
             0xE5FFCCCC,
             () -> UBlocks.SOUR_APPLE,
             () -> UItems.SOUR_APPLE.getDefaultStack()
-    ), ItemGroup.DECORATIONS);
+    ), ItemGroups.NATURAL);
     Block SOUR_APPLE = register("sour_apple", new FruitBlock(FabricBlockSettings.of(Material.GOURD, MapColor.GREEN).sounds(BlockSoundGroup.WOOD), Direction.DOWN, SOUR_APPLE_LEAVES, FruitBlock.DEFAULT_SHAPE));
     Block SOUR_APPLE_SPROUT = register("sour_apple_sprout", new SproutBlock(0xE5FFCC88, () -> UItems.SOUR_APPLE_SEEDS, () -> UTreeGen.SOUR_APPLE_TREE.sapling().map(Block::getDefaultState).get()));
 
@@ -84,7 +85,7 @@ public interface UBlocks {
     }
 
     static <T extends Block> T register(Identifier id, T block, ItemGroup group) {
-        UItems.register(id, new BlockItem(block, new Item.Settings().group(group)));
+        UItems.register(id, ItemGroupRegistry.register(new BlockItem(block, new Item.Settings()), group));
         return register(id, block);
     }
 
@@ -95,7 +96,7 @@ public interface UBlocks {
         if (block instanceof SaplingBlock || block instanceof SproutBlock || block instanceof FruitBlock || block instanceof CropBlock) {
             TRANSLUCENT_BLOCKS.add(block);
         }
-        return Registry.register(Registry.BLOCK, id, block);
+        return Registry.register(Registries.BLOCK, id, block);
     }
 
     static void bootstrap() {

src/main/java/com/minelittlepony/unicopia/block/state/StatePredicate.java

@@ -19,7 +19,6 @@ import net.minecraft.util.JsonHelper;
 import net.minecraft.registry.Registries;
 import net.minecraft.registry.RegistryKeys;
 import net.minecraft.registry.entry.RegistryEntry;
-import net.minecraft.registry.tag.FluidTags;
 import net.minecraft.registry.tag.TagKey;
 import net.minecraft.world.World;
 

src/main/java/com/minelittlepony/unicopia/client/gui/spellbook/SpellbookTraitDexPageContent.java

@@ -12,6 +12,7 @@ import com.minelittlepony.unicopia.client.gui.spellbook.SpellbookChapterList.Cha
 import com.minelittlepony.unicopia.client.gui.spellbook.SpellbookScreen.ImageButton;
 import com.minelittlepony.unicopia.container.SpellbookState;
 import com.minelittlepony.unicopia.entity.player.Pony;
+import com.minelittlepony.unicopia.item.group.ItemGroupRegistry;
 import com.mojang.blaze3d.systems.RenderSystem;
 
 import net.minecraft.client.MinecraftClient;
@@ -22,10 +23,8 @@ import net.minecraft.sound.SoundEvents;
 import net.minecraft.text.Text;
 import net.minecraft.util.Identifier;
 import net.minecraft.util.Util;
-import net.minecraft.util.collection.DefaultedList;
 
 public class SpellbookTraitDexPageContent extends DrawableHelper implements SpellbookChapterList.Content, SpellbookScreen.RecipesChangedListener {
-
     private final Trait[] traits = Trait.values();
     private SpellbookState.PageState state = new SpellbookState.PageState();
 
@@ -127,8 +126,7 @@ public class SpellbookTraitDexPageContent extends DrawableHelper implements Spel
                 SpellTraits.getItems(trait)
                     .sorted(Comparator.comparing(u -> knownItems.contains(u) ? 0 : 1))
                     .forEach(i -> {
-                        DefaultedList<ItemStack> stacks = DefaultedList.of();
+                        List<ItemStack> stacks = ItemGroupRegistry.getVariations(i);
-                        i.appendStacks(ItemGroups.SEARCH, stacks);
                         if (knownItems.contains(i)) {
                             tree.input(stacks);
                         } else {

src/main/java/com/minelittlepony/unicopia/entity/UTradeOffers.java

@@ -6,7 +6,7 @@ import com.minelittlepony.unicopia.UTags;
 import com.minelittlepony.unicopia.ability.magic.spell.effect.SpellType;
 import com.minelittlepony.unicopia.item.GemstoneItem;
 import com.minelittlepony.unicopia.item.UItems;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.fabricmc.fabric.api.object.builder.v1.trade.TradeOfferHelper;
 import net.minecraft.entity.Entity;
@@ -80,7 +80,7 @@ public interface UTradeOffers {
     }
 
     private static Item random(Entity e, TagKey<Item> item, Random rng) {
-        return Registries.entriesForTag(e.world, item).getRandom(rng).get().value();
+        return RegistryUtils.entriesForTag(e.world, item).getRandom(rng).get().value();
     }
 
     static class JarredItemTradeOfferFactory implements TradeOffers.Factory {

src/main/java/com/minelittlepony/unicopia/entity/behaviour/EntityBehaviour.java

@@ -10,7 +10,7 @@ import com.minelittlepony.unicopia.ability.magic.Caster;
 import com.minelittlepony.unicopia.entity.duck.LivingEntityDuck;
 import com.minelittlepony.unicopia.entity.duck.EntityDuck;
 import com.minelittlepony.unicopia.entity.player.Pony;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.Entity.RemovalReason;
@@ -38,7 +38,7 @@ import net.minecraft.registry.Registry;
 public class EntityBehaviour<T extends Entity> {
 
     private static final EntityBehaviour<Entity> DEFAULT = new EntityBehaviour<>();
-    private static final Registry<EntityBehaviour<?>> REGISTRY = Registries.createSimple(Unicopia.id("entity_behaviour"));
+    private static final Registry<EntityBehaviour<?>> REGISTRY = RegistryUtils.createSimple(Unicopia.id("entity_behaviour"));
 
     /**
      * Equivalent of the entity#tick method. Called every tick to update th logic for a disguise.

src/main/java/com/minelittlepony/unicopia/item/GemstoneItem.java

@@ -1,5 +1,6 @@
 package com.minelittlepony.unicopia.item;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.function.Predicate;
 
@@ -14,11 +15,11 @@ import com.minelittlepony.unicopia.ability.magic.spell.trait.SpellTraits;
 import com.minelittlepony.unicopia.client.FlowingText;
 import com.minelittlepony.unicopia.entity.player.PlayerCharmTracker;
 import com.minelittlepony.unicopia.entity.player.Pony;
+import com.minelittlepony.unicopia.item.group.MultiItem;
 
 import net.minecraft.client.item.TooltipContext;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.item.Item;
-import net.minecraft.item.ItemGroup;
 import net.minecraft.item.ItemStack;
 import net.minecraft.text.MutableText;
 import net.minecraft.text.Text;
@@ -26,10 +27,9 @@ import net.minecraft.util.Formatting;
 import net.minecraft.util.Hand;
 import net.minecraft.util.Identifier;
 import net.minecraft.util.TypedActionResult;
-import net.minecraft.util.collection.DefaultedList;
 import net.minecraft.world.World;
 
-public class GemstoneItem extends Item {
+public class GemstoneItem extends Item implements MultiItem {
 
     public GemstoneItem(Settings settings) {
         super(settings);
@@ -90,17 +90,13 @@ public class GemstoneItem extends Item {
     }
 
     @Override
-    public void appendStacks(ItemGroup tab, DefaultedList<ItemStack> items) {
+    public List<ItemStack> getDefaultStacks() {
-        super.appendStacks(tab, items);
+        return Arrays.stream(Affinity.VALUES)
-        if (isIn(tab)) {
+            .flatMap(i -> SpellType.byAffinity(i).stream()
-            for (Affinity i : Affinity.VALUES) {
+                    .filter(type -> type.isObtainable())
-                SpellType.byAffinity(i).forEach(type -> {
+                    .map(type -> enchant(getDefaultStack(), type, i))
-                    if (type.isObtainable()) {
+            )
-                        items.add(enchant(getDefaultStack(), type, i));
+            .toList();
-                    }
-                });
-            }
-        }
     }
 
     @Override

src/main/java/com/minelittlepony/unicopia/item/UItemGroups.java

@@ -1,52 +1,29 @@
 package com.minelittlepony.unicopia.item;
 
-import java.util.function.Supplier;
 import java.util.stream.Stream;
 
-import com.minelittlepony.unicopia.UTags;
+import com.minelittlepony.unicopia.item.group.ItemGroupRegistry;
-import com.minelittlepony.unicopia.Unicopia;
 import com.minelittlepony.unicopia.item.toxin.Toxic;
 import com.minelittlepony.unicopia.item.toxin.ToxicHolder;
-import net.minecraft.item.Item;
+
-import net.minecraft.item.ItemGroup;
+import net.minecraft.item.*;
-import net.minecraft.item.ItemStack;
+import net.minecraft.registry.Registries;
-import net.minecraft.item.Items;
-import net.minecraft.tag.TagKey;
-import net.fabricmc.fabric.api.client.itemgroup.FabricItemGroupBuilder;
-import net.minecraft.util.collection.DefaultedList;
-import net.minecraft.util.registry.Registry;
 
 public interface UItemGroups {
-    ItemGroup ALL_ITEMS = create("items", UItems.EMPTY_JAR::getDefaultStack, () -> {
+    ItemGroup ALL_ITEMS = ItemGroupRegistry.createDynamic("items", UItems.EMPTY_JAR::getDefaultStack, () -> {
         return Stream.concat(Stream.of(Items.APPLE), UItems.ITEMS.stream().filter(item -> !(item instanceof ChameleonItem) || ((ChameleonItem)item).isFullyDisguised()));
     });
-    ItemGroup HORSE_FEED = create("horsefeed", UItems.ZAP_APPLE::getDefaultStack, () -> {
+    ItemGroup HORSE_FEED = ItemGroupRegistry.createDynamic("horsefeed", UItems.ZAP_APPLE::getDefaultStack, () -> {
-        return Registry.ITEM.stream().filter(item -> ((ToxicHolder)item).getToxic(item.getDefaultStack()) != Toxic.EMPTY);
+        return Registries.ITEM.stream().filter(item -> ((ToxicHolder)item).getToxic(item.getDefaultStack()) != Toxic.EMPTY);
     });
 
-    ItemGroup EARTH_PONY_ITEMS = forTag("earth_pony", UItems.APPLE_PIE::getDefaultStack);
+    ItemGroup EARTH_PONY_ITEMS = ItemGroupRegistry.createGroupFromTag("earth_pony", UItems.APPLE_PIE::getDefaultStack);
-    ItemGroup UNICORN_ITEMS = forTag("unicorn", UItems.SPELLBOOK::getDefaultStack);
+    ItemGroup UNICORN_ITEMS = ItemGroupRegistry.createGroupFromTag("unicorn", UItems.SPELLBOOK::getDefaultStack);
-    ItemGroup PEGASUS_ITEMS = forTag("pegasus", UItems.PEGASUS_FEATHER::getDefaultStack);
+    ItemGroup PEGASUS_ITEMS = ItemGroupRegistry.createGroupFromTag("pegasus", UItems.PEGASUS_FEATHER::getDefaultStack);
-    ItemGroup BAT_PONY_ITEMS = forTag("bat_pony", UItems.SUNGLASSES::getDefaultStack);
+    ItemGroup BAT_PONY_ITEMS = ItemGroupRegistry.createGroupFromTag("bat_pony", UItems.SUNGLASSES::getDefaultStack);
-    ItemGroup CHANGELING_ITEMS = forTag("changeling", UItems.LOVE_BOTTLE::getDefaultStack);
+    ItemGroup CHANGELING_ITEMS = ItemGroupRegistry.createGroupFromTag("changeling", UItems.LOVE_BOTTLE::getDefaultStack);
 
-    static ItemGroup forTag(String name, Supplier<ItemStack> icon) {
+    static void bootstrap() {
-        TagKey<Item> key = UTags.item("groups/" + name);
+        UItems.bootstrap();
-        return create(name, icon, () -> {
-            return Registry.ITEM.getEntryList(key)
-                    .stream()
-                    .flatMap(named -> named.stream())
-                    .map(entry -> entry.value());
-        });
     }
-
-    static ItemGroup create(String name, Supplier<ItemStack> icon, Supplier<Stream<Item>> items) {
-        return FabricItemGroupBuilder.create(Unicopia.id(name)).appendItems(list -> {
-            DefaultedList<ItemStack> defs = DefaultedList.of();
-            items.get().forEach(item -> item.appendStacks(ItemGroup.SEARCH, defs));
-            list.addAll(defs);
-        }).icon(icon).build();
-    }
-
-    static void bootstrap() {}
 }

src/main/java/com/minelittlepony/unicopia/item/UItems.java

@@ -7,6 +7,7 @@ import com.minelittlepony.unicopia.*;
 import com.minelittlepony.unicopia.block.UBlocks;
 import com.minelittlepony.unicopia.entity.UEntities;
 import com.minelittlepony.unicopia.item.enchantment.UEnchantments;
+import com.minelittlepony.unicopia.item.group.ItemGroupRegistry;
 import com.minelittlepony.unicopia.item.toxin.UFoodComponents;
 
 import net.minecraft.item.*;
@@ -24,15 +25,15 @@ public interface UItems {
 
     List<Item> ITEMS = new ArrayList<>();
 
-    Item GREEN_APPLE = register("green_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE))));
+    Item GREEN_APPLE = register("green_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().food(FoodComponents.APPLE))), ItemGroups.FOOD_AND_DRINK);
-    Item SWEET_APPLE = register("sweet_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE))));
+    Item SWEET_APPLE = register("sweet_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().food(FoodComponents.APPLE))), ItemGroups.FOOD_AND_DRINK);
-    Item SOUR_APPLE = register("sour_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE))));
+    Item SOUR_APPLE = register("sour_apple", AppleItem.registerTickCallback(new Item(new Item.Settings().food(FoodComponents.APPLE))), ItemGroups.FOOD_AND_DRINK);
 
-    ZapAppleItem ZAP_APPLE = register("zap_apple", AppleItem.registerTickCallback(new ZapAppleItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.ZAP_APPLE))));
+    ZapAppleItem ZAP_APPLE = register("zap_apple", AppleItem.registerTickCallback(new ZapAppleItem(new Item.Settings().food(UFoodComponents.ZAP_APPLE))), ItemGroups.FOOD_AND_DRINK);
-    Item ZAP_BULB = register("zap_bulb", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.ZAP_BULB)));
+    Item ZAP_BULB = register("zap_bulb", new Item(new Item.Settings().food(UFoodComponents.ZAP_BULB)), ItemGroups.FOOD_AND_DRINK);
 
-    Item ROTTEN_APPLE = register("rotten_apple", new RottenAppleItem(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
+    Item ROTTEN_APPLE = register("rotten_apple", new RottenAppleItem(new Item.Settings().food(FoodComponents.APPLE)), ItemGroups.FOOD_AND_DRINK);
-    Item COOKED_ZAP_APPLE = register("cooked_zap_apple", new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.APPLE)));
+    Item COOKED_ZAP_APPLE = register("cooked_zap_apple", new Item(new Item.Settings().food(FoodComponents.APPLE)), ItemGroups.FOOD_AND_DRINK);
 
     Item MUSIC_DISC_CRUSADE = register("music_disc_crusade", USounds.RECORD_CRUSADE, 181);
     Item MUSIC_DISC_PET = register("music_disc_pet", USounds.RECORD_PET, 221);
@@ -42,89 +43,91 @@ public interface UItems {
     FriendshipBraceletItem FRIENDSHIP_BRACELET = register("friendship_bracelet", new FriendshipBraceletItem(
             new FabricItemSettings()
             .rarity(Rarity.UNCOMMON)
-            .group(ItemGroup.TOOLS)
+    ), ItemGroups.TOOLS);
-    ));
 
-    Item EMPTY_JAR = register("empty_jar", new JarItem(new Item.Settings().group(ItemGroup.DECORATIONS).maxCount(16).fireproof(), false, false, false));
+    Item EMPTY_JAR = register("empty_jar", new JarItem(new Item.Settings().maxCount(16).fireproof(), false, false, false), ItemGroups.FUNCTIONAL);
     FilledJarItem FILLED_JAR = register("filled_jar", new FilledJarItem(new Item.Settings().maxCount(1)));
-    Item RAIN_CLOUD_JAR  = register("rain_cloud_jar", new JarItem(new Item.Settings().group(ItemGroup.DECORATIONS).maxCount(1).fireproof(), true, false, false));
+    Item RAIN_CLOUD_JAR  = register("rain_cloud_jar", new JarItem(new Item.Settings().maxCount(1).fireproof(), true, false, false), ItemGroups.FUNCTIONAL);
-    Item STORM_CLOUD_JAR  = register("storm_cloud_jar", new JarItem(new Item.Settings().group(ItemGroup.DECORATIONS).maxCount(1).fireproof(), true, true, false));
+    Item STORM_CLOUD_JAR  = register("storm_cloud_jar", new JarItem(new Item.Settings().maxCount(1).fireproof(), true, true, false), ItemGroups.FUNCTIONAL);
-    Item LIGHTNING_JAR  = register("lightning_jar", new JarItem(new Item.Settings().group(ItemGroup.DECORATIONS).maxCount(1).fireproof(), false, false, true));
+    Item LIGHTNING_JAR  = register("lightning_jar", new JarItem(new Item.Settings().maxCount(1).fireproof(), false, false, true), ItemGroups.FUNCTIONAL);
-    Item ZAP_APPLE_JAM_JAR = register("zap_apple_jam_jar", new JarItem(new Item.Settings().group(ItemGroup.DECORATIONS).maxCount(1).fireproof(), false, false, true));
+    Item ZAP_APPLE_JAM_JAR = register("zap_apple_jam_jar", new JarItem(new Item.Settings().maxCount(1).fireproof(), false, false, true), ItemGroups.FUNCTIONAL);
 
-    Item CRYSTAL_HEART = register("crystal_heart", new CrystalHeartItem(new Item.Settings().group(ItemGroup.DECORATIONS).maxCount(1)));
+    Item CRYSTAL_HEART = register("crystal_heart", new CrystalHeartItem(new Item.Settings().maxCount(1)), ItemGroups.TOOLS);
-    Item CRYSTAL_SHARD = register("crystal_shard", new Item(new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item CRYSTAL_SHARD = register("crystal_shard", new Item(new Item.Settings()), ItemGroups.NATURAL);
 
-    Item GEMSTONE = register("gemstone", new GemstoneItem(new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item GEMSTONE = register("gemstone", new GemstoneItem(new Item.Settings()), ItemGroups.NATURAL);
-    Item BOTCHED_GEM = register("botched_gem", new Item(new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item BOTCHED_GEM = register("botched_gem", new Item(new Item.Settings()), ItemGroups.NATURAL);
 
-    Item PEGASUS_FEATHER = register("pegasus_feather", new Item(new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item PEGASUS_FEATHER = register("pegasus_feather", new Item(new Item.Settings()), ItemGroups.NATURAL);
-    Item GRYPHON_FEATHER = register("gryphon_feather", new Item(new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item GRYPHON_FEATHER = register("gryphon_feather", new Item(new Item.Settings()), ItemGroups.NATURAL);
 
-    Item OAT_SEEDS = register("oat_seeds", new AliasedBlockItem(UBlocks.OATS, new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item OAT_SEEDS = register("oat_seeds", new AliasedBlockItem(UBlocks.OATS, new Item.Settings()), ItemGroups.NATURAL);
-    Item OATS = register("oats", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.OATS)));
+    Item OATS = register("oats", new Item(new Item.Settings().food(UFoodComponents.OATS)), ItemGroups.FOOD_AND_DRINK);
-    Item IMPORTED_OATS = register("imported_oats", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.IMPORTED_OATS)));
+    Item IMPORTED_OATS = register("imported_oats", new Item(new Item.Settings().food(UFoodComponents.IMPORTED_OATS)), ItemGroups.FOOD_AND_DRINK);
-    Item OATMEAL = register("oatmeal", new OatmealItem(new Item.Settings().recipeRemainder(Items.BOWL).maxCount(1).group(ItemGroup.FOOD).food(UFoodComponents.OATMEAL)));
+    Item OATMEAL = register("oatmeal", new OatmealItem(new Item.Settings().recipeRemainder(Items.BOWL).maxCount(1).food(UFoodComponents.OATMEAL)), ItemGroups.FOOD_AND_DRINK);
 
-    Item DAFFODIL_DAISY_SANDWICH = register("daffodil_daisy_sandwich", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.DAFODIL_DAISY_SANDWICH)));
+    Item DAFFODIL_DAISY_SANDWICH = register("daffodil_daisy_sandwich", new Item(new Item.Settings().food(UFoodComponents.DAFODIL_DAISY_SANDWICH)), ItemGroups.FOOD_AND_DRINK);
-    Item HAY_BURGER = register("hay_burger", new Item(new Item.Settings().group(ItemGroup.FOOD).maxCount(1).food(UFoodComponents.HAY_BURGER)));
+    Item HAY_BURGER = register("hay_burger", new Item(new Item.Settings().maxCount(1).food(UFoodComponents.HAY_BURGER)), ItemGroups.FOOD_AND_DRINK);
-    Item HAY_FRIES = register("hay_fries", new Item(new Item.Settings().group(ItemGroup.FOOD).maxCount(16).food(UFoodComponents.HAY_FRIES)));
+    Item HAY_FRIES = register("hay_fries", new Item(new Item.Settings().maxCount(16).food(UFoodComponents.HAY_FRIES)), ItemGroups.FOOD_AND_DRINK);
-    Item WHEAT_WORMS = register("wheat_worms", new Item(new Item.Settings().group(ItemGroup.MISC).maxCount(16).food(UFoodComponents.INSECTS)));
+    Item WHEAT_WORMS = register("wheat_worms", new Item(new Item.Settings().maxCount(16).food(UFoodComponents.INSECTS)), ItemGroups.NATURAL);
-    Item MUFFIN = register("muffin", new MuffinItem(new Item.Settings().group(ItemGroup.FOOD).maxCount(32).food(FoodComponents.BREAD), 0));
+    Item MUFFIN = register("muffin", new MuffinItem(new Item.Settings().maxCount(32).food(FoodComponents.BREAD), 0), ItemGroups.FOOD_AND_DRINK);
-    Item PINECONE = register("pinecone", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.PINECONE).maxCount(3)));
+    Item PINECONE = register("pinecone", new Item(new Item.Settings().food(UFoodComponents.PINECONE).maxCount(3)), ItemGroups.FOOD_AND_DRINK);
-    Item ACORN = register("acorn", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.ACORN).maxCount(16)));
+    Item ACORN = register("acorn", new Item(new Item.Settings().food(UFoodComponents.ACORN).maxCount(16)), ItemGroups.FOOD_AND_DRINK);
 
-    Item PEBBLES = register("pebbles", new RacePredicatedAliasedBlockItem(UBlocks.ROCKS, new Item.Settings().group(ItemGroup.MATERIALS), Race::canUseEarth));
+    Item PEBBLES = register("pebbles", new RacePredicatedAliasedBlockItem(UBlocks.ROCKS, new Item.Settings(), Race::canUseEarth), ItemGroups.NATURAL);
-    Item ROCK = register("rock", new HeavyProjectileItem(new Item.Settings().group(ItemGroup.MATERIALS), 3));
+    Item ROCK = register("rock", new HeavyProjectileItem(new Item.Settings(), 3), ItemGroups.NATURAL);
-    Item WEIRD_ROCK = register("weird_rock", new Item(new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item WEIRD_ROCK = register("weird_rock", new Item(new Item.Settings()), ItemGroups.NATURAL);
-    Item ROCK_STEW = register("rock_stew", new Item(new Item.Settings().group(ItemGroup.FOOD).food(FoodComponents.MUSHROOM_STEW)));
+    Item ROCK_STEW = register("rock_stew", new Item(new Item.Settings().food(FoodComponents.MUSHROOM_STEW)), ItemGroups.FOOD_AND_DRINK);
 
-    Item GREEN_APPLE_SEEDS = register("green_apple_seeds", new AliasedBlockItem(UBlocks.GREEN_APPLE_SPROUT, new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item GREEN_APPLE_SEEDS = register("green_apple_seeds", new AliasedBlockItem(UBlocks.GREEN_APPLE_SPROUT, new Item.Settings()), ItemGroups.NATURAL);
-    Item SWEET_APPLE_SEEDS = register("sweet_apple_seeds", new AliasedBlockItem(UBlocks.SWEET_APPLE_SPROUT, new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item SWEET_APPLE_SEEDS = register("sweet_apple_seeds", new AliasedBlockItem(UBlocks.SWEET_APPLE_SPROUT, new Item.Settings()), ItemGroups.NATURAL);
-    Item SOUR_APPLE_SEEDS = register("sour_apple_seeds", new AliasedBlockItem(UBlocks.SOUR_APPLE_SPROUT, new Item.Settings().group(ItemGroup.MATERIALS)));
+    Item SOUR_APPLE_SEEDS = register("sour_apple_seeds", new AliasedBlockItem(UBlocks.SOUR_APPLE_SPROUT, new Item.Settings()), ItemGroups.NATURAL);
 
-    Item MUG = register("mug", new Item(new Settings().group(ItemGroup.MATERIALS).maxCount(16)));
+    Item MUG = register("mug", new Item(new Settings().maxCount(16)), ItemGroups.TOOLS);
-    Item CIDER = register("cider", new DrinkableItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.CIDER).maxCount(1).recipeRemainder(MUG)));
+    Item CIDER = register("cider", new DrinkableItem(new Item.Settings().food(UFoodComponents.CIDER).maxCount(1).recipeRemainder(MUG)), ItemGroups.FOOD_AND_DRINK);
-    Item JUICE = register("juice", new DrinkableItem(new Item.Settings().group(ItemGroup.FOOD).recipeRemainder(Items.GLASS_BOTTLE).maxCount(1).food(UFoodComponents.JUICE)));
+    Item JUICE = register("juice", new DrinkableItem(new Item.Settings().recipeRemainder(Items.GLASS_BOTTLE).maxCount(1).food(UFoodComponents.JUICE)), ItemGroups.FOOD_AND_DRINK);
-    Item BURNED_JUICE = register("burned_juice", new DrinkableItem(new Item.Settings().group(ItemGroup.FOOD).recipeRemainder(Items.GLASS_BOTTLE).maxCount(1).food(UFoodComponents.BURNED_JUICE)));
+    Item BURNED_JUICE = register("burned_juice", new DrinkableItem(new Item.Settings().recipeRemainder(Items.GLASS_BOTTLE).maxCount(1).food(UFoodComponents.BURNED_JUICE)), ItemGroups.FOOD_AND_DRINK);
-    Item APPLE_PIE = register("apple_pie", new BlockItem(UBlocks.APPLE_PIE, new Item.Settings().group(ItemGroup.FOOD).maxCount(1)));
+    Item APPLE_PIE = register("apple_pie", new BlockItem(UBlocks.APPLE_PIE, new Item.Settings().maxCount(1)), ItemGroups.FOOD_AND_DRINK);
-    Item APPLE_PIE_SLICE = register("apple_pie_slice", new Item(new Item.Settings().group(ItemGroup.FOOD).maxCount(16).food(UFoodComponents.PIE)));
+    Item APPLE_PIE_SLICE = register("apple_pie_slice", new Item(new Item.Settings().maxCount(16).food(UFoodComponents.PIE)), ItemGroups.FOOD_AND_DRINK);
 
-    Item LOVE_BOTTLE = register("love_bottle", new DrinkableItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.LOVE_BOTTLE).maxCount(1).recipeRemainder(Items.GLASS_BOTTLE)));
+    Item LOVE_BOTTLE = register("love_bottle", new DrinkableItem(new Item.Settings().food(UFoodComponents.LOVE_BOTTLE).maxCount(1).recipeRemainder(Items.GLASS_BOTTLE)), ItemGroups.FOOD_AND_DRINK);
-    Item LOVE_BUCKET = register("love_bucket", new DrinkableItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.LOVE_BUCKET).recipeRemainder(Items.BUCKET)));
+    Item LOVE_BUCKET = register("love_bucket", new DrinkableItem(new Item.Settings().food(UFoodComponents.LOVE_BUCKET).recipeRemainder(Items.BUCKET)), ItemGroups.FOOD_AND_DRINK);
-    Item LOVE_MUG = register("love_mug", new DrinkableItem(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.LOVE_MUG).recipeRemainder(MUG)));
+    Item LOVE_MUG = register("love_mug", new DrinkableItem(new Item.Settings().food(UFoodComponents.LOVE_MUG).recipeRemainder(MUG)), ItemGroups.FOOD_AND_DRINK);
 
-    Item GOLDEN_FEATHER = register("golden_feather", new Item(new Item.Settings().rarity(Rarity.UNCOMMON).group(ItemGroup.MATERIALS)));
+    Item GOLDEN_FEATHER = register("golden_feather", new Item(new Item.Settings().rarity(Rarity.UNCOMMON)), ItemGroups.NATURAL);
-    Item GOLDEN_WING = register("golden_wing", new Item(new Item.Settings().rarity(Rarity.UNCOMMON).group(ItemGroup.MATERIALS)));
+    Item GOLDEN_WING = register("golden_wing", new Item(new Item.Settings().rarity(Rarity.UNCOMMON)), ItemGroups.NATURAL);
 
-    Item DRAGON_BREATH_SCROLL = register("dragon_breath_scroll", new DragonBreathScrollItem(new Item.Settings().rarity(Rarity.UNCOMMON).group(ItemGroup.TOOLS)));
+    Item DRAGON_BREATH_SCROLL = register("dragon_breath_scroll", new DragonBreathScrollItem(new Item.Settings().rarity(Rarity.UNCOMMON)), ItemGroups.TOOLS);
 
-    Item WOODEN_POLEARM = register("wooden_polearm", new PolearmItem(ToolMaterials.WOOD, 2, -3.6F, 2, new Item.Settings().group(ItemGroup.COMBAT)));
+    Item WOODEN_POLEARM = register("wooden_polearm", new PolearmItem(ToolMaterials.WOOD, 2, -3.6F, 2, new Item.Settings()), ItemGroups.COMBAT);
-    Item STONE_POLEARM = register("stone_polearm", new PolearmItem(ToolMaterials.STONE, 2, -3.6F, 2, new Item.Settings().group(ItemGroup.COMBAT)));
+    Item STONE_POLEARM = register("stone_polearm", new PolearmItem(ToolMaterials.STONE, 2, -3.6F, 2, new Item.Settings()), ItemGroups.COMBAT);
-    Item IRON_POLEARM = register("iron_polearm", new PolearmItem(ToolMaterials.IRON, 2, -3.6F, 3, new Item.Settings().group(ItemGroup.COMBAT)));
+    Item IRON_POLEARM = register("iron_polearm", new PolearmItem(ToolMaterials.IRON, 2, -3.6F, 3, new Item.Settings()), ItemGroups.COMBAT);
-    Item GOLDEN_POLEARM = register("golden_polearm", new PolearmItem(ToolMaterials.GOLD, 2, -3.6F, 4, new Item.Settings().group(ItemGroup.COMBAT)));
+    Item GOLDEN_POLEARM = register("golden_polearm", new PolearmItem(ToolMaterials.GOLD, 2, -3.6F, 4, new Item.Settings()), ItemGroups.COMBAT);
-    Item DIAMOND_POLEARM = register("diamond_polearm", new PolearmItem(ToolMaterials.DIAMOND, 2, -3.6F, 5, new Item.Settings().group(ItemGroup.COMBAT)));
+    Item DIAMOND_POLEARM = register("diamond_polearm", new PolearmItem(ToolMaterials.DIAMOND, 2, -3.6F, 5, new Item.Settings()), ItemGroups.COMBAT);
-    Item NETHERITE_POLEARM = register("netherite_polearm", new PolearmItem(ToolMaterials.NETHERITE, 2, -3.6F, 5, new Item.Settings().group(ItemGroup.COMBAT).fireproof()));
+    Item NETHERITE_POLEARM = register("netherite_polearm", new PolearmItem(ToolMaterials.NETHERITE, 2, -3.6F, 5, new Item.Settings().fireproof()), ItemGroups.COMBAT);
 
-    Item BUTTERFLY_SPAWN_EGG = register("butterfly_spawn_egg", new SpawnEggItem(UEntities.BUTTERFLY, 0x222200, 0xaaeeff, new Item.Settings().group(ItemGroup.MISC)));
+    Item BUTTERFLY_SPAWN_EGG = register("butterfly_spawn_egg", new SpawnEggItem(UEntities.BUTTERFLY, 0x222200, 0xaaeeff, new Item.Settings()), ItemGroups.SPAWN_EGGS);
-    Item BUTTERFLY = register("butterfly", new Item(new Item.Settings().group(ItemGroup.FOOD).food(UFoodComponents.INSECTS)));
+    Item BUTTERFLY = register("butterfly", new Item(new Item.Settings().food(UFoodComponents.INSECTS)), ItemGroups.FOOD_AND_DRINK);
 
-    Item SPELLBOOK = register("spellbook", new SpellbookItem(new Item.Settings().maxCount(1).rarity(Rarity.UNCOMMON).group(ItemGroup.TOOLS)));
+    Item SPELLBOOK = register("spellbook", new SpellbookItem(new Item.Settings().maxCount(1).rarity(Rarity.UNCOMMON)), ItemGroups.TOOLS);
 
     AmuletItem PEGASUS_AMULET = register("pegasus_amulet", new PegasusAmuletItem(new FabricItemSettings()
             .maxCount(1)
             .maxDamage(890)
-            .rarity(Rarity.UNCOMMON)
+            .rarity(Rarity.UNCOMMON), 900), ItemGroups.TOOLS);
-            .group(ItemGroup.DECORATIONS), 900));
     AlicornAmuletItem ALICORN_AMULET = register("alicorn_amulet", new AlicornAmuletItem(new FabricItemSettings()
             .maxCount(1)
             .maxDamage(1000)
-            .rarity(Rarity.RARE)
+            .rarity(Rarity.RARE)), ItemGroups.TOOLS);
-            .group(ItemGroup.DECORATIONS)));
 
-    GlassesItem SUNGLASSES = register("sunglasses", new GlassesItem(new FabricItemSettings().maxCount(1).group(ItemGroup.COMBAT)));
+    GlassesItem SUNGLASSES = register("sunglasses", new GlassesItem(new FabricItemSettings().maxCount(1)), ItemGroups.COMBAT);
-    GlassesItem BROKEN_SUNGLASSES = register("broken_sunglasses", new GlassesItem(new FabricItemSettings().maxCount(1).group(ItemGroup.COMBAT)));
+    GlassesItem BROKEN_SUNGLASSES = register("broken_sunglasses", new GlassesItem(new FabricItemSettings().maxCount(1)), ItemGroups.COMBAT);
 
+    static <T extends Item> T register(String name, T item, ItemGroup group) {
+        return ItemGroupRegistry.register(register(name, item), group);
+    }
+
+    @Deprecated
     static <T extends Item> T register(String name, T item) {
         return register(Unicopia.id(name), item);
     }
@@ -134,15 +137,14 @@ public interface UItems {
         if (item instanceof BlockItem) {
             ((BlockItem)item).appendBlocks(Item.BLOCK_ITEMS, item);
         }
-        return Registry.register(Registry.ITEM, id, item);
+        return Registry.register(Registries.ITEM, id, item);
     }
 
     static MusicDiscItem register(String name, SoundEvent sound, int seconds) {
         return register(name, new MusicDiscItem(1, sound, new Settings()
                 .maxCount(1)
-                .group(ItemGroup.MISC)
                 .rarity(Rarity.RARE), seconds
-            ) {});
+            ) {}, ItemGroups.TOOLS);
     }
 
     static void bootstrap() {

src/main/java/com/minelittlepony/unicopia/item/ZapAppleItem.java

@@ -1,15 +1,18 @@
 package com.minelittlepony.unicopia.item;
 
+import java.util.List;
+
 import com.minelittlepony.unicopia.UTags;
 import com.minelittlepony.unicopia.Unicopia;
 import com.minelittlepony.unicopia.advancement.UCriteria;
 import com.minelittlepony.unicopia.entity.player.Pony;
+import com.minelittlepony.unicopia.item.group.MultiItem;
 import com.minelittlepony.unicopia.item.toxin.*;
 import com.minelittlepony.unicopia.particle.ParticleUtils;
 import com.minelittlepony.unicopia.particle.UParticles;
 import com.minelittlepony.unicopia.util.MagicalDamageSource;
 import com.minelittlepony.unicopia.util.TraceHelper;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.EntityType;
@@ -24,7 +27,6 @@ import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.server.world.ServerWorld;
 import net.minecraft.text.Text;
 import net.minecraft.util.ActionResult;
-import net.minecraft.util.collection.DefaultedList;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.util.Hand;
 import net.minecraft.util.Rarity;
@@ -33,7 +35,7 @@ import net.minecraft.registry.Registries;
 import net.minecraft.world.World;
 import net.minecraft.world.event.GameEvent;
 
-public class ZapAppleItem extends Item implements ChameleonItem, ToxicHolder {
+public class ZapAppleItem extends Item implements ChameleonItem, ToxicHolder, MultiItem {
     public ZapAppleItem(Settings settings) {
         super(settings);
     }
@@ -98,18 +100,15 @@ public class ZapAppleItem extends Item implements ChameleonItem, ToxicHolder {
     }
 
     @Override
-    public void appendStacks(ItemGroup tab, DefaultedList<ItemStack> items) {
+    public List<ItemStack> getDefaultStacks() {
-        super.appendStacks(tab, items);
+        return Unicopia.SIDE.getPony().map(Pony::getReferenceWorld)
-        if (tab.contains(getDefaultStack())) {
-            Unicopia.SIDE.getPony().map(Pony::getReferenceWorld)
                 .stream()
-                    .flatMap(world -> Registries.valuesForTag(world, UTags.APPLES))
+                .flatMap(world -> RegistryUtils.valuesForTag(world, UTags.APPLES))
-                    .filter(a -> a != this).forEach(item -> {
+                .filter(a -> a != this).map(item -> {
             ItemStack stack = new ItemStack(this);
             stack.getOrCreateNbt().putString("appearance", Registries.ITEM.getId(item).toString());
-                items.add(stack);
+            return stack;
-            });
+        }).toList();
-        }
     }
 
     @Override

src/main/java/com/minelittlepony/unicopia/item/group/ItemGroupRegistry.java

@@ -0,0 +1,70 @@
+package com.minelittlepony.unicopia.item.group;
+
+import java.util.*;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
+import java.util.stream.Stream;
+
+import com.google.common.cache.*;
+import com.minelittlepony.unicopia.UTags;
+import com.minelittlepony.unicopia.Unicopia;
+
+import net.fabricmc.fabric.api.itemgroup.v1.FabricItemGroup;
+import net.fabricmc.fabric.api.itemgroup.v1.ItemGroupEvents;
+import net.minecraft.item.*;
+import net.minecraft.registry.Registries;
+import net.minecraft.registry.tag.TagKey;
+
+public interface ItemGroupRegistry {
+    LoadingCache<Item, List<ItemStack>> STACK_VARIANCES_CACHE = CacheBuilder.newBuilder()
+            .expireAfterAccess(30, TimeUnit.SECONDS)
+            .build(CacheLoader.from(i -> {
+                if (i instanceof MultiItem m) {
+                    return m.getDefaultStacks();
+                }
+                return ItemGroups.SEARCH.getSearchTabStacks().stream().filter(s -> s.getItem() == i).toList();
+            }));
+
+    static List<ItemStack> getVariations(Item item) {
+        return STACK_VARIANCES_CACHE.getUnchecked(item);
+    }
+
+    Map<ItemGroup, Set<Item>> REGISTRY = new HashMap<>();
+
+    static <T extends Item> T register(T item, ItemGroup group) {
+        REGISTRY.computeIfAbsent(group, g -> new HashSet<>()).add(item);
+        return item;
+    }
+
+    static ItemGroup createDynamic(String name, Supplier<ItemStack> icon, Supplier<Stream<Item>> items) {
+        boolean[] reloading = new boolean[1];
+        return FabricItemGroup.builder(Unicopia.id(name)).entries((features, list, k) -> {
+            if (reloading[0]) {
+                return;
+            }
+            reloading[0] = true;
+            items.get().forEach(item -> {
+                list.addAll(ItemGroupRegistry.getVariations(item));
+            });
+            reloading[0] = false;
+        }).icon(icon).build();
+    }
+
+    static ItemGroup createGroupFromTag(String name, Supplier<ItemStack> icon) {
+        TagKey<Item> key = UTags.item("groups/" + name);
+        return createDynamic(name, icon, () -> {
+            return Registries.ITEM.getEntryList(key)
+                    .stream()
+                    .flatMap(named -> named.stream())
+                    .map(entry -> entry.value());
+        });
+    }
+
+    static void bootstrap() {
+        REGISTRY.forEach((group, items) -> {
+            ItemGroupEvents.modifyEntriesEvent(group).register(event -> {
+                event.addAll(items.stream().map(Item::getDefaultStack).toList());
+            });
+        });
+    }
+}

src/main/java/com/minelittlepony/unicopia/item/group/MultiItem.java

@@ -0,0 +1,9 @@
+package com.minelittlepony.unicopia.item.group;
+
+import java.util.List;
+
+import net.minecraft.item.ItemStack;
+
+public interface MultiItem {
+    List<ItemStack> getDefaultStacks();
+}

src/main/java/com/minelittlepony/unicopia/item/group/package-info.java

@@ -0,0 +1 @@
+package com.minelittlepony.unicopia.item.group;

src/main/java/com/minelittlepony/unicopia/item/toxin/Toxics.java

@@ -1,7 +1,7 @@
 package com.minelittlepony.unicopia.item.toxin;
 
 import com.minelittlepony.unicopia.*;
-import com.minelittlepony.unicopia.util.Registries;
+import com.minelittlepony.unicopia.util.RegistryUtils;
 
 import net.minecraft.registry.Registry;
 
@@ -10,7 +10,7 @@ import static com.minelittlepony.unicopia.item.toxin.Ailment.*;
 import static com.minelittlepony.unicopia.item.toxin.Toxin.*;
 
 public interface Toxics {
-    Registry<ToxicRegistryEntry> REGISTRY = Registries.createSimple(Unicopia.id("toxic"));
+    Registry<ToxicRegistryEntry> REGISTRY = RegistryUtils.createSimple(Unicopia.id("toxic"));
 
     Toxic SEVERE_INNERT = Toxic.innert(Toxicity.SEVERE);
 

src/main/java/com/minelittlepony/unicopia/util/RegistryUtils.java

@@ -12,7 +12,7 @@ import net.minecraft.registry.entry.RegistryEntry;
 import net.minecraft.registry.entry.RegistryEntryList;
 import net.minecraft.world.World;
 
-public interface Registries {
+public interface RegistryUtils {
     static <T> Registry<T> createSimple(Identifier id) {
         return FabricRegistryBuilder.from(new SimpleRegistry<T>(RegistryKey.ofRegistry(id), Lifecycle.stable())).buildAndRegister();
     }