5.4.0 Release

Is it 1.22? Is it 1.21.6? Who knows

.github/workflows/build.yml

@@ -1,6 +1,6 @@
 name: Java CI with Gradle
 
-on: [push, pull_request]
+on: [push, pull_request, workflow_dispatch]
 
 jobs:
   build:
@@ -26,7 +26,7 @@ jobs:
       run: ./gradlew build
     - name: Upload Artifacts to GitHub
       # Only upload on the preview repository as there is no CI job for it.
-      if: ${{ github.repository == 'ViaVersionDev' && github.ref_name == 'preview' }}
+      if: ${{ github.repository == 'ViaVersion/ViaVersionDev' && github.ref_name == 'preview' }}
       uses: actions/upload-artifact@v4
       with:
         name: Artifacts

.github/workflows/publish.yml

@@ -4,6 +4,7 @@ on:
     branches:
       - master
       - dev
+  workflow_dispatch:
 
 jobs:
   publish:

api/build.gradle.kts

@@ -29,7 +29,11 @@ dependencies {
     api(libs.snakeYaml)
 
     compileOnlyApi(libs.netty)
-    compileOnlyApi(libs.guava)
+    compileOnlyApi(libs.guava) {
+        exclude("com.google.errorprone", "error_prone_annotations")
+        exclude("org.jspecify", "jspecify")
+        exclude("com.google.j2objc", "j2objc-annotations")
+    }
     compileOnlyApi(libs.checkerQual)
 }
 

api/src/main/java-templates/com/viaversion/viaversion/util/VersionInfo.java

@@ -1,6 +1,6 @@
 /*
  * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
- * Copyright (C) 2016-2024 ViaVersion and contributors
+ * Copyright (C) 2016-2025 ViaVersion and contributors
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal

api/src/main/java/com/viaversion/viaversion/api/configuration/ViaVersionConfig.java

@@ -285,6 +285,13 @@ public interface ViaVersionConfig extends Config {
      */
     boolean isSuppressConversionWarnings();
 
+    /**
+     * Should we hide errors that occur when trying to convert text components?
+     *
+     * @return true if enabled
+     */
+    boolean isSuppressTextComponentConversionWarnings();
+
     /**
      * Should we disable the 1.13 auto-complete feature to stop spam kicks? (for any server lower than 1.13)
      *

api/src/main/java/com/viaversion/viaversion/api/connection/UserConnection.java

@@ -24,6 +24,7 @@ package com.viaversion.viaversion.api.connection;
 
 import com.viaversion.viaversion.api.configuration.ViaVersionConfig;
 import com.viaversion.viaversion.api.data.entity.EntityTracker;
+import com.viaversion.viaversion.api.data.item.ItemHasher;
 import com.viaversion.viaversion.api.minecraft.ClientWorld;
 import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.protocol.packet.PacketTracker;
@@ -99,6 +100,23 @@ public interface UserConnection {
      */
     void addEntityTracker(Class<? extends Protocol> protocolClass, EntityTracker tracker);
 
+    /**
+     * Adds an item hasher to the user connection.
+     *
+     * @param protocolClass protocol class
+     * @param itemHasher   item hasher
+     */
+    void addItemHasher(Class<? extends Protocol> protocolClass, ItemHasher itemHasher);
+
+    /**
+     * Returns the item hasher by the given protocol class if present.
+     *
+     * @param protocolClass protocol class
+     * @param <T>           item hasher type
+     * @return item hasher if present
+     */
+    @Nullable <T extends ItemHasher> T getItemHasher(Class<? extends Protocol> protocolClass);
+
     /**
      * Returns the client world by the given protocol class if present.
      *

api/src/main/java/com/viaversion/viaversion/api/data/entity/EntityTracker.java

@@ -123,6 +123,20 @@ public interface EntityTracker {
      */
     void setClientEntityId(int clientEntityId);
 
+    /**
+     * Returns whether the client player has the "insta build" ability, usually from creative mode.
+     *
+     * @return whether the client player can insta build
+     */
+    boolean canInstaBuild();
+
+    /**
+     * Sets whether the client player has the "insta build" ability, usually from creative mode.
+     *
+     * @param instaBuild whether the client player can insta build
+     */
+    void setInstaBuild(boolean instaBuild);
+
     /**
      * Returns the current world section height (block height / 16).
      * This is always 16 for sub 1.17 worlds.

api/src/main/java/com/viaversion/viaversion/api/data/item/ItemHasher.java

@@ -0,0 +1,51 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.data.item;
+
+import java.util.List;
+
+/**
+ * Used for converting items to hashed items and caching them for later use during serverbound packets.
+ * <p>
+ * Most of this stays in the internal module given non-permanent, imperfect caching as well as missing converters.
+ */
+public interface ItemHasher {
+
+    /**
+     * Returns whether this connection is currently processing a clientbound player inventory packet.
+     * <p>
+     * Used for checking when it is necessary to track/process item data hashes.
+     *
+     * @return true if processing a clientbound inventory packet, false otherwise
+     */
+    boolean isProcessingClientboundInventoryPacket();
+
+    void setProcessingClientboundInventoryPacket(boolean processingClientboundInventoryPacket);
+
+    /**
+     * Sets the enchantment registry for this connection.
+     *
+     * @param enchantments list of enchantment identifiers
+     */
+    void setEnchantments(List<String> enchantments);
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/BlockChangeRecord1_16_2.java

@@ -58,7 +58,7 @@ public class BlockChangeRecord1_16_2 implements BlockChangeRecord {
 
     @Override
     public short getY(int chunkSectionY) {
-        Preconditions.checkArgument(chunkSectionY >= 0, "Invalid chunkSectionY: " + chunkSectionY);
+        Preconditions.checkArgument(chunkSectionY >= 0, "Invalid chunkSectionY: %s", chunkSectionY);
         return (short) ((chunkSectionY << 4) + sectionY);
     }
 

api/src/main/java/com/viaversion/viaversion/api/minecraft/GameMode.java

@@ -24,22 +24,28 @@ package com.viaversion.viaversion.api.minecraft;
 
 public enum GameMode {
 
-    NOT_SET(""),
-    SURVIVAL("Survival Mode"),
-    CREATIVE("Creative Mode"),
-    ADVENTURE("Adventure Mode"),
-    SPECTATOR("Spectator Mode");
+    NOT_SET("", -1),
+    SURVIVAL("Survival Mode", 0),
+    CREATIVE("Creative Mode", 1),
+    ADVENTURE("Adventure Mode", 2),
+    SPECTATOR("Spectator Mode", 3);
 
     private final String text;
+    private final int id;
 
-    GameMode(String text) {
+    GameMode(String text, final int id) {
         this.text = text;
+        this.id = id;
     }
 
     public String text() {
         return text;
     }
 
+    public int id() {
+        return id;
+    }
+
     public static GameMode getById(int id) {
         return switch (id) {
             case -1 -> NOT_SET;

api/src/main/java/com/viaversion/viaversion/api/minecraft/GameProfile.java

@@ -22,11 +22,31 @@
  */
 package com.viaversion.viaversion.api.minecraft;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public record GameProfile(@Nullable String name, @Nullable UUID id, Property[] properties) {
 
+    public GameProfile(@Nullable final String name, @Nullable final UUID id) {
+        this(name, id, new Property[0]);
+    }
+
+    public Map<String, List<Property>> propertiesMap() {
+        final Map<String, List<Property>> map = new HashMap<>();
+        for (Property property : properties) {
+            map.computeIfAbsent(property.name(), k -> new ArrayList<>()).add(property);
+        }
+        return map;
+    }
+
     public record Property(String name, String value, @Nullable String signature) {
+
+        public Property(final String name, final String value) {
+            this(name, value, null);
+        }
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/Holder.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.minecraft;
 
 import it.unimi.dsi.fastutil.ints.Int2IntFunction;
+import java.util.function.Function;
 
 public interface Holder<T> {
 
@@ -89,4 +90,12 @@ public interface Holder<T> {
      * @return a new holder with the id rewritten, or self
      */
     Holder<T> updateId(final Int2IntFunction rewriteFunction);
+
+    /**
+     * Returns a new holder with the value rewritten using the given function, or self if this is an id holder or the value did not change.
+     *
+     * @param rewriteFunction the function to rewrite the value
+     * @return a new holder with the value rewritten, or self
+     */
+    Holder<T> updateValue(final Function<T, T> rewriteFunction);
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/HolderSetImpl.java

@@ -67,11 +67,17 @@ final class HolderSetImpl {
 
         @Override
         public HolderSet rewrite(final Int2IntFunction idRewriter) {
+            // Filter out negative ids as they would come from missing VB mapping data. This happens especially
+            // with block ids which are not mapped and thus written as -1 so VV rewriters can cancel them nicely.
             final int[] mappedIds = new int[ids.length];
-            for (int i = 0; i < mappedIds.length; i++) {
-                mappedIds[i] = idRewriter.applyAsInt(ids[i]);
+            int validCount = 0;
+            for (final int id : ids) {
+                final int mappedId = idRewriter.applyAsInt(id);
+                if (mappedId != -1) {
+                    mappedIds[validCount++] = mappedId;
+                }
             }
-            return new Ids(mappedIds);
+            return new Ids(validCount == ids.length ? mappedIds : Arrays.copyOf(mappedIds, validCount));
         }
 
         @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/IdHolder.java

@@ -24,6 +24,7 @@ package com.viaversion.viaversion.api.minecraft;
 
 import com.google.common.base.Preconditions;
 import it.unimi.dsi.fastutil.ints.Int2IntFunction;
+import java.util.function.Function;
 
 record IdHolder<T>(int id) implements Holder<T> {
 
@@ -57,4 +58,9 @@ record IdHolder<T>(int id) implements Holder<T> {
         }
         return Holder.of(rewrittenId);
     }
+
+    @Override
+    public Holder<T> updateValue(final Function<T, T> rewriteFunction) {
+        return this;
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/Particle.java

@@ -121,7 +121,7 @@ public final class Particle implements IdHolder, Copyable {
 
         @Override
         public ParticleData<T> copy() {
-            return new ParticleData<>(type, copy(value));
+            return new ParticleData<>(type, Copyable.copy(value));
         }
 
         @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/ValueHolder.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.minecraft;
 
 import it.unimi.dsi.fastutil.ints.Int2IntFunction;
+import java.util.function.Function;
 
 record ValueHolder<T>(T value) implements Holder<T> {
 
@@ -45,4 +46,10 @@ record ValueHolder<T>(T value) implements Holder<T> {
     public Holder<T> updateId(final Int2IntFunction rewriteFunction) {
         return this;
     }
+
+    @Override
+    public Holder<T> updateValue(final Function<T, T> rewriteFunction) {
+        final T rewrittenValue = rewriteFunction.apply(value);
+        return rewrittenValue != value ? Holder.of(rewrittenValue) : this;
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/codec/CodecContext.java

@@ -0,0 +1,54 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.codec;
+
+import com.viaversion.viaversion.api.data.MappingData;
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import com.viaversion.viaversion.util.Key;
+import java.util.List;
+
+public interface CodecContext {
+
+    RegistryAccess registryAccess();
+
+    boolean mapped();
+
+    boolean isSupported(StructuredDataKey<?> key);
+
+    interface RegistryAccess {
+
+        Key item(int id);
+
+        Key enchantment(int id);
+
+        Key attributeModifier(int id);
+
+        Key dataComponentType(int id);
+
+        static RegistryAccess of(final List<String> enchantments, final MappingData mappingData) {
+            return new RegistryAccessImpl(enchantments, mappingData);
+        }
+
+        RegistryAccess withMapped(boolean mapped);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/codec/Ops.java

@@ -0,0 +1,133 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.codec;
+
+import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.api.type.Types;
+import java.util.Objects;
+import java.util.function.Consumer;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public interface Ops {
+
+    CodecContext context();
+
+    void writeByte(byte b);
+
+    void writeBytes(byte[] array);
+
+    void writeBoolean(boolean b);
+
+    void writeShort(short s);
+
+    void writeString(CharSequence sequence);
+
+    void writeInt(int i);
+
+    void writeLong(long l);
+
+    void writeFloat(float f);
+
+    void writeDouble(double d);
+
+    void writeInts(int[] array);
+
+    void writeLongs(long[] array);
+
+    void writeList(Consumer<ListSerializer> consumer);
+
+    void writeMap(Consumer<MapSerializer> consumer);
+
+    <V> void write(final Type<V> type, final V value);
+
+    interface ListSerializer {
+
+        <V> ListSerializer write(Type<V> valueType, V value);
+
+        ListSerializer writeList(Consumer<ListSerializer> consumer);
+
+        ListSerializer writeMap(Consumer<MapSerializer> consumer);
+    }
+
+    interface MapSerializer {
+
+        <K, V> MapSerializer write(Type<K> keyType, K key, Type<V> valueType, V value);
+
+        default <V> MapSerializer write(final String key, final Type<V> type, final V value) {
+            write(Types.STRING, key, type, value);
+            return this;
+        }
+
+        /**
+         * Writes the given value or default value if the value is null.
+         *
+         * @param key map key
+         * @param type type of the value
+         * @param value the value to write, or null
+         * @param def default value to write if the value is null
+         * @return self
+         * @param <V> value type
+         */
+        default <V> MapSerializer write(final String key, final Type<V> type, @Nullable final V value, final V def) {
+            write(Types.STRING, key, type, value != null ? value : def);
+            return this;
+        }
+
+        /**
+         * Writes the given value if it is not null.
+         *
+         * @param key map key
+         * @param type type of the value
+         * @param value the value to write, or null
+         * @return self
+         * @param <V> value type
+         */
+        default <V> MapSerializer writeOptional(final String key, final Type<V> type, @Nullable final V value) {
+            if (value != null) {
+                write(Types.STRING, key, type, value);
+            }
+            return this;
+        }
+
+        /**
+         * Writes the given value if it is not null and not equal to the default value.
+         *
+         * @param key map key
+         * @param type type of the value
+         * @param value the value to write, or null
+         * @param def default value to compare against
+         * @return self
+         * @param <V> value type
+         */
+        default <V> MapSerializer writeOptional(final String key, final Type<V> type, @Nullable final V value, final V def) {
+            if (value != null && !Objects.deepEquals(value, def)) {
+                write(Types.STRING, key, type, value);
+            }
+            return this;
+        }
+
+        MapSerializer writeList(String key, Consumer<ListSerializer> consumer);
+
+        MapSerializer writeMap(String key, Consumer<MapSerializer> consumer);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/codec/RegistryAccessImpl.java

@@ -0,0 +1,82 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.codec;
+
+import com.viaversion.viaversion.api.data.FullMappings;
+import com.viaversion.viaversion.api.data.MappingData;
+import com.viaversion.viaversion.util.Key;
+import java.util.List;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+final class RegistryAccessImpl implements CodecContext.RegistryAccess {
+    private final List<String> enchantments;
+    private final MappingData mappingData;
+    private final boolean mapped;
+
+    RegistryAccessImpl(final List<String> enchantments, final MappingData mappingData) {
+        this.enchantments = enchantments;
+        this.mappingData = mappingData;
+        this.mapped = false;
+    }
+
+    private RegistryAccessImpl(final List<String> enchantments, final MappingData mappingData, final boolean mapped) {
+        this.enchantments = enchantments;
+        this.mappingData = mappingData;
+        this.mapped = mapped;
+    }
+
+    @Override
+    public Key item(final int id) {
+        return key(mappingData.getFullItemMappings(), id);
+    }
+
+    @Override
+    public Key enchantment(final int id) {
+        final String identifier = id >= 0 && id < this.enchantments.size() ? this.enchantments.get(id) : null;
+        return key(identifier, id);
+    }
+
+    @Override
+    public Key attributeModifier(final int id) {
+        return key(mappingData.getAttributeMappings(), id);
+    }
+
+    @Override
+    public Key dataComponentType(final int id) {
+        return key(mappingData.getDataComponentSerializerMappings(), id);
+    }
+
+    private Key key(final FullMappings mappings, final int id) {
+        final String identifier = mapped ? mappings.mappedIdentifier(id) : mappings.identifier(id);
+        return key(identifier, id);
+    }
+
+    private Key key(@Nullable final String identifier, final int id) {
+        return identifier != null ? Key.of(identifier) : Key.of("viaversion", "unknown/" + id);
+    }
+
+    @Override
+    public CodecContext.RegistryAccess withMapped(final boolean mapped) {
+        return this.mapped == mapped ? this : new RegistryAccessImpl(this.enchantments, this.mappingData, mapped);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/codec/hash/Hasher.java

@@ -20,22 +20,26 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.type.types.version;
+package com.viaversion.viaversion.api.minecraft.codec.hash;
 
-import com.viaversion.viaversion.api.minecraft.entitydata.EntityData;
-import com.viaversion.viaversion.api.type.Type;
-import com.viaversion.viaversion.api.type.types.entitydata.EntityDataListType;
-import com.viaversion.viaversion.api.type.types.entitydata.EntityDataType1_12;
-import java.util.List;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 
-public final class Types1_12 {
+/**
+ * Hash operations. Note that this is different from Vanilla codecs, where this
+ * instead acts as a (re-usable) hasher directly rather than each method having
+ * self-contained return values.
+ */
+public interface Hasher extends Ops {
 
     /**
-     * Entity data type for 1.12
+     * Returns the current hash value.
+     *
+     * @return the current hash value
      */
-    public static final Type<EntityData> ENTITY_DATA = new EntityDataType1_12();
+    int hash();
+
     /**
-     * Entity data list type for 1.12
+     * Resets the hasher to its initial state.
      */
-    public static final Type<List<EntityData>> ENTITY_DATA_LIST = new EntityDataListType(ENTITY_DATA);
+    void reset();
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/FilledStructuredData.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.minecraft.data;
 
 import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.util.Copyable;
 import io.netty.buffer.ByteBuf;
 import java.util.Objects;
 
@@ -61,7 +62,7 @@ final class FilledStructuredData<T> implements StructuredData<T> {
 
     @Override
     public StructuredData<T> copy() {
-        return new FilledStructuredData<>(this.key, this.copy(this.value), this.id);
+        return new FilledStructuredData<>(this.key, Copyable.copy(this.value), this.id);
     }
 
     @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/StructuredDataContainer.java

@@ -284,6 +284,10 @@ public final class StructuredDataContainer implements Copyable {
         return data;
     }
 
+    public boolean isEmpty() {
+        return data.isEmpty();
+    }
+
     @Override
     public String toString() {
         return "StructuredDataContainer{" +

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/StructuredDataKey.java

@@ -30,9 +30,10 @@ import com.viaversion.viaversion.api.minecraft.Holder;
 import com.viaversion.viaversion.api.minecraft.HolderSet;
 import com.viaversion.viaversion.api.minecraft.PaintingVariant;
 import com.viaversion.viaversion.api.minecraft.SoundEvent;
-import com.viaversion.viaversion.api.minecraft.item.Item;
+import com.viaversion.viaversion.api.minecraft.data.version.StructuredDataKeys1_20_5;
+import com.viaversion.viaversion.api.minecraft.data.version.StructuredDataKeys1_21_2;
+import com.viaversion.viaversion.api.minecraft.data.version.StructuredDataKeys1_21_5;
 import com.viaversion.viaversion.api.minecraft.item.data.AdventureModePredicate;
-import com.viaversion.viaversion.api.minecraft.item.data.AdventureModePredicate.AdventureModePredicateType1_21_5;
 import com.viaversion.viaversion.api.minecraft.item.data.ArmorTrim;
 import com.viaversion.viaversion.api.minecraft.item.data.AttributeModifiers1_20_5;
 import com.viaversion.viaversion.api.minecraft.item.data.AttributeModifiers1_21;
@@ -45,9 +46,10 @@ import com.viaversion.viaversion.api.minecraft.item.data.CustomModelData1_21_4;
 import com.viaversion.viaversion.api.minecraft.item.data.DamageResistant;
 import com.viaversion.viaversion.api.minecraft.item.data.DeathProtection;
 import com.viaversion.viaversion.api.minecraft.item.data.DyedColor;
+import com.viaversion.viaversion.api.minecraft.item.data.Enchantable;
 import com.viaversion.viaversion.api.minecraft.item.data.Enchantments;
+import com.viaversion.viaversion.api.minecraft.item.data.EnumTypes;
 import com.viaversion.viaversion.api.minecraft.item.data.Equippable;
-import com.viaversion.viaversion.api.minecraft.item.data.FilterableString;
 import com.viaversion.viaversion.api.minecraft.item.data.FireworkExplosion;
 import com.viaversion.viaversion.api.minecraft.item.data.Fireworks;
 import com.viaversion.viaversion.api.minecraft.item.data.FoodProperties1_20_5;
@@ -62,22 +64,29 @@ import com.viaversion.viaversion.api.minecraft.item.data.ProvidesTrimMaterial;
 import com.viaversion.viaversion.api.minecraft.item.data.SuspiciousStewEffect;
 import com.viaversion.viaversion.api.minecraft.item.data.ToolProperties;
 import com.viaversion.viaversion.api.minecraft.item.data.TooltipDisplay;
+import com.viaversion.viaversion.api.minecraft.item.data.TropicalFishPattern;
 import com.viaversion.viaversion.api.minecraft.item.data.Unbreakable;
 import com.viaversion.viaversion.api.minecraft.item.data.UseCooldown;
 import com.viaversion.viaversion.api.minecraft.item.data.Weapon;
+import com.viaversion.viaversion.api.minecraft.item.data.WritableBook;
 import com.viaversion.viaversion.api.minecraft.item.data.WrittenBook;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
 import com.viaversion.viaversion.api.type.types.EitherType;
-import com.viaversion.viaversion.api.type.types.version.Types1_20_5;
-import com.viaversion.viaversion.api.type.types.version.Types1_21;
-import com.viaversion.viaversion.api.type.types.version.Types1_21_2;
-import com.viaversion.viaversion.api.type.types.version.Types1_21_4;
-import com.viaversion.viaversion.api.type.types.version.Types1_21_5;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypes;
 import com.viaversion.viaversion.util.Either;
+import com.viaversion.viaversion.util.Key;
 import com.viaversion.viaversion.util.Unit;
 
+/**
+ * Holds data component keys.
+ *
+ * @param identifier string identifier
+ * @param type data type
+ * @param <T> data type
+ * @see VersionedTypes
+ */
 public record StructuredDataKey<T>(String identifier, Type<T> type) {
 
     public static final StructuredDataKey<CompoundTag> CUSTOM_DATA = new StructuredDataKey<>("custom_data", Types.COMPOUND_TAG);
@@ -88,18 +97,18 @@ public record StructuredDataKey<T>(String identifier, Type<T> type) {
     public static final StructuredDataKey<Unit> UNBREAKABLE1_21_5 = new StructuredDataKey<>("unbreakable", Types.EMPTY);
     public static final StructuredDataKey<Tag> CUSTOM_NAME = new StructuredDataKey<>("custom_name", Types.TAG);
     public static final StructuredDataKey<Tag> ITEM_NAME = new StructuredDataKey<>("item_name", Types.TAG);
-    public static final StructuredDataKey<String> ITEM_MODEL = new StructuredDataKey<>("item_model", Types.STRING);
+    public static final StructuredDataKey<Key> ITEM_MODEL = new StructuredDataKey<>("item_model", Types.RESOURCE_LOCATION);
     public static final StructuredDataKey<Tag[]> LORE = new StructuredDataKey<>("lore", new ArrayType<>(Types.TAG, 256));
-    public static final StructuredDataKey<Integer> RARITY = new StructuredDataKey<>("rarity", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> RARITY = new StructuredDataKey<>("rarity", EnumTypes.RARITY);
     public static final StructuredDataKey<Enchantments> ENCHANTMENTS1_20_5 = new StructuredDataKey<>("enchantments", Enchantments.TYPE1_20_5);
     public static final StructuredDataKey<Enchantments> ENCHANTMENTS1_21_5 = new StructuredDataKey<>("enchantments", Enchantments.TYPE1_21_5);
+    // 1.21.5+ predicates are in their own key classes
     public static final StructuredDataKey<AdventureModePredicate> CAN_PLACE_ON1_20_5 = new StructuredDataKey<>("can_place_on", AdventureModePredicate.TYPE1_20_5);
-    public static final StructuredDataKey<AdventureModePredicate> CAN_PLACE_ON1_21_5 = new StructuredDataKey<>("can_place_on", new AdventureModePredicateType1_21_5(Types1_21_5.STRUCTURED_DATA_ARRAY));
     public static final StructuredDataKey<AdventureModePredicate> CAN_BREAK1_20_5 = new StructuredDataKey<>("can_break", AdventureModePredicate.TYPE1_20_5);
-    public static final StructuredDataKey<AdventureModePredicate> CAN_BREAK1_21_5 = new StructuredDataKey<>("can_break", new AdventureModePredicateType1_21_5(Types1_21_5.STRUCTURED_DATA_ARRAY));
     public static final StructuredDataKey<AttributeModifiers1_20_5> ATTRIBUTE_MODIFIERS1_20_5 = new StructuredDataKey<>("attribute_modifiers", AttributeModifiers1_20_5.TYPE);
     public static final StructuredDataKey<AttributeModifiers1_21> ATTRIBUTE_MODIFIERS1_21 = new StructuredDataKey<>("attribute_modifiers", AttributeModifiers1_21.TYPE1_21);
     public static final StructuredDataKey<AttributeModifiers1_21> ATTRIBUTE_MODIFIERS1_21_5 = new StructuredDataKey<>("attribute_modifiers", AttributeModifiers1_21.TYPE1_21_5);
+    public static final StructuredDataKey<AttributeModifiers1_21> ATTRIBUTE_MODIFIERS1_21_6 = new StructuredDataKey<>("attribute_modifiers", AttributeModifiers1_21.TYPE1_21_6);
     public static final StructuredDataKey<Integer> CUSTOM_MODEL_DATA1_20_5 = new StructuredDataKey<>("custom_model_data", Types.VAR_INT);
     public static final StructuredDataKey<CustomModelData1_21_4> CUSTOM_MODEL_DATA1_21_4 = new StructuredDataKey<>("custom_model_data", CustomModelData1_21_4.TYPE);
     public static final StructuredDataKey<Unit> HIDE_ADDITIONAL_TOOLTIP = new StructuredDataKey<>("hide_additional_tooltip", Types.EMPTY);
@@ -113,21 +122,19 @@ public record StructuredDataKey<T>(String identifier, Type<T> type) {
     public static final StructuredDataKey<FoodProperties1_20_5> FOOD1_21 = new StructuredDataKey<>("food", FoodProperties1_20_5.TYPE1_21);
     public static final StructuredDataKey<FoodProperties1_21_2> FOOD1_21_2 = new StructuredDataKey<>("food", FoodProperties1_21_2.TYPE);
     public static final StructuredDataKey<Consumable1_21_2> CONSUMABLE1_21_2 = new StructuredDataKey<>("consumable", Consumable1_21_2.TYPE);
-    public static final StructuredDataKey<Item> USE_REMAINDER1_21_2 = new StructuredDataKey<>("use_remainder", Types1_21_2.ITEM);
-    public static final StructuredDataKey<Item> USE_REMAINDER1_21_4 = new StructuredDataKey<>("use_remainder", Types1_21_4.ITEM);
-    public static final StructuredDataKey<Item> USE_REMAINDER1_21_5 = new StructuredDataKey<>("use_remainder", Types1_21_5.ITEM);
     public static final StructuredDataKey<UseCooldown> USE_COOLDOWN = new StructuredDataKey<>("use_cooldown", UseCooldown.TYPE);
     public static final StructuredDataKey<Unit> FIRE_RESISTANT = new StructuredDataKey<>("fire_resistant", Types.EMPTY);
     public static final StructuredDataKey<DamageResistant> DAMAGE_RESISTANT = new StructuredDataKey<>("damage_resistant", DamageResistant.TYPE);
     public static final StructuredDataKey<ToolProperties> TOOL1_20_5 = new StructuredDataKey<>("tool", ToolProperties.TYPE1_20_5);
     public static final StructuredDataKey<ToolProperties> TOOL1_21_5 = new StructuredDataKey<>("tool", ToolProperties.TYPE1_21_5);
     public static final StructuredDataKey<Weapon> WEAPON = new StructuredDataKey<>("weapon", Weapon.TYPE);
-    public static final StructuredDataKey<Integer> ENCHANTABLE = new StructuredDataKey<>("enchantable", Types.VAR_INT);
+    public static final StructuredDataKey<Enchantable> ENCHANTABLE = new StructuredDataKey<>("enchantable", Enchantable.TYPE);
     public static final StructuredDataKey<Equippable> EQUIPPABLE1_21_2 = new StructuredDataKey<>("equippable", Equippable.TYPE1_21_2);
     public static final StructuredDataKey<Equippable> EQUIPPABLE1_21_5 = new StructuredDataKey<>("equippable", Equippable.TYPE1_21_5);
+    public static final StructuredDataKey<Equippable> EQUIPPABLE1_21_6 = new StructuredDataKey<>("equippable", Equippable.TYPE1_21_6);
     public static final StructuredDataKey<HolderSet> REPAIRABLE = new StructuredDataKey<>("repairable", Types.HOLDER_SET);
     public static final StructuredDataKey<Unit> GLIDER = new StructuredDataKey<>("glider", Types.EMPTY);
-    public static final StructuredDataKey<String> TOOLTIP_STYLE = new StructuredDataKey<>("tooltip_style", Types.STRING);
+    public static final StructuredDataKey<Key> TOOLTIP_STYLE = new StructuredDataKey<>("tooltip_style", Types.RESOURCE_LOCATION);
     public static final StructuredDataKey<DeathProtection> DEATH_PROTECTION = new StructuredDataKey<>("death_protection", DeathProtection.TYPE);
     public static final StructuredDataKey<BlocksAttacks> BLOCKS_ATTACKS = new StructuredDataKey<>("blocks_attacks", BlocksAttacks.TYPE);
     public static final StructuredDataKey<Enchantments> STORED_ENCHANTMENTS1_20_5 = new StructuredDataKey<>("stored_enchantments", Enchantments.TYPE1_20_5);
@@ -138,21 +145,11 @@ public record StructuredDataKey<T>(String identifier, Type<T> type) {
     public static final StructuredDataKey<Integer> MAP_ID = new StructuredDataKey<>("map_id", Types.VAR_INT);
     public static final StructuredDataKey<CompoundTag> MAP_DECORATIONS = new StructuredDataKey<>("map_decorations", Types.COMPOUND_TAG);
     public static final StructuredDataKey<Integer> MAP_POST_PROCESSING = new StructuredDataKey<>("map_post_processing", Types.VAR_INT);
-    public static final StructuredDataKey<Item[]> CHARGED_PROJECTILES1_20_5 = new StructuredDataKey<>("charged_projectiles", Types1_20_5.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CHARGED_PROJECTILES1_21 = new StructuredDataKey<>("charged_projectiles", Types1_21.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CHARGED_PROJECTILES1_21_2 = new StructuredDataKey<>("charged_projectiles", Types1_21_2.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CHARGED_PROJECTILES1_21_4 = new StructuredDataKey<>("charged_projectiles", Types1_21_4.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CHARGED_PROJECTILES1_21_5 = new StructuredDataKey<>("charged_projectiles", Types1_21_5.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> BUNDLE_CONTENTS1_20_5 = new StructuredDataKey<>("bundle_contents", Types1_20_5.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> BUNDLE_CONTENTS1_21 = new StructuredDataKey<>("bundle_contents", Types1_21.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> BUNDLE_CONTENTS1_21_2 = new StructuredDataKey<>("bundle_contents", Types1_21_2.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> BUNDLE_CONTENTS1_21_4 = new StructuredDataKey<>("bundle_contents", Types1_21_4.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> BUNDLE_CONTENTS1_21_5 = new StructuredDataKey<>("bundle_contents", Types1_21_5.ITEM_ARRAY);
     public static final StructuredDataKey<PotionContents> POTION_CONTENTS1_20_5 = new StructuredDataKey<>("potion_contents", PotionContents.TYPE1_20_5);
     public static final StructuredDataKey<PotionContents> POTION_CONTENTS1_21_2 = new StructuredDataKey<>("potion_contents", PotionContents.TYPE1_21_2);
     public static final StructuredDataKey<Float> POTION_DURATION_SCALE = new StructuredDataKey<>("potion_duration_scale", Types.FLOAT);
     public static final StructuredDataKey<SuspiciousStewEffect[]> SUSPICIOUS_STEW_EFFECTS = new StructuredDataKey<>("suspicious_stew_effects", SuspiciousStewEffect.ARRAY_TYPE);
-    public static final StructuredDataKey<FilterableString[]> WRITABLE_BOOK_CONTENT = new StructuredDataKey<>("writable_book_content", FilterableString.ARRAY_TYPE);
+    public static final StructuredDataKey<WritableBook> WRITABLE_BOOK_CONTENT = new StructuredDataKey<>("writable_book_content", WritableBook.TYPE);
     public static final StructuredDataKey<WrittenBook> WRITTEN_BOOK_CONTENT = new StructuredDataKey<>("written_book_content", WrittenBook.TYPE);
     public static final StructuredDataKey<ArmorTrim> TRIM1_20_5 = new StructuredDataKey<>("trim", ArmorTrim.TYPE1_20_5);
     public static final StructuredDataKey<ArmorTrim> TRIM1_21_2 = new StructuredDataKey<>("trim", ArmorTrim.TYPE1_21_2);
@@ -169,51 +166,54 @@ public record StructuredDataKey<T>(String identifier, Type<T> type) {
     public static final StructuredDataKey<Integer> OMINOUS_BOTTLE_AMPLIFIER = new StructuredDataKey<>("ominous_bottle_amplifier", Types.VAR_INT);
     public static final StructuredDataKey<JukeboxPlayable> JUKEBOX_PLAYABLE1_21 = new StructuredDataKey<>("jukebox_playable", JukeboxPlayable.TYPE1_21);
     public static final StructuredDataKey<JukeboxPlayable> JUKEBOX_PLAYABLE1_21_5 = new StructuredDataKey<>("jukebox_playable", JukeboxPlayable.TYPE1_21_5);
-    public static final StructuredDataKey<String> PROVIDES_BANNER_PATTERNS = new StructuredDataKey<>("provides_banner_patterns", Types.STRING);
+    public static final StructuredDataKey<Key> PROVIDES_BANNER_PATTERNS = new StructuredDataKey<>("provides_banner_patterns", Types.TAG_KEY);
     public static final StructuredDataKey<Tag> RECIPES = new StructuredDataKey<>("recipes", Types.TAG);
     public static final StructuredDataKey<LodestoneTracker> LODESTONE_TRACKER = new StructuredDataKey<>("lodestone_tracker", LodestoneTracker.TYPE);
     public static final StructuredDataKey<FireworkExplosion> FIREWORK_EXPLOSION = new StructuredDataKey<>("firework_explosion", FireworkExplosion.TYPE);
     public static final StructuredDataKey<Fireworks> FIREWORKS = new StructuredDataKey<>("fireworks", Fireworks.TYPE);
     public static final StructuredDataKey<GameProfile> PROFILE = new StructuredDataKey<>("profile", Types.GAME_PROFILE);
-    public static final StructuredDataKey<String> NOTE_BLOCK_SOUND = new StructuredDataKey<>("note_block_sound", Types.STRING);
+    public static final StructuredDataKey<Key> NOTE_BLOCK_SOUND = new StructuredDataKey<>("note_block_sound", Types.RESOURCE_LOCATION);
     public static final StructuredDataKey<BannerPatternLayer[]> BANNER_PATTERNS = new StructuredDataKey<>("banner_patterns", BannerPatternLayer.ARRAY_TYPE);
-    public static final StructuredDataKey<Integer> BASE_COLOR = new StructuredDataKey<>("base_color", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> BASE_COLOR = new StructuredDataKey<>("base_color", EnumTypes.DYE_COLOR);
     public static final StructuredDataKey<PotDecorations> POT_DECORATIONS = new StructuredDataKey<>("pot_decorations", PotDecorations.TYPE);
-    public static final StructuredDataKey<Item[]> CONTAINER1_20_5 = new StructuredDataKey<>("container", Types1_20_5.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CONTAINER1_21 = new StructuredDataKey<>("container", Types1_21.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CONTAINER1_21_2 = new StructuredDataKey<>("container", new ArrayType<>(Types1_21_2.ITEM, 256));
-    public static final StructuredDataKey<Item[]> CONTAINER1_21_4 = new StructuredDataKey<>("container", Types1_21_4.ITEM_ARRAY);
-    public static final StructuredDataKey<Item[]> CONTAINER1_21_5 = new StructuredDataKey<>("container", Types1_21_5.ITEM_ARRAY);
     public static final StructuredDataKey<BlockStateProperties> BLOCK_STATE = new StructuredDataKey<>("block_state", BlockStateProperties.TYPE);
     public static final StructuredDataKey<Bee[]> BEES = new StructuredDataKey<>("bees", Bee.ARRAY_TYPE);
     public static final StructuredDataKey<Tag> LOCK = new StructuredDataKey<>("lock", Types.TAG);
     public static final StructuredDataKey<CompoundTag> CONTAINER_LOOT = new StructuredDataKey<>("container_loot", Types.COMPOUND_TAG);
     public static final StructuredDataKey<Holder<SoundEvent>> BREAK_SOUND = new StructuredDataKey<>("break_sound", Types.SOUND_EVENT);
 
-    public static final StructuredDataKey<Integer> VILLAGER_VARIANT = new StructuredDataKey<>("villager/variant", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> VILLAGER_VARIANT = new StructuredDataKey<>("villager/variant", EnumTypes.VILLAGER_TYPE);
     public static final StructuredDataKey<Integer> WOLF_VARIANT = new StructuredDataKey<>("wolf/variant", Types.VAR_INT);
     public static final StructuredDataKey<Integer> WOLF_SOUND_VARIANT = new StructuredDataKey<>("wolf/sound_variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> WOLF_COLLAR = new StructuredDataKey<>("wolf/collar", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> FOX_VARIANT = new StructuredDataKey<>("fox/variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> SALMON_SIZE = new StructuredDataKey<>("salmon/size", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> PARROT_VARIANT = new StructuredDataKey<>("parrot/variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> TROPICAL_FISH_PATTERN = new StructuredDataKey<>("tropical_fish/pattern", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> TROPICAL_FISH_BASE_COLOR = new StructuredDataKey<>("tropical_fish/base_color", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> TROPICAL_FISH_PATTERN_COLOR = new StructuredDataKey<>("tropical_fish/pattern_color", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> MOOSHROOM_VARIANT = new StructuredDataKey<>("mooshroom/variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> RABBIT_VARIANT = new StructuredDataKey<>("rabbit/variant", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> WOLF_COLLAR = new StructuredDataKey<>("wolf/collar", EnumTypes.DYE_COLOR);
+    public static final StructuredDataKey<Integer> FOX_VARIANT = new StructuredDataKey<>("fox/variant", EnumTypes.FOX_VARIANT);
+    public static final StructuredDataKey<Integer> SALMON_SIZE = new StructuredDataKey<>("salmon/size", EnumTypes.SALMON_VARIANT);
+    public static final StructuredDataKey<Integer> PARROT_VARIANT = new StructuredDataKey<>("parrot/variant", EnumTypes.PARROT_VARIANT);
+    public static final StructuredDataKey<TropicalFishPattern> TROPICAL_FISH_PATTERN = new StructuredDataKey<>("tropical_fish/pattern", TropicalFishPattern.TYPE);
+    public static final StructuredDataKey<Integer> TROPICAL_FISH_BASE_COLOR = new StructuredDataKey<>("tropical_fish/base_color", EnumTypes.DYE_COLOR);
+    public static final StructuredDataKey<Integer> TROPICAL_FISH_PATTERN_COLOR = new StructuredDataKey<>("tropical_fish/pattern_color", EnumTypes.DYE_COLOR);
+    public static final StructuredDataKey<Integer> MOOSHROOM_VARIANT = new StructuredDataKey<>("mooshroom/variant", EnumTypes.MUSHROOM_COW_VARIANT);
+    public static final StructuredDataKey<Integer> RABBIT_VARIANT = new StructuredDataKey<>("rabbit/variant", EnumTypes.RABBIT_VARIANT);
     public static final StructuredDataKey<Integer> PIG_VARIANT = new StructuredDataKey<>("pig/variant", Types.VAR_INT);
     public static final StructuredDataKey<Integer> COW_VARIANT = new StructuredDataKey<>("cow/variant", Types.VAR_INT);
     public static final StructuredDataKey<Either<Integer, String>> CHICKEN_VARIANT = new StructuredDataKey<>("chicken/variant", new EitherType<>(Types.VAR_INT, Types.STRING)); // ???
     public static final StructuredDataKey<Integer> FROG_VARIANT = new StructuredDataKey<>("frog/variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> HORSE_VARIANT = new StructuredDataKey<>("horse/variant", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> HORSE_VARIANT = new StructuredDataKey<>("horse/variant", EnumTypes.HORSE_VARIANT);
     public static final StructuredDataKey<Holder<PaintingVariant>> PAINTING_VARIANT = new StructuredDataKey<>("painting/variant", PaintingVariant.TYPE1_21_2);
-    public static final StructuredDataKey<Integer> LLAMA_VARIANT = new StructuredDataKey<>("llama/variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> AXOLOTL_VARIANT = new StructuredDataKey<>("axolotl/variant", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> LLAMA_VARIANT = new StructuredDataKey<>("llama/variant", EnumTypes.LLAMA_VARIANT);
+    public static final StructuredDataKey<Integer> AXOLOTL_VARIANT = new StructuredDataKey<>("axolotl/variant", EnumTypes.AXOLOTL_VARIANT);
     public static final StructuredDataKey<Integer> CAT_VARIANT = new StructuredDataKey<>("cat/variant", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> CAT_COLLAR = new StructuredDataKey<>("cat/collar", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> SHEEP_COLOR = new StructuredDataKey<>("sheep/color", Types.VAR_INT);
-    public static final StructuredDataKey<Integer> SHULKER_COLOR = new StructuredDataKey<>("shulker/color", Types.VAR_INT);
+    public static final StructuredDataKey<Integer> CAT_COLLAR = new StructuredDataKey<>("cat/collar", EnumTypes.DYE_COLOR);
+    public static final StructuredDataKey<Integer> SHEEP_COLOR = new StructuredDataKey<>("sheep/color", EnumTypes.DYE_COLOR);
+    public static final StructuredDataKey<Integer> SHULKER_COLOR = new StructuredDataKey<>("shulker/color", EnumTypes.DYE_COLOR);
+
+    // These are only safe to use after protocol loading
+    public static final StructuredDataKeys1_20_5 V1_20_5 = VersionedTypes.V1_20_5.structuredDataKeys();
+    public static final StructuredDataKeys1_20_5 V1_21 = VersionedTypes.V1_21.structuredDataKeys();
+    public static final StructuredDataKeys1_21_2 V1_21_2 = VersionedTypes.V1_21_2.structuredDataKeys();
+    public static final StructuredDataKeys1_21_2 V1_21_4 = VersionedTypes.V1_21_4.structuredDataKeys();
+    public static final StructuredDataKeys1_21_5 V1_21_5 = VersionedTypes.V1_21_5.structuredDataKeys();
+    public static final StructuredDataKeys1_21_5 V1_21_6 = VersionedTypes.V1_21_6.structuredDataKeys();
 
     @Override
     public String toString() {

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/version/StructuredDataKeys1_20_5.java

@@ -0,0 +1,40 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.data.version;
+
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import com.viaversion.viaversion.api.minecraft.item.Item;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
+
+public class StructuredDataKeys1_20_5 extends VersionedStructuredDataKeys {
+
+    public final StructuredDataKey<Item[]> container;
+    public final StructuredDataKey<Item[]> chargedProjectiles;
+    public final StructuredDataKey<Item[]> bundleContents;
+
+    public StructuredDataKeys1_20_5(final VersionedTypesHolder types) {
+        this.container = add("container", types.itemArray());
+        this.chargedProjectiles = add("charged_projectiles", types.itemArray());
+        this.bundleContents = add("bundle_contents", types.itemArray());
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/version/StructuredDataKeys1_21_2.java

@@ -0,0 +1,43 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.data.version;
+
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import com.viaversion.viaversion.api.minecraft.item.Item;
+import com.viaversion.viaversion.api.minecraft.item.data.ContainterContents.ContainerContentsType;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
+
+public class StructuredDataKeys1_21_2 extends VersionedStructuredDataKeys {
+
+    public final StructuredDataKey<Item[]> container;
+    public final StructuredDataKey<Item[]> chargedProjectiles;
+    public final StructuredDataKey<Item[]> bundleContents;
+    public final StructuredDataKey<Item> useRemainder;
+
+    public StructuredDataKeys1_21_2(final VersionedTypesHolder types) {
+        this.container = add("container", new ContainerContentsType(types.item()));
+        this.chargedProjectiles = add("charged_projectiles", types.itemArray());
+        this.bundleContents = add("bundle_contents", types.itemArray());
+        this.useRemainder = add("use_remainder", types.item());
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/version/StructuredDataKeys1_21_5.java

@@ -0,0 +1,43 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.data.version;
+
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import com.viaversion.viaversion.api.minecraft.item.data.AdventureModePredicate;
+import com.viaversion.viaversion.api.minecraft.item.data.AdventureModePredicate.AdventureModePredicateType1_21_5;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
+
+public class StructuredDataKeys1_21_5 extends StructuredDataKeys1_21_2 {
+
+    public final StructuredDataKey<AdventureModePredicate> canPlaceOn;
+    public final StructuredDataKey<AdventureModePredicate> canBreak;
+
+    public StructuredDataKeys1_21_5(final VersionedTypesHolder types) {
+        super(types);
+        final AdventureModePredicateType1_21_5 adventureModePredicateType = new AdventureModePredicateType1_21_5(types.structuredDataArray());
+        this.canPlaceOn = add("can_place_on", adventureModePredicateType);
+        this.canBreak = add("can_break", adventureModePredicateType);
+        this.unsupportedForOps.add(this.canPlaceOn);
+        this.unsupportedForOps.add(this.canBreak);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/version/VersionedStructuredDataKeys.java

@@ -20,25 +20,31 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.type.types.version;
+package com.viaversion.viaversion.api.minecraft.data.version;
 
-import com.viaversion.viaversion.api.minecraft.chunks.ChunkSection;
-import com.viaversion.viaversion.api.minecraft.entitydata.EntityData;
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
 import com.viaversion.viaversion.api.type.Type;
-import com.viaversion.viaversion.api.type.types.chunk.ChunkSectionType1_9;
-import com.viaversion.viaversion.api.type.types.entitydata.EntityDataListType;
-import com.viaversion.viaversion.api.type.types.entitydata.EntityDataType1_9;
+import it.unimi.dsi.fastutil.objects.ReferenceArraySet;
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Set;
 
-public final class Types1_9 {
-    /**
-     * Entity data type for 1.9
-     */
-    public static final Type<EntityData> ENTITY_DATA = new EntityDataType1_9();
-    /**
-     * Entity data list type for 1.9
-     */
-    public static final Type<List<EntityData>> ENTITY_DATA_LIST = new EntityDataListType(ENTITY_DATA);
+public abstract class VersionedStructuredDataKeys {
 
-    public static final Type<ChunkSection> CHUNK_SECTION = new ChunkSectionType1_9();
+    private final List<StructuredDataKey<?>> keys = new ArrayList<>();
+    protected final Set<StructuredDataKey<?>> unsupportedForOps = new ReferenceArraySet<>();
+
+    protected <T> StructuredDataKey<T> add(final String identifier, final Type<T> type) {
+        final StructuredDataKey<T> key = new StructuredDataKey<>(identifier, type);
+        this.keys.add(key);
+        return key;
+    }
+
+    public List<StructuredDataKey<?>> keys() {
+        return this.keys;
+    }
+
+    public boolean supportsOps(final StructuredDataKey<?> key) {
+        return !unsupportedForOps.contains(key);
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/entities/EntityTypes1_21_6.java

@@ -0,0 +1,318 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.entities;
+
+import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.api.protocol.Protocol;
+import com.viaversion.viaversion.util.EntityTypeUtil;
+import com.viaversion.viaversion.util.Key;
+import java.util.Locale;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public enum EntityTypes1_21_6 implements EntityType {
+
+    ENTITY(null, null),
+
+    AREA_EFFECT_CLOUD(ENTITY),
+    END_CRYSTAL(ENTITY),
+    EVOKER_FANGS(ENTITY),
+    EXPERIENCE_ORB(ENTITY),
+    EYE_OF_ENDER(ENTITY),
+    FALLING_BLOCK(ENTITY),
+    ITEM(ENTITY),
+    TNT(ENTITY),
+    OMINOUS_ITEM_SPAWNER(ENTITY),
+    MARKER(ENTITY),
+    LIGHTNING_BOLT(ENTITY),
+    INTERACTION(ENTITY),
+
+    DISPLAY(ENTITY, null),
+    BLOCK_DISPLAY(DISPLAY),
+    ITEM_DISPLAY(DISPLAY),
+    TEXT_DISPLAY(DISPLAY),
+
+    // Hanging entities
+    HANGING_ENTITY(ENTITY, null),
+    LEASH_KNOT(HANGING_ENTITY),
+    PAINTING(HANGING_ENTITY),
+    ITEM_FRAME(HANGING_ENTITY),
+    GLOW_ITEM_FRAME(ITEM_FRAME),
+
+    // Projectiles
+    PROJECTILE(ENTITY, null),
+    ITEM_PROJECTILE(PROJECTILE, null),
+    SNOWBALL(ITEM_PROJECTILE),
+    ENDER_PEARL(ITEM_PROJECTILE),
+    EGG(ITEM_PROJECTILE),
+    EXPERIENCE_BOTTLE(ITEM_PROJECTILE),
+    FIREWORK_ROCKET(PROJECTILE),
+    LLAMA_SPIT(PROJECTILE),
+    SHULKER_BULLET(PROJECTILE),
+    FISHING_BOBBER(PROJECTILE),
+    WITHER_SKULL(PROJECTILE),
+    DRAGON_FIREBALL(PROJECTILE), // Doesn't actually inherit fireball
+
+    ABSTRACT_THROWN_POTION(ITEM_PROJECTILE, null),
+    SPLASH_POTION(ABSTRACT_THROWN_POTION),
+    LINGERING_POTION(ABSTRACT_THROWN_POTION),
+
+    ABSTRACT_ARROW(PROJECTILE, null),
+    ARROW(ABSTRACT_ARROW),
+    SPECTRAL_ARROW(ABSTRACT_ARROW),
+    TRIDENT(ABSTRACT_ARROW),
+
+    ABSTRACT_FIREBALL(ENTITY, null),
+    FIREBALL(ABSTRACT_FIREBALL),
+    SMALL_FIREBALL(ABSTRACT_FIREBALL),
+
+    ABSTRACT_WIND_CHARGE(PROJECTILE, null),
+    WIND_CHARGE(ABSTRACT_WIND_CHARGE),
+    BREEZE_WIND_CHARGE(ABSTRACT_WIND_CHARGE),
+
+    // Vehicles
+    VEHICLE(ENTITY, null),
+
+    ABSTRACT_MINECART(VEHICLE, null),
+    MINECART(ABSTRACT_MINECART),
+    FURNACE_MINECART(ABSTRACT_MINECART),
+    COMMAND_BLOCK_MINECART(ABSTRACT_MINECART),
+    TNT_MINECART(ABSTRACT_MINECART),
+    SPAWNER_MINECART(ABSTRACT_MINECART),
+
+    ABSTRACT_MINECART_CONTAINER(ABSTRACT_MINECART, null),
+    CHEST_MINECART(ABSTRACT_MINECART_CONTAINER),
+    HOPPER_MINECART(ABSTRACT_MINECART_CONTAINER),
+
+    ABSTRACT_BOAT(VEHICLE, null),
+    ABSTRACT_CHEST_BOAT(ABSTRACT_BOAT, null),
+    ACACIA_BOAT(ABSTRACT_BOAT),
+    ACACIA_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    BAMBOO_CHEST_RAFT(ABSTRACT_CHEST_BOAT),
+    BAMBOO_RAFT(ABSTRACT_BOAT),
+    BIRCH_BOAT(ABSTRACT_BOAT),
+    BIRCH_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    CHERRY_BOAT(ABSTRACT_BOAT),
+    CHERRY_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    DARK_OAK_BOAT(ABSTRACT_BOAT),
+    DARK_OAK_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    JUNGLE_BOAT(ABSTRACT_BOAT),
+    JUNGLE_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    MANGROVE_BOAT(ABSTRACT_BOAT),
+    MANGROVE_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    OAK_BOAT(ABSTRACT_BOAT),
+    OAK_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    PALE_OAK_BOAT(ABSTRACT_BOAT),
+    PALE_OAK_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+    SPRUCE_BOAT(ABSTRACT_BOAT),
+    SPRUCE_CHEST_BOAT(ABSTRACT_CHEST_BOAT),
+
+    // Living entities as a larger subclass
+    LIVING_ENTITY(ENTITY, null),
+    ARMOR_STAND(LIVING_ENTITY),
+    PLAYER(LIVING_ENTITY),
+
+    // Mobs as a larger subclass
+    MOB(LIVING_ENTITY, null),
+    ENDER_DRAGON(MOB),
+
+    SLIME(MOB),
+    MAGMA_CUBE(SLIME),
+
+    // Ambient mobs
+    AMBIENT_CREATURE(MOB, null),
+    BAT(AMBIENT_CREATURE),
+
+    // Flying mobs
+    FLYING_MOB(MOB, null),
+    GHAST(FLYING_MOB),
+    PHANTOM(FLYING_MOB),
+
+    // Pathfinder mobs and its subclasses
+    PATHFINDER_MOB(MOB, null),
+    ALLAY(PATHFINDER_MOB),
+
+    ABSTRACT_GOLEM(PATHFINDER_MOB, null),
+    SNOW_GOLEM(ABSTRACT_GOLEM),
+    IRON_GOLEM(ABSTRACT_GOLEM),
+    SHULKER(ABSTRACT_GOLEM),
+
+    // Ageable mobs and (tamable) animals
+    ABSTRACT_AGEABLE(PATHFINDER_MOB, null),
+    ABSTRACT_VILLAGER(ABSTRACT_AGEABLE, null),
+    VILLAGER(ABSTRACT_VILLAGER),
+    WANDERING_TRADER(ABSTRACT_VILLAGER),
+
+    ABSTRACT_ANIMAL(ABSTRACT_AGEABLE, null),
+    AXOLOTL(ABSTRACT_ANIMAL),
+    CHICKEN(ABSTRACT_ANIMAL),
+    PANDA(ABSTRACT_ANIMAL),
+    PIG(ABSTRACT_ANIMAL),
+    POLAR_BEAR(ABSTRACT_ANIMAL),
+    RABBIT(ABSTRACT_ANIMAL),
+    SHEEP(ABSTRACT_ANIMAL),
+    BEE(ABSTRACT_ANIMAL),
+    TURTLE(ABSTRACT_ANIMAL),
+    FOX(ABSTRACT_ANIMAL),
+    FROG(ABSTRACT_ANIMAL),
+    GOAT(ABSTRACT_ANIMAL),
+    HOGLIN(ABSTRACT_ANIMAL),
+    STRIDER(ABSTRACT_ANIMAL),
+    SNIFFER(ABSTRACT_ANIMAL),
+    ARMADILLO(ABSTRACT_ANIMAL),
+    HAPPY_GHAST(ABSTRACT_ANIMAL),
+
+    ABSTRACT_COW(ABSTRACT_ANIMAL, null),
+    COW(ABSTRACT_COW),
+    MOOSHROOM(ABSTRACT_COW),
+
+    TAMABLE_ANIMAL(ABSTRACT_ANIMAL, null),
+    CAT(TAMABLE_ANIMAL),
+    OCELOT(TAMABLE_ANIMAL),
+    WOLF(TAMABLE_ANIMAL),
+    PARROT(TAMABLE_ANIMAL),
+
+    ABSTRACT_HORSE(ABSTRACT_ANIMAL, null),
+    HORSE(ABSTRACT_HORSE),
+    SKELETON_HORSE(ABSTRACT_HORSE),
+    ZOMBIE_HORSE(ABSTRACT_HORSE),
+    CAMEL(ABSTRACT_HORSE),
+
+    ABSTRACT_CHESTED_HORSE(ABSTRACT_HORSE, null),
+    DONKEY(ABSTRACT_CHESTED_HORSE),
+    MULE(ABSTRACT_CHESTED_HORSE),
+    LLAMA(ABSTRACT_CHESTED_HORSE),
+    TRADER_LLAMA(LLAMA),
+
+    // Monsters
+    ABSTRACT_MONSTER(PATHFINDER_MOB, null),
+    BLAZE(ABSTRACT_MONSTER),
+    CREEPER(ABSTRACT_MONSTER),
+    ENDERMITE(ABSTRACT_MONSTER),
+    ENDERMAN(ABSTRACT_MONSTER),
+    GIANT(ABSTRACT_MONSTER),
+    SILVERFISH(ABSTRACT_MONSTER),
+    VEX(ABSTRACT_MONSTER),
+    WITHER(ABSTRACT_MONSTER),
+    BREEZE(ABSTRACT_MONSTER),
+    ZOGLIN(ABSTRACT_MONSTER),
+    WARDEN(ABSTRACT_MONSTER),
+    CREAKING(ABSTRACT_MONSTER),
+
+    ABSTRACT_SKELETON(ABSTRACT_MONSTER, null),
+    SKELETON(ABSTRACT_SKELETON),
+    STRAY(ABSTRACT_SKELETON),
+    WITHER_SKELETON(ABSTRACT_SKELETON),
+    BOGGED(ABSTRACT_SKELETON),
+
+    ZOMBIE(ABSTRACT_MONSTER),
+    DROWNED(ZOMBIE),
+    HUSK(ZOMBIE),
+    ZOMBIFIED_PIGLIN(ZOMBIE),
+    ZOMBIE_VILLAGER(ZOMBIE),
+
+    GUARDIAN(ABSTRACT_MONSTER),
+    ELDER_GUARDIAN(GUARDIAN),
+
+    SPIDER(ABSTRACT_MONSTER),
+    CAVE_SPIDER(SPIDER),
+
+    ABSTRACT_PIGLIN(ABSTRACT_MONSTER, null),
+    PIGLIN(ABSTRACT_PIGLIN),
+    PIGLIN_BRUTE(ABSTRACT_PIGLIN),
+
+    // Water mobs
+    AGEABLE_WATER_CREATURE(ABSTRACT_AGEABLE, null),
+    DOLPHIN(AGEABLE_WATER_CREATURE),
+
+    SQUID(AGEABLE_WATER_CREATURE),
+    GLOW_SQUID(SQUID),
+
+    WATER_ANIMAL(PATHFINDER_MOB, null),
+    ABSTRACT_FISH(WATER_ANIMAL, null),
+    PUFFERFISH(ABSTRACT_FISH),
+    TADPOLE(ABSTRACT_FISH),
+
+    ABSTRACT_SCHOOLING_FISH(ABSTRACT_FISH, null),
+    COD(ABSTRACT_SCHOOLING_FISH),
+    SALMON(ABSTRACT_SCHOOLING_FISH),
+    TROPICAL_FISH(ABSTRACT_SCHOOLING_FISH),
+
+    // Raiders
+    ABSTRACT_RAIDER(ABSTRACT_MONSTER, null),
+    WITCH(ABSTRACT_RAIDER),
+    RAVAGER(ABSTRACT_RAIDER),
+
+    ABSTRACT_ILLAGER(ABSTRACT_RAIDER, null),
+    SPELLCASTER_ILLAGER(ABSTRACT_ILLAGER, null),
+    VINDICATOR(ABSTRACT_ILLAGER),
+    PILLAGER(ABSTRACT_ILLAGER),
+    EVOKER(SPELLCASTER_ILLAGER),
+    ILLUSIONER(SPELLCASTER_ILLAGER);
+
+    private static final EntityType[] TYPES = EntityTypeUtil.createSizedArray(values());
+    private final EntityType parent;
+    private final String identifier;
+    private int id = -1;
+
+    EntityTypes1_21_6(final EntityType parent) {
+        this.parent = parent;
+        this.identifier = Key.namespaced(name().toLowerCase(Locale.ROOT));
+    }
+
+    EntityTypes1_21_6(final EntityType parent, @Nullable final String identifier) {
+        this.parent = parent;
+        this.identifier = identifier;
+    }
+
+    @Override
+    public int getId() {
+        if (id == -1) {
+            throw new IllegalStateException("Ids have not been initialized yet (type " + name() + ")");
+        }
+        return id;
+    }
+
+    @Override
+    public String identifier() {
+        Preconditions.checkArgument(identifier != null, "Called identifier method on abstract type");
+        return identifier;
+    }
+
+    @Override
+    public @Nullable EntityType getParent() {
+        return parent;
+    }
+
+    @Override
+    public boolean isAbstractType() {
+        return identifier == null;
+    }
+
+    public static EntityType getTypeFromId(final int typeId) {
+        return EntityTypeUtil.getTypeFromId(TYPES, typeId, PIG);
+    }
+
+    public static void initialize(final Protocol<?, ?, ?, ?> protocol) {
+        EntityTypeUtil.initialize(values(), TYPES, protocol, (type, id) -> type.id = id);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/entitydata/types/EntityDataTypes1_20_5.java

@@ -22,12 +22,9 @@
  */
 package com.viaversion.viaversion.api.minecraft.entitydata.types;
 
-import com.viaversion.viaversion.api.minecraft.Particle;
 import com.viaversion.viaversion.api.minecraft.entitydata.EntityDataType;
 import com.viaversion.viaversion.api.type.Types;
-import com.viaversion.viaversion.api.type.types.ArrayType;
-import com.viaversion.viaversion.api.type.types.misc.ParticleType;
-import com.viaversion.viaversion.api.type.types.version.Types1_20_5;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
 
 public final class EntityDataTypes1_20_5 extends AbstractEntityDataTypes {
 
@@ -38,7 +35,7 @@ public final class EntityDataTypes1_20_5 extends AbstractEntityDataTypes {
     public final EntityDataType stringType = add(4, Types.STRING);
     public final EntityDataType componentType = add(5, Types.TAG);
     public final EntityDataType optionalComponentType = add(6, Types.OPTIONAL_TAG);
-    public final EntityDataType itemType = add(7, Types1_20_5.ITEM);
+    public final EntityDataType itemType;
     public final EntityDataType booleanType = add(8, Types.BOOLEAN);
     public final EntityDataType rotationsType = add(9, Types.ROTATIONS);
     public final EntityDataType blockPositionType = add(10, Types.BLOCK_POSITION1_14);
@@ -63,9 +60,10 @@ public final class EntityDataTypes1_20_5 extends AbstractEntityDataTypes {
     public final EntityDataType vector3FType = add(29, Types.VECTOR3F);
     public final EntityDataType quaternionType = add(30, Types.QUATERNION);
 
-    public EntityDataTypes1_20_5(final ParticleType particleType, final ArrayType<Particle> particlesType) {
+    public EntityDataTypes1_20_5(final VersionedTypesHolder types) {
         super(31);
-        this.particleType = add(17, particleType);
-        this.particlesType = add(18, particlesType);
+        this.itemType = add(7, types.item());
+        this.particleType = add(17, types.particle());
+        this.particlesType = add(18, types.particles());
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/entitydata/types/EntityDataTypes1_21.java

@@ -23,14 +23,10 @@
 package com.viaversion.viaversion.api.minecraft.entitydata.types;
 
 import com.viaversion.viaversion.api.minecraft.PaintingVariant;
-import com.viaversion.viaversion.api.minecraft.Particle;
 import com.viaversion.viaversion.api.minecraft.WolfVariant;
 import com.viaversion.viaversion.api.minecraft.entitydata.EntityDataType;
-import com.viaversion.viaversion.api.minecraft.item.Item;
-import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
-import com.viaversion.viaversion.api.type.types.ArrayType;
-import com.viaversion.viaversion.api.type.types.misc.ParticleType;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
 
 public final class EntityDataTypes1_21 extends AbstractEntityDataTypes {
 
@@ -66,10 +62,10 @@ public final class EntityDataTypes1_21 extends AbstractEntityDataTypes {
     public final EntityDataType vector3FType = add(29, Types.VECTOR3F);
     public final EntityDataType quaternionType = add(30, Types.QUATERNION);
 
-    public EntityDataTypes1_21(final Type<Item> itemType, final ParticleType particleType, final ArrayType<Particle> particlesType) {
+    public EntityDataTypes1_21(final VersionedTypesHolder types) {
         super(31);
-        this.itemType = add(7, itemType);
-        this.particleType = add(17, particleType);
-        this.particlesType = add(18, particlesType);
+        this.itemType = add(7, types.item());
+        this.particleType = add(17, types.particle());
+        this.particlesType = add(18, types.particles());
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/entitydata/types/EntityDataTypes1_21_2.java

@@ -23,13 +23,10 @@
 package com.viaversion.viaversion.api.minecraft.entitydata.types;
 
 import com.viaversion.viaversion.api.minecraft.PaintingVariant;
-import com.viaversion.viaversion.api.minecraft.Particle;
 import com.viaversion.viaversion.api.minecraft.WolfVariant;
 import com.viaversion.viaversion.api.minecraft.entitydata.EntityDataType;
-import com.viaversion.viaversion.api.minecraft.item.Item;
-import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
-import com.viaversion.viaversion.api.type.types.misc.ParticleType;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
 
 public final class EntityDataTypes1_21_2 extends AbstractEntityDataTypes {
 
@@ -65,10 +62,10 @@ public final class EntityDataTypes1_21_2 extends AbstractEntityDataTypes {
     public final EntityDataType vector3FType = add(29, Types.VECTOR3F);
     public final EntityDataType quaternionType = add(30, Types.QUATERNION);
 
-    public EntityDataTypes1_21_2(final Type<Item> itemType, final ParticleType particleType, final Type<Particle[]> particlesType) {
+    public EntityDataTypes1_21_2(final VersionedTypesHolder types) {
         super(31);
-        this.itemType = add(7, itemType);
-        this.particleType = add(17, particleType);
-        this.particlesType = add(18, particlesType);
+        this.itemType = add(7, types.item());
+        this.particleType = add(17, types.particle());
+        this.particlesType = add(18, types.particles());
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/entitydata/types/EntityDataTypes1_21_5.java

@@ -23,12 +23,9 @@
 package com.viaversion.viaversion.api.minecraft.entitydata.types;
 
 import com.viaversion.viaversion.api.minecraft.PaintingVariant;
-import com.viaversion.viaversion.api.minecraft.Particle;
 import com.viaversion.viaversion.api.minecraft.entitydata.EntityDataType;
-import com.viaversion.viaversion.api.minecraft.item.Item;
-import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
-import com.viaversion.viaversion.api.type.types.misc.ParticleType;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
 
 public final class EntityDataTypes1_21_5 extends AbstractEntityDataTypes {
 
@@ -68,10 +65,10 @@ public final class EntityDataTypes1_21_5 extends AbstractEntityDataTypes {
     public final EntityDataType vector3FType = add(33, Types.VECTOR3F);
     public final EntityDataType quaternionType = add(34, Types.QUATERNION);
 
-    public EntityDataTypes1_21_5(final Type<Item> itemType, final ParticleType particleType, final Type<Particle[]> particlesType) {
+    public EntityDataTypes1_21_5(final VersionedTypesHolder types) {
         super(35);
-        this.itemType = add(7, itemType);
-        this.particleType = add(17, particleType);
-        this.particlesType = add(18, particlesType);
+        this.itemType = add(7, types.item());
+        this.particleType = add(17, types.particle());
+        this.particlesType = add(18, types.particles());
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/HashedItem.java

@@ -39,4 +39,7 @@ public interface HashedItem extends ItemBase {
     Int2IntMap dataHashesById();
 
     IntSet removedDataIds();
+
+    @Override
+    HashedItem copy();
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/HashedStructuredItem.java

@@ -79,6 +79,11 @@ public class HashedStructuredItem implements HashedItem {
         return this.removedData;
     }
 
+    @Override
+    public HashedItem copy() {
+        return new HashedStructuredItem(identifier, amount, new Int2IntOpenHashMap(dataHashes), new IntOpenHashSet(removedData));
+    }
+
     @Override
     public boolean equals(final Object o) {
         if (this == o) return true;

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/Item.java

@@ -27,7 +27,7 @@ import com.viaversion.viaversion.api.minecraft.data.StructuredDataContainer;
 import com.viaversion.viaversion.util.Copyable;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public interface Item extends ItemBase, Copyable {
+public interface Item extends ItemBase {
 
     /**
      * Returns the item data. Always 0 for 1.13+ items.

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/ItemBase.java

@@ -22,11 +22,13 @@
  */
 package com.viaversion.viaversion.api.minecraft.item;
 
+import com.viaversion.viaversion.util.Copyable;
+
 /**
  * @see Item
  * @see HashedItem
  */
-public interface ItemBase {
+public interface ItemBase extends Copyable {
 
     /**
      * Returns the item identifier.
@@ -64,4 +66,7 @@ public interface ItemBase {
     default boolean isEmpty() {
         return identifier() == 0 || amount() <= 0;
     }
+
+    @Override
+    ItemBase copy();
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/AdventureModePredicate.java

@@ -22,14 +22,17 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.data.StructuredData;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.types.ArrayType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record AdventureModePredicate(BlockPredicate[] predicates, boolean showInTooltip) implements Copyable {
+public record AdventureModePredicate(BlockPredicate[] predicates,
+                                     boolean showInTooltip) implements Copyable, Rewritable {
 
     public AdventureModePredicate(final BlockPredicate[] predicates) {
         this(predicates, true);
@@ -70,16 +73,17 @@ public record AdventureModePredicate(BlockPredicate[] predicates, boolean showIn
         }
     }
 
-    public AdventureModePredicate rewrite(final Int2IntFunction blockIdRewriter) {
+    @Override
+    public AdventureModePredicate rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         final BlockPredicate[] predicates = new BlockPredicate[this.predicates.length];
         for (int i = 0; i < predicates.length; i++) {
-            predicates[i] = this.predicates[i].rewrite(blockIdRewriter);
+            predicates[i] = this.predicates[i].rewrite(connection, protocol, clientbound);
         }
         return new AdventureModePredicate(predicates, showInTooltip);
     }
 
     @Override
     public AdventureModePredicate copy() {
-        return new AdventureModePredicate(copy(predicates), showInTooltip);
+        return new AdventureModePredicate(Copyable.copy(predicates), showInTooltip);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ArmorTrim.java

@@ -22,12 +22,15 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Holder;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record ArmorTrim(Holder<ArmorTrimMaterial> material, Holder<ArmorTrimPattern> pattern, boolean showInTooltip) {
+public record ArmorTrim(Holder<ArmorTrimMaterial> material, Holder<ArmorTrimPattern> pattern,
+                        boolean showInTooltip) implements Rewritable {
 
     public ArmorTrim(Holder<ArmorTrimMaterial> material, Holder<ArmorTrimPattern> pattern) {
         this(material, pattern, true);
@@ -96,15 +99,16 @@ public record ArmorTrim(Holder<ArmorTrimMaterial> material, Holder<ArmorTrimPatt
         }
     };
 
-    public ArmorTrim rewrite(final Int2IntFunction idRewriteFunction) {
+    @Override
+    public ArmorTrim rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         Holder<ArmorTrimMaterial> material = this.material;
         if (material.isDirect()) {
-            material = Holder.of(material.value().rewrite(idRewriteFunction));
+            material = Holder.of(material.value().rewrite(connection, protocol, clientbound));
         }
 
         Holder<ArmorTrimPattern> pattern = this.pattern;
         if (pattern.isDirect()) {
-            pattern = Holder.of(pattern.value().rewrite(idRewriteFunction));
+            pattern = Holder.of(pattern.value().rewrite(connection, protocol, clientbound));
         }
         return new ArmorTrim(material, pattern, showInTooltip);
     }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ArmorTrimMaterial.java

@@ -23,16 +23,19 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 import it.unimi.dsi.fastutil.objects.Object2ObjectArrayMap;
 import java.util.Map;
 
 public record ArmorTrimMaterial(String assetName, int itemId, float itemModelIndex,
-                                Map<String, String> overrideArmorMaterials, Tag description) implements Copyable {
+                                Map<String, String> overrideArmorMaterials,
+                                Tag description) implements Copyable, Rewritable {
 
     public ArmorTrimMaterial(final String assetName, final int itemId, final Map<String, String> overrideArmorMaterials, final Tag description) {
         this(assetName, itemId, 0F, overrideArmorMaterials, description);
@@ -175,8 +178,9 @@ public record ArmorTrimMaterial(String assetName, int itemId, float itemModelInd
         }
     };
 
-    public ArmorTrimMaterial rewrite(final Int2IntFunction idRewriteFunction) {
-        return new ArmorTrimMaterial(assetName, idRewriteFunction.applyAsInt(itemId), itemModelIndex, overrideArmorMaterials, description);
+    @Override
+    public ArmorTrimMaterial rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        return new ArmorTrimMaterial(assetName, Rewritable.rewriteItem(protocol, clientbound, itemId), itemModelIndex, overrideArmorMaterials, description);
     }
 
     @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ArmorTrimPattern.java

@@ -23,13 +23,15 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record ArmorTrimPattern(String assetName, int itemId, Tag description, boolean decal) implements Copyable {
+public record ArmorTrimPattern(String assetName, int itemId, Tag description, boolean decal) implements Copyable, Rewritable {
 
     public ArmorTrimPattern(final String assetName, final Tag description, final boolean decal) {
         this(assetName, 0, description, decal);
@@ -70,8 +72,9 @@ public record ArmorTrimPattern(String assetName, int itemId, Tag description, bo
         }
     };
 
-    public ArmorTrimPattern rewrite(final Int2IntFunction idRewriteFunction) {
-        return new ArmorTrimPattern(assetName, idRewriteFunction.applyAsInt(itemId), description, decal);
+    @Override
+    public ArmorTrimPattern rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        return new ArmorTrimPattern(assetName, Rewritable.rewriteItem(protocol, clientbound, itemId), description, decal);
     }
 
     @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/AttributeModifiers1_20_5.java

@@ -48,7 +48,7 @@ public record AttributeModifiers1_20_5(AttributeModifier[] modifiers, boolean sh
 
     @Override
     public AttributeModifiers1_20_5 copy() {
-        return new AttributeModifiers1_20_5(copy(modifiers), showInTooltip);
+        return new AttributeModifiers1_20_5(Copyable.copy(modifiers), showInTooltip);
     }
 
     public record AttributeModifier(int attribute, ModifierData modifier, int slotType) {

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/AttributeModifiers1_21.java

@@ -22,10 +22,13 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Key;
 import io.netty.buffer.ByteBuf;
 import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
@@ -38,27 +41,49 @@ public record AttributeModifiers1_21(AttributeModifier[] modifiers, boolean show
     public static final Type<AttributeModifiers1_21> TYPE1_21 = new Type<>(AttributeModifiers1_21.class) {
         @Override
         public AttributeModifiers1_21 read(final ByteBuf buffer) {
-            final AttributeModifier[] modifiers = AttributeModifier.ARRAY_TYPE.read(buffer);
+            final AttributeModifier[] modifiers = AttributeModifier.ARRAY_TYPE1_21.read(buffer);
             final boolean showInTooltip = buffer.readBoolean();
             return new AttributeModifiers1_21(modifiers, showInTooltip);
         }
 
         @Override
         public void write(final ByteBuf buffer, final AttributeModifiers1_21 value) {
-            AttributeModifier.ARRAY_TYPE.write(buffer, value.modifiers());
+            AttributeModifier.ARRAY_TYPE1_21.write(buffer, value.modifiers());
             buffer.writeBoolean(value.showInTooltip());
         }
     };
     public static final Type<AttributeModifiers1_21> TYPE1_21_5 = new Type<>(AttributeModifiers1_21.class) {
         @Override
         public AttributeModifiers1_21 read(final ByteBuf buffer) {
-            final AttributeModifier[] modifiers = AttributeModifier.ARRAY_TYPE.read(buffer);
+            final AttributeModifier[] modifiers = AttributeModifier.ARRAY_TYPE1_21.read(buffer);
             return new AttributeModifiers1_21(modifiers);
         }
 
         @Override
         public void write(final ByteBuf buffer, final AttributeModifiers1_21 value) {
-            AttributeModifier.ARRAY_TYPE.write(buffer, value.modifiers());
+            AttributeModifier.ARRAY_TYPE1_21.write(buffer, value.modifiers());
+        }
+
+        @Override
+        public void write(final Ops ops, final AttributeModifiers1_21 value) {
+            ops.write(AttributeModifier.ARRAY_TYPE1_21, value.modifiers);
+        }
+    };
+    public static final Type<AttributeModifiers1_21> TYPE1_21_6 = new Type<>(AttributeModifiers1_21.class) {
+        @Override
+        public AttributeModifiers1_21 read(final ByteBuf buffer) {
+            final AttributeModifier[] modifiers = AttributeModifier.ARRAY_TYPE1_21_6.read(buffer);
+            return new AttributeModifiers1_21(modifiers);
+        }
+
+        @Override
+        public void write(final ByteBuf buffer, final AttributeModifiers1_21 value) {
+            AttributeModifier.ARRAY_TYPE1_21_6.write(buffer, value.modifiers());
+        }
+
+        @Override
+        public void write(final Ops ops, final AttributeModifiers1_21 value) {
+            ops.write(AttributeModifier.ARRAY_TYPE1_21_6, value.modifiers);
         }
     };
 
@@ -66,19 +91,25 @@ public record AttributeModifiers1_21(AttributeModifier[] modifiers, boolean show
         final AttributeModifier[] modifiers = new AttributeModifier[this.modifiers.length];
         for (int i = 0; i < this.modifiers.length; i++) {
             final AttributeModifier modifier = this.modifiers[i];
-            modifiers[i] = new AttributeModifier(rewriteFunction.applyAsInt(modifier.attribute()), modifier.modifier(), modifier.slotType());
+            modifiers[i] = new AttributeModifier(rewriteFunction.applyAsInt(modifier.attribute()), modifier.modifier(), modifier.slotType(), modifier.display());
         }
         return new AttributeModifiers1_21(modifiers, showInTooltip);
     }
 
     @Override
     public AttributeModifiers1_21 copy() {
-        return new AttributeModifiers1_21(copy(modifiers), showInTooltip);
+        return new AttributeModifiers1_21(Copyable.copy(modifiers), showInTooltip);
     }
 
-    public record AttributeModifier(int attribute, ModifierData modifier, int slotType) {
+    public record AttributeModifier(int attribute, ModifierData modifier, int slotType, Display display) {
+        private static final String[] EQUIPMENT_SLOT_GROUPS = {"any", "mainhand", "offhand", "hand", "feet", "legs", "chest", "head", "armor", "body", "saddle"};
+        private static final String[] OPERATION = {"add_value", "add_multiplied_base", "add_multiplied_total"};
 
-        public static final Type<AttributeModifier> TYPE = new Type<>(AttributeModifier.class) {
+        public AttributeModifier(final int attribute, final ModifierData modifier, final int slotType) {
+            this(attribute, modifier, slotType, Display.DEFAULT);
+        }
+
+        public static final Type<AttributeModifier> TYPE1_21 = new Type<>(AttributeModifier.class) {
             @Override
             public AttributeModifier read(final ByteBuf buffer) {
                 final int attribute = Types.VAR_INT.readPrimitive(buffer);
@@ -93,8 +124,62 @@ public record AttributeModifiers1_21(AttributeModifier[] modifiers, boolean show
                 ModifierData.TYPE.write(buffer, value.modifier);
                 Types.VAR_INT.writePrimitive(buffer, value.slotType);
             }
+
+            @Override
+            public void write(final Ops ops, final AttributeModifier value) {
+                final Key attribute = ops.context().registryAccess().attributeModifier(value.attribute);
+                ops.writeMap(map -> map
+                    .write("type", Types.RESOURCE_LOCATION, attribute)
+                    .write("id", Types.RESOURCE_LOCATION, Key.of(value.modifier.id()))
+                    .write("amount", Types.DOUBLE, value.modifier.amount)
+                    .write("operation", Types.STRING, OPERATION[value.modifier.operation()])
+                    .writeOptional("slot", Types.STRING, EQUIPMENT_SLOT_GROUPS[value.slotType()], "any"));
+            }
         };
-        public static final Type<AttributeModifier[]> ARRAY_TYPE = new ArrayType<>(TYPE);
+        public static final Type<AttributeModifier[]> ARRAY_TYPE1_21 = new ArrayType<>(TYPE1_21);
+
+        public static final Type<AttributeModifier> TYPE1_21_6 = new Type<>(AttributeModifier.class) {
+            @Override
+            public AttributeModifier read(final ByteBuf buffer) {
+                final int attribute = Types.VAR_INT.readPrimitive(buffer);
+                final ModifierData modifier = ModifierData.TYPE.read(buffer);
+                final int slot = Types.VAR_INT.readPrimitive(buffer);
+                final int displayType = Types.VAR_INT.readPrimitive(buffer);
+                final Display display = displayType == OverrideText.ID ? new OverrideText(Types.TAG.read(buffer)) : new Display(displayType);
+                return new AttributeModifier(attribute, modifier, slot, display);
+            }
+
+            @Override
+            public void write(final ByteBuf buffer, final AttributeModifier value) {
+                Types.VAR_INT.writePrimitive(buffer, value.attribute);
+                ModifierData.TYPE.write(buffer, value.modifier);
+                Types.VAR_INT.writePrimitive(buffer, value.slotType);
+                value.display.write(buffer);
+            }
+
+            @Override
+            public void write(final Ops ops, final AttributeModifier value) {
+                final Key attribute = ops.context().registryAccess().attributeModifier(value.attribute);
+                ops.writeMap(map -> {
+                    map.write("type", Types.RESOURCE_LOCATION, attribute)
+                        .write("id", Types.RESOURCE_LOCATION, Key.of(value.modifier.id()))
+                        .write("amount", Types.DOUBLE, value.modifier.amount)
+                        .write("operation", Types.STRING, OPERATION[value.modifier.operation()])
+                        .writeOptional("slot", Types.STRING, EQUIPMENT_SLOT_GROUPS[value.slotType()], "any");
+                    if (value.display.equals(Display.DEFAULT)) {
+                        return;
+                    }
+
+                    map.writeMap("display", display -> {
+                        display.write("type", Types.STRING, Display.DISPLAY_TYPES[value.display.id()]);
+                        if (value.display instanceof final OverrideText overrideText) {
+                            display.write("value", Types.TAG, overrideText.component);
+                        }
+                    });
+                });
+            }
+        };
+        public static final Type<AttributeModifier[]> ARRAY_TYPE1_21_6 = new ArrayType<>(TYPE1_21_6);
     }
 
     public record ModifierData(String id, double amount, int operation) {
@@ -116,4 +201,52 @@ public record AttributeModifiers1_21(AttributeModifier[] modifiers, boolean show
             }
         };
     }
+
+    public static class Display implements Copyable {
+        public static final String[] DISPLAY_TYPES = {"default", "hidden", "override_text"};
+        public static final Display DEFAULT = new Display(0);
+        private final int id;
+
+        public Display(final int id) {
+            this.id = id;
+        }
+
+        public int id() {
+            return this.id;
+        }
+
+        public void write(final ByteBuf buf) {
+            Types.VAR_INT.writePrimitive(buf, this.id);
+        }
+
+        @Override
+        public Display copy() {
+            return this;
+        }
+    }
+
+    public static final class OverrideText extends Display {
+        public static final int ID = 2;
+        private final Tag component;
+
+        public OverrideText(final Tag component) {
+            super(ID);
+            this.component = component;
+        }
+
+        public Tag component() {
+            return this.component;
+        }
+
+        @Override
+        public void write(final ByteBuf buf) {
+            super.write(buf);
+            Types.TAG.write(buf, this.component);
+        }
+
+        @Override
+        public OverrideText copy() {
+            return new OverrideText(this.component.copy());
+        }
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Bee.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.CompoundTag;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
@@ -46,6 +47,14 @@ public record Bee(CompoundTag entityData, int ticksInHive, int minTicksInHive) i
             Types.VAR_INT.writePrimitive(buffer, value.ticksInHive);
             Types.VAR_INT.writePrimitive(buffer, value.minTicksInHive);
         }
+
+        @Override
+        public void write(final Ops ops, final Bee value) {
+            ops.writeMap(map -> map
+                .writeOptional("entity_data", Types.COMPOUND_TAG, value.entityData, new CompoundTag())
+                .write("ticks_in_hive", Types.INT, value.ticksInHive)
+                .write("min_ticks_in_hive", Types.INT, value.minTicksInHive));
+        }
     };
     public static final Type<Bee[]> ARRAY_TYPE = new ArrayType<>(TYPE);
 

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/BlockPredicate.java

@@ -23,23 +23,27 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.CompoundTag;
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.HolderSet;
 import com.viaversion.viaversion.api.minecraft.data.StructuredData;
 import com.viaversion.viaversion.api.minecraft.data.predicate.DataComponentMatchers;
 import com.viaversion.viaversion.api.minecraft.data.predicate.DataComponentMatchers.DataComponentMatchersType;
+import com.viaversion.viaversion.api.minecraft.data.predicate.DataComponentPredicate;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public record BlockPredicate(@Nullable HolderSet holderSet, StatePropertyMatcher @Nullable [] propertyMatchers,
-                             @Nullable CompoundTag tag, DataComponentMatchers dataMatchers) implements Copyable {
+                             @Nullable CompoundTag tag,
+                             DataComponentMatchers dataMatchers) implements Copyable, Rewritable {
 
     public BlockPredicate(@Nullable final HolderSet holderSet, final StatePropertyMatcher @Nullable [] propertyMatchers, @Nullable final CompoundTag tag) {
-        this(holderSet, propertyMatchers, tag, null);
+        this(holderSet, propertyMatchers, tag, new DataComponentMatchers(new StructuredData[0], new DataComponentPredicate[0]));
     }
 
     public static final Type<BlockPredicate> TYPE1_20_5 = new Type<>(BlockPredicate.class) {
@@ -96,17 +100,18 @@ public record BlockPredicate(@Nullable HolderSet holderSet, StatePropertyMatcher
         }
     }
 
-    public BlockPredicate rewrite(final Int2IntFunction blockIdRewriter) {
+    @Override
+    public BlockPredicate rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         if (holderSet == null || holderSet.hasTagKey()) {
             return this;
         }
 
-        final HolderSet updatedHolders = holderSet.rewrite(blockIdRewriter);
+        final HolderSet updatedHolders = holderSet.rewrite(Rewritable.blockRewriteFunction(protocol, clientbound));
         return new BlockPredicate(updatedHolders, propertyMatchers, tag);
     }
 
     @Override
     public BlockPredicate copy() {
-        return new BlockPredicate(holderSet, copy(propertyMatchers), tag == null ? null : tag.copy());
+        return new BlockPredicate(holderSet, Copyable.copy(propertyMatchers), tag == null ? null : tag.copy());
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/BlockStateProperties.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.util.Copyable;
@@ -50,6 +51,15 @@ public record BlockStateProperties(Map<String, String> properties) implements Co
                 Types.STRING.write(buffer, entry.getValue());
             }
         }
+
+        @Override
+        public void write(final Ops ops, final BlockStateProperties value) {
+            ops.writeMap(map -> {
+                for (final Map.Entry<String, String> entry : value.properties.entrySet()) {
+                    map.write(Types.STRING, entry.getKey(), Types.STRING, entry.getValue());
+                }
+            });
+        }
     };
 
     @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Consumable1_21_2.java

@@ -22,17 +22,20 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Holder;
 import com.viaversion.viaversion.api.minecraft.SoundEvent;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
 public record Consumable1_21_2(float consumeSeconds, int animationType, Holder<SoundEvent> sound,
-                               boolean hasConsumeParticles, ConsumeEffect<?>[] consumeEffects) implements Copyable {
+                               boolean hasConsumeParticles,
+                               ConsumeEffect<?>[] consumeEffects) implements Copyable, Rewritable {
 
     public static final Type<?>[] EFFECT_TYPES = {
         ApplyStatusEffects.TYPE,
@@ -111,13 +114,14 @@ public record Consumable1_21_2(float consumeSeconds, int animationType, Holder<S
         };
     }
 
-    public Consumable1_21_2 rewrite(final Int2IntFunction soundIdRewriteFunction) {
-        final Holder<SoundEvent> soundHolder = this.sound.updateId(soundIdRewriteFunction);
+    @Override
+    public Consumable1_21_2 rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        final Holder<SoundEvent> soundHolder = this.sound.updateId(Rewritable.soundRewriteFunction(protocol, clientbound));
         return soundHolder == this.sound ? this : new Consumable1_21_2(consumeSeconds, animationType, soundHolder, hasConsumeParticles, consumeEffects);
     }
 
     @Override
     public Consumable1_21_2 copy() {
-        return new Consumable1_21_2(consumeSeconds, animationType, sound, hasConsumeParticles, copy(consumeEffects));
+        return new Consumable1_21_2(consumeSeconds, animationType, sound, hasConsumeParticles, Copyable.copy(consumeEffects));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ContainterContents.java

@@ -0,0 +1,55 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.item.data;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.minecraft.item.Item;
+import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.api.type.types.ArrayType;
+
+public final class ContainterContents {
+
+    // Just write it as Item[] directly, makes processing easier (until op reading is needed)
+    public static final class ContainerContentsType extends ArrayType<Item> {
+        private final Type<Item> itemType;
+
+        public ContainerContentsType(final Type<Item> itemType) {
+            super(itemType, 256);
+            this.itemType = itemType;
+        }
+
+        @Override
+        public void write(final Ops ops, final Item[] value) {
+            ops.writeList(list -> {
+                for (int i = 0; i < value.length; i++) {
+                    final Item item = value[i];
+                    final int slot = i;
+                    list.writeMap(map -> map
+                        .write("slot", Types.INT, slot)
+                        .write("item", itemType, item));
+                }
+            });
+        }
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/CustomModelData1_21_4.java

@@ -22,12 +22,16 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.api.type.types.ArrayType;
+import com.viaversion.viaversion.util.ArrayUtil;
 import com.viaversion.viaversion.util.Copyable;
 import io.netty.buffer.ByteBuf;
 
-public record CustomModelData1_21_4(float[] floats, boolean[] booleans, String[] strings, int[] colors) implements Copyable {
+public record CustomModelData1_21_4(float[] floats, boolean[] booleans, String[] strings,
+                                    int[] colors) implements Copyable {
 
     public static final Type<CustomModelData1_21_4> TYPE = new Type<>(CustomModelData1_21_4.class) {
         @Override
@@ -46,10 +50,19 @@ public record CustomModelData1_21_4(float[] floats, boolean[] booleans, String[]
             Types.STRING_ARRAY.write(buffer, value.strings());
             Types.INT_ARRAY_PRIMITIVE.write(buffer, value.colors());
         }
+
+        @Override
+        public void write(final Ops ops, final CustomModelData1_21_4 value) {
+            ops.writeMap(map -> map
+                .writeOptional("floats", new ArrayType<>(Types.FLOAT), ArrayUtil.boxedArray(value.floats), new Float[0])
+                .writeOptional("flags", new ArrayType<>(Types.BOOLEAN), ArrayUtil.boxedArray(value.booleans), new Boolean[0])
+                .writeOptional("strings", Types.STRING_ARRAY, value.strings(), new String[0])
+                .writeOptional("colors", new ArrayType<>(Types.INT), ArrayUtil.boxedArray(value.colors), new Integer[0]));
+        }
     };
 
     @Override
     public CustomModelData1_21_4 copy() {
-        return new CustomModelData1_21_4(copy(floats), copy(booleans), copy(strings), copy(colors));
+        return new CustomModelData1_21_4(Copyable.copy(floats), Copyable.copy(booleans), Copyable.copy(strings), Copyable.copy(colors));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/DamageResistant.java

@@ -22,22 +22,29 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.Key;
 import io.netty.buffer.ByteBuf;
 
-public record DamageResistant(String typesTagKey) {
+public record DamageResistant(Key typesTagKey) {
 
     public static final Type<DamageResistant> TYPE = new Type<>(DamageResistant.class) {
         @Override
         public DamageResistant read(final ByteBuf buffer) {
-            final String typesTagKey = Types.STRING.read(buffer);
+            final Key typesTagKey = Types.RESOURCE_LOCATION.read(buffer);
             return new DamageResistant(typesTagKey);
         }
 
         @Override
         public void write(final ByteBuf buffer, final DamageResistant value) {
-            Types.STRING.write(buffer, value.typesTagKey());
+            Types.RESOURCE_LOCATION.write(buffer, value.typesTagKey());
+        }
+
+        @Override
+        public void write(final Ops ops, final DamageResistant value) {
+            ops.writeMap(map -> map.write("types", Types.TAG_KEY, value.typesTagKey));
         }
     };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/DeathProtection.java

@@ -44,6 +44,6 @@ public record DeathProtection(ConsumeEffect<?>[] deathEffects) implements Copyab
 
     @Override
     public DeathProtection copy() {
-        return new DeathProtection(copy(deathEffects));
+        return new DeathProtection(Copyable.copy(deathEffects));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/DyedColor.java

@@ -22,7 +22,9 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
 
 public record DyedColor(int rgb, boolean showInTooltip) {
@@ -56,5 +58,10 @@ public record DyedColor(int rgb, boolean showInTooltip) {
         public void write(final ByteBuf buffer, final DyedColor value) {
             buffer.writeInt(value.rgb);
         }
+
+        @Override
+        public void write(final Ops ops, final DyedColor dyedColor) {
+            ops.write(Types.INT, dyedColor.rgb);
+        }
     };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Enchantable.java

@@ -20,26 +20,29 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-package com.viaversion.viaversion.api.type.types.version;
+package com.viaversion.viaversion.api.minecraft.item.data;
 
-import com.viaversion.viaversion.api.minecraft.chunks.ChunkSection;
-import com.viaversion.viaversion.api.minecraft.entitydata.EntityData;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
-import com.viaversion.viaversion.api.type.types.chunk.ChunkSectionType1_8;
-import com.viaversion.viaversion.api.type.types.entitydata.EntityDataListType;
-import com.viaversion.viaversion.api.type.types.entitydata.EntityDataType1_8;
-import java.util.List;
+import com.viaversion.viaversion.api.type.Types;
+import io.netty.buffer.ByteBuf;
 
-public final class Types1_8 {
+public record Enchantable(int value) {
 
-    /**
-     * Entity data type for 1.8
-     */
-    public static final Type<EntityData> ENTITY_DATA = new EntityDataType1_8();
-    /**
-     * Entity data list type for 1.8
-     */
-    public static final Type<List<EntityData>> ENTITY_DATA_LIST = new EntityDataListType(ENTITY_DATA);
+    public static final Type<Enchantable> TYPE = new Type<>(Enchantable.class) {
+        @Override
+        public Enchantable read(final ByteBuf buffer) {
+            return new Enchantable(Types.VAR_INT.readPrimitive(buffer));
+        }
 
-    public static final Type<ChunkSection> CHUNK_SECTION = new ChunkSectionType1_8();
+        @Override
+        public void write(final ByteBuf buffer, final Enchantable value) {
+            Types.VAR_INT.writePrimitive(buffer, value.value);
+        }
+
+        @Override
+        public void write(final Ops ops, final Enchantable enchantable) {
+            ops.writeMap(map -> map.write("value", Types.INT, enchantable.value));
+        }
+    };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Enchantments.java

@@ -22,9 +22,11 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Key;
 import io.netty.buffer.ByteBuf;
 import it.unimi.dsi.fastutil.ints.Int2IntMap;
 import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
@@ -81,6 +83,16 @@ public record Enchantments(Int2IntMap enchantments, boolean showInTooltip) imple
                 Types.VAR_INT.writePrimitive(buffer, entry.getIntValue());
             }
         }
+
+        @Override
+        public void write(final Ops ops, final Enchantments value) {
+            ops.writeMap(map -> {
+                for (final Int2IntMap.Entry entry : value.enchantments.int2IntEntrySet()) {
+                    final Key key = ops.context().registryAccess().enchantment(entry.getIntKey());
+                    map.write(Types.RESOURCE_LOCATION, key, Types.VAR_INT, entry.getIntValue());
+                }
+            });
+        }
     };
 
     public Enchantments(final boolean showInTooltip) {

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/EnumTypes.java

@@ -0,0 +1,51 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.item.data;
+
+import com.viaversion.viaversion.api.type.types.EnumType;
+import com.viaversion.viaversion.api.type.types.EnumType.Fallback;
+import com.viaversion.viaversion.api.type.types.FakeEnumType;
+import com.viaversion.viaversion.api.type.types.RegistryValueType;
+import java.util.List;
+
+import static com.viaversion.viaversion.api.type.types.FakeEnumType.Entry.of;
+
+/**
+ * Enum types that aren't associated with any specific item data in this package.
+ */
+public final class EnumTypes {
+
+    public static final EnumType DYE_COLOR = new EnumType("white", "orange", "magenta", "light_blue", "yellow", "lime", "pink", "gray", "light_gray", "cyan", "purple", "blue", "brown", "green", "red", "black");
+    public static final EnumType RARITY = new EnumType("common", "uncommon", "rare", "epic");
+    public static final EnumType FOX_VARIANT = new EnumType("red", "snow");
+    public static final EnumType SALMON_VARIANT = new EnumType(Fallback.CLAMP, "small", "medium", "large");
+    public static final EnumType PARROT_VARIANT = new EnumType(Fallback.CLAMP, "red_blue", "blue", "green", "yellow_blue", "gray");
+    public static final EnumType MUSHROOM_COW_VARIANT = new EnumType(Fallback.CLAMP, "red", "brown");
+    public static final EnumType HORSE_VARIANT = new EnumType(Fallback.WRAP, "white", "creamy", "chestnut", "brown", "black", "gray", "dark_brown");
+    public static final EnumType LLAMA_VARIANT = new EnumType(Fallback.CLAMP, "creamy", "white", "brown", "gray");
+    public static final EnumType AXOLOTL_VARIANT = new EnumType("lucy", "wild", "gold", "cyan", "blue");
+    // Enums with non-ordinal ids
+    public static final FakeEnumType RABBIT_VARIANT = new FakeEnumType(List.of("brown", "white", "black", "white_splotched", "gold", "salt"), of(99, "evil"));
+    // Pretty much enums, but with a resource location
+    public static final RegistryValueType VILLAGER_TYPE = new RegistryValueType("desert", "jungle", "plains", "savanna", "snow", "swamp", "taiga");
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Equippable.java

@@ -22,24 +22,32 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Holder;
 import com.viaversion.viaversion.api.minecraft.HolderSet;
 import com.viaversion.viaversion.api.minecraft.SoundEvent;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public record Equippable(int equipmentSlot, Holder<SoundEvent> soundEvent, @Nullable String model,
                          @Nullable String cameraOverlay, @Nullable HolderSet allowedEntities, boolean dispensable,
-                         boolean swappable, boolean damageOnHurt, boolean equipOnInteract) {
+                         boolean swappable, boolean damageOnHurt, boolean equipOnInteract,
+                         boolean canBeSheared, Holder<SoundEvent> shearingSound) implements Rewritable {
 
     public Equippable(final int equipmentSlot, final Holder<SoundEvent> soundEvent, @Nullable final String model, @Nullable final String cameraOverlay,
                       @Nullable final HolderSet allowedEntities, final boolean dispensable, final boolean swappable, final boolean damageOnHurt) {
         this(equipmentSlot, soundEvent, model, cameraOverlay, allowedEntities, dispensable, swappable, damageOnHurt, true);
     }
 
+    public Equippable(final int equipmentSlot, final Holder<SoundEvent> soundEvent, @Nullable final String model, @Nullable final String cameraOverlay,
+                      @Nullable final HolderSet allowedEntities, final boolean dispensable, final boolean swappable, final boolean damageOnHurt, final boolean equipOnInteract) {
+        this(equipmentSlot, soundEvent, model, cameraOverlay, allowedEntities, dispensable, swappable, damageOnHurt, equipOnInteract, false, Holder.of(0));
+    }
+
     public static final Type<Equippable> TYPE1_21_2 = new Type<>(Equippable.class) {
         @Override
         public Equippable read(final ByteBuf buffer) {
@@ -94,9 +102,43 @@ public record Equippable(int equipmentSlot, Holder<SoundEvent> soundEvent, @Null
             buffer.writeBoolean(value.equipOnInteract());
         }
     };
+    public static final Type<Equippable> TYPE1_21_6 = new Type<>(Equippable.class) {
+        @Override
+        public Equippable read(final ByteBuf buffer) {
+            final int equipmentSlot = Types.VAR_INT.readPrimitive(buffer);
+            final Holder<SoundEvent> soundEvent = Types.SOUND_EVENT.read(buffer);
+            final String model = Types.OPTIONAL_STRING.read(buffer);
+            final String cameraOverlay = Types.OPTIONAL_STRING.read(buffer);
+            final HolderSet allowedEntities = Types.OPTIONAL_HOLDER_SET.read(buffer);
+            final boolean dispensable = buffer.readBoolean();
+            final boolean swappable = buffer.readBoolean();
+            final boolean damageOnHurt = buffer.readBoolean();
+            final boolean equipOnInteract = buffer.readBoolean();
+            final boolean canBeSheared = buffer.readBoolean();
+            final Holder<SoundEvent> shearingSound = Types.SOUND_EVENT.read(buffer);
+            return new Equippable(equipmentSlot, soundEvent, model, cameraOverlay, allowedEntities, dispensable, swappable, damageOnHurt, equipOnInteract, canBeSheared, shearingSound);
+        }
 
-    public Equippable rewrite(final Int2IntFunction soundIdRewriter) {
-        final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(soundIdRewriter);
-        return soundEvent == this.soundEvent ? this : new Equippable(equipmentSlot, soundEvent, model, cameraOverlay, allowedEntities, dispensable, swappable, damageOnHurt, equipOnInteract);
+        @Override
+        public void write(final ByteBuf buffer, final Equippable value) {
+            Types.VAR_INT.writePrimitive(buffer, value.equipmentSlot());
+            Types.SOUND_EVENT.write(buffer, value.soundEvent());
+            Types.OPTIONAL_STRING.write(buffer, value.model());
+            Types.OPTIONAL_STRING.write(buffer, value.cameraOverlay());
+            Types.OPTIONAL_HOLDER_SET.write(buffer, value.allowedEntities());
+            buffer.writeBoolean(value.dispensable());
+            buffer.writeBoolean(value.swappable());
+            buffer.writeBoolean(value.damageOnHurt());
+            buffer.writeBoolean(value.equipOnInteract());
+            buffer.writeBoolean(value.canBeSheared());
+            Types.SOUND_EVENT.write(buffer, value.shearingSound());
+        }
+    };
+
+    @Override
+    public Equippable rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(Rewritable.soundRewriteFunction(protocol, clientbound));
+        final Holder<SoundEvent> shearingSound = this.shearingSound.updateId(Rewritable.soundRewriteFunction(protocol, clientbound));
+        return soundEvent == this.soundEvent && shearingSound == this.shearingSound ? this : new Equippable(equipmentSlot, soundEvent, model, cameraOverlay, allowedEntities, dispensable, swappable, damageOnHurt, equipOnInteract, canBeSheared, shearingSound);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Filterable.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -74,6 +75,13 @@ public abstract class Filterable<T> {
             optionalElementType.write(buffer, value.filtered());
         }
 
+        @Override
+        public void write(final Ops ops, final F value) {
+            ops.writeMap(map -> map
+                .write("raw", elementType, value.raw())
+                .writeOptional("filtered", elementType, value.filtered()));
+        }
+
         protected abstract F create(T raw, T filtered);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/FilterableComponent.java

@@ -23,12 +23,16 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
+import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public final class FilterableComponent extends Filterable<Tag> {
+public final class FilterableComponent extends Filterable<Tag> implements Copyable, Rewritable {
 
     public static final Type<FilterableComponent> TYPE = new FilterableType<>(Types.TAG, Types.OPTIONAL_TAG, FilterableComponent.class) {
         @Override
@@ -41,4 +45,21 @@ public final class FilterableComponent extends Filterable<Tag> {
     public FilterableComponent(final Tag raw, @Nullable final Tag filtered) {
         super(raw, filtered);
     }
+
+    @Override
+    public FilterableComponent rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        if (protocol.getComponentRewriter() == null) {
+            return this;
+        }
+
+        final FilterableComponent copy = copy();
+        protocol.getComponentRewriter().processTag(connection, copy.raw());
+        protocol.getComponentRewriter().processTag(connection, copy.filtered());
+        return copy;
+    }
+
+    @Override
+    public FilterableComponent copy() {
+        return new FilterableComponent(raw().copy(), filtered() != null ? filtered().copy() : null);
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/FireworkExplosion.java

@@ -22,13 +22,18 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
+import com.viaversion.viaversion.util.ArrayUtil;
 import com.viaversion.viaversion.util.Copyable;
 import io.netty.buffer.ByteBuf;
 
-public record FireworkExplosion(int shape, int[] colors, int[] fadeColors, boolean hasTrail, boolean hasTwinkle) implements Copyable {
+public record FireworkExplosion(int shape, int[] colors, int[] fadeColors, boolean hasTrail,
+                                boolean hasTwinkle) implements Copyable {
+    public static final String[] SHAPES = {"small_ball", "large_ball", "star", "creeper", "burst"};
+
     public static final Type<FireworkExplosion> TYPE = new Type<>(FireworkExplosion.class) {
         @Override
         public FireworkExplosion read(final ByteBuf buffer) {
@@ -48,11 +53,21 @@ public record FireworkExplosion(int shape, int[] colors, int[] fadeColors, boole
             buffer.writeBoolean(value.hasTrail);
             buffer.writeBoolean(value.hasTwinkle);
         }
+
+        @Override
+        public void write(final Ops ops, final FireworkExplosion value) {
+            ops.writeMap(map -> map
+                .write("shape", Types.STRING, SHAPES[value.shape])
+                .writeOptional("colors", new ArrayType<>(Types.INT), ArrayUtil.boxedArray(value.colors), new Integer[0])
+                .writeOptional("fade_colors", new ArrayType<>(Types.INT), ArrayUtil.boxedArray(value.fadeColors), new Integer[0])
+                .writeOptional("has_trail", Types.BOOLEAN, value.hasTrail, false)
+                .writeOptional("has_twinkle", Types.BOOLEAN, value.hasTwinkle, false));
+        }
     };
     public static final Type<FireworkExplosion[]> ARRAY_TYPE = new ArrayType<>(TYPE);
 
     @Override
     public FireworkExplosion copy() {
-        return new FireworkExplosion(shape, copy(colors), copy(fadeColors), hasTrail, hasTwinkle);
+        return new FireworkExplosion(shape, Copyable.copy(colors), Copyable.copy(fadeColors), hasTrail, hasTwinkle);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Fireworks.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.util.Copyable;
@@ -42,10 +43,17 @@ public record Fireworks(int flightDuration, FireworkExplosion[] explosions) impl
             Types.VAR_INT.writePrimitive(buffer, value.flightDuration);
             FireworkExplosion.ARRAY_TYPE.write(buffer, value.explosions);
         }
+
+        @Override
+        public void write(final Ops ops, final Fireworks value) {
+            ops.writeMap(map -> map
+                .writeOptional("flight_duration", Types.UNSIGNED_BYTE, (short) value.flightDuration, (short) 0)
+                .writeOptional("explosions", FireworkExplosion.ARRAY_TYPE, value.explosions, new FireworkExplosion[0]));
+        }
     };
 
     @Override
     public Fireworks copy() {
-        return new Fireworks(flightDuration, copy(explosions));
+        return new Fireworks(flightDuration, Copyable.copy(explosions));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/FoodProperties1_20_5.java

@@ -26,7 +26,7 @@ import com.viaversion.viaversion.api.minecraft.item.Item;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
-import com.viaversion.viaversion.api.type.types.version.Types1_21;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypes;
 import com.viaversion.viaversion.util.Copyable;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -61,7 +61,7 @@ public record FoodProperties1_20_5(int nutrition, float saturationModifier, bool
             final float saturationModifier = buffer.readFloat();
             final boolean canAlwaysEat = buffer.readBoolean();
             final float eatSeconds = buffer.readFloat();
-            final Item usingConvertsTo = Types1_21.OPTIONAL_ITEM.read(buffer);
+            final Item usingConvertsTo = VersionedTypes.V1_21.optionalItem.read(buffer);
             final FoodEffect[] possibleEffects = FoodEffect.ARRAY_TYPE.read(buffer);
             return new FoodProperties1_20_5(nutrition, saturationModifier, canAlwaysEat, eatSeconds, usingConvertsTo, possibleEffects);
         }
@@ -72,14 +72,14 @@ public record FoodProperties1_20_5(int nutrition, float saturationModifier, bool
             buffer.writeFloat(value.saturationModifier);
             buffer.writeBoolean(value.canAlwaysEat);
             buffer.writeFloat(value.eatSeconds);
-            Types1_21.OPTIONAL_ITEM.write(buffer, value.usingConvertsTo);
+            VersionedTypes.V1_21.optionalItem.write(buffer, value.usingConvertsTo);
             FoodEffect.ARRAY_TYPE.write(buffer, value.possibleEffects);
         }
     };
 
     @Override
     public FoodProperties1_20_5 copy() {
-        return new FoodProperties1_20_5(nutrition, saturationModifier, canAlwaysEat, eatSeconds, usingConvertsTo == null ? null : usingConvertsTo.copy(), copy(possibleEffects));
+        return new FoodProperties1_20_5(nutrition, saturationModifier, canAlwaysEat, eatSeconds, usingConvertsTo == null ? null : usingConvertsTo.copy(), Copyable.copy(possibleEffects));
     }
 
     public record FoodEffect(PotionEffect effect, float probability) {

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/FoodProperties1_21_2.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
@@ -43,5 +44,13 @@ public record FoodProperties1_21_2(int nutrition, float saturationModifier, bool
             buffer.writeFloat(value.saturationModifier);
             buffer.writeBoolean(value.canAlwaysEat);
         }
+
+        @Override
+        public void write(final Ops ops, final FoodProperties1_21_2 value) {
+            ops.writeMap(map -> map
+                .write("nutrition", Types.VAR_INT, value.nutrition)
+                .write("saturation", Types.FLOAT, value.saturationModifier)
+                .writeOptional("can_always_eat", Types.BOOLEAN, value.canAlwaysEat, false));
+        }
     };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Instrument1_20_5.java

@@ -22,14 +22,16 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Holder;
 import com.viaversion.viaversion.api.minecraft.SoundEvent;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record Instrument1_20_5(Holder<SoundEvent> soundEvent, int useDuration, float range) {
+public record Instrument1_20_5(Holder<SoundEvent> soundEvent, int useDuration, float range) implements Rewritable {
 
     public static final HolderType<Instrument1_20_5> TYPE = new HolderType<>() {
         @Override
@@ -48,8 +50,9 @@ public record Instrument1_20_5(Holder<SoundEvent> soundEvent, int useDuration, f
         }
     };
 
-    public Instrument1_20_5 rewrite(final Int2IntFunction soundIdRewriteFunction) {
-        final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(soundIdRewriteFunction);
+    @Override
+    public Instrument1_20_5 rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(Rewritable.soundRewriteFunction(protocol, clientbound));
         return soundEvent == this.soundEvent ? this : new Instrument1_20_5(soundEvent, useDuration, range);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Instrument1_21_2.java

@@ -23,16 +23,19 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.Holder;
 import com.viaversion.viaversion.api.minecraft.SoundEvent;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.EitherHolderType;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record Instrument1_21_2(Holder<SoundEvent> soundEvent, float useDuration, float range, Tag description) implements Copyable {
+public record Instrument1_21_2(Holder<SoundEvent> soundEvent, float useDuration, float range,
+                               Tag description) implements Copyable, Rewritable {
 
     public static final HolderType<Instrument1_21_2> TYPE = new HolderType<>() {
         @Override
@@ -54,8 +57,9 @@ public record Instrument1_21_2(Holder<SoundEvent> soundEvent, float useDuration,
     };
     public static final EitherHolderType<Instrument1_21_2> EITHER_HOLDER_TYPE = new EitherHolderType<>(TYPE);
 
-    public Instrument1_21_2 rewrite(final Int2IntFunction soundIdRewriteFunction) {
-        final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(soundIdRewriteFunction);
+    @Override
+    public Instrument1_21_2 rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(Rewritable.soundRewriteFunction(protocol, clientbound));
         return soundEvent == this.soundEvent ? this : new Instrument1_21_2(soundEvent, useDuration, range, description);
     }
 

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/JukeboxPlayable.java

@@ -23,17 +23,19 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.EitherHolder;
 import com.viaversion.viaversion.api.minecraft.Holder;
 import com.viaversion.viaversion.api.minecraft.SoundEvent;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.EitherHolderType;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record JukeboxPlayable(EitherHolder<JukeboxSong> song, boolean showInTooltip) {
+public record JukeboxPlayable(EitherHolder<JukeboxSong> song, boolean showInTooltip) implements Rewritable {
 
     public JukeboxPlayable(final Holder<JukeboxSong> song, final boolean showInTooltip) {
         this(EitherHolder.of(song), showInTooltip);
@@ -70,7 +72,8 @@ public record JukeboxPlayable(EitherHolder<JukeboxSong> song, boolean showInTool
         }
     };
 
-    public JukeboxPlayable rewrite(final Int2IntFunction soundIdRewriteFunction) {
+    @Override
+    public JukeboxPlayable rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         if (this.song.hasKey()) {
             return this;
         }
@@ -80,12 +83,12 @@ public record JukeboxPlayable(EitherHolder<JukeboxSong> song, boolean showInTool
             return this;
         }
 
-        final JukeboxSong rewrittenSong = songHolder.value().rewrite(soundIdRewriteFunction);
+        final JukeboxSong rewrittenSong = songHolder.value().rewrite(connection, protocol, clientbound);
         return rewrittenSong == songHolder.value() ? this : new JukeboxPlayable(Holder.of(rewrittenSong), showInTooltip);
     }
 
     public record JukeboxSong(Holder<SoundEvent> soundEvent, Tag description,
-                              float lengthInSeconds, int comparatorOutput) {
+                              float lengthInSeconds, int comparatorOutput) implements Rewritable {
 
         public static final HolderType<JukeboxSong> TYPE = new HolderType<>() {
             @Override
@@ -106,8 +109,9 @@ public record JukeboxPlayable(EitherHolder<JukeboxSong> song, boolean showInTool
             }
         };
 
-        public JukeboxSong rewrite(final Int2IntFunction soundIdRewriteFunction) {
-            final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(soundIdRewriteFunction);
+        @Override
+        public JukeboxSong rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+            final Holder<SoundEvent> soundEvent = this.soundEvent.updateId(Rewritable.soundRewriteFunction(protocol, clientbound));
             return soundEvent == this.soundEvent ? this : new JukeboxSong(soundEvent, description, lengthInSeconds, comparatorOutput);
         }
     }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/LodestoneTracker.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.minecraft.item.data;
 
 import com.viaversion.viaversion.api.minecraft.GlobalBlockPosition;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
@@ -43,6 +44,12 @@ public record LodestoneTracker(@Nullable GlobalBlockPosition position, boolean t
             Types.OPTIONAL_GLOBAL_POSITION.write(buffer, value.position);
             buffer.writeBoolean(value.tracked);
         }
-    };
 
+        @Override
+        public void write(final Ops ops, final LodestoneTracker value) {
+            ops.writeMap(map -> map
+                .writeOptional("target", Types.GLOBAL_POSITION, value.position)
+                .writeOptional("tracked", Types.BOOLEAN, value.tracked, true));
+        }
+    };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/PotDecorations.java

@@ -22,13 +22,15 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.util.Copyable;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public final class PotDecorations implements Copyable {
+public final class PotDecorations implements Copyable, Rewritable {
 
     public static final Type<PotDecorations> TYPE = new Type<>(PotDecorations.class) {
         @Override
@@ -76,16 +78,17 @@ public final class PotDecorations implements Copyable {
         return index < 0 || index >= itemIds.length ? -1 : itemIds[index];
     }
 
-    public PotDecorations rewrite(final Int2IntFunction idRewriteFunction) {
+    @Override
+    public PotDecorations rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         final int[] newItems = new int[itemIds.length];
         for (int i = 0; i < itemIds.length; i++) {
-            newItems[i] = idRewriteFunction.applyAsInt(itemIds[i]);
+            newItems[i] = Rewritable.rewriteItem(protocol, clientbound, itemIds[i]);
         }
         return new PotDecorations(newItems);
     }
 
     @Override
     public PotDecorations copy() {
-        return new PotDecorations(copy(itemIds));
+        return new PotDecorations(Copyable.copy(itemIds));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/PotionContents.java

@@ -89,6 +89,6 @@ public record PotionContents(@Nullable Integer potion, @Nullable Integer customC
 
     @Override
     public PotionContents copy() {
-        return new PotionContents(potion, customColor, copy(customEffects), customName);
+        return new PotionContents(potion, customColor, Copyable.copy(customEffects), customName);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ProvidesTrimMaterial.java

@@ -22,14 +22,16 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.EitherHolder;
 import com.viaversion.viaversion.api.minecraft.Holder;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.types.misc.EitherHolderType;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record ProvidesTrimMaterial(EitherHolder<ArmorTrimMaterial> material) {
+public record ProvidesTrimMaterial(EitherHolder<ArmorTrimMaterial> material) implements Rewritable {
 
     public static final Type<ProvidesTrimMaterial> TYPE = new Type<>(ProvidesTrimMaterial.class) {
 
@@ -45,12 +47,13 @@ public record ProvidesTrimMaterial(EitherHolder<ArmorTrimMaterial> material) {
         }
     };
 
-    public ProvidesTrimMaterial rewrite(final Int2IntFunction itemIdRewriter) {
+    @Override
+    public ProvidesTrimMaterial rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         if (material.hasKey() || material.holder().hasId()) {
             return this;
         }
 
         final ArmorTrimMaterial trimMaterial = material.holder().value();
-        return new ProvidesTrimMaterial(EitherHolder.of(Holder.of(trimMaterial.rewrite(itemIdRewriter))));
+        return new ProvidesTrimMaterial(EitherHolder.of(Holder.of(trimMaterial.rewrite(connection, protocol, clientbound))));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ToolProperties.java

@@ -22,12 +22,15 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-public record ToolProperties(ToolRule[] rules, float defaultMiningSpeed, int damagePerBlock, boolean canDestroyBlocksInCreative) {
+public record ToolProperties(ToolRule[] rules, float defaultMiningSpeed, int damagePerBlock,
+                             boolean canDestroyBlocksInCreative) implements Rewritable {
 
     public ToolProperties(final ToolRule[] rules, final float defaultMiningSpeed, final int damagePerBlock) {
         this(rules, defaultMiningSpeed, damagePerBlock, false);
@@ -68,10 +71,11 @@ public record ToolProperties(ToolRule[] rules, float defaultMiningSpeed, int dam
         }
     };
 
-    public ToolProperties rewrite(final Int2IntFunction blockIdRewriter) {
+    @Override
+    public ToolProperties rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         final ToolRule[] rules = new ToolRule[this.rules.length];
         for (int i = 0; i < rules.length; i++) {
-            rules[i] = this.rules[i].rewrite(blockIdRewriter);
+            rules[i] = this.rules[i].rewrite(connection, protocol, clientbound);
         }
         return new ToolProperties(rules, defaultMiningSpeed, damagePerBlock, canDestroyBlocksInCreative);
     }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/ToolRule.java

@@ -22,15 +22,18 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.HolderSet;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.ArrayType;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public record ToolRule(HolderSet blocks, @Nullable Float speed, @Nullable Boolean correctForDrops) {
+public record ToolRule(HolderSet blocks, @Nullable Float speed,
+                       @Nullable Boolean correctForDrops) implements Rewritable {
 
     public static final Type<ToolRule> TYPE = new Type<>(ToolRule.class) {
         @Override
@@ -50,7 +53,8 @@ public record ToolRule(HolderSet blocks, @Nullable Float speed, @Nullable Boolea
     };
     public static final Type<ToolRule[]> ARRAY_TYPE = new ArrayType<>(TYPE);
 
-    public ToolRule rewrite(final Int2IntFunction blockIdRewriter) {
-        return blocks.hasIds() ? new ToolRule(blocks.rewrite(blockIdRewriter), speed, correctForDrops) : this;
+    @Override
+    public ToolRule rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
+        return blocks.hasIds() ? new ToolRule(blocks.rewrite(Rewritable.blockRewriteFunction(protocol, clientbound)), speed, correctForDrops) : this;
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/TooltipDisplay.java

@@ -22,15 +22,19 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.Key;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 import it.unimi.dsi.fastutil.ints.IntLinkedOpenHashSet;
 import it.unimi.dsi.fastutil.ints.IntSortedSet;
 
 public record TooltipDisplay(boolean hideTooltip,
-                             IntSortedSet hiddenComponents) { // Keeping the ids raw makes this less annoying to deal with...
+                             IntSortedSet hiddenComponents) implements Rewritable { // Keeping the ids raw makes this less annoying to deal with...
 
     public static final Type<TooltipDisplay> TYPE = new Type<>(TooltipDisplay.class) {
 
@@ -53,16 +57,25 @@ public record TooltipDisplay(boolean hideTooltip,
                 Types.VAR_INT.writePrimitive(buffer, hiddenComponent);
             }
         }
+
+        @Override
+        public void write(final Ops ops, final TooltipDisplay value) {
+            final Key[] hiddenComponents = value.hiddenComponents.intStream().mapToObj(id -> ops.context().registryAccess().dataComponentType(id)).toArray(Key[]::new);
+            ops.writeMap(map -> map
+                .writeOptional("hide_tooltip", Types.BOOLEAN, value.hideTooltip, false)
+                .writeOptional("hidden_components", Types.RESOURCE_LOCATION_ARRAY, hiddenComponents, new Key[0]));
+        }
     };
 
-    public TooltipDisplay rewrite(final Int2IntFunction idRewriter) {
+    @Override
+    public TooltipDisplay rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         if (hiddenComponents.isEmpty()) {
             return this;
         }
 
         final IntSortedSet newHiddenComponents = new IntLinkedOpenHashSet();
         for (final int hiddenComponent : hiddenComponents) {
-            newHiddenComponents.add(idRewriter.applyAsInt(hiddenComponent));
+            newHiddenComponents.add(Rewritable.rewriteDataComponentType(protocol, clientbound, hiddenComponent));
         }
         return new TooltipDisplay(hideTooltip, newHiddenComponents);
     }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/TropicalFishPattern.java

@@ -0,0 +1,83 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.item.data;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.api.type.Types;
+import io.netty.buffer.ByteBuf;
+import java.util.Arrays;
+
+// Completely cooked packed id instead of just using an ordinal. Not even consistent enough for FakeEnumType
+public record TropicalFishPattern(int packedId) {
+
+    public static final Type<TropicalFishPattern> TYPE = new Type<>(TropicalFishPattern.class) {
+        @Override
+        public TropicalFishPattern read(final ByteBuf buffer) {
+            final int packedId = Types.VAR_INT.readPrimitive(buffer);
+            return new TropicalFishPattern(packedId);
+        }
+
+        @Override
+        public void write(final ByteBuf buffer, final TropicalFishPattern value) {
+            Types.VAR_INT.writePrimitive(buffer, value.packedId);
+        }
+
+        @Override
+        public void write(final Ops ops, final TropicalFishPattern value) {
+            final Pattern pattern = Arrays.stream(Pattern.values()).filter(e -> e.packedId == value.packedId).findAny().orElse(Pattern.KOB);
+            ops.write(Types.STRING, pattern.key);
+        }
+    };
+
+    public int sizeId() {
+        return packedId & 0xFF;
+    }
+
+    public int sizeSpecificId() {
+        return packedId >> 8;
+    }
+
+    private enum Pattern {
+        KOB("kob", 0, 0),
+        SUNSTREAK("sunstreak", 0, 1),
+        SNOOPER("snooper", 0, 2),
+        DASHER("dasher", 0, 3),
+        BRINELY("brinely", 0, 4),
+        SPOTTY("spotty", 0, 5),
+        FLOPPER("flopper", 1, 0),
+        STRIPEY("stripey", 1, 1),
+        GLITTER("glitter", 1, 2),
+        BLOCKFISH("blockfish", 1, 3),
+        BETTY("betty", 1, 4),
+        CLAYFISH("clayfish", 1, 5);
+
+        private final String key;
+        private final int packedId;
+
+        Pattern(final String key, final int sizeId, final int sizeSpecificId) {
+            this.key = key;
+            this.packedId = sizeId | (sizeSpecificId << 8);
+        }
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/UseCooldown.java

@@ -22,13 +22,17 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.Key;
+import com.viaversion.viaversion.util.Rewritable;
 import io.netty.buffer.ByteBuf;
-import java.util.function.Function;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public record UseCooldown(float seconds, @Nullable String cooldownGroup) {
+public record UseCooldown(float seconds, @Nullable String cooldownGroup) implements Rewritable {
 
     public static final Type<UseCooldown> TYPE = new Type<>(UseCooldown.class) {
         @Override
@@ -43,14 +47,23 @@ public record UseCooldown(float seconds, @Nullable String cooldownGroup) {
             buffer.writeFloat(value.seconds());
             Types.OPTIONAL_STRING.write(buffer, value.cooldownGroup());
         }
+
+        @Override
+        public void write(final Ops ops, final UseCooldown value) {
+            final Key cooldownGroup = value.cooldownGroup != null ? Key.of(value.cooldownGroup) : null;
+            ops.writeMap(map -> map
+                .write("seconds", Types.FLOAT, value.seconds())
+                .writeOptional("cooldown_group", Types.RESOURCE_LOCATION, cooldownGroup));
+        }
     };
 
-    public UseCooldown rewrite(final Function<String, String> idRewriter) {
+    @Override
+    public UseCooldown rewrite(final UserConnection connection, final Protocol<?, ?, ?, ?> protocol, final boolean clientbound) {
         if (cooldownGroup == null) {
             return this;
         }
 
-        final String mappedCooldownGroup = idRewriter.apply(cooldownGroup);
+        final String mappedCooldownGroup = Rewritable.rewriteItem(protocol, clientbound, cooldownGroup);
         return new UseCooldown(seconds, mappedCooldownGroup);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/Weapon.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
@@ -41,5 +42,12 @@ public record Weapon(int itemDamagePerAttack, float disableBlockingForSeconds) {
             Types.VAR_INT.writePrimitive(buffer, value.itemDamagePerAttack());
             buffer.writeFloat(value.disableBlockingForSeconds());
         }
+
+        @Override
+        public void write(final Ops ops, final Weapon weapon) {
+            ops.writeMap(map -> map
+                .writeOptional("item_damage_per_attack", Types.INT, weapon.itemDamagePerAttack, 1)
+                .writeOptional("disable_blocking_for_seconds", Types.FLOAT, weapon.disableBlockingForSeconds, 0F));
+        }
     };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/WritableBook.java

@@ -0,0 +1,53 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.minecraft.item.data;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.util.Copyable;
+import io.netty.buffer.ByteBuf;
+
+public record WritableBook(FilterableString[] pages) implements Copyable {
+
+    public static final Type<WritableBook> TYPE = new Type<>(WritableBook.class) {
+        @Override
+        public WritableBook read(final ByteBuf buffer) {
+            return new WritableBook(FilterableString.ARRAY_TYPE.read(buffer));
+        }
+
+        @Override
+        public void write(final ByteBuf buffer, final WritableBook value) {
+            FilterableString.ARRAY_TYPE.write(buffer, value.pages);
+        }
+
+        @Override
+        public void write(final Ops ops, final WritableBook writableBook) {
+            ops.writeMap(map -> map.writeOptional("pages", FilterableString.ARRAY_TYPE, writableBook.pages, new FilterableString[0]));
+        }
+    };
+
+    @Override
+    public WritableBook copy() {
+        return new WritableBook(Copyable.copy(pages));
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/item/data/WrittenBook.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.minecraft.item.data;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.util.Copyable;
@@ -49,10 +50,20 @@ public record WrittenBook(FilterableString title, String author, int generation,
             FilterableComponent.ARRAY_TYPE.write(buffer, value.pages);
             buffer.writeBoolean(value.resolved);
         }
+
+        @Override
+        public void write(final Ops ops, final WrittenBook value) {
+            ops.writeMap(map -> map
+                .write("title", FilterableString.TYPE, value.title)
+                .write("author", Types.STRING, value.author)
+                .writeOptional("generation", Types.INT, value.generation, 0)
+                .writeOptional("pages", FilterableComponent.ARRAY_TYPE, value.pages, new FilterableComponent[0])
+                .writeOptional("resolved", Types.BOOLEAN, value.resolved, false));
+        }
     };
 
     @Override
     public WrittenBook copy() {
-        return new WrittenBook(title, author, generation, copy(pages), resolved);
+        return new WrittenBook(title, author, generation, Copyable.copy(pages), resolved);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/protocol/AbstractProtocol.java

@@ -26,6 +26,7 @@ import com.google.common.base.Preconditions;
 import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.data.entity.EntityTracker;
+import com.viaversion.viaversion.api.data.item.ItemHasher;
 import com.viaversion.viaversion.api.protocol.packet.ClientboundPacketType;
 import com.viaversion.viaversion.api.protocol.packet.Direction;
 import com.viaversion.viaversion.api.protocol.packet.PacketType;
@@ -247,6 +248,10 @@ public abstract class AbstractProtocol<CU extends ClientboundPacketType, CM exte
         connection.addEntityTracker(this.getClass(), tracker);
     }
 
+    protected void addItemHasher(UserConnection connection, ItemHasher hasher) {
+        connection.addItemHasher(this.getClass(), hasher);
+    }
+
     protected PacketTypesProvider<CU, CM, SM, SU> createPacketTypesProvider() {
         return new SimplePacketTypesProvider<>(
             packetTypeMap(unmappedClientboundPacketType, unmappedClientboundPacketType),

api/src/main/java/com/viaversion/viaversion/api/protocol/Protocol.java

@@ -39,6 +39,7 @@ import com.viaversion.viaversion.api.rewriter.ItemRewriter;
 import com.viaversion.viaversion.api.rewriter.ParticleRewriter;
 import com.viaversion.viaversion.api.rewriter.TagRewriter;
 import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.api.type.types.version.VersionedTypesHolder;
 import com.viaversion.viaversion.exception.CancelException;
 import com.viaversion.viaversion.exception.InformativeException;
 import com.viaversion.viaversion.util.ProtocolLogger;
@@ -393,10 +394,35 @@ public interface Protocol<CU extends ClientboundPacketType, CM extends Clientbou
         return null;
     }
 
+    /**
+     * Returns the protocol's component rewriter if present.
+     *
+     * @return component rewriter
+     */
     default @Nullable ComponentRewriter getComponentRewriter() {
         return null;
     }
 
+    /**
+     * Returns types which are initialized during protocol loading in {@link #loadMappingData()}.
+     * <p>
+     * Used in various rewriters starting with 1.21.
+     *
+     * @return versioned types
+     */
+    default @Nullable VersionedTypesHolder types() {
+        return null;
+    }
+
+    /**
+     * Similar to {@link #types()}, but for the mapped types.
+     *
+     * @return versioned types
+     */
+    default @Nullable VersionedTypesHolder mappedTypes() {
+        return null;
+    }
+
     /**
      * Returns whether this protocol is a base protocol.
      *

api/src/main/java/com/viaversion/viaversion/api/protocol/version/ProtocolVersion.java

@@ -89,6 +89,7 @@ public class ProtocolVersion implements Comparable<ProtocolVersion> {
     public static final ProtocolVersion v1_21_2 = register(768, "1.21.2-1.21.3", new SubVersionRange("1.21", 2, 3));
     public static final ProtocolVersion v1_21_4 = register(769, "1.21.4");
     public static final ProtocolVersion v1_21_5 = register(770, "1.21.5");
+    public static final ProtocolVersion v1_21_6 = register(771, "1.21.6");
     public static final ProtocolVersion unknown = new ProtocolVersion(VersionType.SPECIAL, -1, -1, "UNKNOWN", null);
 
     static {

api/src/main/java/com/viaversion/viaversion/api/rewriter/ItemRewriter.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.rewriter;
 
 import com.viaversion.viaversion.api.connection.UserConnection;
+import com.viaversion.viaversion.api.minecraft.item.HashedItem;
 import com.viaversion.viaversion.api.minecraft.item.Item;
 import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.type.Type;
@@ -50,6 +51,17 @@ public interface ItemRewriter<T extends Protocol<?, ?, ?, ?>> extends Rewriter<T
     @Nullable
     Item handleItemToServer(UserConnection connection, @Nullable Item item);
 
+    /**
+     * Returns the rewritten item, which may or may not be the same given HashedItem instance.
+     * <p>
+     * Used starting with 1.21.6.
+     *
+     * @param connection user connection
+     * @param item       hashed item
+     * @return rewritten hashed item
+     */
+    HashedItem handleHashedItem(UserConnection connection, HashedItem item);
+
     /**
      * Returns the item type of the current protocol.
      *

api/src/main/java/com/viaversion/viaversion/api/type/CodecWriter.java

@@ -0,0 +1,31 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.type;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+
+@FunctionalInterface
+public interface CodecWriter<T> {
+
+    void write(Ops ops, T value);
+}

api/src/main/java/com/viaversion/viaversion/api/type/OptionalType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -47,4 +48,9 @@ public abstract class OptionalType<T> extends Type<T> {
             type.write(buffer, value);
         }
     }
+
+    @Override
+    public void write(final Ops ops, final T value) {
+        type.write(ops, value);
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/type/Type.java

@@ -22,13 +22,15 @@
  */
 package com.viaversion.viaversion.api.type;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+
 /**
  * Type for buffer reading and writing.
  *
  * @param <T> read/written type
  * @see Types
  */
-public abstract class Type<T> implements ByteBufReader<T>, ByteBufWriter<T> {
+public abstract class Type<T> implements ByteBufReader<T>, ByteBufWriter<T>, CodecWriter<T> {
 
     /* Actual Class */
     private final Class<? super T> outputClass;
@@ -58,7 +60,12 @@ public abstract class Type<T> implements ByteBufReader<T>, ByteBufWriter<T> {
      * @return type name
      */
     public String getTypeName() {
-        return typeName != null && !typeName.isEmpty() ? typeName : this.getClass().getSimpleName();
+        return typeName != null && !typeName.isEmpty() ? typeName : this.getClass().getName();
+    }
+
+    @Override
+    public void write(Ops ops, T value) {
+        throw new UnsupportedOperationException("Write operation not supported for type: " + getTypeName());
     }
 
     /**

api/src/main/java/com/viaversion/viaversion/api/type/Types.java

@@ -41,7 +41,9 @@ import com.viaversion.viaversion.api.minecraft.Vector;
 import com.viaversion.viaversion.api.minecraft.Vector3f;
 import com.viaversion.viaversion.api.minecraft.VillagerData;
 import com.viaversion.viaversion.api.minecraft.blockentity.BlockEntity;
+import com.viaversion.viaversion.api.minecraft.chunks.ChunkSection;
 import com.viaversion.viaversion.api.minecraft.chunks.Heightmap;
+import com.viaversion.viaversion.api.minecraft.entitydata.EntityData;
 import com.viaversion.viaversion.api.minecraft.item.HashedItem;
 import com.viaversion.viaversion.api.minecraft.item.Item;
 import com.viaversion.viaversion.api.minecraft.item.data.Enchantments;
@@ -76,7 +78,15 @@ import com.viaversion.viaversion.api.type.types.block.BlockChangeRecordType;
 import com.viaversion.viaversion.api.type.types.block.BlockEntityType1_18;
 import com.viaversion.viaversion.api.type.types.block.BlockEntityType1_20_2;
 import com.viaversion.viaversion.api.type.types.block.VarLongBlockChangeRecordType;
+import com.viaversion.viaversion.api.type.types.chunk.ChunkSectionType1_13;
+import com.viaversion.viaversion.api.type.types.chunk.ChunkSectionType1_16;
+import com.viaversion.viaversion.api.type.types.chunk.ChunkSectionType1_8;
+import com.viaversion.viaversion.api.type.types.chunk.ChunkSectionType1_9;
 import com.viaversion.viaversion.api.type.types.chunk.HeightmapType;
+import com.viaversion.viaversion.api.type.types.entitydata.EntityDataListType;
+import com.viaversion.viaversion.api.type.types.entitydata.EntityDataType1_12;
+import com.viaversion.viaversion.api.type.types.entitydata.EntityDataType1_8;
+import com.viaversion.viaversion.api.type.types.entitydata.EntityDataType1_9;
 import com.viaversion.viaversion.api.type.types.item.HashedItemType1_21_5;
 import com.viaversion.viaversion.api.type.types.item.ItemShortArrayType1_13;
 import com.viaversion.viaversion.api.type.types.item.ItemShortArrayType1_13_2;
@@ -97,14 +107,19 @@ import com.viaversion.viaversion.api.type.types.misc.CompoundTagType;
 import com.viaversion.viaversion.api.type.types.misc.GameProfileType;
 import com.viaversion.viaversion.api.type.types.misc.HolderSetType;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
+import com.viaversion.viaversion.api.type.types.misc.KeyType;
 import com.viaversion.viaversion.api.type.types.misc.NamedCompoundTagType;
 import com.viaversion.viaversion.api.type.types.misc.PlayerMessageSignatureType;
 import com.viaversion.viaversion.api.type.types.misc.ProfileKeyType;
+import com.viaversion.viaversion.api.type.types.misc.ProfilePropertyType;
 import com.viaversion.viaversion.api.type.types.misc.SoundEventType;
+import com.viaversion.viaversion.api.type.types.misc.TagKeyType;
 import com.viaversion.viaversion.api.type.types.misc.TagType;
 import com.viaversion.viaversion.api.type.types.misc.VillagerDataType;
 import com.viaversion.viaversion.api.type.types.version.Types1_20_5;
+import com.viaversion.viaversion.util.Key;
 import com.viaversion.viaversion.util.Unit;
+import java.util.List;
 import java.util.UUID;
 
 /**
@@ -162,6 +177,11 @@ public final class Types {
     /* MC Types */
     public static final Type<byte[]> SERVERBOUND_CUSTOM_PAYLOAD_DATA = new RemainingBytesType(Short.MAX_VALUE);
 
+    public static final Type<Key> RESOURCE_LOCATION = new KeyType();
+    public static final Type<Key> OPTIONAL_RESOURCE_LOCATION = new KeyType.OptionalKeyType();
+    public static final Type<Key[]> RESOURCE_LOCATION_ARRAY = new ArrayType<>(RESOURCE_LOCATION);
+    public static final Type<Key> TAG_KEY = new TagKeyType();
+
     public static final Type<BlockPosition> BLOCK_POSITION1_8 = new BlockPositionType1_8();
     public static final Type<BlockPosition> OPTIONAL_POSITION1_8 = new BlockPositionType1_8.OptionalBlockPositionType();
     public static final Type<BlockPosition> BLOCK_POSITION1_14 = new BlockPositionType1_14();
@@ -184,6 +204,11 @@ public final class Types {
     public static final Type<GlobalBlockPosition> OPTIONAL_GLOBAL_POSITION = new GlobalBlockPositionType.OptionalGlobalPositionType();
     public static final Type<ChunkPosition> CHUNK_POSITION = new ChunkPositionType();
 
+    public static final Type<ChunkSection> CHUNK_SECTION1_8 = new ChunkSectionType1_8();
+    public static final Type<ChunkSection> CHUNK_SECTION1_9 = new ChunkSectionType1_9();
+    public static final Type<ChunkSection> CHUNK_SECTION1_13 = new ChunkSectionType1_13();
+    public static final Type<ChunkSection> CHUNK_SECTION1_16 = new ChunkSectionType1_16();
+
     public static final Type<BlockEntity> BLOCK_ENTITY1_18 = new BlockEntityType1_18();
     public static final Type<BlockEntity> BLOCK_ENTITY1_20_2 = new BlockEntityType1_20_2();
 
@@ -195,6 +220,8 @@ public final class Types {
     public static final Type<VillagerData> VILLAGER_DATA = new VillagerDataType();
 
     public static final Type<GameProfile> GAME_PROFILE = new GameProfileType();
+    public static final Type<GameProfile.Property> PROFILE_PROPERTY = new ProfilePropertyType();
+    public static final Type<GameProfile.Property[]> PROFILE_PROPERTY_ARRAY = new ArrayType<>(PROFILE_PROPERTY);
     public static final Type<ProfileKey> PROFILE_KEY = new ProfileKeyType();
     public static final Type<ProfileKey> OPTIONAL_PROFILE_KEY = new ProfileKeyType.OptionalProfileKeyType();
 
@@ -222,6 +249,14 @@ public final class Types {
     public static final Type<Heightmap> HEIGHTMAP = new HeightmapType();
     public static final Type<Heightmap[]> HEIGHTMAP_ARRAY = new ArrayType<>(HEIGHTMAP);
 
+    public static final Type<EntityData> ENTITY_DATA1_8 = new EntityDataType1_8();
+    public static final Type<EntityData> ENTITY_DATA1_9 = new EntityDataType1_9();
+    public static final Type<EntityData> ENTITY_DATA1_12 = new EntityDataType1_12();
+
+    public static final Type<List<EntityData>> ENTITY_DATA_LIST1_8 = new EntityDataListType(ENTITY_DATA1_8);
+    public static final Type<List<EntityData>> ENTITY_DATA_LIST1_9 = new EntityDataListType(ENTITY_DATA1_9);
+    public static final Type<List<EntityData>> ENTITY_DATA_LIST1_12 = new EntityDataListType(ENTITY_DATA1_12);
+
     // No longer used past 1.20.2
     public static final Type<Item> ITEM1_8 = new ItemType1_8();
     public static final Type<Item> ITEM1_13 = new ItemType1_13();

api/src/main/java/com/viaversion/viaversion/api/type/types/ArrayType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
@@ -91,4 +92,13 @@ public class ArrayType<T> extends Type<T[]> {
             elementType.write(buffer, o);
         }
     }
+
+    @Override
+    public void write(final Ops ops, final T[] value) {
+        ops.writeList(list -> {
+            for (T element : value) {
+                list.write(elementType, element);
+            }
+        });
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/type/types/BitSetType.java

@@ -36,7 +36,7 @@ public class BitSetType extends Type<BitSet> {
     public BitSetType(final int length) {
         super(BitSet.class);
         this.length = length;
-        this.bytesLength = -Math.floorDiv(-length, 8); // Ceiled quotient
+        this.bytesLength = (int) Math.ceil(length / 8D);
     }
 
     @Override
@@ -48,8 +48,8 @@ public class BitSetType extends Type<BitSet> {
 
     @Override
     public void write(ByteBuf buffer, BitSet object) {
-        Preconditions.checkArgument(object.length() <= length, "BitSet of length " + object.length() + " larger than max length " + length);
+        Preconditions.checkArgument(object.length() <= length, "BitSet of length %s larger than max length %s", object.length(), length);
         final byte[] bytes = object.toByteArray();
-        buffer.writeBytes(Arrays.copyOf(bytes, bytesLength));
+        buffer.writeBytes(bytes.length == bytesLength ? bytes : Arrays.copyOf(bytes, bytesLength));
     }
 }

api/src/main/java/com/viaversion/viaversion/api/type/types/BooleanType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.OptionalType;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
@@ -29,6 +30,7 @@ import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
 
 public class BooleanType extends Type<Boolean> implements TypeConverter<Boolean> {
+
     public BooleanType() {
         super(Boolean.class);
     }
@@ -52,6 +54,11 @@ public class BooleanType extends Type<Boolean> implements TypeConverter<Boolean>
         return (Boolean) o;
     }
 
+    @Override
+    public void write(final Ops ops, final Boolean value) {
+        ops.writeBoolean(value);
+    }
+
     // Lol
     public static final class OptionalBooleanType extends OptionalType<Boolean> {
 

api/src/main/java/com/viaversion/viaversion/api/type/types/ByteArrayType.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.type.types;
 
 import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.OptionalType;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
@@ -61,6 +62,11 @@ public class ByteArrayType extends Type<byte[]> {
         return array;
     }
 
+    @Override
+    public void write(final Ops ops, final byte[] value) {
+        ops.writeBytes(value);
+    }
+
     public static final class OptionalByteArrayType extends OptionalType<byte[]> {
 
         public OptionalByteArrayType() {

api/src/main/java/com/viaversion/viaversion/api/type/types/ByteType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
 import io.netty.buffer.ByteBuf;
@@ -51,6 +52,11 @@ public class ByteType extends Type<Byte> implements TypeConverter<Byte> {
         buffer.writeByte(object);
     }
 
+    @Override
+    public void write(final Ops ops, final Byte value) {
+        ops.writeByte(value);
+    }
+
     @Override
     public Byte from(Object o) {
         if (o instanceof Number number) {

api/src/main/java/com/viaversion/viaversion/api/type/types/DoubleType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
 import io.netty.buffer.ByteBuf;
@@ -58,6 +59,11 @@ public class DoubleType extends Type<Double> implements TypeConverter<Double> {
         buffer.writeDouble(object);
     }
 
+    @Override
+    public void write(final Ops ops, final Double value) {
+        ops.writeDouble(value);
+    }
+
     @Override
     public Double from(Object o) {
         if (o instanceof Number number) {

api/src/main/java/com/viaversion/viaversion/api/type/types/EmptyType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.util.Unit;
 import io.netty.buffer.ByteBuf;
@@ -40,4 +41,11 @@ public final class EmptyType extends Type<Unit> {
     @Override
     public void write(final ByteBuf buffer, final Unit value) {
     }
+
+    @Override
+    public void write(final Ops ops, final Unit value) {
+        // Written as an empty map because lol
+        ops.writeMap(map -> {
+        });
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/type/types/EnumType.java

@@ -0,0 +1,65 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.type.types;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.MathUtil;
+
+public final class EnumType extends VarIntType {
+
+    private final String[] names;
+    private final Fallback fallback;
+
+    public EnumType(final String... names) {
+        this(Fallback.ZERO, names);
+    }
+
+    public EnumType(final Fallback fallback, final String... names) {
+        this.names = names;
+        this.fallback = fallback;
+    }
+
+    @Override
+    public void write(final Ops ops, final Integer value) {
+        final String name;
+        if (value < 0 || value >= names.length) {
+            name = switch (fallback) {
+                case ZERO -> names[0];
+                case WRAP -> names[Math.floorMod(value, names.length)];
+                case CLAMP -> names[MathUtil.clamp(value, 0, names.length - 1)];
+            };
+        } else {
+            name = names[value];
+        }
+        Types.STRING.write(ops, name);
+    }
+
+    public String[] names() {
+        return names;
+    }
+
+    public enum Fallback {
+        ZERO, WRAP, CLAMP
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/type/types/FakeEnumType.java

@@ -0,0 +1,72 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.type.types;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.type.Types;
+import java.util.List;
+
+/**
+ * For enum types with hardcoded custom ids.
+ *
+ * @see EnumType
+ */
+public final class FakeEnumType extends VarIntType {
+
+    private final Entry[] entries;
+
+    public FakeEnumType(final List<String> initialNames, final Entry... remainingEntries) {
+        this.entries = new Entry[initialNames.size() + remainingEntries.length];
+        for (int i = 0; i < initialNames.size(); i++) {
+            this.entries[i] = Entry.of(i, initialNames.get(i));
+        }
+        System.arraycopy(remainingEntries, 0, this.entries, initialNames.size(), remainingEntries.length);
+    }
+
+    public FakeEnumType(final Entry... entries) {
+        this.entries = entries;
+    }
+
+    @Override
+    public void write(final Ops ops, final Integer value) {
+        Entry entry = null;
+        for (final Entry e : entries) {
+            if (e.id == value) {
+                entry = e;
+                break;
+            }
+        }
+        Types.STRING.write(ops, entry != null ? entry.name : entries[0].name);
+    }
+
+    public Entry[] entries() {
+        return entries;
+    }
+
+    public record Entry(int id, String name) {
+
+        public static Entry of(final int id, final String name) {
+            return new Entry(id, name);
+        }
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/type/types/FloatType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.OptionalType;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
@@ -70,6 +71,11 @@ public class FloatType extends Type<Float> implements TypeConverter<Float> {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public void write(final Ops ops, final Float value) {
+        ops.writeFloat(value);
+    }
+
     public static final class OptionalFloatType extends OptionalType<Float> {
 
         public OptionalFloatType() {

api/src/main/java/com/viaversion/viaversion/api/type/types/IntArrayType.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.type.types;
 
 import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
@@ -63,4 +64,9 @@ public class IntArrayType extends Type<int[]> {
         }
         return array;
     }
+
+    @Override
+    public void write(final Ops ops, final int[] value) {
+        ops.writeInts(value);
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/type/types/IntType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
 import io.netty.buffer.ByteBuf;
@@ -49,6 +50,11 @@ public class IntType extends Type<Integer> implements TypeConverter<Integer> {
         buffer.writeInt(object);
     }
 
+    @Override
+    public void write(final Ops ops, final Integer value) {
+        ops.writeInt(value);
+    }
+
     @Override
     public Integer from(Object o) {
         if (o instanceof Number number) {

api/src/main/java/com/viaversion/viaversion/api/type/types/LongArrayType.java

@@ -23,6 +23,7 @@
 package com.viaversion.viaversion.api.type.types;
 
 import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.Types;
 import io.netty.buffer.ByteBuf;
@@ -70,4 +71,9 @@ public class LongArrayType extends Type<long[]> {
             buffer.writeLong(l);
         }
     }
+
+    @Override
+    public void write(final Ops ops, final long[] value) {
+        ops.writeLongs(value);
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/type/types/LongType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.OptionalType;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
@@ -52,6 +53,11 @@ public class LongType extends Type<Long> implements TypeConverter<Long> {
         buffer.writeLong(object);
     }
 
+    @Override
+    public void write(final Ops ops, final Long value) {
+        ops.writeLong(value);
+    }
+
     @Override
     public Long from(Object o) {
         if (o instanceof Number number) {

api/src/main/java/com/viaversion/viaversion/api/type/types/RegistryValueType.java

@@ -0,0 +1,44 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2025 ViaVersion and contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.viaversion.viaversion.api.type.types;
+
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
+import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.util.Key;
+
+public final class RegistryValueType extends VarIntType {
+
+    private final String[] names;
+
+    public RegistryValueType(final String... names) {
+        this.names = names;
+        for (int i = 0; i < names.length; i++) {
+            names[i] = Key.namespaced(names[i]);
+        }
+    }
+
+    @Override
+    public void write(final Ops ops, final Integer value) {
+        Types.STRING.write(ops, names[value]);
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/type/types/ShortType.java

@@ -22,6 +22,7 @@
  */
 package com.viaversion.viaversion.api.type.types;
 
+import com.viaversion.viaversion.api.minecraft.codec.Ops;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.api.type.TypeConverter;
 import io.netty.buffer.ByteBuf;
@@ -58,6 +59,11 @@ public class ShortType extends Type<Short> implements TypeConverter<Short> {
         buffer.writeShort(object);
     }
 
+    @Override
+    public void write(final Ops ops, final Short value) {
+        ops.writeShort(value);
+    }
+
     @Override
     public Short from(Object o) {
         if (o instanceof Number number) {