5.3.1 Release

The original <1.13 warning was added almost 5 years ago, since then more small issues have come up from newer clients having fundamental changes and server stats on those old versions have dropped even more. That said, ViaVersion will keep working on these servers presumably forever

.editorconfig

@@ -2,7 +2,7 @@
 charset = utf-8
 indent_size = 4
 indent_style = space
-insert_final_newline = false
+insert_final_newline = true
 tab_width = 4
 
 [*.java]
@@ -13,4 +13,4 @@ ij_java_generate_final_locals = true
 ij_java_generate_final_parameters = true
 
 [{*.json,*.yml}]
-indent_size = 2
+indent_size = 2

.github/FUNDING.yml

@@ -1,2 +1,3 @@
 github: kennytv
 patreon: kennytv
+custom: ['https://florianmichael.de/donate']

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -21,10 +21,11 @@ body:
 
   - type: textarea
     attributes:
-      label: Console Error
+      label: Server/Client Error
       description: |
         If you encounter warnings/errors in your console, **paste them with https://mclo.gs/ and put the paste link here**.
         If the error is small/less than 10 lines, you may put it directly into this field.
+        **Important**: If you are kicked for `Network Protocol Error` or an encoder/decoder exception, please click the `Open Report Directory` button on your client and paste the newest disconnect file contents.
       value: |
         ```
         Put the mclo.gs link or text here.
@@ -40,7 +41,7 @@ body:
         Describe the unexpected behavior.
         If you want to attach screenshots, use the comment field at the bottom of the page.
       placeholder: |
-        Example: "Placing signs on 1.13.2 causes text to disappear."
+        Example: "Placing signs on 1.21.3 causes text to disappear."
     validations:
       required: true
 
@@ -51,7 +52,7 @@ body:
         List the steps on how we can reproduce the issue. Make sure we can easily understand what you mean with each step.
       placeholder: |
         Example:
-        1. Login with a 1.13.2 client
+        1. Login with a 1.21.3 client
         2. Place a sign
         3. The sign text is displayed wrong
     validations:

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/build.yml

@@ -7,13 +7,15 @@ jobs:
     # Only run on PRs if the source branch is on a different repo. We do not need to run everything twice.
     if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
 
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
 
     steps:
     - name: Checkout Repository
       uses: actions/checkout@v4
-    - name: Validate Gradle Wrapper
-      uses: gradle/actions/wrapper-validation@v3
+      with:
+        persist-credentials: false
+    - name: Set up Gradle
+      uses: gradle/actions/setup-gradle@v4
     - name: Set up JDK 17
       uses: actions/setup-java@v4
       with:
@@ -22,3 +24,10 @@ jobs:
         check-latest: true
     - name: Build with Gradle
       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 == 'ViaVersion/ViaVersionDev' && github.ref_name == 'preview' }}
+      uses: actions/upload-artifact@v4
+      with:
+        name: Artifacts
+        path: build/libs/

.github/workflows/publish.yml

@@ -8,12 +8,14 @@ on:
 jobs:
   publish:
     if: github.repository_owner == 'ViaVersion'
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
       - name: Checkout Repository
         uses: actions/checkout@v4
-      - name: Validate Gradle Wrapper
-        uses: gradle/actions/wrapper-validation@v3
+        with:
+          persist-credentials: false
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@v4
       - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:

.github/workflows/update-gradle-wrapper.yml

@@ -0,0 +1,16 @@
+name: Update Gradle Wrapper
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 0 * * 0"
+
+jobs:
+  update-gradle-wrapper:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Update Gradle Wrapper
+        uses: gradle-update/update-gradle-wrapper-action@v2

.gitignore

@@ -109,4 +109,7 @@ nb-configuration.xml
 .nb-gradle/
 
 ### MacOS ###
-.DS_Store
+.DS_Store
+
+### Run Folder (ViaProxy) ###
+common/run/

README.md

@@ -1,7 +1,7 @@
 # ViaVersion
 
 [![Latest Release](https://img.shields.io/github/v/release/ViaVersion/ViaVersion)](https://viaversion.com)
-[![Build Status](https://github.com/ViaVersion/ViaVersion/actions/workflows/gradle.yml/badge.svg?branch=master)](https://github.com/ViaVersion/ViaVersion/actions)
+[![Build Status](https://github.com/ViaVersion/ViaVersion/actions/workflows/build.yml/badge.svg?branch=master)](https://github.com/ViaVersion/ViaVersion/actions)
 [![Discord](https://img.shields.io/badge/chat-on%20discord-blue.svg)](https://viaversion.com/discord)
 
 **Allows the connection of higher client versions to lower server versions -
@@ -9,13 +9,23 @@ it works on any platform you can think of.**
 
 The base ViaVersion jar runs on Paper and Velocity. We also have projects integrating ViaVersion to run
 on Fabric, Forge, Bungee, Sponge, or as a standalone proxy to join from basically any client version on
-any server version from the past decade. **See [HERE](https://github.com/ViaVersion) for an overview of the different Via\* projects.**
+any server version from the past decade. **See [HERE](https://viaversion.com) for an overview of the different Via\* projects.**
+
+Note that ViaVersion will be able to **run best on either Paper servers or through [ViaFabricPlus](https://github.com/ViaVersion/ViaFabricPlus?tab=readme-ov-file#viafabricplus)** due to having
+direct access to client/server state and more extensive API.
 
 Supported Versions:
 
-![Table (https://i.imgur.com/sTrVnC2.png)](https://i.imgur.com/sTrVnC2.png)
+![Table (https://i.imgur.com/zrQTcf0.png)](https://i.imgur.com/zrQTcf0.png)
 
-**User Docs:** https://docs.viaversion.com/display/VIAVERSION/
+**User Docs:** https://docs.viaversion.com
+
+Snapshot support
+--------
+**ViaVersion will only be released a few days *after* a Minecraft update** unless the protocol changes of the update were trivial. If you want early-access, usually days or even weeks before the final release, you can subscribe to either:
+- [GitHub Sponsors](https://github.com/sponsors/kennytv/sponsorships?sponsor=kennytv&tier_id=385613&preview=false) (preferred option. Use the `/verify` command on this Discord after), or alternatively
+- [Patreon](https://www.patreon.com/kennytv/membership) (see the highest tier and make sure to link Patreon to your Discord account under Settings->Connections)
+  This also includes access to a private repository with the code, which will be pushed to the public repository after the given delay on a Minecraft update.
 
 Releases/Dev Builds
 --------
@@ -67,6 +77,8 @@ dependencies {
 If you need access to the existing protocol or platform implementations, use the parent artifact `viaversion`.
 Please note the [differences in licensing](#license).
 
+Note: If you want to make your own platform implementation of ViaVersion (and additional addons),
+you can use the [ViaLoader](https://github.com/ViaVersion/ViaLoader) project.
 
 Building
 --------
@@ -78,7 +90,7 @@ You need JDK 17 or newer to build ViaVersion.
 
 Mapping Files
 --------------
-Mapping files are generated and managed in our [Mappings repository](https://github.com/ViaVersion/Mappings).
+Mapping files are generated and managed in our [Mappings repository](https://github.com/ViaVersion/Mappings). The generated mapping output is stored [here](./common/src/main/resources/assets/viaversion).
 
 
 Resources
@@ -86,12 +98,11 @@ Resources
 
 - **[Via Mappings Generator](https://github.com/ViaVersion/Mappings)**
 - **[Mojang mappings](https://minecraft.wiki/w/Obfuscation_map)** (Thank you, Mojang, very cool)
-- **[wiki.vg](https://wiki.vg)** (Used for historic information regarding packet structure, we also contribute back)
-- **[Burger](https://github.com/Pokechu22/Burger)** (See [PAaaS](https://github.com/Matsv/Paaas))
+- Previously: **[Burger](https://github.com/Pokechu22/Burger)** (see [PAaaS](https://github.com/Matsv/Paaas)) and **wiki.vg**
 
 License
 --------
-The entirety of the [API directory](api) (including the legacy API directory) is licensed under the MIT License;
+The entirety of the [API directory](api) is licensed under the MIT License;
 see [licenses/MIT.md](licenses/MIT.md) for
 details.
 

api/build.gradle.kts

@@ -19,13 +19,16 @@ dependencies {
     api(libs.vianbt) {
         exclude("it.unimi.dsi", "fastutil")
     }
-    api(libs.gson)
+    api(libs.gson) {
+        exclude("com.google.errorprone", "error_prone_annotations")
+    }
     implementation(rootProject.libs.text) {
         exclude("com.google.code.gson", "gson")
+        exclude("com.google.guava", "guava")
         exclude("com.viaversion", "nbt")
     }
+    api(libs.snakeYaml)
 
-    compileOnlyApi(libs.snakeYaml)
     compileOnlyApi(libs.netty)
     compileOnlyApi(libs.guava)
     compileOnlyApi(libs.checkerQual)

api/src/main/java/com/viaversion/viaversion/api/Via.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/ViaAPI.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
@@ -114,7 +114,8 @@ public interface ViaAPI<T> {
     ProtocolVersion getPlayerProtocolVersion(UUID uuid);
 
     /**
-     * Returns whether Via injected into this player connection.
+     * Returns whether Via injected into this player connection. Note that this method may not work on
+     * clientside implementations and is generally not recommended to be used. Use {@link ConnectionManager} instead.
      *
      * @param uuid uuid of the player
      * @return whether Via has a cached a UserConnection for this player
@@ -122,7 +123,8 @@ public interface ViaAPI<T> {
     boolean isInjected(UUID uuid);
 
     /**
-     * Returns the Via injected UserConnection if present.
+     * Returns whether Via injected into this player connection. Note that this method may not work on
+     * clientside implementations and is generally not recommended to be used. Use {@link ConnectionManager} instead.
      *
      * @param uuid uuid of the player
      * @return user connection if present

api/src/main/java/com/viaversion/viaversion/api/ViaManager.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
@@ -140,6 +140,13 @@ public interface ViaManager {
      */
     void addEnableListener(Runnable runnable);
 
+    /**
+     * Adds a runnable to be executed when ViaVersion has finished its init after the full server load.
+     *
+     * @param runnable runnable to be executed
+     */
+    void addPostEnableListener(Runnable runnable);
+
     /**
      * Returns whether the manager has been initialized (and protocols have been loaded).
      *

api/src/main/java/com/viaversion/viaversion/api/command/ViaCommandSender.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/command/ViaSubCommand.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
@@ -66,7 +66,7 @@ public interface ViaSubCommand {
      *
      * @param sender Command sender
      * @param args   Arguments
-     * @return commands executed succesfully if false, show usage
+     * @return commands executed successfully if false, show usage
      */
     boolean execute(ViaCommandSender sender, String[] args);
 

api/src/main/java/com/viaversion/viaversion/api/command/ViaVersionCommand.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
@@ -30,7 +30,7 @@ public interface ViaVersionCommand {
      * Register your own subcommand inside ViaVersion
      *
      * @param command Your own SubCommand instance to handle it.
-     * @throws IllegalArgumentException throws an exception when the subcommand already exists or if it's not valid, example: spacee
+     * @throws IllegalArgumentException throws an exception when the subcommand already exists or if it's not valid, example: space
      */
     void registerSubCommand(ViaSubCommand command);
 

api/src/main/java/com/viaversion/viaversion/api/configuration/Config.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/ConfigurationProvider.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

@@ -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
@@ -67,9 +67,9 @@ public interface ViaVersionConfig extends Config {
     boolean isShowNewDeathMessages();
 
     /**
-     * Get if metadata errors will be suppressed
+     * Get if entity data errors will be suppressed
      *
-     * @return true if metadata errors suppression is enabled
+     * @return true if entity data errors suppression is enabled
      */
     boolean isSuppressMetadataErrors();
 
@@ -292,13 +292,6 @@ public interface ViaVersionConfig extends Config {
      */
     boolean isDisable1_13AutoComplete();
 
-    /**
-     * Tries to minimize cooldown animation.
-     *
-     * @return true if enabled
-     */
-    boolean isMinimizeCooldown();
-
     /**
      * Enable the serverside blockconnections for 1.13+ clients
      *
@@ -464,4 +457,25 @@ public interface ViaVersionConfig extends Config {
      * @return true if enabled
      */
     boolean handleInvalidItemCount();
+
+    /**
+     * Tries to cancel block break/place sounds sent by 1.8 servers to 1.9+ clients to prevent them from playing twice
+     *
+     * @return true if enabled
+     */
+    boolean cancelBlockSounds();
+
+    /**
+     * Hides scoreboard numbers for 1.20.3+ clients on older server versions.
+     *
+     * @return true if enabled
+     */
+    boolean hideScoreboardNumbers();
+
+    /**
+     * Fixes 1.21+ clients on 1.20.5 servers placing water/lava buckets at the wrong location when moving fast.
+     *
+     * @return true if enabled
+     */
+    boolean fix1_21PlacementRotation();
 }

api/src/main/java/com/viaversion/viaversion/api/connection/ConnectionManager.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
@@ -28,51 +28,81 @@ import java.util.UUID;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
- * Handles injected UserConnections
+ * Handles injected UserConnections.
+ * Check {@link UserConnection#isServerSide()} and {@link UserConnection#isClientSide()} to determine the connection type.
  */
 public interface ConnectionManager {
 
     /**
-     * Returns if Via injected into this player connection.
+     * Returns if Via has injected. See above for the connection types.
      *
-     * @param playerId player uuid
+     * @param uuid player uuid
      * @return true if the player is handled by Via
      */
-    boolean isClientConnected(UUID playerId);
+    boolean hasServerConnection(UUID uuid);
 
-    /**
-     * Frontend connections will have the UUID stored. Override this if your platform isn't always frontend.
-     * UUIDs can't be duplicate between frontend connections.
-     *
-     * @return true if the user is a frontend connection
-     */
-    default boolean isFrontEnd(UserConnection connection) {
-        return !connection.isClientSide();
+    @Deprecated
+    default boolean isClientConnected(UUID uuid) {
+        return hasServerConnection(uuid);
     }
 
     /**
-     * Returns the frontend UserConnection from the player connected to this proxy server
-     * Returns null when there isn't a server or connection was not found
-     * When ViaVersion is reloaded, this method may not return some players.
-     * <p>
-     * Note that connections are removed as soon as their channel is closed,
-     * so avoid using this method during player quits for example.
+     * Returns if Via has injected. See above for the connection types.
      *
-     * @return frontend UserConnection of the player connected to this proxy server
+     * @param uuid player uuid
+     * @return true if the player is handled by Via
      */
-    @Nullable UserConnection getConnectedClient(UUID clientIdentifier);
+    boolean hasClientConnection(UUID uuid);
 
     /**
-     * Returns the UUID from the frontend connection to this proxy server
-     * Returns null when there isn't a server or this connection isn't frontend, or it doesn't have an id
+     * Returns the server UserConnection. See above for the connection types.
      * When ViaVersion is reloaded, this method may not return some players.
      * <p>
      * Note that connections are removed as soon as their channel is closed,
      * so avoid using this method during player quits for example.
      *
-     * @return UUID of the frontend connection to this proxy server
+     * @return server UserConnection of the player or null
      */
-    @Nullable UUID getConnectedClientId(UserConnection connection);
+    @Nullable
+    UserConnection getServerConnection(UUID uuid);
+
+    @Deprecated
+    @Nullable default UserConnection getConnectedClient(UUID uuid) {
+        return getServerConnection(uuid);
+    }
+
+    /**
+     * Returns the client UserConnection. See above for the connection types.
+     * When ViaVersion is reloaded, this method may not return some players.
+     * <p>
+     * Note that connections are removed as soon as their channel is closed,
+     * so avoid using this method during player quits for example.
+     *
+     * @return client UserConnection of the player or null
+     */
+    @Nullable
+    UserConnection getClientConnection(UUID uuid);
+
+    /**
+     * Returns a map containing the UUIDs and server UserConnections
+     * When ViaVersion is reloaded, this method may not return some players.
+     *
+     * @return map containing the UUIDs and frontend UserConnections
+     */
+    Map<UUID, UserConnection> getServerConnections();
+
+    @Deprecated
+    default Map<UUID, UserConnection> getConnectedClients() {
+        return getServerConnections();
+    }
+
+    /**
+     * Returns a map containing the UUIDs and client UserConnections
+     * When ViaVersion is reloaded, this method may not return some players.
+     *
+     * @return map containing the UUIDs and client UserConnections
+     */
+    Map<UUID, UserConnection> getClientConnections();
 
     /**
      * Returns all UserConnections which are registered
@@ -84,15 +114,6 @@ public interface ConnectionManager {
      */
     Set<UserConnection> getConnections();
 
-    /**
-     * Returns a map containing the UUIDs and frontend UserConnections from players connected to this proxy server
-     * Returns empty list when there isn't a server
-     * When ViaVersion is reloaded, this method may not return some players.
-     *
-     * @return map containing the UUIDs and frontend UserConnections from players connected to this proxy server
-     */
-    Map<UUID, UserConnection> getConnectedClients();
-
     void onLoginSuccess(UserConnection connection);
 
     void onDisconnect(UserConnection connection);

api/src/main/java/com/viaversion/viaversion/api/connection/ProtocolInfo.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
@@ -142,4 +142,4 @@ public interface ProtocolInfo {
     ProtocolPipeline getPipeline();
 
     void setPipeline(ProtocolPipeline pipeline);
-}
+}

api/src/main/java/com/viaversion/viaversion/api/connection/StorableObject.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/connection/StoredObject.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
@@ -29,6 +29,11 @@ public abstract class StoredObject implements StorableObject {
         this.user = user;
     }
 
+    public UserConnection user() {
+        return this.user;
+    }
+
+    @Deprecated
     public UserConnection getUser() {
         return user;
     }

api/src/main/java/com/viaversion/viaversion/api/connection/UserConnection.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
@@ -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.minecraft.ClientWorld;
 import com.viaversion.viaversion.api.protocol.Protocol;
 import com.viaversion.viaversion.api.protocol.packet.PacketTracker;
 import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
@@ -99,14 +100,33 @@ public interface UserConnection {
     void addEntityTracker(Class<? extends Protocol> protocolClass, EntityTracker tracker);
 
     /**
-     * Clear stored objects and entity trackers.
+     * Returns the client world by the given protocol class if present.
+     *
+     * @param protocolClass protocol class
+     * @param <T>           client world type
+     * @return client world if present
+     */
+    @Nullable
+    <T extends ClientWorld> T getClientWorld(Class<? extends Protocol> protocolClass);
+
+    /**
+     * Adds a client world to the user connection.
+     * Does not override existing client worlds.
+     *
+     * @param protocolClass protocol class
+     * @param clientWorld   client world
+     */
+    void addClientWorld(Class<? extends Protocol> protocolClass, ClientWorld clientWorld);
+
+    /**
+     * Clear stored objects, entity trackers and client worlds.
      */
     default void clearStoredObjects() {
         clearStoredObjects(false);
     }
 
     /**
-     * Clear stored objects and entity trackers.
+     * Clear stored objects, entity trackers and client worlds.
      * If cleared for a proxy server switch, some stored objects and tracker data will be retained.
      *
      * @param isServerSwitch whether the clear is due to a server switch
@@ -299,23 +319,35 @@ public interface UserConnection {
     void setPendingDisconnect(boolean pendingDisconnect);
 
     /**
-     * Returns whether this is a client-side connection.
-     * This is a mod integrated into the client itself, or for example a backend Velocity connection.
+     * Returns whether this is a backend connection.
+     * This is a mod integrated into the client, or for example a backend Velocity connection.
      *
-     * @return whether this is a client-side connection
+     * @return whether this is a backend connection
      */
     boolean isClientSide();
 
+    /**
+     * Returns whether this is a frontend connection.
+     * This is a plugin integrated into the server, or for example a frontend Velocity connection.
+     *
+     * @return whether this is a frontend connection
+     */
+    default boolean isServerSide() {
+        return !isClientSide();
+    }
+
     /**
      * Returns whether {@link ViaVersionConfig#blockedProtocolVersions()} should be checked for this connection.
      *
      * @return whether blocked protocols should be applied
      */
-    boolean shouldApplyBlockProtocol();
+    default boolean shouldApplyBlockProtocol() {
+        return isServerSide();
+    }
 
     /**
      * Returns a newly generated uuid that will let a packet be passed through without
-     * transformig its contents if used together with {@link PacketWrapper#PASSTHROUGH_ID}.
+     * transforming its contents if used together with {@link PacketWrapper#PASSTHROUGH_ID}.
      *
      * @return generated passthrough token
      */

api/src/main/java/com/viaversion/viaversion/api/data/BiMappings.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/data/BiMappingsBase.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/data/FullMappings.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
@@ -53,6 +53,14 @@ public interface FullMappings extends BiMappings {
      */
     @Nullable String identifier(int id);
 
+    /**
+     * Returns the unmapped string identifier for the given mapped identifier.
+     *
+     * @param mappedIdentifier mapped identifier
+     * @return unmapped string identifier, or null if not found
+     */
+    @Nullable String identifier(String mappedIdentifier);
+
     /**
      * Returns the mapped string identifier for the given mapped id.
      *

api/src/main/java/com/viaversion/viaversion/api/data/FullMappingsBase.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
@@ -84,7 +84,18 @@ public class FullMappingsBase implements FullMappings {
     }
 
     @Override
-    public String mappedIdentifier(final int mappedId) {
+    public @Nullable String identifier(final String mappedIdentifier) {
+        final int mappedId = mappedId(mappedIdentifier);
+        if (mappedId == -1) {
+            return null;
+        }
+
+        final int id = mappings.inverse().getNewId(mappedId);
+        return id != -1 ? identifier(id) : null;
+    }
+
+    @Override
+    public @Nullable String mappedIdentifier(final int mappedId) {
         if (mappedId < 0 || mappedId >= mappedIdToString.length) {
             return null;
         }

api/src/main/java/com/viaversion/viaversion/api/data/IdentityMappings.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/data/Int2IntMapBiMappings.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/data/Int2IntMapMappings.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/data/IntArrayMappings.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/data/MappingData.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
@@ -35,54 +35,84 @@ public interface MappingData {
     void load();
 
     /**
-     * Returns the mapped block state id, or -1 if unmapped.
+     * Returns the mapped block state id, or 0 if unmapped.
      *
      * @param id unmapped block state id
-     * @return mapped block state id, or -1 if unmapped
+     * @return mapped block state id, or 0 if unmapped
      * @throws NullPointerException if this mappingdata does not hold block state mappings
      */
     int getNewBlockStateId(int id);
 
     /**
-     * Returns the mapped block id, or -1 if unmapped.
+     * Returns the mapped block id, or 0 if unmapped.
      *
      * @param id unmapped block id
-     * @return mapped block id, or -1 if unmapped
+     * @return mapped block id, or 0 if unmapped
      * @throws NullPointerException if this mappingdata does not hold block mappings
      */
     int getNewBlockId(int id);
 
+    /**
+     * Returns the backwards mapped block id, or 1 if unmapped.
+     *
+     * @param id mapped block id
+     * @return backwards mapped block id, or 1 if unmapped
+     */
     int getOldBlockId(int id);
 
     /**
-     * Returns the mapped item id, or -1 if unmapped.
+     * Returns the mapped item id, or 0 if unmapped.
      *
      * @param id unmapped item id
-     * @return mapped item id, or -1 if unmapped
+     * @return mapped item id, or 0 if unmapped
      * @throws NullPointerException if this mappingdata does not hold item mappings
      */
     int getNewItemId(int id);
 
     /**
-     * Returns the backwards mapped item id, or -1 if unmapped.
+     * Returns the backwards mapped item id, or 1 if unmapped.
      *
      * @param id mapped item id
-     * @return backwards mapped item id, or -1 if unmapped
+     * @return backwards mapped item id, or 1 if unmapped
      * @throws NullPointerException if this mappingdata does not hold item mappings
      */
     int getOldItemId(int id);
 
     /**
-     * Returns the mapped particle id, or -1 if unmapped.
+     * Returns the mapped particle id, or 0 if unmapped.
      *
      * @param id unmapped particle id
-     * @return mapped particle id, or -1 if unmapped
+     * @return mapped particle id, or 0 if unmapped
      * @throws NullPointerException if this mappingdata does not hold particle mappings
      */
     int getNewParticleId(int id);
 
+    /**
+     * Returns the mapped attribute id, or 0 if unmapped.
+     *
+     * @param id unmapped attribute id
+     * @return mapped attribute id, or 0 if unmapped
+     * @throws NullPointerException if this mappingdata does not hold attribute mappings
+     */
     int getNewAttributeId(int id);
 
+    /**
+     * Returns the mapped sound id, or 0 if unmapped.
+     *
+     * @param id unmapped sound id
+     * @return mapped sound id, or 0 if unmapped
+     * @throws NullPointerException if this mappingdata does not hold sound mappings
+     */
+    int getNewSoundId(int id);
+
+    /**
+     * Returns the backwards mapped sound id, or 1 if unmapped.
+     *
+     * @param i mapped sound id
+     * @return backwards mapped sound id, or 1 if unmapped
+     */
+    int getOldSoundId(int i);
+
     /**
      * Returns a list of tags to send if present.
      *
@@ -122,10 +152,10 @@ public interface MappingData {
 
     @Nullable Mappings getEnchantmentMappings();
 
-    @Nullable Mappings getAttributeMappings();
-
     @Nullable Mappings getPaintingMappings();
 
+    @Nullable FullMappings getAttributeMappings();
+
     @Nullable FullMappings getEntityMappings();
 
     @Nullable FullMappings getArgumentTypeMappings();

api/src/main/java/com/viaversion/viaversion/api/data/MappingDataBase.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
@@ -43,6 +43,7 @@ public class MappingDataBase implements MappingData {
     protected FullMappings entityMappings;
     protected FullMappings recipeSerializerMappings;
     protected FullMappings itemDataSerializerMappings;
+    protected FullMappings attributeMappings;
     protected ParticleMappings particleMappings;
     protected BiMappings itemMappings;
     protected BiMappings blockMappings;
@@ -53,7 +54,6 @@ public class MappingDataBase implements MappingData {
     protected Mappings enchantmentMappings;
     protected Mappings paintingMappings;
     protected Mappings menuMappings;
-    protected Mappings attributeMappings;
     protected Map<RegistryType, List<TagData>> tags;
 
     public MappingDataBase(final String unmappedVersion, final String mappedVersion) {
@@ -76,8 +76,6 @@ public class MappingDataBase implements MappingData {
         menuMappings = loadMappings(data, "menus");
         enchantmentMappings = loadMappings(data, "enchantments");
         paintingMappings = loadMappings(data, "paintings");
-        attributeMappings = loadMappings(data, "attributes");
-
 
         final CompoundTag unmappedIdentifierData = readUnmappedIdentifiersFile("identifiers-" + unmappedVersion + ".nbt");
         final CompoundTag mappedIdentifierData = readMappedIdentifiersFile("identifiers-" + mappedVersion + ".nbt");
@@ -87,6 +85,7 @@ public class MappingDataBase implements MappingData {
             argumentTypeMappings = loadFullMappings(data, unmappedIdentifierData, mappedIdentifierData, "argumenttypes");
             recipeSerializerMappings = loadFullMappings(data, unmappedIdentifierData, mappedIdentifierData, "recipe_serializers");
             itemDataSerializerMappings = loadFullMappings(data, unmappedIdentifierData, mappedIdentifierData, "data_component_type");
+            attributeMappings = loadFullMappings(data, unmappedIdentifierData, mappedIdentifierData, "attributes");
 
             final List<String> unmappedParticles = identifiersFromGlobalIds(unmappedIdentifierData, "particles");
             final List<String> mappedParticles = identifiersFromGlobalIds(mappedIdentifierData, "particles");
@@ -180,7 +179,7 @@ public class MappingDataBase implements MappingData {
 
     @Override
     public int getOldBlockId(final int id) {
-        return blockMappings.getNewIdOrDefault(id, 1);
+        return blockMappings.inverse().getNewIdOrDefault(id, 1);
     }
 
     @Override
@@ -203,6 +202,16 @@ public class MappingDataBase implements MappingData {
         return checkValidity(id, attributeMappings.getNewId(id), "attributes");
     }
 
+    @Override
+    public int getNewSoundId(final int id) {
+        return checkValidity(id, soundMappings.getNewId(id), "sound");
+    }
+
+    @Override
+    public int getOldSoundId(final int i) {
+        return soundMappings.getNewIdOrDefault(i, 0);
+    }
+
     @Override
     public @Nullable List<TagData> getTags(final RegistryType type) {
         return tags != null ? tags.get(type) : null;
@@ -262,7 +271,7 @@ public class MappingDataBase implements MappingData {
     }
 
     @Override
-    public @Nullable Mappings getAttributeMappings() {
+    public @Nullable FullMappings getAttributeMappings() {
         return attributeMappings;
     }
 
@@ -315,4 +324,4 @@ public class MappingDataBase implements MappingData {
 
     protected void loadExtras(final CompoundTag data) {
     }
-}
+}

api/src/main/java/com/viaversion/viaversion/api/data/MappingDataLoader.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
@@ -30,7 +30,6 @@ import com.google.gson.JsonObject;
 import com.google.gson.JsonSyntaxException;
 import com.viaversion.nbt.io.NBTIO;
 import com.viaversion.nbt.io.TagReader;
-import com.viaversion.nbt.tag.ByteTag;
 import com.viaversion.nbt.tag.CompoundTag;
 import com.viaversion.nbt.tag.IntArrayTag;
 import com.viaversion.nbt.tag.IntTag;
@@ -211,68 +210,64 @@ public class MappingDataLoader {
             return null;
         }
 
-        final ByteTag serializationStragetyTag = tag.getUnchecked("id");
-        final IntTag mappedSizeTag = tag.getUnchecked("mappedSize");
-        final byte strategy = serializationStragetyTag.asByte();
+        final int mappedSize = tag.getIntTag("mappedSize").asInt();
+        final byte strategy = tag.getByteTag("id").asByte();
         final V mappings;
         if (strategy == DIRECT_ID) {
             final IntArrayTag valuesTag = tag.getIntArrayTag("val");
-            return IntArrayMappings.of(valuesTag.getValue(), mappedSizeTag.asInt());
+            return IntArrayMappings.of(valuesTag.getValue(), mappedSize);
         } else if (strategy == SHIFTS_ID) {
-            final IntArrayTag shiftsAtTag = tag.getIntArrayTag("at");
-            final IntArrayTag shiftsTag = tag.getIntArrayTag("to");
-            final IntTag sizeTag = tag.getUnchecked("size");
-            final int[] shiftsAt = shiftsAtTag.getValue();
-            final int[] shiftsTo = shiftsTag.getValue();
-            final int size = sizeTag.asInt();
+            final int[] shiftsAt = tag.getIntArrayTag("at").getValue();
+            final int[] shiftsTo = tag.getIntArrayTag("to").getValue();
+            final int size = tag.getIntTag("size").asInt();
             mappings = holderSupplier.get(size);
 
-            // Handle values until first shift
             if (shiftsAt[0] != 0) {
+                // Add identity values before the first shift
                 final int to = shiftsAt[0];
                 for (int id = 0; id < to; id++) {
                     addConsumer.addTo(mappings, id, id);
                 }
             }
 
-            // Handle shifts
+            // Read shifts
             for (int i = 0; i < shiftsAt.length; i++) {
+                final boolean isLast = i == shiftsAt.length - 1;
                 final int from = shiftsAt[i];
-                final int to = i == shiftsAt.length - 1 ? size : shiftsAt[i + 1];
+                final int to = isLast ? size : shiftsAt[i + 1];
                 int mappedId = shiftsTo[i];
                 for (int id = from; id < to; id++) {
                     addConsumer.addTo(mappings, id, mappedId++);
                 }
             }
         } else if (strategy == CHANGES_ID) {
-            final IntArrayTag changesAtTag = tag.getIntArrayTag("at");
-            final IntArrayTag valuesTag = tag.getIntArrayTag("val");
-            final IntTag sizeTag = tag.getUnchecked("size");
+            final int[] changesAt = tag.getIntArrayTag("at").getValue();
+            final int[] values = tag.getIntArrayTag("val").getValue();
+            final int size = tag.getIntTag("size").asInt();
             final boolean fillBetween = tag.get("nofill") == null;
-            final int[] changesAt = changesAtTag.getValue();
-            final int[] values = valuesTag.getValue();
-            mappings = holderSupplier.get(sizeTag.asInt());
+            mappings = holderSupplier.get(size);
 
+            int nextUnhandledId = 0;
             for (int i = 0; i < changesAt.length; i++) {
-                final int id = changesAt[i];
+                final int changedId = changesAt[i];
                 if (fillBetween) {
                     // Fill from after the last change to before this change with unchanged ids
-                    final int previousId = i != 0 ? changesAt[i - 1] + 1 : 0;
-                    for (int identity = previousId; identity < id; identity++) {
-                        addConsumer.addTo(mappings, identity, identity);
+                    for (int id = nextUnhandledId; id < changedId; id++) {
+                        addConsumer.addTo(mappings, id, id);
                     }
+                    nextUnhandledId = changedId + 1;
                 }
 
                 // Assign the changed value
-                addConsumer.addTo(mappings, id, values[i]);
+                addConsumer.addTo(mappings, changedId, values[i]);
             }
         } else if (strategy == IDENTITY_ID) {
-            final IntTag sizeTag = tag.getUnchecked("size");
-            return new IdentityMappings(sizeTag.asInt(), mappedSizeTag.asInt());
+            final IntTag sizeTag = tag.getIntTag("size");
+            return new IdentityMappings(sizeTag.asInt(), mappedSize);
         } else {
             throw new IllegalArgumentException("Unknown serialization strategy: " + strategy);
         }
-        return mappingsSupplier.create(mappings, mappedSizeTag.asInt());
+        return mappingsSupplier.create(mappings, mappedSize);
     }
 
     public @Nullable List<String> identifiersFromGlobalIds(final CompoundTag mappingsTag, final String key) {
@@ -295,7 +290,7 @@ public class MappingDataLoader {
      * @return map with indexes hashed by their id value
      */
     public Object2IntMap<String> indexedObjectToMap(final JsonObject object) {
-        final Object2IntMap<String> map = new Object2IntOpenHashMap<>(object.size(), .99F);
+        final Object2IntMap<String> map = new Object2IntOpenHashMap<>(object.size());
         map.defaultReturnValue(-1);
         for (final Map.Entry<String, JsonElement> entry : object.entrySet()) {
             map.put(entry.getValue().getAsString(), Integer.parseInt(entry.getKey()));
@@ -310,7 +305,7 @@ public class MappingDataLoader {
      * @return map with indexes hashed by their id value
      */
     public Object2IntMap<String> arrayToMap(final JsonArray array) {
-        final Object2IntMap<String> map = new Object2IntOpenHashMap<>(array.size(), .99F);
+        final Object2IntMap<String> map = new Object2IntOpenHashMap<>(array.size());
         map.defaultReturnValue(-1);
         for (int i = 0; i < array.size(); i++) {
             map.put(array.get(i).getAsString(), i);

api/src/main/java/com/viaversion/viaversion/api/data/Mappings.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/data/ParticleMappings.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
@@ -36,6 +36,7 @@ public class ParticleMappings extends FullMappingsBase {
         addBlockParticle("falling_dust");
         addBlockParticle("block_marker");
         addBlockParticle("dust_pillar");
+        addBlockParticle("block_crumble");
         addItemParticle("item");
     }
 

api/src/main/java/com/viaversion/viaversion/api/data/entity/ClientEntityIdChangeListener.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/data/entity/DimensionData.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/data/entity/EntityTracker.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
@@ -78,7 +78,7 @@ public interface EntityTracker {
     void removeEntity(int id);
 
     /**
-     * Clears stored entity types and data.
+     * Clears stored entity types and data, only leaving behind the client entity.
      */
     void clearEntities();
 
@@ -102,11 +102,19 @@ public interface EntityTracker {
     @Nullable StoredEntityData entityDataIfPresent(int id);
 
     /**
-     * Returns the client entity id or -1 if unset.
+     * Returns whether the client entity id has been set.
      *
-     * @return client entity id or -1 if unset
+     * @return whether the client entity id has been set
      */
-    int clientEntityId();
+    boolean hasClientEntityId();
+
+    /**
+     * Returns the client entity id. Should be wrapped around {@link #hasClientEntityId()}.
+     *
+     * @return client entity id
+     * @throws IllegalStateException if the client entity id has not been set
+     */
+    int clientEntityId() throws IllegalStateException;
 
     /**
      * Sets the client entity id.
@@ -115,6 +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.
@@ -169,12 +191,4 @@ public interface EntityTracker {
     @Nullable DimensionData dimensionData(int dimensionId);
 
     void setDimensions(Map<String, DimensionData> dimensions);
-
-    /**
-     * Adds the client player entity to the tracker.
-     * If the client entity has not been set yet, this will return false.
-     *
-     * @return whether the client has been tracked
-     */
-    boolean trackClientEntity();
 }

api/src/main/java/com/viaversion/viaversion/api/data/entity/StoredEntityData.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
@@ -66,4 +66,4 @@ public interface StoredEntityData {
      * @param object object to store
      */
     void put(Object object);
-}
+}

api/src/main/java/com/viaversion/viaversion/api/data/entity/TrackedEntity.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
@@ -55,4 +55,4 @@ public interface TrackedEntity {
     boolean hasSentEntityData();
 
     void sentEntityData(boolean sentEntityData);
-}
+}

api/src/main/java/com/viaversion/viaversion/api/debug/DebugHandler.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
@@ -22,7 +22,6 @@
  */
 package com.viaversion.viaversion.api.debug;
 
-import com.google.common.annotations.Beta;
 import com.viaversion.viaversion.api.Via;
 import com.viaversion.viaversion.api.protocol.packet.Direction;
 import com.viaversion.viaversion.api.protocol.packet.PacketType;
@@ -50,7 +49,6 @@ public interface DebugHandler {
      *
      * @param packetTypeName packet type name
      */
-    @Beta
     void addPacketTypeNameToLog(String packetTypeName);
 
     /**
@@ -59,7 +57,6 @@ public interface DebugHandler {
      *
      * @param packetType packet type
      */
-    @Beta
     void addPacketTypeToLog(PacketType packetType);
 
     /**
@@ -67,22 +64,44 @@ public interface DebugHandler {
      *
      * @param packetTypeName packet type name
      */
-    @Beta
     boolean removePacketTypeNameToLog(String packetTypeName);
 
     /**
      * Resets packet type filters.
      */
-    @Beta
     void clearPacketTypesToLog();
 
     /**
-     * Returns whether packets should be logged after being transformed.
+     * Sets whether packets should be logged before and after being transformed.
+     *
+     * @param logPacketTransform whether packets should be logged
+     */
+    default void setLogPacketTransform(boolean logPacketTransform) {
+        setLogPrePacketTransform(logPacketTransform);
+        setLogPostPacketTransform(logPacketTransform);
+    }
+
+    /**
+     * Returns whether packets should be logged before being transformed.
      * Set to true by default.
      *
+     * @return whether packets should be logged before being transformed
+     */
+    boolean logPrePacketTransform();
+
+    /**
+     * Sets whether packets should be logged before being transformed.
+     *
+     * @param logPrePacketTransform whether packets should be logged before being transformed
+     */
+    void setLogPrePacketTransform(boolean logPrePacketTransform);
+
+    /**
+     * Returns whether packets should be logged after being transformed.
+     * Set to false by default.
+     *
      * @return whether packets should be logged after being transformed
      */
-    @Beta
     boolean logPostPacketTransform();
 
     /**
@@ -90,7 +109,6 @@ public interface DebugHandler {
      *
      * @param logPostPacketTransform whether packets should be logged after being transformed
      */
-    @Beta
     void setLogPostPacketTransform(boolean logPostPacketTransform);
 
     /**
@@ -103,7 +121,6 @@ public interface DebugHandler {
      */
     boolean shouldLog(PacketWrapper wrapper, Direction direction);
 
-    @Beta
     default void enableAndLogIds(final PacketType... packetTypes) {
         setEnabled(true);
         for (final PacketType packetType : packetTypes) {

api/src/main/java/com/viaversion/viaversion/api/legacy/LegacyViaAPI.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/legacy/bossbar/BossBar.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/legacy/bossbar/BossColor.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/legacy/bossbar/BossFlag.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/legacy/bossbar/BossStyle.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/minecraft/AnimalVariant.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;
+
+import com.viaversion.viaversion.api.type.Types;
+import com.viaversion.viaversion.api.type.types.misc.HolderType;
+import io.netty.buffer.ByteBuf;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/**
+ * Represents an animal variant (e.g. for cows, pigs, chickens).
+ *
+ * @param modelType model type id
+ * @param texture texture path
+ * @param biomes biomes this variant can spawn in, if limited to specific biomes
+ */
+public record AnimalVariant(int modelType, String texture, @Nullable HolderSet biomes) {
+
+    public static HolderType<AnimalVariant> TYPE = new HolderType<>() {
+        @Override
+        public AnimalVariant readDirect(final ByteBuf buffer) {
+            final int modelType = Types.VAR_INT.readPrimitive(buffer);
+            final String texture = Types.STRING.read(buffer);
+            final HolderSet biomes = Types.OPTIONAL_HOLDER_SET.read(buffer);
+            return new AnimalVariant(modelType, texture, biomes);
+        }
+
+        @Override
+        public void writeDirect(final ByteBuf buffer, final AnimalVariant variant) {
+            Types.VAR_INT.writePrimitive(buffer, variant.modelType());
+            Types.STRING.write(buffer, variant.texture());
+            Types.OPTIONAL_HOLDER_SET.write(buffer, variant.biomes());
+        }
+    };
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/BlockChangeRecord.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
@@ -65,4 +65,4 @@ public interface BlockChangeRecord {
     int getBlockId();
 
     void setBlockId(int blockId);
-}
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/BlockChangeRecord1_16_2.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/minecraft/BlockChangeRecord1_8.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/minecraft/BlockFace.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/minecraft/BlockPosition.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
@@ -37,6 +37,13 @@ public class BlockPosition {
         return new BlockPosition(x + face.modX(), y + face.modY(), z + face.modZ());
     }
 
+    public double distanceFromCenterSquared(final double x, final double y, final double z) {
+        final double dx = this.x + 0.5 - x;
+        final double dy = this.y + 0.5 - y;
+        final double dz = this.z + 0.5 - z;
+        return dx * dx + dy * dy + dz * dz;
+    }
+
     public int x() {
         return x;
     }

api/src/main/java/com/viaversion/viaversion/api/minecraft/ChunkPosition.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
@@ -66,6 +66,17 @@ public final class ChunkPosition {
         return (long) chunkX & 0xffffffffL | ((long) chunkZ & 0xffffffffL) << 32;
     }
 
+    /**
+     * Returns a long key for the given block coordinates.
+     *
+     * @param x the block X coordinate
+     * @param z the block Z coordinate
+     * @return the chunk key
+     */
+    public static long chunkKeyForBlock(final int x, final int z) {
+        return chunkKey(x >> 4, z >> 4);
+    }
+
     @Override
     public boolean equals(final Object o) {
         if (this == o) return true;

api/src/main/java/com/viaversion/viaversion/api/minecraft/ClientWorld.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
@@ -23,13 +23,12 @@
 package com.viaversion.viaversion.api.minecraft;
 
 import com.viaversion.viaversion.api.connection.StorableObject;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Stored up until 1.14 to be used in chunk sending.
  */
 public class ClientWorld implements StorableObject {
-    private Environment environment;
+    private Environment environment = Environment.NORMAL;
 
     public ClientWorld() {
     }
@@ -38,11 +37,20 @@ public class ClientWorld implements StorableObject {
         this.environment = environment;
     }
 
-    public @Nullable Environment getEnvironment() {
+    public Environment getEnvironment() {
         return environment;
     }
 
-    public void setEnvironment(final int environmentId) {
+    /**
+     * Sets the environment of the world and returns whether the environment was changed.
+     *
+     * @param environmentId the id of the environment to set
+     * @return whether the environment was changed
+     */
+    public boolean setEnvironment(final int environmentId) {
+        final int previousEnvironmentId = environment.id();
         this.environment = Environment.getEnvironmentById(environmentId);
+
+        return previousEnvironmentId != environmentId;
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/EitherHolder.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;
+
+public interface EitherHolder<T> {
+
+    /**
+     * Returns a direct or indirect value holder.
+     *
+     * @param value the value
+     * @param <T>   the type of the value
+     * @return a new direct holder
+     */
+    static <T> EitherHolder<T> of(final Holder<T> value) {
+        return new EitherHolderImpl<>(value, null);
+    }
+
+    /**
+     * Returns an indirect holder via the resource key.
+     *
+     * @param key  the resource key
+     * @param <T> the type of the value
+     * @return a new holder with the given resource key
+     */
+    static <T> EitherHolder<T> of(final String key) {
+        return new EitherHolderImpl<>(null, key);
+    }
+
+    /**
+     * Returns true if this holder is backed by a direct value.
+     *
+     * @return true if the holder is direct
+     * @see #hasKey()
+     */
+    boolean hasHolder();
+
+    /**
+     * Returns true if this holder has a resource key.
+     *
+     * @return true if this holder has a resource key
+     * @see #hasHolder()
+     */
+    boolean hasKey();
+
+    /**
+     * Returns the value of this holder.
+     *
+     * @return the value of this holder
+     * @throws IllegalArgumentException if this contains a resource key instead of a holder
+     * @see #hasHolder()
+     */
+    Holder<T> holder();
+
+    /**
+     * Returns the resource key.
+     *
+     * @return the resource key
+     * @throws IllegalArgumentException if this contains a holder instead of a resource key
+     * @see #hasKey()
+     */
+    String key();
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/EitherHolderImpl.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;
+
+import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.util.EitherImpl;
+
+final class EitherHolderImpl<T> extends EitherImpl<Holder<T>, String> implements EitherHolder<T> {
+
+    EitherHolderImpl(final Holder<T> left, final String value) {
+        super(left, value);
+    }
+
+    @Override
+    public boolean hasHolder() {
+        return isLeft();
+    }
+
+    @Override
+    public boolean hasKey() {
+        return isRight();
+    }
+
+    @Override
+    public Holder<T> holder() {
+        Preconditions.checkArgument(hasHolder(), "Either does not have a holder");
+        return left();
+    }
+
+    @Override
+    public String key() {
+        Preconditions.checkArgument(hasKey(), "Either does not have a key");
+        return right();
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/Environment.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/minecraft/EulerAngle.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/minecraft/GameMode.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
@@ -24,28 +24,35 @@ package com.viaversion.viaversion.api.minecraft;
 
 public enum GameMode {
 
-    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 0 -> SURVIVAL;
+            case -1 -> NOT_SET;
             case 1 -> CREATIVE;
             case 2 -> ADVENTURE;
             case 3 -> SPECTATOR;
-            default -> throw new IllegalArgumentException("Unknown gamemode id: " + id);
+            default /*0*/ -> SURVIVAL;
         };
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/GameProfile.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/minecraft/GlobalBlockPosition.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/minecraft/Holder.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
@@ -22,6 +22,8 @@
  */
 package com.viaversion.viaversion.api.minecraft;
 
+import it.unimi.dsi.fastutil.ints.Int2IntFunction;
+
 public interface Holder<T> {
 
     /**
@@ -33,7 +35,7 @@ public interface Holder<T> {
      * @throws IllegalArgumentException if the id is negative
      */
     static <T> Holder<T> of(final int id) {
-        return new HolderImpl<>(id);
+        return new IdHolder<>(id);
     }
 
     /**
@@ -44,7 +46,7 @@ public interface Holder<T> {
      * @return a new direct holder
      */
     static <T> Holder<T> of(final T value) {
-        return new HolderImpl<>(value);
+        return new ValueHolder<>(value);
     }
 
     /**
@@ -79,4 +81,12 @@ public interface Holder<T> {
      * @see #hasId()
      */
     int id();
+
+    /**
+     * Returns a new holder with the id rewritten using the given function, or self if this is a direct holder or the id did not change.
+     *
+     * @param rewriteFunction the function to rewrite the id
+     * @return a new holder with the id rewritten, or self
+     */
+    Holder<T> updateId(final Int2IntFunction rewriteFunction);
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/HolderSet.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
@@ -36,7 +36,7 @@ public interface HolderSet {
      * @return a new holder set
      */
     static HolderSet of(final String tagKey) {
-        return new HolderSetImpl(tagKey);
+        return new HolderSetImpl.Tag(tagKey);
     }
 
     /**
@@ -46,7 +46,7 @@ public interface HolderSet {
      * @return a new holder set
      */
     static HolderSet of(final int[] ids) {
-        return new HolderSetImpl(ids);
+        return new HolderSetImpl.Ids(ids);
     }
 
     /**

api/src/main/java/com/viaversion/viaversion/api/minecraft/HolderSetImpl.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
@@ -22,50 +22,63 @@
  */
 package com.viaversion.viaversion.api.minecraft;
 
-import com.viaversion.viaversion.util.EitherImpl;
 import it.unimi.dsi.fastutil.ints.Int2IntFunction;
+import java.util.Arrays;
 
-final class HolderSetImpl extends EitherImpl<String, int[]> implements HolderSet {
+final class HolderSetImpl {
 
-    HolderSetImpl(final String tagKey) {
-        super(tagKey, null);
-    }
+    record Tag(String tagKey) implements HolderSet {
+        @Override
+        public boolean hasTagKey() {
+            return true;
+        }
 
-    HolderSetImpl(final int[] ids) {
-        super(null, ids);
-    }
+        @Override
+        public int[] ids() {
+            throw new IllegalArgumentException("This holder set has a tag key");
+        }
 
-    @Override
-    public String tagKey() {
-        return left();
-    }
+        @Override
+        public boolean hasIds() {
+            return false;
+        }
 
-    @Override
-    public boolean hasTagKey() {
-        return isLeft();
-    }
-
-    @Override
-    public int[] ids() {
-        return right();
-    }
-
-    @Override
-    public boolean hasIds() {
-        return isRight();
-    }
-
-    @Override
-    public HolderSet rewrite(final Int2IntFunction idRewriter) {
-        if (hasTagKey()) {
+        @Override
+        public HolderSet rewrite(final Int2IntFunction idRewriter) {
             return this;
         }
+    }
 
-        final int[] ids = ids();
-        final int[] mappedIds = new int[ids.length];
-        for (int i = 0; i < mappedIds.length; i++) {
-            mappedIds[i] = idRewriter.apply(ids[i]);
+    record Ids(int[] ids) implements HolderSet {
+        @Override
+        public boolean hasTagKey() {
+            return false;
+        }
+
+        @Override
+        public String tagKey() {
+            throw new IllegalArgumentException("This holder set has direct ids");
+        }
+
+        @Override
+        public boolean hasIds() {
+            return true;
+        }
+
+        @Override
+        public HolderSet rewrite(final Int2IntFunction idRewriter) {
+            final int[] mappedIds = new int[ids.length];
+            for (int i = 0; i < mappedIds.length; i++) {
+                mappedIds[i] = idRewriter.applyAsInt(ids[i]);
+            }
+            return new Ids(mappedIds);
+        }
+
+        @Override
+        public String toString() {
+            return "Ids{" +
+                "ids=" + Arrays.toString(ids) +
+                '}';
         }
-        return new HolderSetImpl(mappedIds);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/IdHolder.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
@@ -23,49 +23,38 @@
 package com.viaversion.viaversion.api.minecraft;
 
 import com.google.common.base.Preconditions;
+import it.unimi.dsi.fastutil.ints.Int2IntFunction;
 
-final class HolderImpl<T> implements Holder<T> {
+record IdHolder<T>(int id) implements Holder<T> {
 
-    private final T value;
-    private final int id;
-
-    HolderImpl(final int id) {
+    IdHolder {
         Preconditions.checkArgument(id >= 0, "id cannot be negative");
-        this.value = null;
-        this.id = id;
-    }
-
-    HolderImpl(final T value) {
-        this.value = value;
-        this.id = -1;
     }
 
     @Override
     public boolean isDirect() {
-        return id == -1;
+        return false;
     }
 
     @Override
     public boolean hasId() {
-        return id != -1;
+        return true;
     }
 
     @Override
     public T value() {
-        Preconditions.checkArgument(isDirect(), "Holder is not direct");
-        return value;
+        throw new IllegalArgumentException("Holder is not direct");
     }
 
     @Override
-    public int id() {
-        return id;
-    }
-
-    @Override
-    public String toString() {
-        return "HolderImpl{" +
-            "value=" + value +
-            ", id=" + id +
-            '}';
+    public Holder<T> updateId(final Int2IntFunction rewriteFunction) {
+        final int rewrittenId = rewriteFunction.applyAsInt(id);
+        if (rewrittenId == id) {
+            return this;
+        }
+        if (rewrittenId == -1) {
+            throw new IllegalArgumentException("Received invalid id in updateId");
+        }
+        return Holder.of(rewrittenId);
     }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/PaintingVariant.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
@@ -22,13 +22,19 @@
  */
 package com.viaversion.viaversion.api.minecraft;
 
+import com.viaversion.nbt.tag.Tag;
 import com.viaversion.viaversion.api.type.Types;
 import com.viaversion.viaversion.api.type.types.misc.HolderType;
 import io.netty.buffer.ByteBuf;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
-public record PaintingVariant(int width, int height, String assetId) {
+public record PaintingVariant(int width, int height, String assetId, @Nullable Tag title, @Nullable Tag author) {
 
-    public static HolderType<PaintingVariant> TYPE = new HolderType<>() {
+    public PaintingVariant(final int width, final int height, final String assetId) {
+        this(width, height, assetId, null, null);
+    }
+
+    public static HolderType<PaintingVariant> TYPE1_21 = new HolderType<>() {
         @Override
         public PaintingVariant readDirect(final ByteBuf buffer) {
             final int width = Types.VAR_INT.readPrimitive(buffer);
@@ -44,4 +50,24 @@ public record PaintingVariant(int width, int height, String assetId) {
             Types.STRING.write(buffer, variant.assetId());
         }
     };
+    public static HolderType<PaintingVariant> TYPE1_21_2 = new HolderType<>() {
+        @Override
+        public PaintingVariant readDirect(final ByteBuf buffer) {
+            final int width = Types.VAR_INT.readPrimitive(buffer);
+            final int height = Types.VAR_INT.readPrimitive(buffer);
+            final String assetId = Types.STRING.read(buffer);
+            final Tag title = Types.OPTIONAL_TAG.read(buffer);
+            final Tag author = Types.OPTIONAL_TAG.read(buffer);
+            return new PaintingVariant(width, height, assetId, title, author);
+        }
+
+        @Override
+        public void writeDirect(final ByteBuf buffer, final PaintingVariant variant) {
+            Types.VAR_INT.writePrimitive(buffer, variant.width());
+            Types.VAR_INT.writePrimitive(buffer, variant.height());
+            Types.STRING.write(buffer, variant.assetId());
+            Types.OPTIONAL_TAG.write(buffer, variant.title());
+            Types.OPTIONAL_TAG.write(buffer, variant.author());
+        }
+    };
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/Particle.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
@@ -24,12 +24,13 @@ package com.viaversion.viaversion.api.minecraft;
 
 import com.viaversion.viaversion.api.protocol.packet.PacketWrapper;
 import com.viaversion.viaversion.api.type.Type;
+import com.viaversion.viaversion.util.Copyable;
 import com.viaversion.viaversion.util.IdHolder;
 import io.netty.buffer.ByteBuf;
 import java.util.ArrayList;
 import java.util.List;
 
-public final class Particle implements IdHolder {
+public final class Particle implements IdHolder, Copyable {
     private final List<ParticleData<?>> arguments = new ArrayList<>(4);
     private int id;
 
@@ -72,6 +73,15 @@ public final class Particle implements IdHolder {
         arguments.set(index, new ParticleData<>(type, value));
     }
 
+    @Override
+    public Particle copy() {
+        final Particle particle = new Particle(id);
+        for (ParticleData<?> argument : arguments) {
+            particle.arguments.add(argument.copy());
+        }
+        return particle;
+    }
+
     @Override
     public String toString() {
         return "Particle{" +
@@ -80,7 +90,7 @@ public final class Particle implements IdHolder {
             '}';
     }
 
-    public static final class ParticleData<T> {
+    public static final class ParticleData<T> implements Copyable {
         private final Type<T> type;
         private T value;
 
@@ -109,6 +119,11 @@ public final class Particle implements IdHolder {
             wrapper.write(type, value);
         }
 
+        @Override
+        public ParticleData<T> copy() {
+            return new ParticleData<>(type, copy(value));
+        }
+
         @Override
         public String toString() {
             return "ParticleData{" +

api/src/main/java/com/viaversion/viaversion/api/minecraft/PlayerMessageSignature.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/minecraft/ProfileKey.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/minecraft/Quaternion.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/minecraft/RegistryEntry.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
@@ -23,11 +23,23 @@
 package com.viaversion.viaversion.api.minecraft;
 
 import com.viaversion.nbt.tag.Tag;
+import com.viaversion.viaversion.util.Copyable;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public record RegistryEntry(String key, @Nullable Tag tag) {
+/**
+ * Represents an entry in a registry.
+ *
+ * @param key key of the registry entry
+ * @param tag data of the registry entry, or null if the client should use its default
+ */
+public record RegistryEntry(String key, @Nullable Tag tag) implements Copyable {
 
     public RegistryEntry withKey(final String key) {
         return new RegistryEntry(key, tag != null ? tag.copy() : null);
     }
+
+    @Override
+    public RegistryEntry copy() {
+        return new RegistryEntry(key, tag != null ? tag.copy() : null);
+    }
 }

api/src/main/java/com/viaversion/viaversion/api/minecraft/RegistryType.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/minecraft/SoundEvent.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/minecraft/TagData.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/minecraft/ValueHolder.java

@@ -0,0 +1,48 @@
+/*
+ * 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;
+
+import it.unimi.dsi.fastutil.ints.Int2IntFunction;
+
+record ValueHolder<T>(T value) implements Holder<T> {
+
+    @Override
+    public boolean isDirect() {
+        return true;
+    }
+
+    @Override
+    public boolean hasId() {
+        return false;
+    }
+
+    @Override
+    public int id() {
+        return -1;
+    }
+
+    @Override
+    public Holder<T> updateId(final Int2IntFunction rewriteFunction) {
+        return this;
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/Vector.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/minecraft/Vector3f.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/minecraft/VillagerData.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/minecraft/WolfVariant.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/minecraft/WorldIdentifiers.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/minecraft/blockentity/BlockEntity.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/minecraft/blockentity/BlockEntityImpl.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/minecraft/chunks/BaseChunk.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
@@ -143,6 +143,16 @@ public class BaseChunk implements Chunk {
         this.heightMap = heightMap;
     }
 
+    @Override
+    public Heightmap[] heightmaps() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void setHeightmaps(final Heightmap[] heightmaps) {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public List<CompoundTag> getBlockEntities() {
         return blockEntities;

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/Chunk.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
@@ -79,7 +79,8 @@ public interface Chunk {
      * @return chunk section bit mask, only non-null for 1.17+ chunks
      * @see #getBitmask()
      */
-    @Nullable BitSet getChunkMask();
+    @Nullable
+    BitSet getChunkMask();
 
     void setChunkMask(BitSet chunkSectionMask);
 
@@ -88,7 +89,8 @@ public interface Chunk {
      *
      * @return array of nullable chunk sections
      */
-    @Nullable ChunkSection[] getSections();
+    @Nullable
+    ChunkSection[] getSections();
 
     void setSections(ChunkSection[] sections);
 
@@ -106,10 +108,15 @@ public interface Chunk {
      *
      * @return compoundtag containing heightmaps if present
      */
-    @Nullable CompoundTag getHeightMap();
+    @Nullable
+    CompoundTag getHeightMap();
 
     void setHeightMap(@Nullable CompoundTag heightMap);
 
+    Heightmap[] heightmaps();
+
+    void setHeightmaps(Heightmap[] heightmaps);
+
     /**
      * Returns a list of block entities.
      *

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/Chunk1_18.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
@@ -123,6 +123,16 @@ public class Chunk1_18 implements Chunk {
         this.heightMap = heightMap;
     }
 
+    @Override
+    public Heightmap[] heightmaps() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void setHeightmaps(final Heightmap[] heightmaps) {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public List<CompoundTag> getBlockEntities() {
         throw new UnsupportedOperationException();

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/Chunk1_21_5.java

@@ -0,0 +1,145 @@
+/*
+ * 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.chunks;
+
+import com.viaversion.nbt.tag.CompoundTag;
+import com.viaversion.viaversion.api.minecraft.blockentity.BlockEntity;
+import java.util.BitSet;
+import java.util.List;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class Chunk1_21_5 implements Chunk {
+    protected final int x;
+    protected final int z;
+    protected ChunkSection[] sections;
+    protected Heightmap[] heightmaps;
+    protected final List<BlockEntity> blockEntities;
+
+    public Chunk1_21_5(int x, int z, ChunkSection[] sections, Heightmap[] heightmaps, List<BlockEntity> blockEntities) {
+        this.x = x;
+        this.z = z;
+        this.sections = sections;
+        this.heightmaps = heightmaps;
+        this.blockEntities = blockEntities;
+    }
+
+    @Override
+    public boolean isBiomeData() {
+        return false;
+    }
+
+    @Override
+    public int getX() {
+        return x;
+    }
+
+    @Override
+    public int getZ() {
+        return z;
+    }
+
+    @Override
+    public boolean isFullChunk() {
+        return true;
+    }
+
+    @Override
+    public boolean isIgnoreOldLightData() {
+        return false;
+    }
+
+    @Override
+    public void setIgnoreOldLightData(boolean ignoreOldLightData) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public int getBitmask() {
+        return -1;
+    }
+
+    @Override
+    public void setBitmask(int bitmask) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @Nullable BitSet getChunkMask() {
+        return null;
+    }
+
+    @Override
+    public void setChunkMask(BitSet chunkSectionMask) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public ChunkSection[] getSections() {
+        return sections;
+    }
+
+    @Override
+    public void setSections(ChunkSection[] sections) {
+        this.sections = sections;
+    }
+
+    @Override
+    public int @Nullable [] getBiomeData() {
+        return null;
+    }
+
+    @Override
+    public void setBiomeData(int @Nullable [] biomeData) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @Nullable CompoundTag getHeightMap() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void setHeightMap(final CompoundTag heightMap) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Heightmap[] heightmaps() {
+        return heightmaps;
+    }
+
+    @Override
+    public void setHeightmaps(final Heightmap[] heightmaps) {
+        this.heightmaps = heightmaps;
+    }
+
+    @Override
+    public List<CompoundTag> getBlockEntities() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public List<BlockEntity> blockEntities() {
+        return blockEntities;
+    }
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/ChunkSection.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/minecraft/chunks/ChunkSectionImpl.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
@@ -37,14 +37,14 @@ public class ChunkSectionImpl implements ChunkSection {
     public ChunkSectionImpl(final boolean holdsLight) {
         addPalette(PaletteType.BLOCKS, new DataPaletteImpl(ChunkSection.SIZE));
         if (holdsLight) {
-            this.light = new ChunkSectionLightImpl();
+            this.light = ChunkSectionLightImpl.createWithBlockLight();
         }
     }
 
     public ChunkSectionImpl(final boolean holdsLight, final int expectedPaletteLength) {
         addPalette(PaletteType.BLOCKS, new DataPaletteImpl(ChunkSection.SIZE, expectedPaletteLength));
         if (holdsLight) {
-            this.light = new ChunkSectionLightImpl();
+            this.light = ChunkSectionLightImpl.createWithBlockLight();
         }
     }
 

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/ChunkSectionLight.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
@@ -35,7 +35,7 @@ public interface ChunkSectionLight {
     /**
      * Returns whether the section has sky light.
      *
-     * @return true if skylight is present
+     * @return true if sky light is present
      */
     boolean hasSkyLight();
 
@@ -43,7 +43,7 @@ public interface ChunkSectionLight {
      * Returns whether the section has block light.
      * This returns true unless specifically set to null.
      *
-     * @return true if skylight is present
+     * @return true if block light is present
      */
     boolean hasBlockLight();
 

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/ChunkSectionLightImpl.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
@@ -30,9 +30,17 @@ public class ChunkSectionLightImpl implements ChunkSectionLight {
     private NibbleArray blockLight;
     private NibbleArray skyLight;
 
-    public ChunkSectionLightImpl() {
-        // Block light is always written
-        this.blockLight = new NibbleArray(ChunkSection.SIZE);
+    protected ChunkSectionLightImpl() {
+    }
+
+    public static ChunkSectionLight createWithBlockLight() {
+        final ChunkSectionLightImpl light = new ChunkSectionLightImpl();
+        light.blockLight = new NibbleArray(ChunkSection.SIZE);
+        return light;
+    }
+
+    public static ChunkSectionLight createEmpty() {
+        return new ChunkSectionLightImpl();
     }
 
     @Override

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/DataPalette.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/minecraft/chunks/DataPaletteImpl.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/minecraft/chunks/Heightmap.java

@@ -0,0 +1,26 @@
+/*
+ * 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.chunks;
+
+public record Heightmap(int type, long[] data) {
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/chunks/NibbleArray.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/minecraft/chunks/PaletteType.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
@@ -41,4 +41,4 @@ public enum PaletteType {
     public int highestBitsPerValue() {
         return highestBitsPerValue;
     }
-}
+}

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/EmptyStructuredData.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
@@ -53,6 +53,11 @@ final class EmptyStructuredData<T> implements StructuredData<T> {
         return this.key;
     }
 
+    @Override
+    public StructuredData<T> copy() {
+        return new EmptyStructuredData<>(this.key, this.id);
+    }
+
     @Override
     public T value() {
         return null;

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/FilledStructuredData.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
@@ -59,6 +59,11 @@ final class FilledStructuredData<T> implements StructuredData<T> {
         return key;
     }
 
+    @Override
+    public StructuredData<T> copy() {
+        return new FilledStructuredData<>(this.key, this.copy(this.value), this.id);
+    }
+
     @Override
     public T value() {
         return value;

api/src/main/java/com/viaversion/viaversion/api/minecraft/data/StructuredData.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
@@ -22,11 +22,12 @@
  */
 package com.viaversion.viaversion.api.minecraft.data;
 
+import com.viaversion.viaversion.util.Copyable;
 import com.viaversion.viaversion.util.IdHolder;
 import io.netty.buffer.ByteBuf;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public interface StructuredData<T> extends IdHolder {
+public interface StructuredData<T> extends IdHolder, Copyable {
 
     /**
      * Returns filled structured data, equivalent to an Optional with a value in vanilla.
@@ -52,15 +53,17 @@ public interface StructuredData<T> extends IdHolder {
         return new EmptyStructuredData<>(key, id);
     }
 
-    void setValue(final T value);
+    @Nullable
+    T value();
 
-    void write(final ByteBuf buffer);
+    void setValue(final T value);
 
     void setId(final int id);
 
     StructuredDataKey<T> key();
 
-    @Nullable T value();
+    @Override
+    StructuredData<T> copy();
 
     /**
      * Returns whether the structured data is present. Even if true, the value may be null.
@@ -77,4 +80,6 @@ public interface StructuredData<T> extends IdHolder {
      * @return true if the structured data is empty
      */
     boolean isEmpty();
+
+    void write(final ByteBuf buffer);
 }