Merge remote-tracking branch 'refs/remotes/upstream/dev/3.0.0'

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -0,0 +1,69 @@
+name: Bug Report
+description: Report issues with Velocity not working properly.
+labels: ["type: bug"]
+body:
+  - type: textarea
+    attributes:
+      label: Expected Behavior
+      description: What you expected to work and how.
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Actual Behavior
+      description: What actually happens.
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Steps to Reproduce
+      description: Information on how we can reproduce this bug on our own, this can be e.g. just an explanation, a video or your Velocity config.
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Plugin List
+      description: |
+        All plugins running on your proxy and the backend server you're experiencing this issue on.
+        Use `/velocity plugins` to list plugins on Velocity and `/plugins` to list plugins on your backend server.
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Velocity Version
+      description: |
+        The full, unmodified output of running `/velocity info`.
+        *"Latest"* is not a version. We require you to paste the text, not a screenshot.
+        <details>
+        <summary>Example</summary>
+        
+        ```
+        [17:44:10 INFO]: Velocity 3.3.0-SNAPSHOT (git-9d25d309-b400)  
+        [17:44:10 INFO]: Copyright 2018-2023 Velocity Contributors. Velocity is licensed under the terms of the GNU General Public License v3.  
+        [17:44:10 INFO]: velocitypowered.com - GitHub  
+        ```
+        </details>
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Additional Information
+      description: Anything else you think is helpful.
+    validations:
+      required: false
+
+  - type: markdown
+    attributes:
+      value: |
+        Before submitting this issue, please ensure the following:
+
+        1. You are running the latest version of Velocity from [our downloads page](https://papermc.io/downloads/velocity).
+        2. You searched for and ensured there isn't already an open issue regarding this.
+
+        If you think you have a bug, but are not sure, feel free to ask in the `#velocity-help` channel on our
+        [Discord](https://discord.gg/papermc).

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,10 @@
+blank_issues_enabled: false
+contact_links:
+  - name: PaperMC Discord
+    url: https://discord.gg/papermc
+    about: If you are having issues with the proxy not connecting to servers or have other minor issues, come ask us on our Discord server!
+  - name: Exploit Report
+    url: https://discord.gg/papermc
+    about: |
+      Due to GitHub not currently allowing private issues, exploit reports are currently handled via our Discord.
+      To report an exploit, see the #paper-exploit-report channel.

.github/ISSUE_TEMPLATE/feature-request.yml

@@ -0,0 +1,48 @@
+name: Feature Request
+description: Request for a feature to be implemented into Velocity.
+labels: ["type: feature"]
+body:
+  - type: textarea
+    attributes:
+      label: Requested Feature
+      description: |
+        Please describe as best as you can what you'd like to be added to Velocity.
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Why is this needed?
+      description: |
+        Please describe why do you need this feature.
+        Do you think it could be useful? Is it due to another problem?
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Alternative Solutions
+      description: |
+        Are there any alternative solutions to implementing a new feature?
+        What have you tried instead?
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Additional Information
+      description: Anything else you want to add.
+    validations:
+      required: false
+
+  - type: markdown
+    attributes:
+      value: |
+        Before submitting this request, please ensure the following:
+        
+        1. You are running the latest version of Velocity from [our downloads page](https://papermc.io/downloads/velocity).
+        2. You searched for and ensured there isn't already an open issue regarding this.
+        3. The feature you're requesting has to be implemented on Velocity and not on the backend server.
+        
+        If you are unsure whether your problem can already be fixed in another way, feel free to ask in the `#velocity-help` channel on our
+        [Discord](https://discord.gg/papermc).

api/build.gradle.kts

@@ -67,7 +67,9 @@ tasks {
             "https://google.github.io/guice/api-docs/${libs.guice.get().version}/javadoc/",
             "https://docs.oracle.com/en/java/javase/17/docs/api/",
             "https://jd.advntr.dev/api/${libs.adventure.bom.get().version}/",
-            "https://javadoc.io/doc/com.github.ben-manes.caffeine/caffeine"
+            "https://jd.advntr.dev/text-minimessage/${libs.adventure.bom.get().version}/",
+            "https://jd.advntr.dev/key/${libs.adventure.bom.get().version}/",
+            "https://javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/${libs.caffeine.get().version}/",
         )
 
         o.tags(

api/src/main/java/com/velocitypowered/api/command/CommandManager.java

@@ -44,7 +44,7 @@ public interface CommandManager {
    * @param otherAliases additional aliases
    * @throws IllegalArgumentException if one of the given aliases is already registered, or
    *         the given command does not implement a registrable {@link Command} subinterface
-   * @see Command for a list of registrable {@link Command} subinterfaces
+   * @see Command for a list of registrable Command subinterfaces
    */
   default void register(String alias, Command command, String... otherAliases) {
     register(metaBuilder(alias).aliases(otherAliases).build(), command);
@@ -65,7 +65,7 @@ public interface CommandManager {
    * @param command the command to register
    * @throws IllegalArgumentException if one of the given aliases is already registered, or
    *         the given command does not implement a registrable {@link Command} subinterface
-   * @see Command for a list of registrable {@link Command} subinterfaces
+   * @see Command for a list of registrable Command subinterfaces
    */
   void register(CommandMeta meta, Command command);
 

api/src/main/java/com/velocitypowered/api/event/player/ServerResourcePackRemoveEvent.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2018-2023 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.player;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.event.ResultedEvent;
+import com.velocitypowered.api.event.annotation.AwaitingEvent;
+import com.velocitypowered.api.proxy.ServerConnection;
+import java.util.UUID;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/**
+ * This event is fired when the downstream server tries to remove a resource pack from player
+ * or clear all of them. The proxy will wait on this event to finish before forwarding the
+ * action to the user. If this event is denied, no resource packs will be removed from player.
+ */
+@AwaitingEvent
+public class ServerResourcePackRemoveEvent implements ResultedEvent<ResultedEvent.GenericResult> {
+
+  private GenericResult result;
+  private final @MonotonicNonNull UUID packId;
+  private final ServerConnection serverConnection;
+
+  /**
+   * Instantiates this event.
+   */
+  public ServerResourcePackRemoveEvent(UUID packId, ServerConnection serverConnection) {
+    this.result = ResultedEvent.GenericResult.allowed();
+    this.packId = packId;
+    this.serverConnection = serverConnection;
+  }
+
+  /**
+   * Returns the id of the resource pack, if it's null all the resource packs
+   * from player will be cleared.
+   *
+   * @return the id
+   */
+  @Nullable
+  public UUID getPackId() {
+    return packId;
+  }
+
+  /**
+   * Returns the server that tries to remove a resource pack from player or clear all of them.
+   *
+   * @return the server connection
+   */
+  public ServerConnection getServerConnection() {
+    return serverConnection;
+  }
+
+  @Override
+  public GenericResult getResult() {
+    return this.result;
+  }
+
+  @Override
+  public void setResult(GenericResult result) {
+    this.result = Preconditions.checkNotNull(result, "result");
+  }
+}

api/src/main/java/com/velocitypowered/api/event/player/configuration/PlayerConfigurationEvent.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.player.configuration;
+
+import com.velocitypowered.api.event.annotation.AwaitingEvent;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.ServerConnection;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is executed when a player entered the configuration state and can be configured by Velocity.
+ * <p>Velocity will wait for this event before continuing/ending the configuration state.</p>
+ *
+ * @param player The player who can be configured.
+ * @param server The server that is currently configuring the player.
+ * @since 3.3.0
+ * @sinceMinecraft 1.20.2
+ */
+@AwaitingEvent
+public record PlayerConfigurationEvent(@NotNull Player player, ServerConnection server) {
+}

api/src/main/java/com/velocitypowered/api/event/player/configuration/PlayerEnterConfigurationEvent.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.player.configuration;
+
+import com.velocitypowered.api.event.annotation.AwaitingEvent;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.ServerConnection;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is executed when a player is about to enter the configuration state.
+ * It is <b>not</b> called for the initial configuration of a player after login.
+ * <p>Velocity will wait for this event before asking the client to enter configuration state.
+ * However due to backend server being unable to keep the connection alive during state changes,
+ * Velocity will only wait for a maximum of 5 seconds.</p>
+ *
+ * @param player The player who is about to enter configuration state.
+ * @param server The server that wants to reconfigure the player.
+ * @since 3.3.0
+ * @sinceMinecraft 1.20.2
+ */
+@AwaitingEvent
+public record PlayerEnterConfigurationEvent(@NotNull Player player, ServerConnection server) {
+}

api/src/main/java/com/velocitypowered/api/event/player/configuration/PlayerEnteredConfigurationEvent.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.player.configuration;
+
+import com.velocitypowered.api.network.ProtocolState;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.ServerConnection;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is executed when a player has entered the configuration state.
+ * <p>From this moment on, until the {@link PlayerFinishedConfigurationEvent} is executed,
+ * the {@linkplain Player#getProtocolState()} method is guaranteed
+ * to return {@link ProtocolState#CONFIGURATION}.</p>
+ *
+ * @param player The player who has entered the configuration state.
+ * @param server The server that will now (re-)configure the player.
+ * @since 3.3.0
+ * @sinceMinecraft 1.20.2
+ */
+public record PlayerEnteredConfigurationEvent(@NotNull Player player, ServerConnection server) {
+}

api/src/main/java/com/velocitypowered/api/event/player/configuration/PlayerFinishConfigurationEvent.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.player.configuration;
+
+import com.velocitypowered.api.event.annotation.AwaitingEvent;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.ServerConnection;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is executed when a player is about to finish the configuration state.
+ * <p>Velocity will wait for this event before asking the client to finish the configuration state.
+ * However due to backend server being unable to keep the connection alive during state changes,
+ * Velocity will only wait for a maximum of 5 seconds. If you need to hold a player in configuration
+ * state, use the {@link PlayerConfigurationEvent}.</p>
+ *
+ * @param player The player who is about to finish the configuration phase.
+ * @param server The server that has (re-)configured the player.
+ * @since 3.3.0
+ * @sinceMinecraft 1.20.2
+ */
+@AwaitingEvent
+public record PlayerFinishConfigurationEvent(@NotNull Player player, @NotNull ServerConnection server) {
+}

api/src/main/java/com/velocitypowered/api/event/player/configuration/PlayerFinishedConfigurationEvent.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.player.configuration;
+
+import com.velocitypowered.api.network.ProtocolState;
+import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.ServerConnection;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is executed when a player has finished the configuration state.
+ * <p>From this moment on, the {@link Player#getProtocolState()} method
+ * will return {@link ProtocolState#PLAY}.</p>
+ *
+ * @param player The player who has finished the configuration state.
+ * @param server The server that has (re-)configured the player.
+ * @since 3.3.0
+ * @sinceMinecraft 1.20.2
+ */
+public record PlayerFinishedConfigurationEvent(@NotNull Player player, @NotNull ServerConnection server) {
+}

api/src/main/java/com/velocitypowered/api/event/proxy/server/ServerRegisteredEvent.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.proxy.server;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.server.RegisteredServer;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is fired by the proxy after a backend server is registered to the server map.
+ * Currently, it may occur when a server is registered dynamically at runtime or when a server is
+ * replaced due to configuration reload.
+ *
+ * @see com.velocitypowered.api.proxy.ProxyServer#registerServer(ServerInfo)
+ *
+ * @param registeredServer A {@link RegisteredServer} that has been registered.
+ * @since 3.3.0
+ */
+@Beta
+public record ServerRegisteredEvent(@NotNull RegisteredServer registeredServer) {
+  public ServerRegisteredEvent {
+    Preconditions.checkNotNull(registeredServer, "registeredServer");
+  }
+}

api/src/main/java/com/velocitypowered/api/event/proxy/server/ServerUnregisteredEvent.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.event.proxy.server;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.server.RegisteredServer;
+import com.velocitypowered.api.proxy.server.ServerInfo;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * This event is fired by the proxy after a backend server is unregistered from the server map.
+ * Currently, it may occur when a server is unregistered dynamically at runtime
+ * or when a server is replaced due to configuration reload.
+ *
+ * @see com.velocitypowered.api.proxy.ProxyServer#unregisterServer(ServerInfo)
+ *
+ * @param unregisteredServer A {@link RegisteredServer} that has been unregistered.
+ * @since 3.3.0
+ */
+@Beta
+public record ServerUnregisteredEvent(@NotNull RegisteredServer unregisteredServer) {
+  public ServerUnregisteredEvent {
+    Preconditions.checkNotNull(unregisteredServer, "unregisteredServer");
+  }
+}

api/src/main/java/com/velocitypowered/api/network/ProtocolVersion.java

@@ -87,7 +87,7 @@ public enum ProtocolVersion implements Ordered<ProtocolVersion> {
   MINECRAFT_1_20_2(764, "1.20.2"),
   MINECRAFT_1_20_3(765, "1.20.3", "1.20.4"),
   MINECRAFT_1_20_5(766, "1.20.5", "1.20.6"),
-  MINECRAFT_1_21(767, "1.21");
+  MINECRAFT_1_21(767, "1.21", "1.21.1");
 
   private static final int SNAPSHOT_BIT = 30;
 

api/src/main/java/com/velocitypowered/api/proxy/Player.java

@@ -21,6 +21,7 @@ import com.velocitypowered.api.proxy.player.TabList;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.api.util.ServerLink;
 import java.net.InetSocketAddress;
 import java.util.Collection;
 import java.util.List;
@@ -461,4 +462,16 @@ public interface Player extends
    * @sinceMinecraft 1.20.5
    */
   void requestCookie(Key key);
+
+  /**
+   * Send the player a list of custom links to display in their client's pause menu.
+   *
+   * <p>Note that later packets sent by the backend server may override links sent by the proxy.
+   *
+   * @param links an ordered list of {@link ServerLink}s to send to the player
+   * @throws IllegalArgumentException if the player is from a version lower than 1.21
+   * @since 3.3.0
+   * @sinceMinecraft 1.21
+   */
+  void setServerLinks(@NotNull List<ServerLink> links);
 }

api/src/main/java/com/velocitypowered/api/util/ServerLink.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2021-2024 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.util;
+
+import com.google.common.base.Preconditions;
+import java.net.URI;
+import java.util.Optional;
+import net.kyori.adventure.text.Component;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Represents a custom URL servers can show in player pause menus.
+ * Links can be of a built-in type or use a custom component text label.
+ */
+public final class ServerLink {
+
+  private @Nullable Type type;
+  private @Nullable Component label;
+  private final URI url;
+
+  private ServerLink(Component label, String url) {
+    this.label = Preconditions.checkNotNull(label, "label");
+    this.url = URI.create(url);
+  }
+
+  private ServerLink(Type type, String url) {
+    this.type = Preconditions.checkNotNull(type, "type");
+    this.url = URI.create(url);
+  }
+
+  /**
+   * Construct a server link with a custom component label.
+   *
+   * @param label a custom component label to display
+   * @param link  the URL to open when clicked
+   */
+  public static ServerLink serverLink(Component label, String link) {
+    return new ServerLink(label, link);
+  }
+
+  /**
+   * Construct a server link with a built-in type.
+   *
+   * @param type the {@link Type built-in type} of link
+   * @param link the URL to open when clicked
+   */
+  public static ServerLink serverLink(Type type, String link) {
+    return new ServerLink(type, link);
+  }
+
+  /**
+   * Get the type of the server link.
+   *
+   * @return the type of the server link
+   */
+  public Optional<Type> getBuiltInType() {
+    return Optional.ofNullable(type);
+  }
+
+  /**
+   * Get the custom component label of the server link.
+   *
+   * @return the custom component label of the server link
+   */
+  public Optional<Component> getCustomLabel() {
+    return Optional.ofNullable(label);
+  }
+
+  /**
+   * Get the link {@link URI}.
+   *
+   * @return the link {@link URI}
+   */
+  public URI getUrl() {
+    return url;
+  }
+
+  /**
+   * Built-in types of server links.
+   *
+   * @apiNote {@link Type#BUG_REPORT} links are shown on the connection error screen
+   */
+  public enum Type {
+    BUG_REPORT,
+    COMMUNITY_GUIDELINES,
+    SUPPORT,
+    STATUS,
+    FEEDBACK,
+    COMMUNITY,
+    WEBSITE,
+    FORUMS,
+    NEWS,
+    ANNOUNCEMENTS
+  }
+
+}

gradle/libs.versions.toml

@@ -11,7 +11,7 @@ shadow = "io.github.goooler.shadow:8.1.5"
 spotless = "com.diffplug.spotless:6.25.0"
 
 [libraries]
-adventure-bom = "net.kyori:adventure-bom:4.16.0"
+adventure-bom = "net.kyori:adventure-bom:4.17.0"
 adventure-facet = "net.kyori:adventure-platform-facet:4.3.2"
 asm = "org.ow2.asm:asm:9.6"
 auto-service = "com.google.auto.service:auto-service:1.0.1"

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -45,7 +45,7 @@ import com.velocitypowered.proxy.command.builtin.ShutdownCommand;
 import com.velocitypowered.proxy.command.builtin.VelocityCommand;
 import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.connection.util.ServerListPingHandler;
 import com.velocitypowered.proxy.console.VelocityConsole;
 import com.velocitypowered.proxy.crypto.EncryptionUtils;

proxy/src/main/java/com/velocitypowered/proxy/command/builtin/VelocityCommand.java

@@ -379,7 +379,7 @@ public final class VelocityCommand {
                 this.heapGenerator.invoke(hotspotMbean, file.toString(), true);
               } catch (Throwable e1) {
                 // This should not occur
-                throw new RuntimeException(e);
+                throw new RuntimeException(e1);
               }
               src.sendMessage(Component.text("Heap dump saved to " + file, NamedTextColor.GREEN));
             };

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -60,7 +60,7 @@ public class VelocityConfiguration implements ProxyConfig {
   private static final Logger logger = LogManager.getLogger(VelocityConfiguration.class);
 
   @Expose
-  private String bind = "0.0.0.0:25577";
+  private String bind = "0.0.0.0:25565";
   @Expose
   private String motd = "<aqua>A Velocity Server";
   @Expose
@@ -503,7 +503,7 @@ public class VelocityConfiguration implements ProxyConfig {
       final PingPassthroughMode pingPassthroughMode = config.getEnumOrElse("ping-passthrough",
               PingPassthroughMode.DISABLED);
 
-      final String bind = config.getOrElse("bind", "0.0.0.0:25577");
+      final String bind = config.getOrElse("bind", "0.0.0.0:25565");
       final int maxPlayers = config.getIntOrElse("show-max-players", 500);
       final boolean onlineMode = config.getOrElse("online-mode", true);
       final boolean forceKeyAuthentication = config.getOrElse("force-key-authentication", true);
@@ -830,7 +830,7 @@ public class VelocityConfiguration implements ProxyConfig {
     @Expose
     private boolean queryEnabled = false;
     @Expose
-    private int queryPort = 25577;
+    private int queryPort = 25565;
     @Expose
     private String queryMap = "Velocity";
     @Expose
@@ -849,7 +849,7 @@ public class VelocityConfiguration implements ProxyConfig {
     private Query(CommentedConfig config) {
       if (config != null) {
         this.queryEnabled = config.getOrElse("enabled", false);
-        this.queryPort = config.getIntOrElse("port", 25577);
+        this.queryPort = config.getIntOrElse("port", 25565);
         this.queryMap = config.getOrElse("map", "Velocity");
         this.showPlugins = config.getOrElse("show-plugins", false);
       }

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftConnection.java

@@ -47,7 +47,8 @@ import com.velocitypowered.proxy.protocol.netty.MinecraftCompressorAndLengthEnco
 import com.velocitypowered.proxy.protocol.netty.MinecraftDecoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
 import com.velocitypowered.proxy.protocol.netty.MinecraftVarintLengthEncoder;
-import com.velocitypowered.proxy.protocol.netty.PlayPacketQueueHandler;
+import com.velocitypowered.proxy.protocol.netty.PlayPacketQueueInboundHandler;
+import com.velocitypowered.proxy.protocol.netty.PlayPacketQueueOutboundHandler;
 import com.velocitypowered.proxy.protocol.packet.SetCompressionPacket;
 import com.velocitypowered.proxy.util.except.QuietDecoderException;
 import io.netty.buffer.ByteBuf;
@@ -148,13 +149,11 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
         return;
       }
 
-      if (msg instanceof MinecraftPacket) {
+      if (msg instanceof MinecraftPacket pkt) {
-        MinecraftPacket pkt = (MinecraftPacket) msg;
         if (!pkt.handle(activeSessionHandler)) {
           activeSessionHandler.handleGeneric((MinecraftPacket) msg);
         }
-      } else if (msg instanceof HAProxyMessage) {
+      } else if (msg instanceof HAProxyMessage proxyMessage) {
-        HAProxyMessage proxyMessage = (HAProxyMessage) msg;
         this.remoteAddress = new InetSocketAddress(proxyMessage.sourceAddress(),
             proxyMessage.sourcePort());
       } else if (msg instanceof ByteBuf) {
@@ -383,9 +382,14 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
     if (state == StateRegistry.CONFIG) {
       // Activate the play packet queue
       addPlayPacketQueueHandler();
-    } else if (this.channel.pipeline().get(Connections.PLAY_PACKET_QUEUE) != null) {
+    } else {
       // Remove the queue
-      this.channel.pipeline().remove(Connections.PLAY_PACKET_QUEUE);
+      if (this.channel.pipeline().get(Connections.PLAY_PACKET_QUEUE_OUTBOUND) != null) {
+        this.channel.pipeline().remove(Connections.PLAY_PACKET_QUEUE_OUTBOUND);
+      }
+      if (this.channel.pipeline().get(Connections.PLAY_PACKET_QUEUE_INBOUND) != null) {
+        this.channel.pipeline().remove(Connections.PLAY_PACKET_QUEUE_INBOUND);
+      }
     }
   }
 
@@ -393,10 +397,13 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
    * Adds the play packet queue handler.
    */
   public void addPlayPacketQueueHandler() {
-    if (this.channel.pipeline().get(Connections.PLAY_PACKET_QUEUE) == null) {
+    if (this.channel.pipeline().get(Connections.PLAY_PACKET_QUEUE_OUTBOUND) == null) {
-      this.channel.pipeline().addAfter(Connections.MINECRAFT_ENCODER, Connections.PLAY_PACKET_QUEUE,
+      this.channel.pipeline().addAfter(Connections.MINECRAFT_ENCODER, Connections.PLAY_PACKET_QUEUE_OUTBOUND,
-          new PlayPacketQueueHandler(this.protocolVersion,
+           new PlayPacketQueueOutboundHandler(this.protocolVersion, channel.pipeline().get(MinecraftEncoder.class).getDirection()));
-              channel.pipeline().get(MinecraftEncoder.class).getDirection()));
+    }
+    if (this.channel.pipeline().get(Connections.PLAY_PACKET_QUEUE_INBOUND) == null) {
+      this.channel.pipeline().addAfter(Connections.MINECRAFT_DECODER, Connections.PLAY_PACKET_QUEUE_INBOUND,
+           new PlayPacketQueueInboundHandler(this.protocolVersion, channel.pipeline().get(MinecraftDecoder.class).getDirection()));
     }
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -29,6 +29,7 @@ import com.velocitypowered.api.event.connection.PreTransferEvent;
 import com.velocitypowered.api.event.player.CookieRequestEvent;
 import com.velocitypowered.api.event.player.CookieStoreEvent;
 import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
+import com.velocitypowered.api.event.player.ServerResourcePackRemoveEvent;
 import com.velocitypowered.api.event.player.ServerResourcePackSendEvent;
 import com.velocitypowered.api.event.proxy.ProxyPingEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
@@ -40,8 +41,8 @@ import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.VelocityResourcePackInfo;
-import com.velocitypowered.proxy.connection.player.resourcepack.ResourcePackHandler;
+import com.velocitypowered.proxy.connection.player.resourcepack.handler.ResourcePackHandler;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.StateRegistry;
@@ -258,6 +259,13 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(RemoveResourcePackPacket packet) {
+    final ServerResourcePackRemoveEvent event = new ServerResourcePackRemoveEvent(
+            packet.getId(), this.serverConn);
+    server.getEventManager().fire(event).thenAcceptAsync(serverResourcePackRemoveEvent -> {
+      if (playerConnection.isClosed()) {
+        return;
+      }
+      if (serverResourcePackRemoveEvent.getResult().isAllowed()) {
         final ConnectedPlayer player = serverConn.getPlayer();
         final ResourcePackHandler handler = player.resourcePackHandler();
         if (packet.getId() != null) {
@@ -266,6 +274,11 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
           handler.clearAppliedResourcePacks();
         }
         playerConnection.write(packet);
+      }
+    }, playerConnection.eventLoop()).exceptionally((ex) -> {
+      logger.error("Exception while handling resource pack remove for {}", playerConnection, ex);
+      return null;
+    });
     return true;
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BungeeCordMessageResponder.java

@@ -37,7 +37,6 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import java.util.Optional;
 import java.util.StringJoiner;
-import net.kyori.adventure.identity.Identity;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.serializer.ComponentSerializer;
 import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
@@ -143,7 +142,7 @@ public class BungeeCordMessageResponder {
         out.writeUTF("PlayerList");
         out.writeUTF(info.getServerInfo().getName());
 
-        StringJoiner joiner = new StringJoiner(", ");
+        final StringJoiner joiner = new StringJoiner(", ");
         for (Player online : info.getPlayersConnected()) {
           joiner.add(online.getUsername());
         }
@@ -187,10 +186,9 @@ public class BungeeCordMessageResponder {
 
     Component messageComponent = serializer.deserialize(message);
     if (target.equals("ALL")) {
-      proxy.sendMessage(Identity.nil(), messageComponent);
+      proxy.sendMessage(messageComponent);
     } else {
-      proxy.getPlayer(target).ifPresent(player -> player.sendMessage(Identity.nil(),
+      proxy.getPlayer(target).ifPresent(player -> player.sendMessage(messageComponent));
-          messageComponent));
     }
   }
 
@@ -262,6 +260,13 @@ public class BungeeCordMessageResponder {
     });
   }
 
+  private void processKickRaw(ByteBufDataInput in) {
+    proxy.getPlayer(in.readUTF()).ifPresent(player -> {
+      String kickReason = in.readUTF();
+      player.disconnect(GsonComponentSerializer.gson().deserialize(kickReason));
+    });
+  }
+
   private void processForwardToPlayer(ByteBufDataInput in) {
     Optional<Player> player = proxy.getPlayer(in.readUTF());
     if (player.isPresent()) {
@@ -374,6 +379,9 @@ public class BungeeCordMessageResponder {
       case "KickPlayer":
         this.processKick(in);
         break;
+      case "KickPlayerRaw":
+        this.processKickRaw(in);
+        break;
       default:
         // Do nothing, unknown command
         break;

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/ConfigSessionHandler.java

@@ -21,6 +21,7 @@ import com.velocitypowered.api.event.connection.PreTransferEvent;
 import com.velocitypowered.api.event.player.CookieRequestEvent;
 import com.velocitypowered.api.event.player.CookieStoreEvent;
 import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
+import com.velocitypowered.api.event.player.ServerResourcePackRemoveEvent;
 import com.velocitypowered.api.event.player.ServerResourcePackSendEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;
@@ -29,7 +30,8 @@ import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.client.ClientConfigSessionHandler;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.handler.ResourcePackHandler;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
@@ -41,6 +43,7 @@ import com.velocitypowered.proxy.protocol.packet.ClientboundStoreCookiePacket;
 import com.velocitypowered.proxy.protocol.packet.DisconnectPacket;
 import com.velocitypowered.proxy.protocol.packet.KeepAlivePacket;
 import com.velocitypowered.proxy.protocol.packet.PluginMessagePacket;
+import com.velocitypowered.proxy.protocol.packet.RemoveResourcePackPacket;
 import com.velocitypowered.proxy.protocol.packet.ResourcePackRequestPacket;
 import com.velocitypowered.proxy.protocol.packet.ResourcePackResponsePacket;
 import com.velocitypowered.proxy.protocol.packet.TransferPacket;
@@ -132,7 +135,8 @@ public class ConfigSessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(KeepAlivePacket packet) {
-    serverConn.ensureConnected().write(packet);
+    serverConn.getPendingPings().put(packet.getRandomId(), System.nanoTime());
+    serverConn.getPlayer().getConnection().write(packet);
     return true;
   }
 
@@ -192,31 +196,53 @@ public class ConfigSessionHandler implements MinecraftSessionHandler {
   }
 
   @Override
-  public boolean handle(FinishedUpdatePacket packet) {
+  public boolean handle(RemoveResourcePackPacket packet) {
-    MinecraftConnection smc = serverConn.ensureConnected();
+    final MinecraftConnection playerConnection = this.serverConn.getPlayer().getConnection();
-    ConnectedPlayer player = serverConn.getPlayer();
+
-    ClientConfigSessionHandler configHandler =
+    final ServerResourcePackRemoveEvent event = new ServerResourcePackRemoveEvent(
-        (ClientConfigSessionHandler) player.getConnection().getActiveSessionHandler();
+            packet.getId(), this.serverConn);
+    server.getEventManager().fire(event).thenAcceptAsync(serverResourcePackRemoveEvent -> {
+      if (playerConnection.isClosed()) {
+        return;
+      }
+      if (serverResourcePackRemoveEvent.getResult().isAllowed()) {
+        final ConnectedPlayer player = serverConn.getPlayer();
+        final ResourcePackHandler handler = player.resourcePackHandler();
+        if (packet.getId() != null) {
+          handler.remove(packet.getId());
+        } else {
+          handler.clearAppliedResourcePacks();
+        }
+        playerConnection.write(packet);
+      }
+    }, playerConnection.eventLoop()).exceptionally((ex) -> {
+      logger.error("Exception while handling resource pack remove for {}", playerConnection, ex);
+      return null;
+    });
+    return true;
+  }
+
+  @Override
+  public boolean handle(FinishedUpdatePacket packet) {
+    final MinecraftConnection smc = serverConn.ensureConnected();
+    final ConnectedPlayer player = serverConn.getPlayer();
+    final ClientConfigSessionHandler configHandler = (ClientConfigSessionHandler) player.getConnection().getActiveSessionHandler();
 
-    smc.setAutoReading(false);
-    // Even when not auto reading messages are still decoded. Decode them with the correct state
     smc.getChannel().pipeline().get(MinecraftDecoder.class).setState(StateRegistry.PLAY);
-    configHandler.handleBackendFinishUpdate(serverConn).thenAcceptAsync((unused) -> {
+    //noinspection DataFlowIssue
+    configHandler.handleBackendFinishUpdate(serverConn).thenRunAsync(() -> {
+      smc.write(FinishedUpdatePacket.INSTANCE);
       if (serverConn == player.getConnectedServer()) {
         smc.setActiveSessionHandler(StateRegistry.PLAY);
-        player.sendPlayerListHeaderAndFooter(
+        player.sendPlayerListHeaderAndFooter(player.getPlayerListHeader(), player.getPlayerListFooter());
-            player.getPlayerListHeader(), player.getPlayerListFooter());
         // The client cleared the tab list. TODO: Restore changes done via TabList API
         player.getTabList().clearAllSilent();
       } else {
-        smc.setActiveSessionHandler(StateRegistry.PLAY,
+        smc.setActiveSessionHandler(StateRegistry.PLAY, new TransitionSessionHandler(server, serverConn, resultFuture));
-            new TransitionSessionHandler(server, serverConn, resultFuture));
       }
-      if (player.resourcePackHandler().getFirstAppliedPack() == null
+      if (player.resourcePackHandler().getFirstAppliedPack() == null && resourcePackToApply != null) {
-              && resourcePackToApply != null) {
         player.resourcePackHandler().queueResourcePack(resourcePackToApply);
       }
-      smc.setAutoReading(true);
     }, smc.eventLoop());
     return true;
   }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/LoginSessionHandler.java

@@ -19,6 +19,7 @@ package com.velocitypowered.proxy.connection.backend;
 
 import com.velocitypowered.api.event.player.CookieRequestEvent;
 import com.velocitypowered.api.event.player.ServerLoginPluginMessageEvent;
+import com.velocitypowered.api.event.player.configuration.PlayerEnteredConfigurationEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
 import com.velocitypowered.proxy.VelocityServer;
@@ -142,10 +143,8 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(ServerLoginSuccessPacket packet) {
-    if (server.getConfiguration().getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN
+    if (server.getConfiguration().getPlayerInfoForwardingMode() == PlayerInfoForwarding.MODERN && !informationForwarded) {
-        && !informationForwarded) {
+      resultFuture.complete(ConnectionRequestResults.forDisconnect(MODERN_IP_FORWARDING_FAILURE, serverConn.getServer()));
-      resultFuture.complete(ConnectionRequestResults.forDisconnect(MODERN_IP_FORWARDING_FAILURE,
-          serverConn.getServer()));
       serverConn.disconnect();
       return true;
     }
@@ -156,22 +155,20 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
     // Move into the PLAY phase.
     MinecraftConnection smc = serverConn.ensureConnected();
     if (smc.getProtocolVersion().lessThan(ProtocolVersion.MINECRAFT_1_20_2)) {
-      smc.setActiveSessionHandler(StateRegistry.PLAY,
+      smc.setActiveSessionHandler(StateRegistry.PLAY, new TransitionSessionHandler(server, serverConn, resultFuture));
-          new TransitionSessionHandler(server, serverConn, resultFuture));
     } else {
       smc.write(new LoginAcknowledgedPacket());
-      smc.setActiveSessionHandler(StateRegistry.CONFIG,
+      smc.setActiveSessionHandler(StateRegistry.CONFIG, new ConfigSessionHandler(server, serverConn, resultFuture));
-          new ConfigSessionHandler(server, serverConn, resultFuture));
       ConnectedPlayer player = serverConn.getPlayer();
       if (player.getClientSettingsPacket() != null) {
         smc.write(player.getClientSettingsPacket());
       }
-      if (player.getConnection().getActiveSessionHandler() instanceof ClientPlaySessionHandler) {
+      if (player.getConnection().getActiveSessionHandler() instanceof ClientPlaySessionHandler clientPlaySessionHandler) {
         smc.setAutoReading(false);
-        ((ClientPlaySessionHandler) player.getConnection()
+        clientPlaySessionHandler.doSwitch().thenAcceptAsync((unused) -> smc.setAutoReading(true), smc.eventLoop());
-            .getActiveSessionHandler()).doSwitch().thenAcceptAsync((unused) -> {
+      } else {
-              smc.setAutoReading(true);
+        // Initial login - the player is already in configuration state.
-            }, smc.eventLoop());
+        server.getEventManager().fireAndForget(new PlayerEnteredConfigurationEvent(player, serverConn));
       }
     }
 
@@ -211,7 +208,7 @@ public class LoginSessionHandler implements MinecraftSessionHandler {
               The connection to the remote server was unexpectedly closed.
               This is usually because the remote server does not have \
               BungeeCord IP forwarding correctly enabled.
-              See https://velocitypowered.com/wiki/users/forwarding/ for instructions \
+              See https://docs.papermc.io/velocity/player-information-forwarding for instructions \
               on how to configure player info forwarding correctly."""));
     } else {
       resultFuture.completeExceptionally(

proxy/src/main/java/com/velocitypowered/proxy/connection/client/AuthSessionHandler.java

@@ -178,11 +178,11 @@ public class AuthSessionHandler implements MinecraftSessionHandler {
       inbound.disconnect(Component.translatable("multiplayer.disconnect.invalid_player_data"));
     } else {
       loginState = State.ACKNOWLEDGED;
-      mcConnection.setActiveSessionHandler(StateRegistry.CONFIG,
+      mcConnection.setActiveSessionHandler(StateRegistry.CONFIG, new ClientConfigSessionHandler(server, connectedPlayer));
-          new ClientConfigSessionHandler(server, connectedPlayer));
 
-      server.getEventManager().fire(new PostLoginEvent(connectedPlayer))
+      server.getEventManager().fire(new PostLoginEvent(connectedPlayer)).thenCompose(ignored -> {
-          .thenCompose((ignored) -> connectToInitialServer(connectedPlayer)).exceptionally((ex) -> {
+        return connectToInitialServer(connectedPlayer);
+      }).exceptionally((ex) -> {
         logger.error("Exception while connecting {} to initial server", connectedPlayer, ex);
         return null;
       });
@@ -224,8 +224,7 @@ public class AuthSessionHandler implements MinecraftSessionHandler {
         player.disconnect0(reason.get(), true);
       } else {
         if (!server.registerConnection(player)) {
-          player.disconnect0(Component.translatable("velocity.error.already-connected-proxy"),
+          player.disconnect0(Component.translatable("velocity.error.already-connected-proxy"), true);
-              true);
           return;
         }
 
@@ -238,10 +237,10 @@ public class AuthSessionHandler implements MinecraftSessionHandler {
         loginState = State.SUCCESS_SENT;
         if (inbound.getProtocolVersion().lessThan(ProtocolVersion.MINECRAFT_1_20_2)) {
           loginState = State.ACKNOWLEDGED;
-          mcConnection.setActiveSessionHandler(StateRegistry.PLAY,
+          mcConnection.setActiveSessionHandler(StateRegistry.PLAY, new InitialConnectSessionHandler(player, server));
-              new InitialConnectSessionHandler(player, server));
+          server.getEventManager().fire(new PostLoginEvent(player)).thenCompose((ignored) -> {
-          server.getEventManager().fire(new PostLoginEvent(player))
+            return connectToInitialServer(player);
-              .thenCompose((ignored) -> connectToInitialServer(player)).exceptionally((ex) -> {
+          }).exceptionally((ex) -> {
             logger.error("Exception while connecting {} to initial server", player, ex);
             return null;
           });

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientConfigSessionHandler.java

@@ -19,6 +19,9 @@ package com.velocitypowered.proxy.connection.client;
 
 import com.velocitypowered.api.event.player.CookieReceiveEvent;
 import com.velocitypowered.api.event.player.PlayerClientBrandEvent;
+import com.velocitypowered.api.event.player.configuration.PlayerConfigurationEvent;
+import com.velocitypowered.api.event.player.configuration.PlayerFinishConfigurationEvent;
+import com.velocitypowered.api.event.player.configuration.PlayerFinishedConfigurationEvent;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
@@ -46,8 +49,6 @@ import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 /**
  * Handles the client config stage.
@@ -59,6 +60,7 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
   private final ConnectedPlayer player;
   private String brandChannel = null;
 
+  private CompletableFuture<?> configurationFuture;
   private CompletableFuture<Void> configSwitchFuture;
 
   /**
@@ -78,12 +80,13 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
   }
 
   @Override
-  public boolean handle(final KeepAlivePacket packet) {
+  public void deactivated() {
-    final VelocityServerConnection serverConnection = player.getConnectedServer();
+    configurationFuture = null;
-    if (!this.sendKeepAliveToBackend(serverConnection, packet)) {
-      final VelocityServerConnection connectionInFlight = player.getConnectionInFlight();
-      this.sendKeepAliveToBackend(connectionInFlight, packet);
   }
+
+  @Override
+  public boolean handle(final KeepAlivePacket packet) {
+    player.forwardKeepAlive(packet);
     return true;
   }
 
@@ -104,8 +107,7 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(FinishedUpdatePacket packet) {
-    player.getConnection()
+    player.getConnection().setActiveSessionHandler(StateRegistry.PLAY, new ClientPlaySessionHandler(server, player));
-        .setActiveSessionHandler(StateRegistry.PLAY, new ClientPlaySessionHandler(server, player));
 
     configSwitchFuture.complete(null);
     return true;
@@ -139,12 +141,14 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(KnownPacksPacket packet) {
-    if (player.getConnectionInFlight() != null) {
+    callConfigurationEvent().thenRun(() -> {
-      player.getConnectionInFlight().ensureConnected().write(packet);
+      player.getConnectionInFlightOrConnectedServer().ensureConnected().write(packet);
-      return true;
+    }).exceptionally(ex -> {
-    }
+      logger.error("Error forwarding known packs response to backend:", ex);
+      return null;
+    });
 
-    return false;
+    return true;
   }
 
   @Override
@@ -207,26 +211,25 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
 
   @Override
   public void exception(Throwable throwable) {
-    player.disconnect(
+    player.disconnect(Component.translatable("velocity.error.player-connection-error", NamedTextColor.RED));
-        Component.translatable("velocity.error.player-connection-error", NamedTextColor.RED));
   }
 
-  private boolean sendKeepAliveToBackend(
+  /**
-          final @Nullable VelocityServerConnection serverConnection,
+   * Calls the {@link PlayerConfigurationEvent}.
-          final @NotNull KeepAlivePacket packet
+   * For 1.20.5+ backends this is done when the client responds to
-  ) {
+   * the known packs request. The response is delayed until the event
-    if (serverConnection != null) {
+   * has been called.
-      final Long sentTime = serverConnection.getPendingPings().remove(packet.getRandomId());
+   * For 1.20.2-1.20.4 servers this is done when the client acknowledges
-      if (sentTime != null) {
+   * the end of the configuration.
-        final MinecraftConnection smc = serverConnection.getConnection();
+   * This is handled differently because for 1.20.5+ servers can't keep
-        if (smc != null) {
+   * their connection alive between states and older servers don't have
-          player.setPing(TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - sentTime));
+   * the known packs transaction.
-          smc.write(packet);
+   */
-          return true;
+  private CompletableFuture<?> callConfigurationEvent() {
+    if (configurationFuture != null) {
+      return configurationFuture;
     }
-      }
+    return configurationFuture = server.getEventManager().fire(new PlayerConfigurationEvent(player, player.getConnectionInFlightOrConnectedServer()));
-    }
-    return false;
   }
 
   /**
@@ -246,14 +249,18 @@ public class ClientConfigSessionHandler implements MinecraftSessionHandler {
       smc.write(brandPacket);
     }
 
-    player.getConnection().eventLoop().execute(() -> {
+    callConfigurationEvent().thenCompose(v -> {
+      return server.getEventManager().fire(new PlayerFinishConfigurationEvent(player, serverConn))
+          .completeOnTimeout(null, 5, TimeUnit.SECONDS);
+    }).thenRunAsync(() -> {
       player.getConnection().write(FinishedUpdatePacket.INSTANCE);
       player.getConnection().getChannel().pipeline().get(MinecraftEncoder.class).setState(StateRegistry.PLAY);
+      server.getEventManager().fireAndForget(new PlayerFinishedConfigurationEvent(player, serverConn));
+    }, player.getConnection().eventLoop()).exceptionally(ex -> {
+      logger.error("Error finishing configuration state:", ex);
+      return null;
     });
 
-    smc.write(FinishedUpdatePacket.INSTANCE);
-    smc.getChannel().pipeline().get(MinecraftEncoder.class).setState(StateRegistry.PLAY);
-
     return configSwitchFuture;
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -27,6 +27,7 @@ import com.velocitypowered.api.event.player.CookieReceiveEvent;
 import com.velocitypowered.api.event.player.PlayerChannelRegisterEvent;
 import com.velocitypowered.api.event.player.PlayerClientBrandEvent;
 import com.velocitypowered.api.event.player.TabCompleteEvent;
+import com.velocitypowered.api.event.player.configuration.PlayerEnteredConfigurationEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
@@ -53,6 +54,7 @@ import com.velocitypowered.proxy.protocol.packet.ServerboundCookieResponsePacket
 import com.velocitypowered.proxy.protocol.packet.TabCompleteRequestPacket;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponsePacket;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponsePacket.Offer;
+import com.velocitypowered.proxy.protocol.packet.chat.ChatAcknowledgementPacket;
 import com.velocitypowered.proxy.protocol.packet.chat.ChatHandler;
 import com.velocitypowered.proxy.protocol.packet.chat.ChatTimeKeeper;
 import com.velocitypowered.proxy.protocol.packet.chat.CommandHandler;
@@ -84,7 +86,6 @@ import java.util.Queue;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentLinkedQueue;
-import java.util.concurrent.TimeUnit;
 import net.kyori.adventure.key.Key;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
@@ -176,17 +177,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(KeepAlivePacket packet) {
-    final VelocityServerConnection serverConnection = player.getConnectedServer();
+    player.forwardKeepAlive(packet);
-    if (serverConnection != null) {
-      final Long sentTime = serverConnection.getPendingPings().remove(packet.getRandomId());
-      if (sentTime != null) {
-        final MinecraftConnection smc = serverConnection.getConnection();
-        if (smc != null) {
-          player.setPing(TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - sentTime));
-          smc.write(packet);
-        }
-      }
-    }
     return true;
   }
 
@@ -406,6 +397,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     // Complete client switch
     player.getConnection().setActiveSessionHandler(StateRegistry.CONFIG);
     VelocityServerConnection serverConnection = player.getConnectedServer();
+    server.getEventManager().fireAndForget(new PlayerEnteredConfigurationEvent(player, serverConnection));
     if (serverConnection != null) {
       MinecraftConnection smc = serverConnection.ensureConnected();
       CompletableFuture.runAsync(() -> {
@@ -421,6 +413,15 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     return true;
   }
 
+  @Override
+  public boolean handle(ChatAcknowledgementPacket packet) {
+    if (player.getCurrentServer().isEmpty()) {
+      return true;
+    }
+    player.getChatQueue().handleAcknowledgement(packet.offset());
+    return true;
+  }
+
   @Override
   public boolean handle(ServerboundCookieResponsePacket packet) {
     server.getEventManager()
@@ -512,7 +513,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
    * @return a future that completes when the switch is complete
    */
   public CompletableFuture<Void> doSwitch() {
-    VelocityServerConnection existingConnection = player.getConnectedServer();
+    final VelocityServerConnection existingConnection = player.getConnectedServer();
 
     if (existingConnection != null) {
       // Shut down the existing server connection.

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -37,6 +37,7 @@ import com.velocitypowered.api.event.player.KickedFromServerEvent.ServerKickResu
 import com.velocitypowered.api.event.player.PlayerModInfoEvent;
 import com.velocitypowered.api.event.player.PlayerSettingsChangedEvent;
 import com.velocitypowered.api.event.player.ServerPreConnectEvent;
+import com.velocitypowered.api.event.player.configuration.PlayerEnterConfigurationEvent;
 import com.velocitypowered.api.network.ProtocolState;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.permission.PermissionFunction;
@@ -54,18 +55,21 @@ import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.api.util.ServerLink;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.adventure.VelocityBossBarImplementation;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
-import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.bundle.BundleDelimiterHandler;
-import com.velocitypowered.proxy.connection.player.resourcepack.ResourcePackHandler;
+import com.velocitypowered.proxy.connection.player.resourcepack.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.handler.ResourcePackHandler;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.connection.util.VelocityInboundConnection;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.netty.MinecraftEncoder;
+import com.velocitypowered.proxy.protocol.packet.BundleDelimiterPacket;
 import com.velocitypowered.proxy.protocol.packet.ClientSettingsPacket;
 import com.velocitypowered.proxy.protocol.packet.ClientboundCookieRequestPacket;
 import com.velocitypowered.proxy.protocol.packet.ClientboundStoreCookiePacket;
@@ -80,7 +84,9 @@ import com.velocitypowered.proxy.protocol.packet.chat.ChatType;
 import com.velocitypowered.proxy.protocol.packet.chat.ComponentHolder;
 import com.velocitypowered.proxy.protocol.packet.chat.PlayerChatCompletionPacket;
 import com.velocitypowered.proxy.protocol.packet.chat.builder.ChatBuilderFactory;
+import com.velocitypowered.proxy.protocol.packet.chat.builder.ChatBuilderV2;
 import com.velocitypowered.proxy.protocol.packet.chat.legacy.LegacyChatPacket;
+import com.velocitypowered.proxy.protocol.packet.config.ClientboundServerLinksPacket;
 import com.velocitypowered.proxy.protocol.packet.config.StartUpdatePacket;
 import com.velocitypowered.proxy.protocol.packet.title.GenericTitlePacket;
 import com.velocitypowered.proxy.protocol.util.ByteBufDataOutput;
@@ -106,6 +112,7 @@ import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
 import net.kyori.adventure.audience.MessageType;
 import net.kyori.adventure.bossbar.BossBar;
 import net.kyori.adventure.identity.Identity;
@@ -629,6 +636,10 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
     return connectionInFlight;
   }
 
+  public VelocityServerConnection getConnectionInFlightOrConnectedServer() {
+    return connectionInFlight != null ? connectionInFlight : connectedServer;
+  }
+
   public void resetInFlightConnection() {
     connectionInFlight = null;
   }
@@ -806,7 +817,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
             }, connection.eventLoop());
       } else if (event.getResult() instanceof final Notify res) {
         if (event.kickedDuringServerConnect() && previousConnection != null) {
-          sendMessage(Identity.nil(), res.getMessageComponent());
+          sendMessage(res.getMessageComponent());
         } else {
           disconnect(res.getMessageComponent());
         }
@@ -1057,6 +1068,22 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
         }, connection.eventLoop());
   }
 
+  @Override
+  public void setServerLinks(final @NotNull List<ServerLink> links) {
+    Preconditions.checkNotNull(links, "links");
+    Preconditions.checkArgument(
+        this.getProtocolVersion().noLessThan(ProtocolVersion.MINECRAFT_1_21),
+        "Player version must be at least 1.21 to be able to set server links");
+
+    if (connection.getState() != StateRegistry.PLAY
+        && connection.getState() != StateRegistry.CONFIG) {
+      throw new IllegalStateException("Can only send server links in CONFIGURATION or PLAY protocol");
+    }
+
+    connection.write(new ClientboundServerLinksPacket(List.copyOf(links).stream()
+        .map(l -> new ClientboundServerLinksPacket.ServerLink(l, getProtocolVersion())).toList()));
+  }
+
   @Override
   public void addCustomChatCompletions(@NotNull Collection<String> completions) {
     Preconditions.checkNotNull(completions, "completions");
@@ -1088,10 +1115,11 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
         "input cannot be greater than " + LegacyChatPacket.MAX_SERVERBOUND_MESSAGE_LENGTH
             + " characters in length");
     if (getProtocolVersion().noLessThan(ProtocolVersion.MINECRAFT_1_19)) {
-      this.chatQueue.hijack(getChatBuilderFactory().builder().asPlayer(this).message(input),
+      ChatBuilderV2 message = getChatBuilderFactory().builder().asPlayer(this).message(input);
-          (instant, item) -> {
+      this.chatQueue.queuePacket(chatState -> {
-            item.setTimestamp(instant);
+        message.setTimestamp(chatState.lastTimestamp);
-            return item.toServer();
+        message.setLastSeenMessages(chatState.createLastSeen());
+        return message.toServer();
       });
     } else {
       ensureBackendConnection().write(getChatBuilderFactory().builder()
@@ -1217,18 +1245,48 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
     }
   }
 
+  /**
+   * Forwards the keep alive packet to the backend server it belongs to.
+   * This is either the connection in flight or the connected server.
+   */
+  public boolean forwardKeepAlive(final KeepAlivePacket packet) {
+    if (!this.sendKeepAliveToBackend(connectedServer, packet)) {
+      return this.sendKeepAliveToBackend(connectionInFlight, packet);
+    }
+    return false;
+  }
+
+  private boolean sendKeepAliveToBackend(final @Nullable VelocityServerConnection serverConnection, final @NotNull KeepAlivePacket packet) {
+    if (serverConnection != null) {
+      final Long sentTime = serverConnection.getPendingPings().remove(packet.getRandomId());
+      if (sentTime != null) {
+        final MinecraftConnection smc = serverConnection.getConnection();
+        if (smc != null) {
+          setPing(TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - sentTime));
+          smc.write(packet);
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
   /**
    * Switches the connection to the client into config state.
    */
   public void switchToConfigState() {
-    CompletableFuture.runAsync(() -> {
+    server.getEventManager().fire(new PlayerEnterConfigurationEvent(this, getConnectionInFlightOrConnectedServer()))
+        .completeOnTimeout(null, 5, TimeUnit.SECONDS).thenRunAsync(() -> {
+          if (bundleHandler.isInBundleSession()) {
+            bundleHandler.toggleBundleSession();
+            connection.write(BundleDelimiterPacket.INSTANCE);
+          }
           connection.write(StartUpdatePacket.INSTANCE);
-      connection.getChannel().pipeline()
+          connection.getChannel().pipeline().get(MinecraftEncoder.class).setState(StateRegistry.CONFIG);
-          .get(MinecraftEncoder.class).setState(StateRegistry.CONFIG);
           // Make sure we don't send any play packets to the player after update start
           connection.addPlayPacketQueueHandler();
         }, connection.eventLoop()).exceptionally((ex) -> {
-      logger.error("Error switching player connection to config state:", ex);
+          logger.error("Error switching player connection to config state", ex);
           return null;
         });
   }
@@ -1363,24 +1421,20 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
         }
 
         switch (status.getStatus()) {
-          case ALREADY_CONNECTED:
+          case ALREADY_CONNECTED -> sendMessage(ConnectionMessages.ALREADY_CONNECTED);
-            sendMessage(Identity.nil(), ConnectionMessages.ALREADY_CONNECTED);
+          case CONNECTION_IN_PROGRESS -> sendMessage(ConnectionMessages.IN_PROGRESS);
-            break;
+          case CONNECTION_CANCELLED -> {
-          case CONNECTION_IN_PROGRESS:
-            sendMessage(Identity.nil(), ConnectionMessages.IN_PROGRESS);
-            break;
-          case CONNECTION_CANCELLED:
             // Ignored; the plugin probably already handled this.
-            break;
+          }
-          case SERVER_DISCONNECTED:
+          case SERVER_DISCONNECTED -> {
-            Component reason = status.getReasonComponent()
+            final Component reason = status.getReasonComponent()
                     .orElse(ConnectionMessages.INTERNAL_SERVER_CONNECTION_ERROR);
             handleConnectionException(toConnect,
                     DisconnectPacket.create(reason, getProtocolVersion(), connection.getState()), status.isSafe());
-            break;
+          }
-          default:
+          default -> {
             // The only remaining value is successful (no need to do anything!)
-            break;
+          }
         }
       }, connection.eventLoop()).thenApply(Result::isSuccessful);
     }

proxy/src/main/java/com/velocitypowered/proxy/connection/player/bundle/BundleDelimiterHandler.java

@@ -15,10 +15,11 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.connection.client;
+package com.velocitypowered.proxy.connection.player.bundle;
 
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
+import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.protocol.StateRegistry;
 import com.velocitypowered.proxy.protocol.packet.BundleDelimiterPacket;
 import java.util.concurrent.CompletableFuture;

proxy/src/main/java/com/velocitypowered/proxy/connection/player/resourcepack/VelocityResourcePackInfo.java

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.connection.player;
+package com.velocitypowered.proxy.connection.player.resourcepack;
 
 import com.google.common.base.Preconditions;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;

proxy/src/main/java/com/velocitypowered/proxy/connection/player/resourcepack/handler/Legacy117ResourcePackHandler.java

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.connection.player.resourcepack;
+package com.velocitypowered.proxy.connection.player.resourcepack.handler;
 
 import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
 import com.velocitypowered.proxy.VelocityServer;

proxy/src/main/java/com/velocitypowered/proxy/connection/player/resourcepack/handler/LegacyResourcePackHandler.java

@@ -15,13 +15,14 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.connection.player.resourcepack;
+package com.velocitypowered.proxy.connection.player.resourcepack.handler;
 
 import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
+import com.velocitypowered.proxy.connection.player.resourcepack.ResourcePackResponseBundle;
 import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.Collection;

proxy/src/main/java/com/velocitypowered/proxy/connection/player/resourcepack/handler/ModernResourcePackHandler.java

@@ -15,7 +15,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.connection.player.resourcepack;
+package com.velocitypowered.proxy.connection.player.resourcepack.handler;
 
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Multimaps;
@@ -23,6 +23,7 @@ import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
+import com.velocitypowered.proxy.connection.player.resourcepack.ResourcePackResponseBundle;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.LinkedList;

proxy/src/main/java/com/velocitypowered/proxy/connection/player/resourcepack/handler/ResourcePackHandler.java

@@ -15,14 +15,15 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.velocitypowered.proxy.connection.player.resourcepack;
+package com.velocitypowered.proxy.connection.player.resourcepack.handler;
 
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
-import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.ResourcePackResponseBundle;
+import com.velocitypowered.proxy.connection.player.resourcepack.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.protocol.packet.ResourcePackRequestPacket;
 import com.velocitypowered.proxy.protocol.packet.ResourcePackResponsePacket;
 import com.velocitypowered.proxy.protocol.packet.chat.ComponentHolder;

proxy/src/main/java/com/velocitypowered/proxy/network/Connections.java

@@ -35,7 +35,8 @@ public class Connections {
   public static final String MINECRAFT_DECODER = "minecraft-decoder";
   public static final String MINECRAFT_ENCODER = "minecraft-encoder";
   public static final String READ_TIMEOUT = "read-timeout";
-  public static final String PLAY_PACKET_QUEUE = "play-packet-queue";
+  public static final String PLAY_PACKET_QUEUE_OUTBOUND = "play-packet-queue-outbound";
+  public static final String PLAY_PACKET_QUEUE_INBOUND = "play-packet-queue-inbound";
 
   private Connections() {
     throw new AssertionError();

proxy/src/main/java/com/velocitypowered/proxy/plugin/VelocityPluginManager.java

@@ -43,13 +43,13 @@ import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.HashSet;
+import java.util.HashMap;
 import java.util.IdentityHashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
-import java.util.Set;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
@@ -86,35 +86,48 @@ public class VelocityPluginManager implements PluginManager {
     checkNotNull(directory, "directory");
     checkArgument(directory.toFile().isDirectory(), "provided path isn't a directory");
 
-    List<PluginDescription> found = new ArrayList<>();
+    Map<String, PluginDescription> foundCandidates = new LinkedHashMap<>();
     JavaPluginLoader loader = new JavaPluginLoader(server, directory);
 
     try (DirectoryStream<Path> stream = Files.newDirectoryStream(directory,
         p -> p.toFile().isFile() && p.toString().endsWith(".jar"))) {
       for (Path path : stream) {
         try {
-          found.add(loader.loadCandidate(path));
+          PluginDescription candidate = loader.loadCandidate(path);
+
+          // If we found a duplicate candidate (with the same ID), don't load it.
+          PluginDescription maybeExistingCandidate = foundCandidates.putIfAbsent(
+              candidate.getId(), candidate);
+
+          if (maybeExistingCandidate != null) {
+            logger.error("Refusing to load plugin at path {} since we already "
+                    + "loaded a plugin with the same ID {} from {}",
+                candidate.getSource().map(Objects::toString).orElse("<UNKNOWN>"),
+                candidate.getId(),
+                maybeExistingCandidate.getSource().map(Objects::toString).orElse("<UNKNOWN>"));
+          }
         } catch (Throwable e) {
           logger.error("Unable to load plugin {}", path, e);
         }
       }
     }
 
-    if (found.isEmpty()) {
+    if (foundCandidates.isEmpty()) {
       // No plugins found
       return;
     }
 
-    List<PluginDescription> sortedPlugins = PluginDependencyUtils.sortCandidates(found);
+    List<PluginDescription> sortedPlugins = PluginDependencyUtils.sortCandidates(
+        new ArrayList<>(foundCandidates.values()));
 
-    Set<String> loadedPluginsById = new HashSet<>();
+    Map<String, PluginDescription> loadedCandidates = new HashMap<>();
     Map<PluginContainer, Module> pluginContainers = new LinkedHashMap<>();
     // Now load the plugins
     pluginLoad:
     for (PluginDescription candidate : sortedPlugins) {
       // Verify dependencies
       for (PluginDependency dependency : candidate.getDependencies()) {
-        if (!dependency.isOptional() && !loadedPluginsById.contains(dependency.getId())) {
+        if (!dependency.isOptional() && !loadedCandidates.containsKey(dependency.getId())) {
           logger.error("Can't load plugin {} due to missing dependency {}", candidate.getId(),
               dependency.getId());
           continue pluginLoad;
@@ -125,7 +138,7 @@ public class VelocityPluginManager implements PluginManager {
         PluginDescription realPlugin = loader.createPluginFromCandidate(candidate);
         VelocityPluginContainer container = new VelocityPluginContainer(realPlugin);
         pluginContainers.put(container, loader.createModule(container));
-        loadedPluginsById.add(realPlugin.getId());
+        loadedCandidates.put(realPlugin.getId(), realPlugin);
       } catch (Throwable e) {
         logger.error("Can't create module for plugin {}", candidate.getId(), e);
       }

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftDecoder.java

@@ -56,8 +56,7 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
 
   @Override
   public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
-    if (msg instanceof ByteBuf) {
+    if (msg instanceof ByteBuf buf) {
-      ByteBuf buf = (ByteBuf) msg;
       tryDecode(ctx, buf);
     } else {
       ctx.fireChannelRead(msg);
@@ -147,4 +146,8 @@ public class MinecraftDecoder extends ChannelInboundHandlerAdapter {
     this.state = state;
     this.setProtocolVersion(registry.version);
   }
+
+  public ProtocolUtils.Direction getDirection() {
+    return direction;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/PlayPacketQueueInboundHandler.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2023 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.protocol.netty;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.protocol.StateRegistry;
+import io.netty.channel.ChannelDuplexHandler;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.util.ReferenceCountUtil;
+import java.util.ArrayDeque;
+import java.util.Queue;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Queues up any pending PLAY packets while the client is in the CONFIG state.
+ *
+ * <p>Much of the Velocity API (i.e. chat messages) utilize PLAY packets, however the client is
+ * incapable of receiving these packets during the CONFIG state. Certain events such as the
+ * ServerPreConnectEvent may be called during this time, and we need to ensure that any API that
+ * uses these packets will work as expected.
+ *
+ * <p>This handler will queue up any packets that are sent to the client during this time, and send
+ * them once the client has (re)entered the PLAY state.
+ */
+public class PlayPacketQueueInboundHandler extends ChannelDuplexHandler {
+
+  private final StateRegistry.PacketRegistry.ProtocolRegistry registry;
+  private final Queue<Object> queue = new ArrayDeque<>();
+
+  /**
+   * Provides registries for client &amp; server bound packets.
+   *
+   * @param version the protocol version
+   */
+  public PlayPacketQueueInboundHandler(ProtocolVersion version, ProtocolUtils.Direction direction) {
+    this.registry = StateRegistry.CONFIG.getProtocolRegistry(direction, version);
+  }
+
+  @Override
+  public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
+    if (msg instanceof final MinecraftPacket packet) {
+      // If the packet exists in the CONFIG state, we want to always
+      // ensure that it gets handled by the current handler
+      if (this.registry.containsPacket(packet)) {
+        ctx.fireChannelRead(msg);
+        return;
+      }
+    }
+
+    // Otherwise, queue the packet
+    this.queue.offer(msg);
+  }
+
+  @Override
+  public void channelInactive(@NotNull ChannelHandlerContext ctx) throws Exception {
+    this.releaseQueue(ctx, false);
+
+    super.channelInactive(ctx);
+  }
+
+  @Override
+  public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
+    this.releaseQueue(ctx, ctx.channel().isActive());
+  }
+
+  private void releaseQueue(ChannelHandlerContext ctx, boolean active) {
+    // Handle all the queued packets
+    Object msg;
+    while ((msg = this.queue.poll()) != null) {
+      if (active) {
+        ctx.fireChannelRead(msg);
+      } else {
+        ReferenceCountUtil.release(msg);
+      }
+    }
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/PlayPacketQueueOutboundHandler.java

@@ -25,7 +25,7 @@ import io.netty.channel.ChannelDuplexHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;
 import io.netty.util.ReferenceCountUtil;
-import io.netty.util.internal.PlatformDependent;
+import java.util.ArrayDeque;
 import java.util.Queue;
 import org.jetbrains.annotations.NotNull;
 
@@ -40,38 +40,36 @@ import org.jetbrains.annotations.NotNull;
  * <p>This handler will queue up any packets that are sent to the client during this time, and send
  * them once the client has (re)entered the PLAY state.
  */
-public class PlayPacketQueueHandler extends ChannelDuplexHandler {
+public class PlayPacketQueueOutboundHandler extends ChannelDuplexHandler {
 
   private final StateRegistry.PacketRegistry.ProtocolRegistry registry;
-  private final Queue<MinecraftPacket> queue = PlatformDependent.newMpscQueue();
+  private final Queue<MinecraftPacket> queue = new ArrayDeque<>();
 
   /**
    * Provides registries for client &amp; server bound packets.
    *
    * @param version the protocol version
    */
-  public PlayPacketQueueHandler(ProtocolVersion version, ProtocolUtils.Direction direction) {
+  public PlayPacketQueueOutboundHandler(ProtocolVersion version, ProtocolUtils.Direction direction) {
-    this.registry =
+    this.registry = StateRegistry.CONFIG.getProtocolRegistry(direction, version);
-        StateRegistry.CONFIG.getProtocolRegistry(direction, version);
   }
 
   @Override
-  public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise)
+  public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
-      throws Exception {
+    if (!(msg instanceof final MinecraftPacket packet)) {
-    if (!(msg instanceof MinecraftPacket)) {
       ctx.write(msg, promise);
       return;
     }
 
     // If the packet exists in the CONFIG state, we want to always
     // ensure that it gets sent out to the client
-    if (this.registry.containsPacket(((MinecraftPacket) msg))) {
+    if (this.registry.containsPacket(packet)) {
       ctx.write(msg, promise);
       return;
     }
 
     // Otherwise, queue the packet
-    this.queue.offer((MinecraftPacket) msg);
+    this.queue.offer(packet);
   }
 
   @Override
@@ -87,10 +85,6 @@ public class PlayPacketQueueHandler extends ChannelDuplexHandler {
   }
 
   private void releaseQueue(ChannelHandlerContext ctx, boolean active) {
-    if (this.queue.isEmpty()) {
-      return;
-    }
-
     // Send out all the queued packets
     MinecraftPacket packet;
     while ((packet = this.queue.poll()) != null) {

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/ResourcePackRequestPacket.java

@@ -21,7 +21,7 @@ import com.google.common.base.Preconditions;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
+import com.velocitypowered.proxy.connection.player.resourcepack.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/ChatAcknowledgementPacket.java

@@ -54,4 +54,8 @@ public class ChatAcknowledgementPacket implements MinecraftPacket {
                 "offset=" + offset +
                 '}';
     }
+
+    public int offset() {
+        return offset;
+    }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/ChatQueue.java

@@ -23,7 +23,9 @@ import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import io.netty.channel.ChannelFuture;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import java.time.Instant;
+import java.util.BitSet;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Function;
 
 /**
@@ -32,9 +34,10 @@ import java.util.function.Function;
  */
 public class ChatQueue {
 
-  private final Object internalLock;
+  private final Object internalLock = new Object();
   private final ConnectedPlayer player;
-  private CompletableFuture<WrappedPacket> packetFuture;
+  private final ChatState chatState = new ChatState();
+  private CompletableFuture<Void> head = CompletableFuture.completedFuture(null);
 
   /**
    * Instantiates a {@link ChatQueue} for a specific {@link ConnectedPlayer}.
@@ -43,8 +46,19 @@ public class ChatQueue {
    */
   public ChatQueue(ConnectedPlayer player) {
     this.player = player;
-    this.packetFuture = CompletableFuture.completedFuture(new WrappedPacket(Instant.EPOCH, null));
+  }
-    this.internalLock = new Object();
+
+  private void queueTask(Task task) {
+    synchronized (internalLock) {
+      MinecraftConnection smc = player.ensureAndGetCurrentServer().ensureConnected();
+      head = head.thenCompose(v -> {
+        try {
+          return task.update(chatState, smc).exceptionally(ignored -> null);
+        } catch (Throwable ignored) {
+          return CompletableFuture.completedFuture(null);
+        }
+      });
+    }
   }
 
   /**
@@ -52,121 +66,115 @@ public class ChatQueue {
    * packets. This maintains order on the server-level for the client insertions of commands
    * and messages. All entries are locked through an internal object lock.
    *
-   * @param nextPacket the {@link CompletableFuture} which will provide the next-processed packet.
+   * @param nextPacket       a function mapping {@link LastSeenMessages} state to a {@link CompletableFuture} that will
-   * @param timestamp  the {@link Instant} timestamp of this packet so we can allow piggybacking.
+   *                         provide the next-processed packet. This should include the fixed {@link LastSeenMessages}.
+   * @param timestamp        the new {@link Instant} timestamp of this packet to update the internal chat state.
+   * @param lastSeenMessages the new {@link LastSeenMessages} last seen messages to update the internal chat state.
    */
-  public void queuePacket(CompletableFuture<MinecraftPacket> nextPacket, Instant timestamp) {
+  public void queuePacket(Function<LastSeenMessages, CompletableFuture<MinecraftPacket>> nextPacket, @Nullable Instant timestamp, @Nullable LastSeenMessages lastSeenMessages) {
-    synchronized (internalLock) { // wait for the lock to resolve - we don't want to drop packets
+    queueTask((chatState, smc) -> {
-      MinecraftConnection smc = player.ensureAndGetCurrentServer().ensureConnected();
+      LastSeenMessages newLastSeenMessages = chatState.updateFromMessage(timestamp, lastSeenMessages);
-
+      return nextPacket.apply(newLastSeenMessages).thenCompose(packet -> writePacket(packet, smc));
-      CompletableFuture<WrappedPacket> nextInLine = WrappedPacket.wrap(timestamp, nextPacket);
+    });
-      this.packetFuture = awaitChat(smc, this.packetFuture,
-          nextInLine); // we await chat, binding `this.packetFuture` -> `nextInLine`
-    }
   }
 
   /**
-   * Hijacks the latest sent packet's timestamp to provide an in-order packet without polling the
+   * Hijacks the latest sent packet's chat state to provide an in-order packet without polling the
    * physical, or prior packets sent through the stream.
    *
-   * @param packet        the {@link MinecraftPacket} to send.
+   * @param packetFunction a function that maps the prior {@link ChatState} into a new packet.
-   * @param instantMapper the {@link InstantPacketMapper} which maps the prior timestamp and current
+   * @param <T>            the type of packet to send.
-   *                      packet to a new packet.
-   * @param <K>           the type of base to expect when mapping the packet.
-   * @param <V>           the type of packet for instantMapper type-checking.
    */
-  public <K, V extends MinecraftPacket> void hijack(K packet,
+  public <T extends MinecraftPacket> void queuePacket(Function<ChatState, T> packetFunction) {
-      InstantPacketMapper<K, V> instantMapper) {
+    queueTask((chatState, smc) -> {
-    synchronized (internalLock) {
+      T packet = packetFunction.apply(chatState);
-      CompletableFuture<K> trueFuture = CompletableFuture.completedFuture(packet);
+      return writePacket(packet, smc);
-      MinecraftConnection smc = player.ensureAndGetCurrentServer().ensureConnected();
+    });
-
-      this.packetFuture = hijackCurrentPacket(smc, this.packetFuture, trueFuture, instantMapper);
-    }
   }
 
-  private static Function<WrappedPacket, WrappedPacket> writePacket(MinecraftConnection connection) {
+  public void handleAcknowledgement(int offset) {
-    return wrappedPacket -> {
+    queueTask((chatState, smc) -> {
-      if (!connection.isClosed()) {
+      int ackCountToForward = chatState.accumulateAckCount(offset);
-        ChannelFuture future = wrappedPacket.write(connection);
+      if (ackCountToForward > 0) {
+        return writePacket(new ChatAcknowledgementPacket(ackCountToForward), smc);
+      }
+      return CompletableFuture.completedFuture(null);
+    });
+  }
+
+  private static <T extends MinecraftPacket> CompletableFuture<Void> writePacket(T packet, MinecraftConnection smc) {
+    return CompletableFuture.runAsync(() -> {
+      if (!smc.isClosed()) {
+        ChannelFuture future = smc.write(packet);
         if (future != null) {
           future.awaitUninterruptibly();
         }
       }
-
+    }, smc.eventLoop());
-      return wrappedPacket;
-    };
   }
 
-  private static <T extends MinecraftPacket> CompletableFuture<WrappedPacket> awaitChat(
+  private interface Task {
-      MinecraftConnection connection,
+    CompletableFuture<Void> update(ChatState chatState, MinecraftConnection smc);
-      CompletableFuture<WrappedPacket> binder,
-      CompletableFuture<WrappedPacket> future
-  ) {
-    // the binder will run -> then the future will get the `write packet` caller
-    return binder.thenCompose(ignored -> future.thenApply(writePacket(connection)));
-  }
-
-  private static <K, V extends MinecraftPacket> CompletableFuture<WrappedPacket> hijackCurrentPacket(
-      MinecraftConnection connection,
-      CompletableFuture<WrappedPacket> binder,
-      CompletableFuture<K> future,
-      InstantPacketMapper<K, V> packetMapper
-  ) {
-    CompletableFuture<WrappedPacket> awaitedFuture = new CompletableFuture<>();
-    // the binder will complete -> then the future will get the `write packet` caller
-    binder.whenComplete((previous, ignored) -> {
-      // map the new packet into a better "designed" packet with the hijacked packet's timestamp
-      WrappedPacket.wrap(previous.timestamp,
-              future.thenApply(item -> packetMapper.map(previous.timestamp, item)))
-          .thenApplyAsync(writePacket(connection), connection.eventLoop())
-          .whenComplete(
-              (packet, throwable) -> awaitedFuture.complete(throwable != null ? null : packet));
-    });
-    return awaitedFuture;
   }
 
   /**
-   * Provides an {@link Instant} based timestamp mapper from an existing object to create a packet.
+   * Tracks the last Secure Chat state that we received from the client. This is important to always have a valid 'last
+   * seen' state that is consistent with future and past updates from the client (which may be signed). This state is
+   * used to construct 'spoofed' command packets from the proxy to the server.
+   * <ul>
+   *     <li>If we last forwarded a chat or command packet from the client, we have a known 'last seen' that we can
+   *     reuse.</li>
+   *     <li>If we last forwarded a {@link ChatAcknowledgementPacket}, the previous 'last seen' cannot be reused. We
+   *     cannot predict an up-to-date 'last seen', as we do not know which messages the client actually saw.</li>
+   *     <li>Therefore, we need to hold back any acknowledgement packets so that we can continue to reuse the last valid
+   *     'last seen' state.</li>
+   *     <li>However, there is a limit to the number of messages that can remain unacknowledged on the server.</li>
+   *     <li>To address this, we know that if the client has moved its 'last seen' window far enough, we can fill in the
+   *     gap with dummy 'last seen', and it will never be checked.</li>
+   * </ul>
    *
-   * @param <K> The base object type to map.
+   * Note that this is effectively unused for 1.20.5+ clients, as commands without any signature do not send 'last seen'
-   * @param <V> The resulting packet type.
+   * updates.
    */
-  public interface InstantPacketMapper<K, V extends MinecraftPacket> {
+  public static class ChatState {
+    private static final int MINIMUM_DELAYED_ACK_COUNT = LastSeenMessages.WINDOW_SIZE;
+    private static final BitSet DUMMY_LAST_SEEN_MESSAGES = new BitSet();
 
-    /**
+    public volatile Instant lastTimestamp = Instant.EPOCH;
-     * Maps a value into a packet with it and a timestamp.
+    private volatile BitSet lastSeenMessages = new BitSet();
-     *
+    private final AtomicInteger delayedAckCount = new AtomicInteger();
-     * @param nextInstant   the {@link Instant} timestamp to use for tracking.
-     * @param currentObject the current item to map to the packet.
-     * @return The resulting packet from the mapping.
-     */
-    V map(Instant nextInstant, K currentObject);
-  }
 
-  private static class WrappedPacket {
+    private ChatState() {
-
-    private final Instant timestamp;
-    private final MinecraftPacket packet;
-
-    private WrappedPacket(Instant timestamp, MinecraftPacket packet) {
-      this.timestamp = timestamp;
-      this.packet = packet;
     }
 
     @Nullable
-    public ChannelFuture write(MinecraftConnection connection) {
+    public LastSeenMessages updateFromMessage(@Nullable Instant timestamp, @Nullable LastSeenMessages lastSeenMessages) {
-      if (packet != null) {
+      if (timestamp != null) {
-        return connection.write(packet);
+        this.lastTimestamp = timestamp;
+      }
+      if (lastSeenMessages != null) {
+        // We held back some acknowledged messages, so flush that out now that we have a known 'last seen' state again
+        int delayedAckCount = this.delayedAckCount.getAndSet(0);
+        this.lastSeenMessages = lastSeenMessages.getAcknowledged();
+        return lastSeenMessages.offset(delayedAckCount);
       }
       return null;
     }
 
-    private static CompletableFuture<WrappedPacket> wrap(Instant timestamp,
+    public int accumulateAckCount(int ackCount) {
-        CompletableFuture<MinecraftPacket> nextPacket) {
+      int delayedAckCount = this.delayedAckCount.addAndGet(ackCount);
-      return nextPacket
+      int ackCountToForward = delayedAckCount - MINIMUM_DELAYED_ACK_COUNT;
-          .thenApply(pkt -> new WrappedPacket(timestamp, pkt))
+      if (ackCountToForward >= LastSeenMessages.WINDOW_SIZE) {
-          .exceptionally(ignored -> new WrappedPacket(timestamp, null));
+        // Because we only forward acknowledgements above the window size, we don't have to shift the previous 'last seen' state
+        this.lastSeenMessages = DUMMY_LAST_SEEN_MESSAGES;
+        this.delayedAckCount.set(MINIMUM_DELAYED_ACK_COUNT);
+        return ackCountToForward;
+      }
+      return 0;
+    }
+
+    public LastSeenMessages createLastSeen() {
+      return new LastSeenMessages(0, lastSeenMessages);
     }
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/CommandHandler.java

@@ -23,11 +23,13 @@ import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import java.time.Instant;
 import java.util.concurrent.CompletableFuture;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public interface CommandHandler<T extends MinecraftPacket> {
 
@@ -53,11 +55,12 @@ public interface CommandHandler<T extends MinecraftPacket> {
   }
 
   default void queueCommandResult(VelocityServer server, ConnectedPlayer player,
-      Function<CommandExecuteEvent, CompletableFuture<MinecraftPacket>> futurePacketCreator,
+      BiFunction<CommandExecuteEvent, LastSeenMessages, CompletableFuture<MinecraftPacket>> futurePacketCreator,
-      String message, Instant timestamp) {
+      String message, Instant timestamp, @Nullable LastSeenMessages lastSeenMessages) {
+      CompletableFuture<CommandExecuteEvent> eventFuture = server.getCommandManager().callCommandEvent(player, message);
       player.getChatQueue().queuePacket(
-        server.getCommandManager().callCommandEvent(player, message)
+        newLastSeenMessages -> eventFuture
-            .thenComposeAsync(futurePacketCreator)
+            .thenComposeAsync(event -> futurePacketCreator.apply(event, newLastSeenMessages))
             .thenApply(pkt -> {
               if (server.getConfiguration().isLogCommandExecutions()) {
                 logger.info("{} -> executed command /{}", player, message);
@@ -68,6 +71,6 @@ public interface CommandHandler<T extends MinecraftPacket> {
               player.sendMessage(
                   Component.translatable("velocity.command.generic-error", NamedTextColor.RED));
               return null;
-            }), timestamp);
+            }), timestamp, lastSeenMessages);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/LastSeenMessages.java

@@ -24,7 +24,8 @@ import java.util.BitSet;
 
 public class LastSeenMessages {
 
-  private static final int DIV_FLOOR = -Math.floorDiv(-20, 8);
+  public static final int WINDOW_SIZE = 20;
+  private static final int DIV_FLOOR = -Math.floorDiv(-WINDOW_SIZE, 8);
   private int offset;
   private BitSet acknowledged;
 
@@ -33,6 +34,11 @@ public class LastSeenMessages {
     this.acknowledged = new BitSet();
   }
 
+  public LastSeenMessages(int offset, BitSet acknowledged) {
+    this.offset = offset;
+    this.acknowledged = acknowledged;
+  }
+
   public LastSeenMessages(ByteBuf buf) {
     this.offset = ProtocolUtils.readVarInt(buf);
 
@@ -46,14 +52,18 @@ public class LastSeenMessages {
     buf.writeBytes(Arrays.copyOf(acknowledged.toByteArray(), DIV_FLOOR));
   }
 
-  public boolean isEmpty() {
-    return acknowledged.isEmpty();
-  }
-
   public int getOffset() {
     return this.offset;
   }
 
+  public BitSet getAcknowledged() {
+    return acknowledged;
+  }
+
+  public LastSeenMessages offset(final int offset) {
+    return new LastSeenMessages(this.offset + offset, acknowledged);
+  }
+
   @Override
   public String toString() {
     return "LastSeenMessages{" +

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/builder/ChatBuilderV2.java

@@ -21,6 +21,7 @@ import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.packet.chat.ChatType;
+import com.velocitypowered.proxy.protocol.packet.chat.LastSeenMessages;
 import java.time.Instant;
 import net.kyori.adventure.identity.Identity;
 import net.kyori.adventure.text.Component;
@@ -36,6 +37,7 @@ public abstract class ChatBuilderV2 {
   protected @Nullable Identity senderIdentity;
   protected Instant timestamp;
   protected ChatType type = ChatType.CHAT;
+  protected @Nullable LastSeenMessages lastSeenMessages;
 
   protected ChatBuilderV2(ProtocolVersion version) {
     this.version = version;
@@ -77,6 +79,11 @@ public abstract class ChatBuilderV2 {
     return this;
   }
 
+  public ChatBuilderV2 setLastSeenMessages(LastSeenMessages lastSeenMessages) {
+    this.lastSeenMessages = lastSeenMessages;
+    return this;
+  }
+
   public abstract MinecraftPacket toClient();
 
   public abstract MinecraftPacket toServer();

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/keyed/KeyedChatHandler.java

@@ -91,11 +91,12 @@ public class KeyedChatHandler implements
       });
     }
     chatQueue.queuePacket(
-        chatFuture.exceptionally((ex) -> {
+        newLastSeen -> chatFuture.exceptionally((ex) -> {
           logger.error("Exception while handling player chat for {}", player, ex);
           return null;
         }),
-        packet.getExpiry()
+        packet.getExpiry(),
+        null
     );
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/keyed/KeyedCommandHandler.java

@@ -43,7 +43,7 @@ public class KeyedCommandHandler implements CommandHandler<KeyedPlayerCommandPac
 
   @Override
   public void handlePlayerCommandInternal(KeyedPlayerCommandPacket packet) {
-    queueCommandResult(this.server, this.player, event -> {
+    queueCommandResult(this.server, this.player, (event, newLastSeenMessages) -> {
       CommandExecuteEvent.CommandResult result = event.getResult();
       IdentifiedKey playerKey = player.getIdentifiedKey();
       if (result == CommandExecuteEvent.CommandResult.denied()) {
@@ -111,6 +111,6 @@ public class KeyedCommandHandler implements CommandHandler<KeyedPlayerCommandPac
         }
         return null;
       });
-    }, packet.getCommand(), packet.getTimestamp());
+    }, packet.getCommand(), packet.getTimestamp(), null);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/legacy/LegacyCommandHandler.java

@@ -42,7 +42,7 @@ public class LegacyCommandHandler implements CommandHandler<LegacyChatPacket> {
   @Override
   public void handlePlayerCommandInternal(LegacyChatPacket packet) {
     String command = packet.getMessage().substring(1);
-    queueCommandResult(this.server, this.player, event -> {
+    queueCommandResult(this.server, this.player, (event, newLastSeenMessages) -> {
       CommandExecuteEvent.CommandResult result = event.getResult();
       if (result == CommandExecuteEvent.CommandResult.denied()) {
         return CompletableFuture.completedFuture(null);
@@ -62,6 +62,6 @@ public class LegacyCommandHandler implements CommandHandler<LegacyChatPacket> {
         }
         return null;
       });
-    }, command, Instant.now());
+    }, command, Instant.now(), null);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionChatBuilder.java

@@ -41,6 +41,7 @@ public class SessionChatBuilder extends ChatBuilderV2 {
 
   @Override
   public MinecraftPacket toServer() {
+    LastSeenMessages lastSeenMessages = this.lastSeenMessages != null ? this.lastSeenMessages : new LastSeenMessages();
     if (message.startsWith("/")) {
       if (version.noLessThan(ProtocolVersion.MINECRAFT_1_20_5)) {
         UnsignedPlayerCommandPacket command = new UnsignedPlayerCommandPacket();
@@ -52,7 +53,7 @@ public class SessionChatBuilder extends ChatBuilderV2 {
         command.salt = 0L;
         command.timeStamp = timestamp;
         command.argumentSignatures = new SessionPlayerCommandPacket.ArgumentSignatures();
-        command.lastSeenMessages = new LastSeenMessages();
+        command.lastSeenMessages = lastSeenMessages;
         return command;
       }
     } else {
@@ -62,7 +63,7 @@ public class SessionChatBuilder extends ChatBuilderV2 {
       chat.signature = new byte[0];
       chat.timestamp = timestamp;
       chat.salt = 0L;
-      chat.lastSeenMessages = new LastSeenMessages();
+      chat.lastSeenMessages = lastSeenMessages;
       return chat;
     }
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionChatHandler.java

@@ -29,6 +29,8 @@ import com.velocitypowered.proxy.protocol.packet.chat.ChatQueue;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
+import java.util.concurrent.CompletableFuture;
+
 public class SessionChatHandler implements ChatHandler<SessionPlayerChatPacket> {
 
   private static final Logger logger = LogManager.getLogger(SessionChatHandler.class);
@@ -51,8 +53,9 @@ public class SessionChatHandler implements ChatHandler<SessionPlayerChatPacket>
     ChatQueue chatQueue = this.player.getChatQueue();
     EventManager eventManager = this.server.getEventManager();
     PlayerChatEvent toSend = new PlayerChatEvent(player, packet.getMessage());
+    CompletableFuture<PlayerChatEvent> eventFuture = eventManager.fire(toSend);
     chatQueue.queuePacket(
-        eventManager.fire(toSend)
+        newLastSeenMessages -> eventFuture
             .thenApply(pme -> {
               PlayerChatEvent.ChatResult chatResult = pme.getResult();
               if (!chatResult.isAllowed()) {
@@ -70,15 +73,17 @@ public class SessionChatHandler implements ChatHandler<SessionPlayerChatPacket>
                 }
                 return this.player.getChatBuilderFactory().builder().message(packet.message)
                     .setTimestamp(packet.timestamp)
+                    .setLastSeenMessages(newLastSeenMessages)
                     .toServer();
               }
-              return packet;
+              return packet.withLastSeenMessages(newLastSeenMessages);
             })
             .exceptionally((ex) -> {
               logger.error("Exception while handling player chat for {}", player, ex);
               return null;
             }),
-        packet.getTimestamp()
+        packet.getTimestamp(),
+        packet.getLastSeenMessages()
     );
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionCommandHandler.java

@@ -18,13 +18,14 @@
 package com.velocitypowered.proxy.protocol.packet.chat.session;
 
 import com.velocitypowered.api.event.command.CommandExecuteEvent;
-import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
+import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.packet.chat.ChatAcknowledgementPacket;
 import com.velocitypowered.proxy.protocol.packet.chat.CommandHandler;
 import java.util.concurrent.CompletableFuture;
 import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class SessionCommandHandler implements CommandHandler<SessionPlayerCommandPacket> {
 
@@ -41,55 +42,41 @@ public class SessionCommandHandler implements CommandHandler<SessionPlayerComman
     return SessionPlayerCommandPacket.class;
   }
 
-  @Override
+  @Nullable
-  public void handlePlayerCommandInternal(SessionPlayerCommandPacket packet) {
+  private MinecraftPacket consumeCommand(SessionPlayerCommandPacket packet) {
-    queueCommandResult(this.server, this.player, event -> {
+    if (packet.lastSeenMessages == null) {
-      CommandExecuteEvent.CommandResult result = event.getResult();
+      return null;
-      if (result == CommandExecuteEvent.CommandResult.denied()) {
+    }
     if (packet.isSigned()) {
+      // Any signed message produced by the client *must* be passed through to the server in order to maintain a
+      // consistent state for future messages.
       logger.fatal("A plugin tried to deny a command with signable component(s). "
           + "This is not supported. "
           + "Disconnecting player " + player.getUsername() + ". Command packet: " + packet);
       player.disconnect(Component.text(
           "A proxy plugin caused an illegal protocol state. "
               + "Contact your network administrator."));
+      return null;
     }
-        // We seemingly can't actually do this if signed args exist, if not, we can probs keep stuff happy
+    // An unsigned command with a 'last seen' update will not happen as of 1.20.5+, but for earlier versions - we still
-        if (player.getProtocolVersion().noLessThan(ProtocolVersion.MINECRAFT_1_19_3) && packet.lastSeenMessages != null) {
+    // need to pass through the acknowledgement
-          return CompletableFuture.completedFuture(new ChatAcknowledgementPacket(packet.lastSeenMessages.getOffset()));
+    final int offset = packet.lastSeenMessages.getOffset();
+    if (offset != 0) {
+      return new ChatAcknowledgementPacket(offset);
     }
-        return CompletableFuture.completedFuture(null);
+    return null;
   }
 
-      String commandToRun = result.getCommand().orElse(packet.command);
+  @Nullable
-      if (result.isForwardToServer()) {
+  private MinecraftPacket forwardCommand(SessionPlayerCommandPacket packet, String newCommand) {
-        if (packet.isSigned() && commandToRun.equals(packet.command)) {
+    if (newCommand.equals(packet.command)) {
-          return CompletableFuture.completedFuture(packet);
-        } else {
-          if (packet.isSigned()) {
-            logger.fatal("A plugin tried to change a command with signed component(s). "
-                + "This is not supported. "
-                + "Disconnecting player " + player.getUsername() + ". Command packet: " + packet);
-            player.disconnect(Component.text(
-                "A proxy plugin caused an illegal protocol state. "
-                    + "Contact your network administrator."));
-            return CompletableFuture.completedFuture(null);
-          }
-
-          return CompletableFuture.completedFuture(this.player.getChatBuilderFactory()
-              .builder()
-              .setTimestamp(packet.timeStamp)
-              .asPlayer(this.player)
-              .message("/" + commandToRun)
-              .toServer());
-        }
-      }
-
-      return runCommand(this.server, this.player, commandToRun, hasRun -> {
-        if (!hasRun) {
-          if (packet.isSigned() && commandToRun.equals(packet.command)) {
       return packet;
-          } else {
+    }
+    return modifyCommand(packet, newCommand);
+  }
+
+  @Nullable
+  private MinecraftPacket modifyCommand(SessionPlayerCommandPacket packet, String newCommand) {
     if (packet.isSigned()) {
       logger.fatal("A plugin tried to change a command with signed component(s). "
           + "This is not supported. "
@@ -103,16 +90,33 @@ public class SessionCommandHandler implements CommandHandler<SessionPlayerComman
     return this.player.getChatBuilderFactory()
         .builder()
         .setTimestamp(packet.timeStamp)
+        .setLastSeenMessages(packet.lastSeenMessages)
         .asPlayer(this.player)
-                .message("/" + commandToRun)
+        .message("/" + newCommand)
         .toServer();
   }
+
+  @Override
+  public void handlePlayerCommandInternal(SessionPlayerCommandPacket packet) {
+    queueCommandResult(this.server, this.player, (event, newLastSeenMessages) -> {
+      SessionPlayerCommandPacket fixedPacket = packet.withLastSeenMessages(newLastSeenMessages);
+
+      CommandExecuteEvent.CommandResult result = event.getResult();
+      if (result == CommandExecuteEvent.CommandResult.denied()) {
+        return CompletableFuture.completedFuture(consumeCommand(fixedPacket));
       }
-        if (player.getProtocolVersion().noLessThan(ProtocolVersion.MINECRAFT_1_19_3) && packet.lastSeenMessages != null) {
+
-          return new ChatAcknowledgementPacket(packet.lastSeenMessages.getOffset());
+      String commandToRun = result.getCommand().orElse(fixedPacket.command);
+      if (result.isForwardToServer()) {
+        return CompletableFuture.completedFuture(forwardCommand(fixedPacket, commandToRun));
       }
-        return null;
+
+      return runCommand(this.server, this.player, commandToRun, hasRun -> {
+        if (hasRun) {
+          return consumeCommand(fixedPacket);
+        }
+        return forwardCommand(fixedPacket, commandToRun);
       });
-    }, packet.command, packet.timeStamp);
+    }, packet.command, packet.timeStamp, packet.lastSeenMessages);
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionPlayerChatPacket.java

@@ -100,4 +100,15 @@ public class SessionPlayerChatPacket implements MinecraftPacket {
     buf.readBytes(signature);
     return signature;
   }
+
+  public SessionPlayerChatPacket withLastSeenMessages(LastSeenMessages lastSeenMessages) {
+    SessionPlayerChatPacket packet = new SessionPlayerChatPacket();
+    packet.message = message;
+    packet.timestamp = timestamp;
+    packet.salt = salt;
+    packet.signed = signed;
+    packet.signature = signature;
+    packet.lastSeenMessages = lastSeenMessages;
+    return packet;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/SessionPlayerCommandPacket.java

@@ -25,6 +25,8 @@ import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packet.chat.LastSeenMessages;
 import com.velocitypowered.proxy.util.except.QuietDecoderException;
 import io.netty.buffer.ByteBuf;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 import java.time.Instant;
 import java.util.List;
 
@@ -63,8 +65,7 @@ public class SessionPlayerCommandPacket implements MinecraftPacket {
   }
 
   public boolean isSigned() {
-    if (salt == 0) return false;
+    return !argumentSignatures.isEmpty();
-    return !lastSeenMessages.isEmpty() || !argumentSignatures.isEmpty();
   }
 
   @Override
@@ -83,6 +84,21 @@ public class SessionPlayerCommandPacket implements MinecraftPacket {
             '}';
   }
 
+  public SessionPlayerCommandPacket withLastSeenMessages(@Nullable LastSeenMessages lastSeenMessages) {
+    if (lastSeenMessages == null) {
+      UnsignedPlayerCommandPacket packet = new UnsignedPlayerCommandPacket();
+      packet.command = command;
+      return packet;
+    }
+    SessionPlayerCommandPacket packet = new SessionPlayerCommandPacket();
+    packet.command = command;
+    packet.timeStamp = timeStamp;
+    packet.salt = salt;
+    packet.argumentSignatures = argumentSignatures;
+    packet.lastSeenMessages = lastSeenMessages;
+    return packet;
+  }
+
   public static class ArgumentSignatures {
 
     private final List<ArgumentSignature> entries;

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/chat/session/UnsignedPlayerCommandPacket.java

@@ -19,7 +19,9 @@ package com.velocitypowered.proxy.protocol.packet.chat.session;
 
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.protocol.packet.chat.LastSeenMessages;
 import io.netty.buffer.ByteBuf;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class UnsignedPlayerCommandPacket extends SessionPlayerCommandPacket {
 
@@ -33,6 +35,11 @@ public class UnsignedPlayerCommandPacket extends SessionPlayerCommandPacket {
     ProtocolUtils.writeString(buf, this.command);
   }
 
+  @Override
+  public SessionPlayerCommandPacket withLastSeenMessages(@Nullable LastSeenMessages lastSeenMessages) {
+    return this;
+  }
+
   public boolean isSigned() {
     return false;
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/config/ClientboundServerLinksPacket.java

@@ -18,6 +18,7 @@
 package com.velocitypowered.proxy.protocol.packet.config;
 
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.util.ServerLink;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
@@ -66,6 +67,13 @@ public class ClientboundServerLinksPacket implements MinecraftPacket {
     }
 
     public record ServerLink(int id, ComponentHolder displayName, String url) {
+
+        public ServerLink(com.velocitypowered.api.util.ServerLink link, ProtocolVersion protocolVersion) {
+            this(link.getBuiltInType().map(Enum::ordinal).orElse(-1),
+                link.getCustomLabel().map(c -> new ComponentHolder(protocolVersion, c)).orElse(null),
+                link.getUrl().toString());
+        }
+
         private static ServerLink read(ByteBuf buf, ProtocolVersion version) {
             if (buf.readBoolean()) {
                 return new ServerLink(ProtocolUtils.readVarInt(buf), null, ProtocolUtils.readString(buf));

proxy/src/main/java/com/velocitypowered/proxy/server/ServerMap.java

@@ -19,6 +19,8 @@ package com.velocitypowered.proxy.server;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.event.proxy.server.ServerRegisteredEvent;
+import com.velocitypowered.api.event.proxy.server.ServerUnregisteredEvent;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.proxy.VelocityServer;
@@ -84,6 +86,10 @@ public class ServerMap {
       throw new IllegalArgumentException(
           "Server with name " + serverInfo.getName() + " already registered");
     } else if (existing == null) {
+      if (server != null) {
+        server.getEventManager().fireAndForget(new ServerRegisteredEvent(rs));
+      }
+
       return rs;
     } else {
       return existing;
@@ -107,5 +113,9 @@ public class ServerMap {
         "Trying to remove server %s with differing information", serverInfo.getName());
     Preconditions.checkState(servers.remove(lowerName, rs),
         "Server with name %s replaced whilst unregistering", serverInfo.getName());
+
+    if (server != null) {
+      server.getEventManager().fireAndForget(new ServerUnregisteredEvent(rs));
+    }
   }
 }

proxy/src/main/resources/default-velocity.toml

@@ -1,8 +1,8 @@
 # Config version. Do not change this
 config-version = "2.7"
 
-# What port should the proxy be bound to? By default, we'll bind to all addresses on port 25577.
+# What port should the proxy be bound to? By default, we'll bind to all addresses on port 25565.
-bind = "0.0.0.0:25577"
+bind = "0.0.0.0:25565"
 
 # What should be the MOTD? This gets displayed when the player adds your server to
 # their server list. Only MiniMessage format is accepted.
@@ -150,7 +150,7 @@ accepts-transfers = false
 enabled = false
 
 # If query is enabled, on what port should the query protocol listen on?
-port = 25577
+port = 25565
 
 # This is the map name that is reported to the query services.
 map = "Velocity"