Added 1.21.6 support

Fix FabledSkyBlock errors on new versions of the plugin

.github/workflows/java-ci.yml

@@ -21,7 +21,7 @@ jobs:
           java-version: 21
 
       - name: Setup build cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v4
         with:
           path: ~/.gradle/caches
           key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}

.github/workflows/publish-release.yml

@@ -19,7 +19,7 @@ jobs:
           java-version: 21
 
       - name: Setup build cache
-        uses: actions/cache@v2.1.6
+        uses: actions/cache@v4
         with:
           path: ~/.gradle/caches
           key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}

build.gradle.kts

@@ -36,6 +36,8 @@ dependencies {
     implementation(project(path = ":eco-core:core-nms:v1_21", configuration = "reobf"))
     implementation(project(path = ":eco-core:core-nms:v1_21_3", configuration = "reobf"))
     implementation(project(path = ":eco-core:core-nms:v1_21_4", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21_5", configuration = "reobf"))
+    implementation(project(path = ":eco-core:core-nms:v1_21_6", configuration = "reobf"))
 }
 
 allprojects {

eco-api/src/main/java/com/willfp/eco/core/packet/Packet.java

@@ -6,10 +6,51 @@ import org.jetbrains.annotations.NotNull;
 
 /**
  * Represents a packet.
- *
- * @param handle The NMS handle.
  */
-public record Packet(@NotNull Object handle) {
+public class Packet {
+    /**
+     * The packet handle.
+     */
+    private Object handle;
+
+    /**
+     * Create a new packet.
+     *
+     * @param handle The packet handle.
+     */
+    public Packet(@NotNull final Object handle) {
+        this.handle = handle;
+    }
+
+    /**
+     * Get the packet handle.
+     *
+     * @return The packet handle.
+     */
+    public Object getHandle() {
+        return handle;
+    }
+
+    /**
+     * Set the packet handle.
+     *
+     * @param handle The packet handle.
+     */
+    public void setHandle(@NotNull final Object handle) {
+        this.handle = handle;
+    }
+
+    /**
+     * Get the packet handle, compatible with the old record-based packet system.
+     *
+     * @return The packet handle.
+     * @deprecated Use {@link #getHandle()} instead.
+     */
+    @Deprecated
+    public Object handle() {
+        return handle;
+    }
+
     /**
      * Send to a player.
      *

eco-api/src/main/java/com/willfp/eco/core/proxy/ProxyConstants.java

@@ -31,7 +31,9 @@ public final class ProxyConstants {
             "v1_20_R3",
             "v1_21",
             "v1_21_3",
-            "v1_21_4"
+            "v1_21_4",
+            "v1_21_5",
+            "v1_21_6"
     );
 
     private ProxyConstants() {

eco-core/core-nms/build.gradle.kts

@@ -1,5 +1,5 @@
 plugins {
-    id("io.papermc.paperweight.userdev") version "2.0.0-beta.14" apply false
+    id("io.papermc.paperweight.userdev") version "2.0.0-beta.17" apply false
 }
 
 

eco-core/core-nms/common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/packet/EcoChannelDuplexHandler.kt

@@ -23,7 +23,7 @@ class EcoChannelDuplexHandler(
             event.handleReceive()
 
             if (!event.isCancelled) {
-                super.channelRead(ctx, msg)
+                super.channelRead(ctx, event.packet.handle)
             }
         } else {
             super.channelRead(ctx, msg)
@@ -39,7 +39,7 @@ class EcoChannelDuplexHandler(
             event.handleSend()
 
             if (!event.isCancelled) {
-                super.write(ctx, msg, promise)
+                super.write(ctx, event.packet.handle, promise)
             }
         } else {
             super.write(ctx, msg, promise)

eco-core/core-nms/common/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/packet/display/PacketWindowItems.kt

@@ -15,7 +15,7 @@ import org.bukkit.inventory.ItemStack
 import java.util.UUID
 import java.util.concurrent.ConcurrentHashMap
 
-class PacketWindowItems(
+open class PacketWindowItems(
     private val plugin: EcoPlugin
 ) : PacketListener {
     private val lastKnownWindowIDs = ConcurrentHashMap<UUID, Int>()
@@ -52,7 +52,7 @@ class PacketWindowItems(
     }
 
 
-    private fun modifyWindowItems(
+    protected fun modifyWindowItems(
         itemStacks: MutableList<ItemStack>,
         windowId: Int,
         player: Player

eco-core/core-nms/modern/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/common/modern/NewEcoFastItemStack.kt

@@ -144,7 +144,7 @@ open class NewEcoFastItemStack(
 
     override fun getDisplayName(): String = displayNameComponent.toLegacy()
 
-    private fun <T> net.minecraft.world.item.ItemStack.modifyComponent(
+    protected fun <T> net.minecraft.world.item.ItemStack.modifyComponent(
         component: DataComponentType<T>,
         modifier: (T) -> T
     ) {

eco-core/core-nms/v1_21_4/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_4/packet/NewItemsPacketSetCreativeSlot.kt

@@ -6,6 +6,7 @@ import com.willfp.eco.core.packet.PacketListener
 import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
 import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.DisplayFrame
 import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.lastDisplayFrame
+import net.minecraft.network.protocol.game.ClientboundContainerSetContentPacket
 import net.minecraft.network.protocol.game.ServerboundSetCreativeModeSlotPacket
 
 object NewItemsPacketSetCreativeSlot : PacketListener {

eco-core/core-nms/v1_21_5/build.gradle.kts

@@ -0,0 +1,52 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    id("io.papermc.paperweight.userdev")
+}
+
+group = "com.willfp"
+version = rootProject.version
+
+dependencies {
+    implementation(project(":eco-core:core-nms:modern"))
+    implementation(project(":eco-core:core-nms:common"))
+    paperweight.paperDevBundle("1.21.5-R0.1-SNAPSHOT")
+
+    implementation("net.kyori:adventure-text-minimessage:4.11.0") {
+        version {
+            strictly("4.11.0")
+        }
+        exclude(group = "net.kyori", module = "adventure-api")
+    }
+}
+
+tasks {
+    build {
+        dependsOn(reobfJar)
+    }
+
+    reobfJar {
+        mustRunAfter(shadowJar)
+    }
+
+    shadowJar {
+        relocate(
+            "com.willfp.eco.internal.spigot.proxy.common",
+            "com.willfp.eco.internal.spigot.proxy.v1_21_5.common"
+        )
+        relocate(
+            "net.kyori.adventure.text.minimessage",
+            "com.willfp.eco.internal.spigot.proxy.v1_21_5.minimessage"
+        )
+    }
+
+    compileJava {
+        options.release.set(21)
+    }
+
+    compileKotlin {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_21)
+        }
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.command.PluginCommandBase
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommandBase) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/CommonsInitializer.kt

@@ -0,0 +1,171 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.internal.spigot.proxy.CommonsInitializerProxy
+import com.willfp.eco.internal.spigot.proxy.common.CommonsProvider
+import com.willfp.eco.internal.spigot.proxy.common.packet.PacketInjectorListener
+import com.willfp.eco.internal.spigot.proxy.common.toResourceLocation
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.serializer.json.JSONComponentSerializer
+import net.minecraft.core.component.DataComponents
+import net.minecraft.core.registries.BuiltInRegistries
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.Tag
+import net.minecraft.resources.ResourceLocation
+import net.minecraft.server.level.ServerPlayer
+import net.minecraft.world.entity.PathfinderMob
+import net.minecraft.world.item.Item
+import org.bukkit.Bukkit
+import org.bukkit.Material
+import org.bukkit.NamespacedKey
+import org.bukkit.craftbukkit.CraftServer
+import org.bukkit.craftbukkit.entity.CraftEntity
+import org.bukkit.craftbukkit.entity.CraftMob
+import org.bukkit.craftbukkit.entity.CraftPlayer
+import org.bukkit.craftbukkit.inventory.CraftItemStack
+import org.bukkit.craftbukkit.inventory.CraftMetaArmor
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataContainer
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.craftbukkit.util.CraftMagicNumbers
+import org.bukkit.craftbukkit.util.CraftNamespacedKey
+import org.bukkit.entity.LivingEntity
+import org.bukkit.entity.Mob
+import org.bukkit.entity.Player
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataContainer
+import java.lang.reflect.Field
+
+class CommonsInitializer : CommonsInitializerProxy {
+    override fun init(plugin: EcoPlugin) {
+        CommonsProvider.setIfNeeded(CommonsProviderImpl)
+        plugin.onEnable {
+            plugin.eventManager.registerListener(PacketInjectorListener)
+        }
+    }
+
+    object CommonsProviderImpl : CommonsProvider {
+        private val cisHandle: Field = CraftItemStack::class.java.getDeclaredField("handle").apply {
+            isAccessible = true
+        }
+
+        private val pdcRegsitry = CraftMetaArmor::class.java
+            .superclass // Access CraftMetaItem
+            .getDeclaredField("DATA_TYPE_REGISTRY")
+            .apply { isAccessible = true }
+            .get(null) as CraftPersistentDataTypeRegistry
+
+        override val nbtTagString = 8
+
+        override fun toPathfinderMob(mob: Mob): PathfinderMob? {
+            val craft = mob as? CraftMob ?: return null
+            return craft.handle as? PathfinderMob
+        }
+
+        override fun toResourceLocation(namespacedKey: NamespacedKey): ResourceLocation =
+            CraftNamespacedKey.toMinecraft(namespacedKey)
+
+        override fun asNMSStack(itemStack: ItemStack): net.minecraft.world.item.ItemStack {
+            return if (itemStack !is CraftItemStack) {
+                CraftItemStack.asNMSCopy(itemStack)
+            } else {
+                cisHandle[itemStack] as net.minecraft.world.item.ItemStack? ?: CraftItemStack.asNMSCopy(itemStack)
+            }
+        }
+
+        override fun asBukkitStack(itemStack: net.minecraft.world.item.ItemStack): ItemStack {
+            return CraftItemStack.asCraftMirror(itemStack)
+        }
+
+        override fun mergeIfNeeded(itemStack: ItemStack, nmsStack: net.minecraft.world.item.ItemStack) {
+            if (itemStack !is CraftItemStack) {
+                itemStack.itemMeta = CraftItemStack.asCraftMirror(nmsStack).itemMeta
+            }
+        }
+
+        override fun toBukkitEntity(entity: net.minecraft.world.entity.LivingEntity): LivingEntity? =
+            CraftEntity.getEntity(Bukkit.getServer() as CraftServer, entity) as? LivingEntity
+
+        override fun makePdc(tag: CompoundTag, base: Boolean): PersistentDataContainer {
+            fun emptyPdc(): CraftPersistentDataContainer = CraftPersistentDataContainer(pdcRegsitry)
+
+            fun CompoundTag?.toPdc(): PersistentDataContainer {
+                val pdc = emptyPdc()
+                this ?: return pdc
+                val keys = this.keySet()
+                for (key in keys) {
+                    pdc.put(key, this[key])
+                }
+
+                return pdc
+            }
+
+            return if (base) {
+                tag.toPdc()
+            } else {
+                if (tag.contains("PublicBukkitValues")) {
+                    tag.getCompound("PublicBukkitValues").get().toPdc()
+                } else {
+                    emptyPdc()
+                }
+            }
+        }
+
+        override fun setPdc(
+            tag: CompoundTag,
+            pdc: PersistentDataContainer?,
+            item: net.minecraft.world.item.ItemStack?
+        ) {
+            fun CraftPersistentDataContainer.toTag(): CompoundTag {
+                val compound = CompoundTag()
+                val rawPublicMap: Map<String, Tag> = this.raw
+                for ((key, value) in rawPublicMap) {
+                    compound.put(key, value)
+                }
+
+                return compound
+            }
+
+            val container = when (pdc) {
+                is CraftPersistentDataContainer? -> pdc
+                else -> null
+            }
+
+            if (item != null) {
+                if (container != null && !container.isEmpty) {
+                    for (key in tag.keySet()) {
+                        tag.remove(key)
+                    }
+
+                    tag.merge(container.toTag())
+                } else {
+                    item.remove(DataComponents.CUSTOM_DATA)
+                }
+            } else {
+                if (container != null && !container.isEmpty) {
+                    tag.put("PublicBukkitValues", container.toTag())
+                } else {
+                    tag.remove("PublicBukkitValues")
+                }
+            }
+        }
+
+        override fun materialToItem(material: Material): Item =
+            BuiltInRegistries.ITEM.getOptional(material.key.toResourceLocation())
+                .orElseThrow { IllegalArgumentException("Material is not item!") }
+
+        override fun itemToMaterial(item: Item) =
+            Material.getMaterial(BuiltInRegistries.ITEM.getKey(item).path.uppercase())
+                ?: throw IllegalArgumentException("Invalid material!")
+
+        override fun toNMS(player: Player): ServerPlayer {
+            return (player as CraftPlayer).handle
+        }
+
+        override fun toNMS(component: Component): net.minecraft.network.chat.Component {
+            val json = JSONComponentSerializer.json().serialize(component)
+            val holderLookupProvider = (Bukkit.getServer() as CraftServer).server.registryAccess()
+
+            return net.minecraft.network.chat.Component.Serializer.fromJson(json, holderLookupProvider)!!
+        }
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/DisplayName.kt

@@ -0,0 +1,57 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.packet.Packet
+import com.willfp.eco.core.packet.sendPacket
+import com.willfp.eco.internal.spigot.proxy.DisplayNameProxy
+import com.willfp.eco.internal.spigot.proxy.common.toNMS
+import net.kyori.adventure.text.Component
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket
+import net.minecraft.network.syncher.EntityDataAccessor
+import net.minecraft.network.syncher.SynchedEntityData
+import net.minecraft.world.entity.Entity
+import org.bukkit.craftbukkit.entity.CraftLivingEntity
+import org.bukkit.entity.LivingEntity
+import org.bukkit.entity.Player
+import java.util.Optional
+
+@Suppress("UNCHECKED_CAST")
+class DisplayName : DisplayNameProxy {
+    private val displayNameAccessor = Entity::class.java
+        .declaredFields
+        .filter { it.type == EntityDataAccessor::class.java }
+        .toList()[2]
+        .apply { isAccessible = true }
+        .get(null) as EntityDataAccessor<Optional<net.minecraft.network.chat.Component>>
+
+    private val customNameVisibleAccessor = Entity::class.java
+        .declaredFields
+        .filter { it.type == EntityDataAccessor::class.java }
+        .toList()[3]
+        .apply { isAccessible = true }
+        .get(null) as EntityDataAccessor<Boolean>
+
+    override fun setClientsideDisplayName(
+        entity: LivingEntity,
+        player: Player,
+        displayName: Component,
+        visible: Boolean
+    ) {
+        if (entity !is CraftLivingEntity) {
+            return
+        }
+
+        val nmsComponent = displayName.toNMS()
+
+        val nmsEntity = entity.handle
+
+        val packet = ClientboundSetEntityDataPacket(
+            nmsEntity.id,
+            listOf(
+                SynchedEntityData.DataValue.create(displayNameAccessor, Optional.of(nmsComponent)),
+                SynchedEntityData.DataValue.create(customNameVisibleAccessor, visible)
+            )
+        )
+
+        player.sendPacket(Packet(packet))
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/DummyEntityFactory.kt

@@ -0,0 +1,15 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.internal.entities.EcoDummyEntity
+import com.willfp.eco.internal.spigot.proxy.DummyEntityFactoryProxy
+import org.bukkit.Location
+import org.bukkit.craftbukkit.CraftWorld
+import org.bukkit.entity.Entity
+import org.bukkit.entity.Zombie
+
+class DummyEntityFactory : DummyEntityFactoryProxy {
+    override fun createDummyEntity(location: Location): Entity {
+        val world = location.world as CraftWorld
+        return EcoDummyEntity(world.createEntity(location, Zombie::class.java))
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/EntityControllerFactory.kt

@@ -0,0 +1,12 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.entities.ai.EntityController
+import com.willfp.eco.internal.spigot.proxy.EntityControllerFactoryProxy
+import com.willfp.eco.internal.spigot.proxy.v1_21_5.entity.EcoEntityController
+import org.bukkit.entity.Mob
+
+class EntityControllerFactory : EntityControllerFactoryProxy {
+    override fun <T : Mob> createEntityController(entity: T): EntityController<T> {
+        return EcoEntityController(entity)
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/ExtendedPersistentDataContainerFactory.kt

@@ -0,0 +1,91 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.data.ExtendedPersistentDataContainer
+import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
+import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.inventory.CraftItemStack
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataContainer
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataContainer
+import org.bukkit.persistence.PersistentDataType
+import java.lang.reflect.Field
+
+class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+
+        // Cross-version compatibility:
+        val registryField: Field = try {
+            CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+        } catch (e: NoSuchFieldException) {
+            CraftPersistentDataContainer::class.java.superclass.getDeclaredField("registry")
+        }
+
+        this.registry = registryField
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
+
+    override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
+        return when (pdc) {
+            is CraftPersistentDataContainer -> EcoPersistentDataContainer(pdc)
+            else -> throw IllegalArgumentException("Custom PDC instance ${pdc::class.java.name} is not supported!")
+        }
+    }
+
+    override fun newPdc(): PersistentDataContainer {
+        return CraftPersistentDataContainer(registry)
+    }
+
+    inner class EcoPersistentDataContainer(
+        private val handle: CraftPersistentDataContainer
+    ) : ExtendedPersistentDataContainer {
+        @Suppress("UNCHECKED_CAST")
+        private val customDataTags: MutableMap<String, Tag> =
+            CraftPersistentDataContainer::class.java.getDeclaredField("customDataTags")
+                .apply { isAccessible = true }.get(handle) as MutableMap<String, Tag>
+
+        override fun <T : Any, Z : Any> set(key: String, dataType: PersistentDataType<T, Z>, value: Z) {
+            customDataTags[key] =
+                registry.wrap(dataType, dataType.toPrimitive(value, handle.adapterContext))
+        }
+
+        override fun <T : Any, Z : Any> has(key: String, dataType: PersistentDataType<T, Z>): Boolean {
+            val value = customDataTags[key] ?: return false
+            return registry.isInstanceOf(dataType, value)
+        }
+
+        override fun <T : Any, Z : Any> get(key: String, dataType: PersistentDataType<T, Z>): Z? {
+            val value = customDataTags[key] ?: return null
+            return dataType.fromPrimitive(registry.extract<T, Tag>(dataType, value), handle.adapterContext)
+        }
+
+        override fun <T : Any, Z : Any> getOrDefault(
+            key: String,
+            dataType: PersistentDataType<T, Z>,
+            defaultValue: Z
+        ): Z {
+            return get(key, dataType) ?: defaultValue
+        }
+
+        override fun remove(key: String) {
+            customDataTags.remove(key)
+        }
+
+        override fun getAllKeys(): MutableSet<String> {
+            return customDataTags.keys
+        }
+
+        override fun getBase(): PersistentDataContainer {
+            return handle
+        }
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/FastItemStackFactory.kt

@@ -0,0 +1,13 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.fast.FastItemStack
+import com.willfp.eco.internal.spigot.proxy.FastItemStackFactoryProxy
+import com.willfp.eco.internal.spigot.proxy.common.modern.NewEcoFastItemStack
+import com.willfp.eco.internal.spigot.proxy.v1_21_5.item.NewerEcoFastItemStack
+import org.bukkit.inventory.ItemStack
+
+class FastItemStackFactory : FastItemStackFactoryProxy {
+    override fun create(itemStack: ItemStack): FastItemStack {
+        return NewerEcoFastItemStack(itemStack)
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/MiniMessageTranslator.kt

@@ -0,0 +1,33 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.internal.spigot.proxy.MiniMessageTranslatorProxy
+import com.willfp.eco.util.toLegacy
+import net.kyori.adventure.text.minimessage.MiniMessage
+
+class MiniMessageTranslator : MiniMessageTranslatorProxy {
+    override fun format(message: String): String {
+        var mut = message
+
+        val startsWithPrefix = mut.startsWith(Display.PREFIX)
+        if (startsWithPrefix) {
+            mut = mut.substring(2)
+        }
+
+        mut = mut.replace('§', '&')
+
+        val miniMessage = runCatching {
+            MiniMessage.miniMessage().deserialize(
+                mut
+            ).toLegacy()
+        }.getOrNull() ?: mut
+
+        mut = if (startsWithPrefix) {
+            Display.PREFIX + miniMessage
+        } else {
+            miniMessage
+        }
+
+        return mut
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/PacketHandler.kt

@@ -0,0 +1,46 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.packet.PacketListener
+import com.willfp.eco.internal.spigot.proxy.PacketHandlerProxy
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.PacketHeldItemSlot
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.PacketSetSlot
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.clearFrames
+import com.willfp.eco.internal.spigot.proxy.v1_21_5.packet.NewItemsPacketOpenWindowMerchant
+import com.willfp.eco.internal.spigot.proxy.v1_21_5.packet.NewItemsPacketSetCreativeSlot
+import com.willfp.eco.internal.spigot.proxy.v1_21_5.packet.NewItemsPacketWindowItems
+import net.minecraft.network.protocol.Packet
+import org.bukkit.craftbukkit.entity.CraftPlayer
+import org.bukkit.entity.Player
+
+class PacketHandler : PacketHandlerProxy {
+    override fun sendPacket(player: Player, packet: com.willfp.eco.core.packet.Packet) {
+        if (player !is CraftPlayer) {
+            return
+        }
+
+        val handle = packet.handle
+
+        if (handle !is Packet<*>) {
+            return
+        }
+
+        player.handle.connection.send(handle)
+    }
+
+    override fun clearDisplayFrames() {
+        clearFrames()
+    }
+
+    override fun getPacketListeners(plugin: EcoPlugin): List<PacketListener> {
+        // No PacketAutoRecipe for 1.21.3+ because recipes have been changed internally
+
+        return listOf(
+            PacketHeldItemSlot,
+            NewItemsPacketOpenWindowMerchant,
+            NewItemsPacketSetCreativeSlot,
+            PacketSetSlot,
+            NewItemsPacketWindowItems(plugin)
+        )
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/SNBTConverter.kt

@@ -0,0 +1,81 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.mojang.serialization.Dynamic
+import com.willfp.eco.core.items.TestableItem
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem
+import com.willfp.eco.internal.spigot.proxy.SNBTConverterProxy
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.NbtOps
+import net.minecraft.nbt.SnbtPrinterTagVisitor
+import net.minecraft.nbt.TagParser
+import net.minecraft.server.MinecraftServer
+import net.minecraft.util.datafix.fixes.References
+import org.bukkit.Bukkit
+import org.bukkit.craftbukkit.CraftServer
+import org.bukkit.craftbukkit.inventory.CraftItemStack
+import org.bukkit.craftbukkit.util.CraftMagicNumbers
+import org.bukkit.inventory.ItemStack
+
+private val registryAccess = (Bukkit.getServer() as CraftServer).server.registryAccess()
+
+class SNBTConverter : SNBTConverterProxy {
+    private fun parseItemSNBT(snbt: String): CompoundTag? {
+        val nbt = runCatching { TagParser.parseCompoundFully(snbt) }.getOrNull() ?: return null
+        val dataVersion = if (nbt.contains("DataVersion")) {
+            nbt.getInt("DataVersion").get()
+        } else null
+
+        // If the data version is the same as the server's data version, we don't need to fix it
+
+        if (dataVersion == CraftMagicNumbers.INSTANCE.dataVersion) {
+            return nbt
+        }
+
+        return MinecraftServer.getServer().fixerUpper.update(
+            References.ITEM_STACK,
+            Dynamic(NbtOps.INSTANCE, nbt),
+            dataVersion ?: 3700, // 3700 is the 1.20.4 data version
+            CraftMagicNumbers.INSTANCE.dataVersion
+        ).value as CompoundTag
+    }
+
+    override fun fromSNBT(snbt: String): ItemStack? {
+        val tag = parseItemSNBT(snbt) ?: return null
+        val nms = net.minecraft.world.item.ItemStack.parse(registryAccess, tag).orElse(null) ?: return null
+        return CraftItemStack.asBukkitCopy(nms)
+    }
+
+    override fun toSNBT(itemStack: ItemStack): String {
+        val nms = CraftItemStack.asNMSCopy(itemStack)
+        val tag = nms.save(registryAccess) as CompoundTag
+        tag.putInt("DataVersion", CraftMagicNumbers.INSTANCE.dataVersion)
+        return SnbtPrinterTagVisitor().visit(tag)
+    }
+
+    override fun makeSNBTTestable(snbt: String): TestableItem {
+        val tag = parseItemSNBT(snbt) ?: return EmptyTestableItem()
+        val nms = net.minecraft.world.item.ItemStack.parse(registryAccess, tag).orElse(null)
+            ?: return EmptyTestableItem()
+
+        tag.remove("Count")
+        return SNBTTestableItem(CraftItemStack.asBukkitCopy(nms), tag)
+    }
+
+    class SNBTTestableItem(
+        private val item: ItemStack,
+        private val tag: CompoundTag
+    ) : TestableItem {
+        override fun matches(itemStack: ItemStack?): Boolean {
+            if (itemStack == null) {
+                return false
+            }
+
+            val nms = CraftItemStack.asNMSCopy(itemStack)
+            val nmsTag = nms.save(registryAccess) as CompoundTag
+            nmsTag.remove("Count")
+            return tag.copy().merge(nmsTag) == nmsTag && itemStack.type == item.type
+        }
+
+        override fun getItem(): ItemStack = item
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/Skull.kt

@@ -0,0 +1,18 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.internal.spigot.proxy.SkullProxy
+import com.willfp.eco.internal.spigot.proxy.common.modern.texture
+import org.bukkit.inventory.meta.SkullMeta
+
+class Skull : SkullProxy {
+    override fun setSkullTexture(
+        meta: SkullMeta,
+        base64: String
+    ) {
+        meta.texture = base64
+    }
+
+    override fun getSkullTexture(
+        meta: SkullMeta
+    ): String? = meta.texture
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/TPS.kt

@@ -0,0 +1,11 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5
+
+import com.willfp.eco.internal.spigot.proxy.TPSProxy
+import org.bukkit.Bukkit
+import org.bukkit.craftbukkit.CraftServer
+
+class TPS : TPSProxy {
+    override fun getTPS(): Double {
+        return (Bukkit.getServer() as CraftServer).handle.server.tps1.average
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/entity/EcoEntityController.kt

@@ -0,0 +1,95 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5.entity
+
+import com.willfp.eco.core.entities.ai.CustomGoal
+import com.willfp.eco.core.entities.ai.EntityController
+import com.willfp.eco.core.entities.ai.EntityGoal
+import com.willfp.eco.core.entities.ai.TargetGoal
+import com.willfp.eco.internal.spigot.proxy.common.ai.CustomGoalFactory
+import com.willfp.eco.internal.spigot.proxy.common.ai.getGoalFactory
+import com.willfp.eco.internal.spigot.proxy.common.toPathfinderMob
+import net.minecraft.world.entity.PathfinderMob
+import net.minecraft.world.entity.ai.goal.Goal
+import org.bukkit.entity.Mob
+
+class EcoEntityController<T : Mob>(
+    private val handle: T
+) : EntityController<T> {
+    override fun addEntityGoal(priority: Int, goal: EntityGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        nms.goalSelector.addGoal(
+            priority,
+            goal.getGoalFactory()?.create(goal, nms) ?: return this
+        )
+
+        return this
+    }
+
+    override fun removeEntityGoal(goal: EntityGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        val predicate: (Goal) -> Boolean = if (goal is CustomGoal<*>) {
+            { CustomGoalFactory.isGoalOfType(it, goal) }
+        } else {
+            { goal.getGoalFactory()?.isGoalOfType(it) == true }
+        }
+
+        for (wrapped in nms.goalSelector.availableGoals.toSet()) {
+            if (predicate(wrapped.goal)) {
+                nms.goalSelector.removeGoal(wrapped.goal)
+            }
+        }
+
+        return this
+    }
+
+    override fun clearEntityGoals(): EntityController<T> {
+        val nms = getNms() ?: return this
+        nms.goalSelector.availableGoals.clear()
+        return this
+    }
+
+    override fun addTargetGoal(priority: Int, goal: TargetGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        nms.targetSelector.addGoal(
+            priority, goal.getGoalFactory()?.create(goal, nms) ?: return this
+        )
+
+        nms.targetSelector
+
+        return this
+    }
+
+    override fun removeTargetGoal(goal: TargetGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        val predicate: (Goal) -> Boolean = if (goal is CustomGoal<*>) {
+            { CustomGoalFactory.isGoalOfType(it, goal) }
+        } else {
+            { goal.getGoalFactory()?.isGoalOfType(it) == true }
+        }
+
+        for (wrapped in nms.targetSelector.availableGoals.toSet()) {
+            if (predicate(wrapped.goal)) {
+                nms.targetSelector.removeGoal(wrapped.goal)
+            }
+        }
+
+        return this
+    }
+
+    override fun clearTargetGoals(): EntityController<T> {
+        val nms = getNms() ?: return this
+        nms.targetSelector.availableGoals.clear()
+        return this
+    }
+
+    private fun getNms(): PathfinderMob? {
+        return handle.toPathfinderMob()
+    }
+
+    override fun getEntity(): T {
+        return handle
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/item/NewerEcoFastItemStack.kt

@@ -0,0 +1,185 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5.item
+
+import com.willfp.eco.internal.spigot.proxy.common.modern.NewEcoFastItemStack
+import net.minecraft.core.component.DataComponents
+import net.minecraft.world.item.component.TooltipDisplay
+import org.bukkit.inventory.ItemFlag
+import org.bukkit.inventory.ItemStack
+
+
+open class NewerEcoFastItemStack(
+    bukkit: ItemStack,
+) : NewEcoFastItemStack(bukkit) {
+    override fun addItemFlags(vararg hideFlags: ItemFlag) {
+        for (flag in hideFlags) {
+            when (flag) {
+                ItemFlag.HIDE_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ENCHANTMENTS, true)
+                    }
+                }
+
+                ItemFlag.HIDE_ATTRIBUTES -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ATTRIBUTE_MODIFIERS, true)
+                    }
+                }
+
+                ItemFlag.HIDE_UNBREAKABLE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.UNBREAKABLE, true)
+                    }
+                }
+
+                ItemFlag.HIDE_DESTROYS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_BREAK, true)
+                    }
+                }
+
+                ItemFlag.HIDE_PLACED_ON -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_PLACE_ON, true)
+                    }
+                }
+
+                ItemFlag.HIDE_ADDITIONAL_TOOLTIP -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        TooltipDisplay(true, tooltip.hiddenComponents)
+                    }
+                }
+
+                ItemFlag.HIDE_DYE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.DYED_COLOR, true)
+                    }
+                }
+
+                ItemFlag.HIDE_ARMOR_TRIM -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.TRIM, true)
+                    }
+                }
+
+                ItemFlag.HIDE_STORED_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.STORED_ENCHANTMENTS, true)
+                    }
+                }
+            }
+        }
+
+        apply()
+    }
+
+    override fun removeItemFlags(vararg hideFlags: ItemFlag) {
+        for (flag in hideFlags) {
+            when (flag) {
+                ItemFlag.HIDE_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ENCHANTMENTS, false)
+                    }
+                }
+
+                ItemFlag.HIDE_ATTRIBUTES -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ATTRIBUTE_MODIFIERS, false)
+                    }
+                }
+
+                ItemFlag.HIDE_UNBREAKABLE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.UNBREAKABLE, false)
+                    }
+                }
+
+                ItemFlag.HIDE_DESTROYS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_BREAK, false)
+                    }
+                }
+
+                ItemFlag.HIDE_PLACED_ON -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_PLACE_ON, false)
+                    }
+                }
+
+                ItemFlag.HIDE_ADDITIONAL_TOOLTIP -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        TooltipDisplay(false, tooltip.hiddenComponents)
+                    }
+                }
+
+                ItemFlag.HIDE_DYE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.DYED_COLOR, false)
+                    }
+                }
+
+                ItemFlag.HIDE_ARMOR_TRIM -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.TRIM, false)
+                    }
+                }
+
+                ItemFlag.HIDE_STORED_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.STORED_ENCHANTMENTS, false)
+                    }
+                }
+            }
+        }
+
+        apply()
+    }
+
+    override fun hasItemFlag(flag: ItemFlag): Boolean {
+        return when (flag) {
+            ItemFlag.HIDE_ENCHANTS -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.ENCHANTMENTS)
+            }
+
+            ItemFlag.HIDE_ATTRIBUTES -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.ATTRIBUTE_MODIFIERS)
+            }
+
+            ItemFlag.HIDE_UNBREAKABLE -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.UNBREAKABLE)
+            }
+
+            ItemFlag.HIDE_DESTROYS -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.CAN_BREAK)
+            }
+
+            ItemFlag.HIDE_PLACED_ON -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.CAN_PLACE_ON)
+            }
+
+            ItemFlag.HIDE_ADDITIONAL_TOOLTIP -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                tooltip.hideTooltip
+            }
+
+            ItemFlag.HIDE_DYE -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.DYED_COLOR)
+            }
+
+            ItemFlag.HIDE_ARMOR_TRIM -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.TRIM)
+            }
+
+            ItemFlag.HIDE_STORED_ENCHANTS -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.STORED_ENCHANTMENTS)
+            }
+        }
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/packet/NewItemsPacketOpenWindowMerchant.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5.packet
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.packet.PacketEvent
+import com.willfp.eco.core.packet.PacketListener
+import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
+import net.minecraft.network.protocol.game.ClientboundMerchantOffersPacket
+import net.minecraft.world.item.trading.MerchantOffers
+
+object NewItemsPacketOpenWindowMerchant : PacketListener {
+    private val field = ClientboundMerchantOffersPacket::class.java
+        .declaredFields
+        .first { it.type == MerchantOffers::class.java }
+        .apply { isAccessible = true }
+
+    override fun onSend(event: PacketEvent) {
+        val packet = event.packet.handle as? ClientboundMerchantOffersPacket ?: return
+
+        val offers = MerchantOffers()
+
+        for (offer in packet.offers) {
+            val new = offer.copy()
+
+            Display.display(new.baseCostA.itemStack.asBukkitStack(), event.player)
+            if (new.costB.isPresent) {
+                Display.display(new.costB.get().itemStack.asBukkitStack(), event.player)
+            }
+            Display.display(new.result.asBukkitStack(), event.player)
+
+            offers += new
+        }
+
+        field.set(packet, offers)
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/packet/NewItemsPacketSetCreativeSlot.kt

@@ -0,0 +1,19 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5.packet
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.packet.PacketEvent
+import com.willfp.eco.core.packet.PacketListener
+import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.DisplayFrame
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.lastDisplayFrame
+import net.minecraft.network.protocol.game.ServerboundSetCreativeModeSlotPacket
+
+object NewItemsPacketSetCreativeSlot : PacketListener {
+    override fun onReceive(event: PacketEvent) {
+        val packet = event.packet.handle as? ServerboundSetCreativeModeSlotPacket ?: return
+
+        Display.revert(packet.itemStack.asBukkitStack())
+
+        event.player.lastDisplayFrame = DisplayFrame.EMPTY
+    }
+}

eco-core/core-nms/v1_21_5/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_5/packet/NewItemsPacketWindowItems.kt

@@ -0,0 +1,52 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_5.packet
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.packet.PacketEvent
+import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
+import com.willfp.eco.internal.spigot.proxy.common.asNMSStack
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.PacketWindowItems
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.DisplayFrame
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.lastDisplayFrame
+import net.minecraft.network.protocol.game.ClientboundContainerSetContentPacket
+import java.util.UUID
+import java.util.concurrent.ConcurrentHashMap
+
+class NewItemsPacketWindowItems(
+    plugin: EcoPlugin
+) : PacketWindowItems(plugin) {
+    private val lastKnownWindowIDs = ConcurrentHashMap<UUID, Int>()
+
+    override fun onSend(event: PacketEvent) {
+        val packet = event.packet.handle as? ClientboundContainerSetContentPacket ?: return
+        val player = event.player
+
+        Display.display(packet.carriedItem.asBukkitStack(), player)
+
+        val windowId = packet.containerId
+
+        val lastKnownID = lastKnownWindowIDs[player.uniqueId]
+        lastKnownWindowIDs[player.uniqueId] = windowId
+
+        // If there is any change in window ID at any point,
+        // Remove the last display frame to prevent any potential conflicts.
+        // If the window ID is not zero (not a player inventory), then remove too,
+        // as GUIs are not player inventories.
+        if (lastKnownID != windowId || windowId != 0) {
+            player.lastDisplayFrame = DisplayFrame.EMPTY
+        }
+
+        val itemStacks = packet.items.map { it.asBukkitStack() }
+
+        val newItems = modifyWindowItems(itemStacks.toMutableList(), windowId, player)
+
+        val newPacket = ClientboundContainerSetContentPacket(
+            packet.containerId,
+            packet.stateId,
+            newItems.map { it.asNMSStack() },
+            packet.carriedItem,
+        )
+
+        event.packet.handle = newPacket
+    }
+}

eco-core/core-nms/v1_21_6/build.gradle.kts

@@ -0,0 +1,52 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    id("io.papermc.paperweight.userdev")
+}
+
+group = "com.willfp"
+version = rootProject.version
+
+dependencies {
+    implementation(project(":eco-core:core-nms:modern"))
+    implementation(project(":eco-core:core-nms:common"))
+    paperweight.paperDevBundle("1.21.6-R0.1-SNAPSHOT")
+
+    implementation("net.kyori:adventure-text-minimessage:4.11.0") {
+        version {
+            strictly("4.11.0")
+        }
+        exclude(group = "net.kyori", module = "adventure-api")
+    }
+}
+
+tasks {
+    build {
+        dependsOn(reobfJar)
+    }
+
+    reobfJar {
+        mustRunAfter(shadowJar)
+    }
+
+    shadowJar {
+        relocate(
+            "com.willfp.eco.internal.spigot.proxy.common",
+            "com.willfp.eco.internal.spigot.proxy.v1_21_6.common"
+        )
+        relocate(
+            "net.kyori.adventure.text.minimessage",
+            "com.willfp.eco.internal.spigot.proxy.v1_21_6.minimessage"
+        )
+    }
+
+    compileJava {
+        options.release.set(21)
+    }
+
+    compileKotlin {
+        compilerOptions {
+            jvmTarget.set(JvmTarget.JVM_21)
+        }
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/BukkitCommands.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.command.PluginCommandBase
+import com.willfp.eco.internal.spigot.proxy.BukkitCommandsProxy
+import org.bukkit.Bukkit
+import org.bukkit.command.Command
+import org.bukkit.command.SimpleCommandMap
+import org.bukkit.craftbukkit.CraftServer
+import java.lang.reflect.Field
+
+class BukkitCommands : BukkitCommandsProxy {
+    private val knownCommandsField: Field by lazy {
+        SimpleCommandMap::class.java.getDeclaredField("knownCommands")
+            .apply {
+                isAccessible = true
+            }
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    private val knownCommands: MutableMap<String, Command>
+        get() = knownCommandsField.get(getCommandMap()) as MutableMap<String, Command>
+
+    override fun getCommandMap(): SimpleCommandMap {
+        return (Bukkit.getServer() as CraftServer).commandMap
+    }
+
+    override fun syncCommands() {
+        (Bukkit.getServer() as CraftServer).syncCommands()
+    }
+
+    override fun unregisterCommand(command: PluginCommandBase) {
+        knownCommands.remove(command.name)
+        knownCommands.remove("${command.plugin.name.lowercase()}:${command.name}")
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/CommonsInitializer.kt

@@ -0,0 +1,172 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import ca.spottedleaf.dataconverter.minecraft.MCDataConverter
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.internal.spigot.proxy.CommonsInitializerProxy
+import com.willfp.eco.internal.spigot.proxy.common.CommonsProvider
+import com.willfp.eco.internal.spigot.proxy.common.packet.PacketInjectorListener
+import com.willfp.eco.internal.spigot.proxy.common.toResourceLocation
+import io.papermc.paper.adventure.PaperAdventure
+import net.kyori.adventure.text.Component
+import net.kyori.adventure.text.serializer.json.JSONComponentSerializer
+import net.minecraft.core.component.DataComponents
+import net.minecraft.core.registries.BuiltInRegistries
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.Tag
+import net.minecraft.network.chat.ComponentSerialization
+import net.minecraft.resources.ResourceLocation
+import net.minecraft.server.level.ServerPlayer
+import net.minecraft.world.entity.PathfinderMob
+import net.minecraft.world.item.Item
+import org.bukkit.Bukkit
+import org.bukkit.Material
+import org.bukkit.NamespacedKey
+import org.bukkit.craftbukkit.CraftServer
+import org.bukkit.craftbukkit.entity.CraftEntity
+import org.bukkit.craftbukkit.entity.CraftMob
+import org.bukkit.craftbukkit.entity.CraftPlayer
+import org.bukkit.craftbukkit.inventory.CraftItemStack
+import org.bukkit.craftbukkit.inventory.CraftMetaArmor
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataContainer
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.craftbukkit.util.CraftMagicNumbers
+import org.bukkit.craftbukkit.util.CraftNamespacedKey
+import org.bukkit.entity.LivingEntity
+import org.bukkit.entity.Mob
+import org.bukkit.entity.Player
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataContainer
+import java.lang.reflect.Field
+
+class CommonsInitializer : CommonsInitializerProxy {
+    override fun init(plugin: EcoPlugin) {
+        CommonsProvider.setIfNeeded(CommonsProviderImpl)
+        plugin.onEnable {
+            plugin.eventManager.registerListener(PacketInjectorListener)
+        }
+    }
+
+    object CommonsProviderImpl : CommonsProvider {
+        private val cisHandle: Field = CraftItemStack::class.java.getDeclaredField("handle").apply {
+            isAccessible = true
+        }
+
+        private val pdcRegsitry = CraftMetaArmor::class.java
+            .superclass // Access CraftMetaItem
+            .getDeclaredField("DATA_TYPE_REGISTRY")
+            .apply { isAccessible = true }
+            .get(null) as CraftPersistentDataTypeRegistry
+
+        override val nbtTagString = 8
+
+        override fun toPathfinderMob(mob: Mob): PathfinderMob? {
+            val craft = mob as? CraftMob ?: return null
+            return craft.handle as? PathfinderMob
+        }
+
+        override fun toResourceLocation(namespacedKey: NamespacedKey): ResourceLocation =
+            CraftNamespacedKey.toMinecraft(namespacedKey)
+
+        override fun asNMSStack(itemStack: ItemStack): net.minecraft.world.item.ItemStack {
+            return if (itemStack !is CraftItemStack) {
+                CraftItemStack.asNMSCopy(itemStack)
+            } else {
+                cisHandle[itemStack] as net.minecraft.world.item.ItemStack? ?: CraftItemStack.asNMSCopy(itemStack)
+            }
+        }
+
+        override fun asBukkitStack(itemStack: net.minecraft.world.item.ItemStack): ItemStack {
+            return CraftItemStack.asCraftMirror(itemStack)
+        }
+
+        override fun mergeIfNeeded(itemStack: ItemStack, nmsStack: net.minecraft.world.item.ItemStack) {
+            if (itemStack !is CraftItemStack) {
+                itemStack.itemMeta = CraftItemStack.asCraftMirror(nmsStack).itemMeta
+            }
+        }
+
+        override fun toBukkitEntity(entity: net.minecraft.world.entity.LivingEntity): LivingEntity? =
+            CraftEntity.getEntity(Bukkit.getServer() as CraftServer, entity) as? LivingEntity
+
+        override fun makePdc(tag: CompoundTag, base: Boolean): PersistentDataContainer {
+            fun emptyPdc(): CraftPersistentDataContainer = CraftPersistentDataContainer(pdcRegsitry)
+
+            fun CompoundTag?.toPdc(): PersistentDataContainer {
+                val pdc = emptyPdc()
+                this ?: return pdc
+                val keys = this.keySet()
+                for (key in keys) {
+                    pdc.put(key, this[key])
+                }
+
+                return pdc
+            }
+
+            return if (base) {
+                tag.toPdc()
+            } else {
+                if (tag.contains("PublicBukkitValues")) {
+                    tag.getCompound("PublicBukkitValues").get().toPdc()
+                } else {
+                    emptyPdc()
+                }
+            }
+        }
+
+        override fun setPdc(
+            tag: CompoundTag,
+            pdc: PersistentDataContainer?,
+            item: net.minecraft.world.item.ItemStack?
+        ) {
+            fun CraftPersistentDataContainer.toTag(): CompoundTag {
+                val compound = CompoundTag()
+                val rawPublicMap: Map<String, Tag> = this.raw
+                for ((key, value) in rawPublicMap) {
+                    compound.put(key, value)
+                }
+
+                return compound
+            }
+
+            val container = when (pdc) {
+                is CraftPersistentDataContainer? -> pdc
+                else -> null
+            }
+
+            if (item != null) {
+                if (container != null && !container.isEmpty) {
+                    for (key in tag.keySet()) {
+                        tag.remove(key)
+                    }
+
+                    tag.merge(container.toTag())
+                } else {
+                    item.remove(DataComponents.CUSTOM_DATA)
+                }
+            } else {
+                if (container != null && !container.isEmpty) {
+                    tag.put("PublicBukkitValues", container.toTag())
+                } else {
+                    tag.remove("PublicBukkitValues")
+                }
+            }
+        }
+
+        override fun materialToItem(material: Material): Item =
+            BuiltInRegistries.ITEM.getOptional(material.key.toResourceLocation())
+                .orElseThrow { IllegalArgumentException("Material is not item!") }
+
+        override fun itemToMaterial(item: Item) =
+            Material.getMaterial(BuiltInRegistries.ITEM.getKey(item).path.uppercase())
+                ?: throw IllegalArgumentException("Invalid material!")
+
+        override fun toNMS(player: Player): ServerPlayer {
+            return (player as CraftPlayer).handle
+        }
+
+        override fun toNMS(component: Component): net.minecraft.network.chat.Component {
+            // TODO: Don't have hard dependency on paper
+            return PaperAdventure.asVanilla(component)
+        }
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/DisplayName.kt

@@ -0,0 +1,57 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.packet.Packet
+import com.willfp.eco.core.packet.sendPacket
+import com.willfp.eco.internal.spigot.proxy.DisplayNameProxy
+import com.willfp.eco.internal.spigot.proxy.common.toNMS
+import net.kyori.adventure.text.Component
+import net.minecraft.network.protocol.game.ClientboundSetEntityDataPacket
+import net.minecraft.network.syncher.EntityDataAccessor
+import net.minecraft.network.syncher.SynchedEntityData
+import net.minecraft.world.entity.Entity
+import org.bukkit.craftbukkit.entity.CraftLivingEntity
+import org.bukkit.entity.LivingEntity
+import org.bukkit.entity.Player
+import java.util.Optional
+
+@Suppress("UNCHECKED_CAST")
+class DisplayName : DisplayNameProxy {
+    private val displayNameAccessor = Entity::class.java
+        .declaredFields
+        .filter { it.type == EntityDataAccessor::class.java }
+        .toList()[2]
+        .apply { isAccessible = true }
+        .get(null) as EntityDataAccessor<Optional<net.minecraft.network.chat.Component>>
+
+    private val customNameVisibleAccessor = Entity::class.java
+        .declaredFields
+        .filter { it.type == EntityDataAccessor::class.java }
+        .toList()[3]
+        .apply { isAccessible = true }
+        .get(null) as EntityDataAccessor<Boolean>
+
+    override fun setClientsideDisplayName(
+        entity: LivingEntity,
+        player: Player,
+        displayName: Component,
+        visible: Boolean
+    ) {
+        if (entity !is CraftLivingEntity) {
+            return
+        }
+
+        val nmsComponent = displayName.toNMS()
+
+        val nmsEntity = entity.handle
+
+        val packet = ClientboundSetEntityDataPacket(
+            nmsEntity.id,
+            listOf(
+                SynchedEntityData.DataValue.create(displayNameAccessor, Optional.of(nmsComponent)),
+                SynchedEntityData.DataValue.create(customNameVisibleAccessor, visible)
+            )
+        )
+
+        player.sendPacket(Packet(packet))
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/DummyEntityFactory.kt

@@ -0,0 +1,15 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.internal.entities.EcoDummyEntity
+import com.willfp.eco.internal.spigot.proxy.DummyEntityFactoryProxy
+import org.bukkit.Location
+import org.bukkit.craftbukkit.CraftWorld
+import org.bukkit.entity.Entity
+import org.bukkit.entity.Zombie
+
+class DummyEntityFactory : DummyEntityFactoryProxy {
+    override fun createDummyEntity(location: Location): Entity {
+        val world = location.world as CraftWorld
+        return EcoDummyEntity(world.createEntity(location, Zombie::class.java))
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/EntityControllerFactory.kt

@@ -0,0 +1,12 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.entities.ai.EntityController
+import com.willfp.eco.internal.spigot.proxy.EntityControllerFactoryProxy
+import com.willfp.eco.internal.spigot.proxy.v1_21_6.entity.EcoEntityController
+import org.bukkit.entity.Mob
+
+class EntityControllerFactory : EntityControllerFactoryProxy {
+    override fun <T : Mob> createEntityController(entity: T): EntityController<T> {
+        return EcoEntityController(entity)
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/ExtendedPersistentDataContainerFactory.kt

@@ -0,0 +1,91 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.data.ExtendedPersistentDataContainer
+import com.willfp.eco.internal.spigot.proxy.ExtendedPersistentDataContainerFactoryProxy
+import net.minecraft.nbt.Tag
+import org.bukkit.Material
+import org.bukkit.craftbukkit.inventory.CraftItemStack
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataContainer
+import org.bukkit.craftbukkit.persistence.CraftPersistentDataTypeRegistry
+import org.bukkit.inventory.ItemStack
+import org.bukkit.persistence.PersistentDataContainer
+import org.bukkit.persistence.PersistentDataType
+import java.lang.reflect.Field
+
+class ExtendedPersistentDataContainerFactory : ExtendedPersistentDataContainerFactoryProxy {
+    private val registry: CraftPersistentDataTypeRegistry
+
+    init {
+        /*
+         Can't grab actual instance since it's in CraftMetaItem (which is package-private)
+         And getting it would mean more janky reflection
+         */
+        val item = CraftItemStack.asCraftCopy(ItemStack(Material.STONE))
+        val pdc = item.itemMeta!!.persistentDataContainer
+
+        // Cross-version compatibility:
+        val registryField: Field = try {
+            CraftPersistentDataContainer::class.java.getDeclaredField("registry")
+        } catch (e: NoSuchFieldException) {
+            CraftPersistentDataContainer::class.java.superclass.getDeclaredField("registry")
+        }
+
+        this.registry = registryField
+            .apply { isAccessible = true }.get(pdc) as CraftPersistentDataTypeRegistry
+    }
+
+    override fun adapt(pdc: PersistentDataContainer): ExtendedPersistentDataContainer {
+        return when (pdc) {
+            is CraftPersistentDataContainer -> EcoPersistentDataContainer(pdc)
+            else -> throw IllegalArgumentException("Custom PDC instance ${pdc::class.java.name} is not supported!")
+        }
+    }
+
+    override fun newPdc(): PersistentDataContainer {
+        return CraftPersistentDataContainer(registry)
+    }
+
+    inner class EcoPersistentDataContainer(
+        private val handle: CraftPersistentDataContainer
+    ) : ExtendedPersistentDataContainer {
+        @Suppress("UNCHECKED_CAST")
+        private val customDataTags: MutableMap<String, Tag> =
+            CraftPersistentDataContainer::class.java.getDeclaredField("customDataTags")
+                .apply { isAccessible = true }.get(handle) as MutableMap<String, Tag>
+
+        override fun <T : Any, Z : Any> set(key: String, dataType: PersistentDataType<T, Z>, value: Z) {
+            customDataTags[key] =
+                registry.wrap(dataType, dataType.toPrimitive(value, handle.adapterContext))
+        }
+
+        override fun <T : Any, Z : Any> has(key: String, dataType: PersistentDataType<T, Z>): Boolean {
+            val value = customDataTags[key] ?: return false
+            return registry.isInstanceOf(dataType, value)
+        }
+
+        override fun <T : Any, Z : Any> get(key: String, dataType: PersistentDataType<T, Z>): Z? {
+            val value = customDataTags[key] ?: return null
+            return dataType.fromPrimitive(registry.extract<T, Tag>(dataType, value), handle.adapterContext)
+        }
+
+        override fun <T : Any, Z : Any> getOrDefault(
+            key: String,
+            dataType: PersistentDataType<T, Z>,
+            defaultValue: Z
+        ): Z {
+            return get(key, dataType) ?: defaultValue
+        }
+
+        override fun remove(key: String) {
+            customDataTags.remove(key)
+        }
+
+        override fun getAllKeys(): MutableSet<String> {
+            return customDataTags.keys
+        }
+
+        override fun getBase(): PersistentDataContainer {
+            return handle
+        }
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/FastItemStackFactory.kt

@@ -0,0 +1,13 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.fast.FastItemStack
+import com.willfp.eco.internal.spigot.proxy.FastItemStackFactoryProxy
+import com.willfp.eco.internal.spigot.proxy.common.modern.NewEcoFastItemStack
+import com.willfp.eco.internal.spigot.proxy.v1_21_6.item.NewerEcoFastItemStack
+import org.bukkit.inventory.ItemStack
+
+class FastItemStackFactory : FastItemStackFactoryProxy {
+    override fun create(itemStack: ItemStack): FastItemStack {
+        return NewerEcoFastItemStack(itemStack)
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/MiniMessageTranslator.kt

@@ -0,0 +1,33 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.internal.spigot.proxy.MiniMessageTranslatorProxy
+import com.willfp.eco.util.toLegacy
+import net.kyori.adventure.text.minimessage.MiniMessage
+
+class MiniMessageTranslator : MiniMessageTranslatorProxy {
+    override fun format(message: String): String {
+        var mut = message
+
+        val startsWithPrefix = mut.startsWith(Display.PREFIX)
+        if (startsWithPrefix) {
+            mut = mut.substring(2)
+        }
+
+        mut = mut.replace('§', '&')
+
+        val miniMessage = runCatching {
+            MiniMessage.miniMessage().deserialize(
+                mut
+            ).toLegacy()
+        }.getOrNull() ?: mut
+
+        mut = if (startsWithPrefix) {
+            Display.PREFIX + miniMessage
+        } else {
+            miniMessage
+        }
+
+        return mut
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/PacketHandler.kt

@@ -0,0 +1,46 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.packet.PacketListener
+import com.willfp.eco.internal.spigot.proxy.PacketHandlerProxy
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.PacketHeldItemSlot
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.PacketSetSlot
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.clearFrames
+import com.willfp.eco.internal.spigot.proxy.v1_21_6.packet.NewItemsPacketOpenWindowMerchant
+import com.willfp.eco.internal.spigot.proxy.v1_21_6.packet.NewItemsPacketSetCreativeSlot
+import com.willfp.eco.internal.spigot.proxy.v1_21_6.packet.NewItemsPacketWindowItems
+import net.minecraft.network.protocol.Packet
+import org.bukkit.craftbukkit.entity.CraftPlayer
+import org.bukkit.entity.Player
+
+class PacketHandler : PacketHandlerProxy {
+    override fun sendPacket(player: Player, packet: com.willfp.eco.core.packet.Packet) {
+        if (player !is CraftPlayer) {
+            return
+        }
+
+        val handle = packet.handle
+
+        if (handle !is Packet<*>) {
+            return
+        }
+
+        player.handle.connection.send(handle)
+    }
+
+    override fun clearDisplayFrames() {
+        clearFrames()
+    }
+
+    override fun getPacketListeners(plugin: EcoPlugin): List<PacketListener> {
+        // No PacketAutoRecipe for 1.21.3+ because recipes have been changed internally
+
+        return listOf(
+            PacketHeldItemSlot,
+            NewItemsPacketOpenWindowMerchant,
+            NewItemsPacketSetCreativeSlot,
+            PacketSetSlot,
+            NewItemsPacketWindowItems(plugin)
+        )
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/SNBTConverter.kt

@@ -0,0 +1,95 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.mojang.serialization.Dynamic
+import com.willfp.eco.core.items.TestableItem
+import com.willfp.eco.core.recipe.parts.EmptyTestableItem
+import com.willfp.eco.internal.spigot.proxy.SNBTConverterProxy
+import net.minecraft.nbt.CompoundTag
+import net.minecraft.nbt.NbtOps
+import net.minecraft.nbt.SnbtPrinterTagVisitor
+import net.minecraft.nbt.TagParser
+import net.minecraft.server.MinecraftServer
+import net.minecraft.util.datafix.fixes.References
+import org.bukkit.Bukkit
+import org.bukkit.craftbukkit.CraftServer
+import org.bukkit.craftbukkit.inventory.CraftItemStack
+import org.bukkit.craftbukkit.util.CraftMagicNumbers
+import org.bukkit.inventory.ItemStack
+
+private val registryAccess = (Bukkit.getServer() as CraftServer).server.registryAccess()
+
+class SNBTConverter : SNBTConverterProxy {
+    private fun parseItemSNBT(snbt: String): CompoundTag? {
+        val nbt = runCatching { TagParser.parseCompoundFully(snbt) }.getOrNull() ?: return null
+        val dataVersion = if (nbt.contains("DataVersion")) {
+            nbt.getInt("DataVersion").get()
+        } else null
+
+        // If the data version is the same as the server's data version, we don't need to fix it
+
+        if (dataVersion == CraftMagicNumbers.INSTANCE.dataVersion) {
+            return nbt
+        }
+
+        return MinecraftServer.getServer().fixerUpper.update(
+            References.ITEM_STACK,
+            Dynamic(NbtOps.INSTANCE, nbt),
+            dataVersion ?: 3700, // 3700 is the 1.20.4 data version
+            CraftMagicNumbers.INSTANCE.dataVersion
+        ).value as CompoundTag
+    }
+
+
+    private fun nmsToNbt(nms: net.minecraft.world.item.ItemStack): CompoundTag {
+        return net.minecraft.world.item.ItemStack.CODEC
+            .encodeStart(registryAccess.createSerializationContext(NbtOps.INSTANCE), nms)
+            .result()
+            .get() as CompoundTag
+    }
+
+    private fun nbtToNms(tag: CompoundTag): net.minecraft.world.item.ItemStack? {
+        return net.minecraft.world.item.ItemStack.CODEC
+            .parse(registryAccess.createSerializationContext(NbtOps.INSTANCE), tag)
+            .result()
+            .orElse(null)
+    }
+
+    override fun fromSNBT(snbt: String): ItemStack? {
+        val tag = parseItemSNBT(snbt) ?: return null
+        val nms = nbtToNms(tag) ?: return null
+        return CraftItemStack.asBukkitCopy(nms)
+    }
+
+    override fun toSNBT(itemStack: ItemStack): String {
+        val nms = CraftItemStack.asNMSCopy(itemStack)
+        val tag = nmsToNbt(nms)
+        tag.putInt("DataVersion", CraftMagicNumbers.INSTANCE.dataVersion)
+        return SnbtPrinterTagVisitor().visit(tag)
+    }
+
+    override fun makeSNBTTestable(snbt: String): TestableItem {
+        val tag = parseItemSNBT(snbt) ?: return EmptyTestableItem()
+        val nms = nbtToNms(tag)
+
+        tag.remove("Count")
+        return SNBTTestableItem(CraftItemStack.asBukkitCopy(nms), tag)
+    }
+
+    inner class SNBTTestableItem(
+        private val item: ItemStack,
+        private val tag: CompoundTag
+    ) : TestableItem {
+        override fun matches(itemStack: ItemStack?): Boolean {
+            if (itemStack == null) {
+                return false
+            }
+
+            val nms = CraftItemStack.asNMSCopy(itemStack)
+            val nmsTag = nmsToNbt(nms)
+            nmsTag.remove("Count")
+            return tag.copy().merge(nmsTag) == nmsTag && itemStack.type == item.type
+        }
+
+        override fun getItem(): ItemStack = item
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/Skull.kt

@@ -0,0 +1,18 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.internal.spigot.proxy.SkullProxy
+import com.willfp.eco.internal.spigot.proxy.common.modern.texture
+import org.bukkit.inventory.meta.SkullMeta
+
+class Skull : SkullProxy {
+    override fun setSkullTexture(
+        meta: SkullMeta,
+        base64: String
+    ) {
+        meta.texture = base64
+    }
+
+    override fun getSkullTexture(
+        meta: SkullMeta
+    ): String? = meta.texture
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/TPS.kt

@@ -0,0 +1,11 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6
+
+import com.willfp.eco.internal.spigot.proxy.TPSProxy
+import org.bukkit.Bukkit
+import org.bukkit.craftbukkit.CraftServer
+
+class TPS : TPSProxy {
+    override fun getTPS(): Double {
+        return (Bukkit.getServer() as CraftServer).handle.server.tps1.average
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/entity/EcoEntityController.kt

@@ -0,0 +1,95 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6.entity
+
+import com.willfp.eco.core.entities.ai.CustomGoal
+import com.willfp.eco.core.entities.ai.EntityController
+import com.willfp.eco.core.entities.ai.EntityGoal
+import com.willfp.eco.core.entities.ai.TargetGoal
+import com.willfp.eco.internal.spigot.proxy.common.ai.CustomGoalFactory
+import com.willfp.eco.internal.spigot.proxy.common.ai.getGoalFactory
+import com.willfp.eco.internal.spigot.proxy.common.toPathfinderMob
+import net.minecraft.world.entity.PathfinderMob
+import net.minecraft.world.entity.ai.goal.Goal
+import org.bukkit.entity.Mob
+
+class EcoEntityController<T : Mob>(
+    private val handle: T
+) : EntityController<T> {
+    override fun addEntityGoal(priority: Int, goal: EntityGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        nms.goalSelector.addGoal(
+            priority,
+            goal.getGoalFactory()?.create(goal, nms) ?: return this
+        )
+
+        return this
+    }
+
+    override fun removeEntityGoal(goal: EntityGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        val predicate: (Goal) -> Boolean = if (goal is CustomGoal<*>) {
+            { CustomGoalFactory.isGoalOfType(it, goal) }
+        } else {
+            { goal.getGoalFactory()?.isGoalOfType(it) == true }
+        }
+
+        for (wrapped in nms.goalSelector.availableGoals.toSet()) {
+            if (predicate(wrapped.goal)) {
+                nms.goalSelector.removeGoal(wrapped.goal)
+            }
+        }
+
+        return this
+    }
+
+    override fun clearEntityGoals(): EntityController<T> {
+        val nms = getNms() ?: return this
+        nms.goalSelector.availableGoals.clear()
+        return this
+    }
+
+    override fun addTargetGoal(priority: Int, goal: TargetGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        nms.targetSelector.addGoal(
+            priority, goal.getGoalFactory()?.create(goal, nms) ?: return this
+        )
+
+        nms.targetSelector
+
+        return this
+    }
+
+    override fun removeTargetGoal(goal: TargetGoal<in T>): EntityController<T> {
+        val nms = getNms() ?: return this
+
+        val predicate: (Goal) -> Boolean = if (goal is CustomGoal<*>) {
+            { CustomGoalFactory.isGoalOfType(it, goal) }
+        } else {
+            { goal.getGoalFactory()?.isGoalOfType(it) == true }
+        }
+
+        for (wrapped in nms.targetSelector.availableGoals.toSet()) {
+            if (predicate(wrapped.goal)) {
+                nms.targetSelector.removeGoal(wrapped.goal)
+            }
+        }
+
+        return this
+    }
+
+    override fun clearTargetGoals(): EntityController<T> {
+        val nms = getNms() ?: return this
+        nms.targetSelector.availableGoals.clear()
+        return this
+    }
+
+    private fun getNms(): PathfinderMob? {
+        return handle.toPathfinderMob()
+    }
+
+    override fun getEntity(): T {
+        return handle
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/item/NewerEcoFastItemStack.kt

@@ -0,0 +1,185 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6.item
+
+import com.willfp.eco.internal.spigot.proxy.common.modern.NewEcoFastItemStack
+import net.minecraft.core.component.DataComponents
+import net.minecraft.world.item.component.TooltipDisplay
+import org.bukkit.inventory.ItemFlag
+import org.bukkit.inventory.ItemStack
+
+
+open class NewerEcoFastItemStack(
+    bukkit: ItemStack,
+) : NewEcoFastItemStack(bukkit) {
+    override fun addItemFlags(vararg hideFlags: ItemFlag) {
+        for (flag in hideFlags) {
+            when (flag) {
+                ItemFlag.HIDE_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ENCHANTMENTS, true)
+                    }
+                }
+
+                ItemFlag.HIDE_ATTRIBUTES -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ATTRIBUTE_MODIFIERS, true)
+                    }
+                }
+
+                ItemFlag.HIDE_UNBREAKABLE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.UNBREAKABLE, true)
+                    }
+                }
+
+                ItemFlag.HIDE_DESTROYS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_BREAK, true)
+                    }
+                }
+
+                ItemFlag.HIDE_PLACED_ON -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_PLACE_ON, true)
+                    }
+                }
+
+                ItemFlag.HIDE_ADDITIONAL_TOOLTIP -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        TooltipDisplay(true, tooltip.hiddenComponents)
+                    }
+                }
+
+                ItemFlag.HIDE_DYE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.DYED_COLOR, true)
+                    }
+                }
+
+                ItemFlag.HIDE_ARMOR_TRIM -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.TRIM, true)
+                    }
+                }
+
+                ItemFlag.HIDE_STORED_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.STORED_ENCHANTMENTS, true)
+                    }
+                }
+            }
+        }
+
+        apply()
+    }
+
+    override fun removeItemFlags(vararg hideFlags: ItemFlag) {
+        for (flag in hideFlags) {
+            when (flag) {
+                ItemFlag.HIDE_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ENCHANTMENTS, false)
+                    }
+                }
+
+                ItemFlag.HIDE_ATTRIBUTES -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.ATTRIBUTE_MODIFIERS, false)
+                    }
+                }
+
+                ItemFlag.HIDE_UNBREAKABLE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.UNBREAKABLE, false)
+                    }
+                }
+
+                ItemFlag.HIDE_DESTROYS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_BREAK, false)
+                    }
+                }
+
+                ItemFlag.HIDE_PLACED_ON -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.CAN_PLACE_ON, false)
+                    }
+                }
+
+                ItemFlag.HIDE_ADDITIONAL_TOOLTIP -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        TooltipDisplay(false, tooltip.hiddenComponents)
+                    }
+                }
+
+                ItemFlag.HIDE_DYE -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.DYED_COLOR, false)
+                    }
+                }
+
+                ItemFlag.HIDE_ARMOR_TRIM -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.TRIM, false)
+                    }
+                }
+
+                ItemFlag.HIDE_STORED_ENCHANTS -> {
+                    handle.modifyComponent(DataComponents.TOOLTIP_DISPLAY) { tooltip ->
+                        tooltip.withHidden(DataComponents.STORED_ENCHANTMENTS, false)
+                    }
+                }
+            }
+        }
+
+        apply()
+    }
+
+    override fun hasItemFlag(flag: ItemFlag): Boolean {
+        return when (flag) {
+            ItemFlag.HIDE_ENCHANTS -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.ENCHANTMENTS)
+            }
+
+            ItemFlag.HIDE_ATTRIBUTES -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.ATTRIBUTE_MODIFIERS)
+            }
+
+            ItemFlag.HIDE_UNBREAKABLE -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.UNBREAKABLE)
+            }
+
+            ItemFlag.HIDE_DESTROYS -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.CAN_BREAK)
+            }
+
+            ItemFlag.HIDE_PLACED_ON -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.CAN_PLACE_ON)
+            }
+
+            ItemFlag.HIDE_ADDITIONAL_TOOLTIP -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                tooltip.hideTooltip
+            }
+
+            ItemFlag.HIDE_DYE -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.DYED_COLOR)
+            }
+
+            ItemFlag.HIDE_ARMOR_TRIM -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.TRIM)
+            }
+
+            ItemFlag.HIDE_STORED_ENCHANTS -> {
+                val tooltip = handle.get(DataComponents.TOOLTIP_DISPLAY) ?: return false
+                !tooltip.shows(DataComponents.STORED_ENCHANTMENTS)
+            }
+        }
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/packet/NewItemsPacketOpenWindowMerchant.kt

@@ -0,0 +1,35 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6.packet
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.packet.PacketEvent
+import com.willfp.eco.core.packet.PacketListener
+import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
+import net.minecraft.network.protocol.game.ClientboundMerchantOffersPacket
+import net.minecraft.world.item.trading.MerchantOffers
+
+object NewItemsPacketOpenWindowMerchant : PacketListener {
+    private val field = ClientboundMerchantOffersPacket::class.java
+        .declaredFields
+        .first { it.type == MerchantOffers::class.java }
+        .apply { isAccessible = true }
+
+    override fun onSend(event: PacketEvent) {
+        val packet = event.packet.handle as? ClientboundMerchantOffersPacket ?: return
+
+        val offers = MerchantOffers()
+
+        for (offer in packet.offers) {
+            val new = offer.copy()
+
+            Display.display(new.baseCostA.itemStack.asBukkitStack(), event.player)
+            if (new.costB.isPresent) {
+                Display.display(new.costB.get().itemStack.asBukkitStack(), event.player)
+            }
+            Display.display(new.result.asBukkitStack(), event.player)
+
+            offers += new
+        }
+
+        field.set(packet, offers)
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/packet/NewItemsPacketSetCreativeSlot.kt

@@ -0,0 +1,19 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6.packet
+
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.packet.PacketEvent
+import com.willfp.eco.core.packet.PacketListener
+import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.DisplayFrame
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.lastDisplayFrame
+import net.minecraft.network.protocol.game.ServerboundSetCreativeModeSlotPacket
+
+object NewItemsPacketSetCreativeSlot : PacketListener {
+    override fun onReceive(event: PacketEvent) {
+        val packet = event.packet.handle as? ServerboundSetCreativeModeSlotPacket ?: return
+
+        Display.revert(packet.itemStack.asBukkitStack())
+
+        event.player.lastDisplayFrame = DisplayFrame.EMPTY
+    }
+}

eco-core/core-nms/v1_21_6/src/main/kotlin/com/willfp/eco/internal/spigot/proxy/v1_21_6/packet/NewItemsPacketWindowItems.kt

@@ -0,0 +1,52 @@
+package com.willfp.eco.internal.spigot.proxy.v1_21_6.packet
+
+import com.willfp.eco.core.EcoPlugin
+import com.willfp.eco.core.display.Display
+import com.willfp.eco.core.packet.PacketEvent
+import com.willfp.eco.internal.spigot.proxy.common.asBukkitStack
+import com.willfp.eco.internal.spigot.proxy.common.asNMSStack
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.PacketWindowItems
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.DisplayFrame
+import com.willfp.eco.internal.spigot.proxy.common.packet.display.frame.lastDisplayFrame
+import net.minecraft.network.protocol.game.ClientboundContainerSetContentPacket
+import java.util.UUID
+import java.util.concurrent.ConcurrentHashMap
+
+class NewItemsPacketWindowItems(
+    plugin: EcoPlugin
+) : PacketWindowItems(plugin) {
+    private val lastKnownWindowIDs = ConcurrentHashMap<UUID, Int>()
+
+    override fun onSend(event: PacketEvent) {
+        val packet = event.packet.handle as? ClientboundContainerSetContentPacket ?: return
+        val player = event.player
+
+        Display.display(packet.carriedItem.asBukkitStack(), player)
+
+        val windowId = packet.containerId
+
+        val lastKnownID = lastKnownWindowIDs[player.uniqueId]
+        lastKnownWindowIDs[player.uniqueId] = windowId
+
+        // If there is any change in window ID at any point,
+        // Remove the last display frame to prevent any potential conflicts.
+        // If the window ID is not zero (not a player inventory), then remove too,
+        // as GUIs are not player inventories.
+        if (lastKnownID != windowId || windowId != 0) {
+            player.lastDisplayFrame = DisplayFrame.EMPTY
+        }
+
+        val itemStacks = packet.items.map { it.asBukkitStack() }
+
+        val newItems = modifyWindowItems(itemStacks.toMutableList(), windowId, player)
+
+        val newPacket = ClientboundContainerSetContentPacket(
+            packet.containerId,
+            packet.stateId,
+            newItems.map { it.asNMSStack() },
+            packet.carriedItem,
+        )
+
+        event.packet.handle = newPacket
+    }
+}

eco-core/core-plugin/src/main/kotlin/com/willfp/eco/internal/spigot/integrations/antigrief/AntigriefFabledSkyBlock.kt

@@ -1,6 +1,6 @@
 package com.willfp.eco.internal.spigot.integrations.antigrief
 
-import com.craftaro.skyblock.SkyBlock
+import com.songoda.skyblock.SkyBlock
 import com.willfp.eco.core.integrations.antigrief.AntigriefIntegration
 import org.bukkit.Location
 import org.bukkit.block.Block

gradle.properties

@@ -1,3 +1,3 @@
-version = 6.75.2
+version = 6.76.1
 kotlin.daemon.jvmargs=-Xmx2g -XX:+UseG1GC -XX:MaxMetaspaceSize=512m
 org.gradle.parallel=true

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.12-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.14.1-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME

settings.gradle.kts

@@ -1,5 +1,6 @@
 pluginManagement {
     repositories {
+        maven("https://repo.papermc.io/repository/maven-public/")
         gradlePluginPortal()
     }
 }
@@ -28,7 +29,9 @@ include(":eco-core:core-nms:v1_20_R3")
 include(":eco-core:core-nms:v1_21")
 include(":eco-core:core-nms:v1_21_3")
 include(":eco-core:core-nms:v1_21_4")
+include(":eco-core:core-nms:v1_21_5")
+include(":eco-core:core-nms:v1_21_6")
 include(":eco-core:core-proxy")
 include(":eco-core:core-plugin")
 include(":eco-core:core-backend")
-include(":eco-core:core-backend-modern")
+include(":eco-core:core-backend-modern")