fix: 1.21.9+ client crash and add copper golem support

- Fix skinLayersIndex for 1.21.9+ (index 16 instead of 17)
- Fix shoulderIndex offset for 1.21.9+
- Refactor Viewable to use shared ExecutorService
- Add CopperGolemState and WeatheringCopperState enums
- Register copper_golem entity type for 1.21.9+

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

api/src/main/java/lol/pyr/znpcsplus/util/CopperGolemState.java

@@ -0,0 +1,9 @@
+package lol.pyr.znpcsplus.util;
+
+public enum CopperGolemState {
+    IDLE,
+    GETTING_ITEM,
+    GETTING_NO_ITEM,
+    DROPPING_ITEM,
+    DROPPING_NO_ITEM
+}

api/src/main/java/lol/pyr/znpcsplus/util/WeatheringCopperState.java

@@ -0,0 +1,8 @@
+package lol.pyr.znpcsplus.util;
+
+public enum WeatheringCopperState {
+    UNAFFECTED,
+    EXPOSED,
+    WEATHERED,
+    OXIDIZED
+}

plugin/src/main/java/lol/pyr/znpcsplus/ZNpcsPlus.java

@@ -66,10 +66,7 @@ import java.io.IOException;
 import java.io.PrintWriter;
 import java.nio.file.Files;
 import java.nio.file.StandardOpenOption;
-import java.util.ArrayList;
+import java.util.*;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.List;
 
 public class ZNpcsPlus {
     private final LegacyComponentSerializer textSerializer = LegacyComponentSerializer.builder()
@@ -98,6 +95,7 @@ public class ZNpcsPlus {
 
         NpcPropertyRegistryProvider.register(bootstrap, propertyRegistry);
         shutdownTasks.add(NpcPropertyRegistryProvider::unregister);
+        shutdownTasks.add(Viewable::shutdownExecutor);
     }
 
     private void log(String str) {
@@ -215,6 +213,7 @@ public class ZNpcsPlus {
 
     public void onDisable() {
         NpcApiProvider.unregister();
+        Collections.reverse(shutdownTasks);
         for (Runnable runnable : shutdownTasks) try {
             runnable.run();
         } catch (Throwable throwable) {
@@ -297,6 +296,8 @@ public class ZNpcsPlus {
         registerEnumParser(manager, WoldVariant.class, incorrectUsageMessage);
         registerEnumParser(manager, NpcStorageType.class, incorrectUsageMessage);
         registerEnumParser(manager, SkeletonType.class, incorrectUsageMessage);
+        registerEnumParser(manager, CopperGolemState.class, incorrectUsageMessage);
+        registerEnumParser(manager, WeatheringCopperState.class, incorrectUsageMessage);
 
         manager.registerCommand("npc", new MultiCommand(bootstrap.loadHelpMessage("root"))
                 .addSubcommand("center", new CenterCommand(npcRegistry))

plugin/src/main/java/lol/pyr/znpcsplus/entity/EntityPropertyRegistryImpl.java

@@ -93,6 +93,8 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
         registerEnumSerializer(ArmadilloState.class);
         registerEnumSerializer(WoldVariant.class);
         registerEnumSerializer(SkeletonType.class);
+        registerEnumSerializer(CopperGolemState.class);
+        registerEnumSerializer(WeatheringCopperState.class);
 
         registerPrimitiveSerializers(Integer.class, Boolean.class, Double.class, Float.class, Long.class, Short.class, Byte.class, String.class);
 
@@ -201,7 +203,8 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
         // Player
         register(new DummyProperty<>("skin", SkinDescriptor.class, false));
         final int skinLayersIndex;
-        if (ver.isNewerThanOrEquals(ServerVersion.V_1_17)) skinLayersIndex = 17;
+        if (ver.isNewerThanOrEquals(ServerVersion.V_1_21_9)) skinLayersIndex = 16;
+        else if (ver.isNewerThanOrEquals(ServerVersion.V_1_17)) skinLayersIndex = 17;
         else if (ver.isNewerThanOrEquals(ServerVersion.V_1_16)) skinLayersIndex = 16;
         else if (ver.isNewerThanOrEquals(ServerVersion.V_1_14)) skinLayersIndex = 15;
         else if (ver.isNewerThanOrEquals(ServerVersion.V_1_10)) skinLayersIndex = 13;
@@ -561,6 +564,7 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
             return compound;
         };
         int shoulderIndex = skinLayersIndex+2;
+        if (ver.isNewerThanOrEquals(ServerVersion.V_1_21_9)) shoulderIndex += 1;
         register(new NBTProperty<>("shoulder_entity_left", ParrotVariant.class, shoulderIndex++, parrotVariantDecoder, true));
         register(new NBTProperty<>("shoulder_entity_right", ParrotVariant.class, shoulderIndex, parrotVariantDecoder, true));
 
@@ -734,6 +738,12 @@ public class EntityPropertyRegistryImpl implements EntityPropertyRegistry {
 
         // Creaking
         register(new BooleanProperty("creaking_crumbling", 18, false, legacyBooleans));
+
+        if (!ver.isNewerThanOrEquals(ServerVersion.V_1_21_9)) return;
+
+        // Copper Golem
+        register(new EncodedIntegerProperty<>("weathering_copper_state", WeatheringCopperState.UNAFFECTED, 16, Enum::ordinal));
+        register(new EncodedIntegerProperty<>("copper_golem_state", CopperGolemState.IDLE, 17, Enum::ordinal));
     }
 
     private void registerSerializer(PropertySerializer<?> serializer) {

plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeRegistryImpl.java

@@ -402,6 +402,12 @@ public class NpcTypeRegistryImpl implements NpcTypeRegistry {
         register(builder(p, "creaking", EntityTypes.CREAKING)
                 .setHologramOffset(0.725)
                 .addProperties("creaking_active"));
+
+        if (!version.isNewerThanOrEquals(ServerVersion.V_1_21_9)) return;
+
+        register(builder(p, "copper_golem", EntityTypes.COPPER_GOLEM)
+                .setHologramOffset(-0.995)
+                .addProperties("weathering_copper_state", "copper_golem_state"));
     }
 
     public Collection<NpcType> getAll() {

plugin/src/main/java/lol/pyr/znpcsplus/util/Viewable.java

@@ -5,9 +5,7 @@ import org.bukkit.entity.Player;
 import java.lang.ref.Reference;
 import java.lang.ref.WeakReference;
 import java.util.*;
-import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.*;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.stream.Collectors;
 
 public abstract class Viewable {
@@ -22,34 +20,20 @@ public abstract class Viewable {
         }
     }
 
-    private boolean queueRunning = false;
+    private final static ExecutorService visibilityExecutor = Executors.newSingleThreadExecutor();
-    private final Queue<Runnable> visibilityTaskQueue = new ConcurrentLinkedQueue<>();
+
+    public static void shutdownExecutor() {
+        visibilityExecutor.shutdown();
+    }
+
     private final Set<Player> viewers = ConcurrentHashMap.newKeySet();
 
     public Viewable() {
         all.add(new WeakReference<>(this));
     }
 
-    private void tryRunQueue() {
-        if (visibilityTaskQueue.isEmpty() || queueRunning) return;
-        queueRunning = true;
-        FutureUtil.exceptionPrintingRunAsync(() -> {
-            while (!visibilityTaskQueue.isEmpty()) try {
-                visibilityTaskQueue.remove().run();
-            } catch (Exception e) {
-                e.printStackTrace();
-            }
-            queueRunning = false;
-        });
-    }
-
-    private void queueVisibilityTask(Runnable runnable) {
-        visibilityTaskQueue.add(runnable);
-        tryRunQueue();
-    }
-
     public void delete() {
-        queueVisibilityTask(() -> {
+        visibilityExecutor.submit(() -> {
             UNSAFE_hideAll();
             viewers.clear();
             synchronized (all) {
@@ -60,10 +44,9 @@ public abstract class Viewable {
 
     public CompletableFuture<Void> respawn() {
         CompletableFuture<Void> future = new CompletableFuture<>();
-        queueVisibilityTask(() -> {
+        visibilityExecutor.submit(() -> {
             UNSAFE_hideAll();
-            UNSAFE_showAll().join();
+            UNSAFE_showAll().thenRun(() -> future.complete(null));
-            future.complete(null);
         });
         return future;
     }
@@ -75,20 +58,19 @@ public abstract class Viewable {
 
     public CompletableFuture<Void> show(Player player) {
         CompletableFuture<Void> future = new CompletableFuture<>();
-        queueVisibilityTask(() -> {
+        visibilityExecutor.submit(() -> {
             if (viewers.contains(player)) {
                 future.complete(null);
                 return;
             }
             viewers.add(player);
-            UNSAFE_show(player).join();
+            UNSAFE_show(player).thenRun(() -> future.complete(null));
-            future.complete(null);
         });
         return future;
     }
 
     public void hide(Player player) {
-        queueVisibilityTask(() -> {
+        visibilityExecutor.submit(() -> {
             if (!viewers.contains(player)) return;
             viewers.remove(player);
             UNSAFE_hide(player);