--- a/net/minecraft/server/level/PlayerChunkMap.java
+++ b/net/minecraft/server/level/PlayerChunkMap.java
@@ -104,6 +104,10 @@
 import org.apache.commons.lang3.mutable.MutableBoolean;
 import org.slf4j.Logger;
 
+// CraftBukkit start
+import org.bukkit.craftbukkit.generator.CustomChunkGenerator;
+// CraftBukkit end
+
 public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.c {
 
     private static final byte CHUNK_TYPE_REPLACEABLE = -1;
@@ -146,6 +150,27 @@
     public int serverViewDistance;
     private WorldGenContext worldGenContext;
 
+    // CraftBukkit start - recursion-safe executor for Chunk loadCallback() and unloadCallback()
+    public final CallbackExecutor callbackExecutor = new CallbackExecutor();
+    public static final class CallbackExecutor implements java.util.concurrent.Executor, Runnable {
+
+        private final java.util.Queue<Runnable> queue = new java.util.ArrayDeque<>();
+
+        @Override
+        public void execute(Runnable runnable) {
+            queue.add(runnable);
+        }
+
+        @Override
+        public void run() {
+            Runnable task;
+            while ((task = queue.poll()) != null) {
+                task.run();
+            }
+        }
+    };
+    // CraftBukkit end
+
     public PlayerChunkMap(WorldServer worldserver, Convertable.ConversionSession convertable_conversionsession, DataFixer datafixer, StructureTemplateManager structuretemplatemanager, Executor executor, IAsyncTaskHandler<Runnable> iasynctaskhandler, ILightAccess ilightaccess, ChunkGenerator chunkgenerator, WorldLoadListener worldloadlistener, ChunkStatusUpdateListener chunkstatusupdatelistener, Supplier<WorldPersistentData> supplier, int i, boolean flag) {
         super(new RegionStorageInfo(convertable_conversionsession.getLevelId(), worldserver.dimension(), "chunk"), convertable_conversionsession.getDimensionPath(worldserver.dimension()).resolve("region"), datafixer, flag);
         this.visibleChunkMap = this.updatingChunkMap.clone();
@@ -166,7 +191,13 @@
         IRegistryCustom iregistrycustom = worldserver.registryAccess();
         long j = worldserver.getSeed();
 
-        if (chunkgenerator instanceof ChunkGeneratorAbstract chunkgeneratorabstract) {
+        // CraftBukkit start - SPIGOT-7051: It's a rigged game! Use delegate for random state creation, otherwise it is not so random.
+        ChunkGenerator randomGenerator = chunkgenerator;
+        if (randomGenerator instanceof CustomChunkGenerator customChunkGenerator) {
+            randomGenerator = customChunkGenerator.getDelegate();
+        }
+        if (randomGenerator instanceof ChunkGeneratorAbstract chunkgeneratorabstract) {
+            // CraftBukkit end
             this.randomState = RandomState.create((GeneratorSettingBase) chunkgeneratorabstract.generatorSettings().value(), (HolderGetter) iregistrycustom.lookupOrThrow(Registries.NOISE), j);
         } else {
             this.randomState = RandomState.create(GeneratorSettingBase.dummy(), (HolderGetter) iregistrycustom.lookupOrThrow(Registries.NOISE), j);
@@ -332,16 +363,19 @@
             CompletableFuture<List<ChunkResult<IChunkAccess>>> completablefuture1 = SystemUtils.sequence(list);
             CompletableFuture<ChunkResult<List<IChunkAccess>>> completablefuture2 = completablefuture1.thenApply((list2) -> {
                 List<IChunkAccess> list3 = Lists.newArrayList();
-                int l1 = 0;
+                // CraftBukkit start - decompile error
+                int cnt = 0;
 
-                for (Iterator iterator = list2.iterator(); iterator.hasNext(); ++l1) {
+                for (Iterator iterator = list2.iterator(); iterator.hasNext(); ++cnt) {
+                    final int l1 = cnt;
+                    // CraftBukkit end
                     ChunkResult<IChunkAccess> chunkresult = (ChunkResult) iterator.next();
 
                     if (chunkresult == null) {
                         throw this.debugFuturesAndCreateReportedException(new IllegalStateException("At least one of the chunk futures were null"), "n/a");
                     }
 
-                    IChunkAccess ichunkaccess = (IChunkAccess) chunkresult.orElse((Object) null);
+                    IChunkAccess ichunkaccess = (IChunkAccess) chunkresult.orElse(null); // CraftBukkit - decompile error
 
                     if (ichunkaccess == null) {
                         return ChunkResult.error(() -> {
@@ -538,7 +572,7 @@
 
     private void scheduleUnload(long i, PlayerChunk playerchunk) {
         CompletableFuture<IChunkAccess> completablefuture = playerchunk.getChunkToSave();
-        Consumer consumer = (ichunkaccess) -> {
+        Consumer<IChunkAccess> consumer = (ichunkaccess) -> { // CraftBukkit - decompile error
             CompletableFuture<IChunkAccess> completablefuture1 = playerchunk.getChunkToSave();
 
             if (completablefuture1 != completablefuture) {
@@ -708,7 +742,7 @@
         };
 
         return completablefuture.thenComposeAsync((chunkresult) -> {
-            List<IChunkAccess> list = (List) chunkresult.orElse((Object) null);
+            List<IChunkAccess> list = (List) chunkresult.orElse(null); // CraftBukkit - decompile error
 
             if (list == null) {
                 this.releaseLightTicket(chunkcoordintpair);
@@ -773,7 +807,21 @@
 
     private static void postLoadProtoChunk(WorldServer worldserver, List<NBTTagCompound> list) {
         if (!list.isEmpty()) {
-            worldserver.addWorldGenChunkEntities(EntityTypes.loadEntitiesRecursive(list, worldserver));
+            // CraftBukkit start - these are spawned serialized (DefinedStructure) and we don't call an add event below at the moment due to ordering complexities
+            worldserver.addWorldGenChunkEntities(EntityTypes.loadEntitiesRecursive(list, worldserver).filter((entity) -> {
+                boolean needsRemoval = false;
+                net.minecraft.server.dedicated.DedicatedServer server = worldserver.getCraftServer().getServer();
+                if (!server.areNpcsEnabled() && entity instanceof net.minecraft.world.entity.npc.NPC) {
+                    entity.discard(null); // CraftBukkit - add Bukkit remove cause
+                    needsRemoval = true;
+                }
+                if (!server.isSpawningAnimals() && (entity instanceof net.minecraft.world.entity.animal.EntityAnimal || entity instanceof net.minecraft.world.entity.animal.EntityWaterAnimal)) {
+                    entity.discard(null); // CraftBukkit - add Bukkit remove cause
+                    needsRemoval = true;
+                }
+                return !needsRemoval;
+            }));
+            // CraftBukkit end
         }
 
     }
@@ -879,7 +927,7 @@
         if (!playerchunk.wasAccessibleSinceLastSave()) {
             return false;
         } else {
-            IChunkAccess ichunkaccess = (IChunkAccess) playerchunk.getChunkToSave().getNow((Object) null);
+            IChunkAccess ichunkaccess = (IChunkAccess) playerchunk.getChunkToSave().getNow(null); // CraftBukkit - decompile error
 
             if (!(ichunkaccess instanceof ProtoChunkExtension) && !(ichunkaccess instanceof Chunk)) {
                 return false;
@@ -1040,7 +1088,8 @@
                 return ichunkaccess instanceof Chunk ? Optional.of((Chunk) ichunkaccess) : Optional.empty();
             });
 
-            csvwriter.writeRow(chunkcoordintpair.x, chunkcoordintpair.z, playerchunk.getTicketLevel(), optional.isPresent(), optional.map(IChunkAccess::getStatus).orElse((Object) null), optional1.map(Chunk::getFullStatus).orElse((Object) null), printFuture(playerchunk.getFullChunkFuture()), printFuture(playerchunk.getTickingChunkFuture()), printFuture(playerchunk.getEntityTickingChunkFuture()), this.distanceManager.getTicketDebugString(i), this.anyPlayerCloseEnoughForSpawning(chunkcoordintpair), optional1.map((chunk) -> {
+            // CraftBukkit - decompile error
+            csvwriter.writeRow(chunkcoordintpair.x, chunkcoordintpair.z, playerchunk.getTicketLevel(), optional.isPresent(), optional.map(IChunkAccess::getStatus).orElse(null), optional1.map(Chunk::getFullStatus).orElse(null), printFuture(playerchunk.getFullChunkFuture()), printFuture(playerchunk.getTickingChunkFuture()), printFuture(playerchunk.getEntityTickingChunkFuture()), this.distanceManager.getTicketDebugString(i), this.anyPlayerCloseEnoughForSpawning(chunkcoordintpair), optional1.map((chunk) -> {
                 return chunk.getBlockEntities().size();
             }).orElse(0), tickingtracker.getTicketDebugString(i), tickingtracker.getLevel(i), optional1.map((chunk) -> {
                 return chunk.getBlockTicks().count();
@@ -1053,7 +1102,7 @@
 
     private static String printFuture(CompletableFuture<ChunkResult<Chunk>> completablefuture) {
         try {
-            ChunkResult<Chunk> chunkresult = (ChunkResult) completablefuture.getNow((Object) null);
+            ChunkResult<Chunk> chunkresult = (ChunkResult) completablefuture.getNow(null); // CraftBukkit - decompile error
 
             return chunkresult != null ? (chunkresult.isSuccess() ? "done" : "unloaded") : "not completed";
         } catch (CompletionException completionexception) {
@@ -1065,12 +1114,14 @@
 
     private CompletableFuture<Optional<NBTTagCompound>> readChunk(ChunkCoordIntPair chunkcoordintpair) {
         return this.read(chunkcoordintpair).thenApplyAsync((optional) -> {
-            return optional.map(this::upgradeChunkTag);
+            return optional.map((nbttagcompound) -> upgradeChunkTag(nbttagcompound, chunkcoordintpair)); // CraftBukkit
         }, SystemUtils.backgroundExecutor());
     }
 
-    private NBTTagCompound upgradeChunkTag(NBTTagCompound nbttagcompound) {
-        return this.upgradeChunkTag(this.level.dimension(), this.overworldDataStorage, nbttagcompound, this.generator.getTypeNameForDataFixer());
+    // CraftBukkit start
+    private NBTTagCompound upgradeChunkTag(NBTTagCompound nbttagcompound, ChunkCoordIntPair chunkcoordintpair) {
+        return this.upgradeChunkTag(this.level.getTypeKey(), this.overworldDataStorage, nbttagcompound, this.generator.getTypeNameForDataFixer(), chunkcoordintpair, level);
+        // CraftBukkit end
     }
 
     boolean anyPlayerCloseEnoughForSpawning(ChunkCoordIntPair chunkcoordintpair) {
@@ -1473,7 +1524,7 @@
         public final Set<ServerPlayerConnection> seenBy = Sets.newIdentityHashSet();
 
         public EntityTracker(final Entity entity, final int i, final int j, final boolean flag) {
-            this.serverEntity = new EntityTrackerEntry(PlayerChunkMap.this.level, entity, j, flag, this::broadcast);
+            this.serverEntity = new EntityTrackerEntry(PlayerChunkMap.this.level, entity, j, flag, this::broadcast, seenBy); // CraftBukkit
             this.entity = entity;
             this.range = i;
             this.lastSectionPos = SectionPosition.of((EntityAccess) entity);
@@ -1533,6 +1584,11 @@
                 double d2 = d0 * d0;
                 boolean flag = d1 <= d2 && this.entity.broadcastToPlayer(entityplayer) && PlayerChunkMap.this.isChunkTracked(entityplayer, this.entity.chunkPosition().x, this.entity.chunkPosition().z);
 
+                // CraftBukkit start - respect vanish API
+                if (!entityplayer.getBukkitEntity().canSee(this.entity.getBukkitEntity())) {
+                    flag = false;
+                }
+                // CraftBukkit end
                 if (flag) {
                     if (this.seenBy.add(entityplayer.connection)) {
                         this.serverEntity.addPairing(entityplayer);