--- a/net/minecraft/server/level/PlayerChunkMap.java
+++ b/net/minecraft/server/level/PlayerChunkMap.java
@@ -109,6 +109,12 @@
 import org.apache.commons.lang3.mutable.MutableObject;
 import org.slf4j.Logger;
 
+// CraftBukkit start
+import net.minecraft.world.level.levelgen.GeneratorSettings;
+import org.bukkit.craftbukkit.generator.CustomChunkGenerator;
+import org.bukkit.entity.Player;
+// CraftBukkit end
+
 public class PlayerChunkMap extends IChunkLoader implements PlayerChunk.d {
 
     private static final byte CHUNK_TYPE_REPLACEABLE = -1;
@@ -151,6 +157,27 @@
     private final Queue<Runnable> unloadQueue;
     int viewDistance;
 
+    // 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(convertable_conversionsession.getDimensionPath(worldserver.dimension()).resolve("region"), datafixer, flag);
         this.visibleChunkMap = this.updatingChunkMap.clone();
@@ -169,6 +196,11 @@
         this.storageName = path.getFileName().toString();
         this.level = worldserver;
         this.generator = chunkgenerator;
+        // CraftBukkit start - SPIGOT-7051: It's a rigged game! Use delegate for random state creation, otherwise it is not so random.
+        if (chunkgenerator instanceof CustomChunkGenerator) {
+            chunkgenerator = ((CustomChunkGenerator) chunkgenerator).getDelegate();
+        }
+        // CraftBukkit end
         IRegistryCustom iregistrycustom = worldserver.registryAccess();
         long j = worldserver.getSeed();
 
@@ -335,9 +367,12 @@
             CompletableFuture<List<Either<IChunkAccess, PlayerChunk.Failure>>> completablefuture1 = SystemUtils.sequence(list);
             CompletableFuture<Either<List<IChunkAccess>, PlayerChunk.Failure>> completablefuture2 = completablefuture1.thenApply((list2) -> {
                 List<IChunkAccess> list3 = Lists.newArrayList();
-                final 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
                     final Either<IChunkAccess, PlayerChunk.Failure> either = (Either) iterator.next();
 
                     if (either == null) {
@@ -543,7 +578,7 @@
 
     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) {
@@ -634,9 +669,9 @@
                 ProtoChunk protochunk = ChunkRegionLoader.read(this.level, this.poiManager, chunkcoordintpair, (NBTTagCompound) optional.get());
 
                 this.markPosition(chunkcoordintpair, protochunk.getStatus().getChunkType());
-                return Either.left(protochunk);
+                return Either.<IChunkAccess, PlayerChunk.Failure>left(protochunk); // CraftBukkit - decompile error
             } else {
-                return Either.left(this.createEmptyChunk(chunkcoordintpair));
+                return Either.<IChunkAccess, PlayerChunk.Failure>left(this.createEmptyChunk(chunkcoordintpair)); // CraftBukkit - decompile error
             }
         }, this.mainThreadExecutor).exceptionallyAsync((throwable) -> {
             return this.handleChunkLoadFailure(throwable, chunkcoordintpair);
@@ -751,7 +786,21 @@
 
     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();
+                    needsRemoval = true;
+                }
+                if (!server.isSpawningAnimals() && (entity instanceof net.minecraft.world.entity.animal.EntityAnimal || entity instanceof net.minecraft.world.entity.animal.EntityWaterAnimal)) {
+                    entity.discard();
+                    needsRemoval = true;
+                }
+                return !needsRemoval;
+            }));
+            // CraftBukkit end
         }
 
     }
@@ -852,7 +901,7 @@
         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;
@@ -1014,7 +1063,8 @@
                 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();
@@ -1027,7 +1077,7 @@
 
     private static String printFuture(CompletableFuture<Either<Chunk, PlayerChunk.Failure>> completablefuture) {
         try {
-            Either<Chunk, PlayerChunk.Failure> either = (Either) completablefuture.getNow((Object) null);
+            Either<Chunk, PlayerChunk.Failure> either = (Either) completablefuture.getNow(null); // CraftBukkit - decompile error
 
             return either != null ? (String) either.map((chunk) -> {
                 return "done";
@@ -1043,12 +1093,14 @@
 
     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) {
@@ -1503,7 +1555,7 @@
         public final Set<ServerPlayerConnection> seenBy = Sets.newIdentityHashSet();
 
         public EntityTracker(Entity entity, int i, int j, 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);
@@ -1562,6 +1614,11 @@
                 double d2 = d0 * d0;
                 boolean flag = d1 <= d2 && this.entity.broadcastToPlayer(entityplayer);
 
+                // 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);
