update headless dev command

# Conflicts:
#	core/src/main/java/com/volmit/iris/core/commands/CommandDeveloper.java
#	core/src/main/java/com/volmit/iris/core/commands/CommandIris.java
#	core/src/main/java/com/volmit/iris/core/nms/v1X/NMSBinding1X.java
#	core/src/main/java/com/volmit/iris/core/tools/IrisPackBenchmarking.java
#	nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/NMSBinding.java
#	nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/NMSBinding.java
#	nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/NMSBinding.java
#	nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/NMSBinding.java
#	nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/NMSBinding.java
#	nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/NMSBinding.java
#	nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/NMSBinding.java

build.gradle

@@ -1,5 +1,3 @@
-import xyz.jpenilla.runpaper.task.RunServer
-
 /*
  * Iris is a World Generator for Minecraft Bukkit Servers
  * Copyright (c) 2021 Arcane Arts (Volmit Software)
@@ -32,11 +30,10 @@ plugins {
     id 'java-library'
     id "io.github.goooler.shadow" version "8.1.7"
     id "de.undercouch.download" version "5.0.1"
-    id "xyz.jpenilla.run-paper" version "2.3.1"
 }
 
 
-version '3.6.6-1.20.1-1.21.4'
+version '3.6.5-1.20.1-1.21.4'
 
 // ADD YOURSELF AS A NEW LINE IF YOU WANT YOUR OWN BUILD TASK GENERATED
 // ======================== WINDOWS =============================
@@ -56,11 +53,6 @@ registerCustomOutputTaskUnix('PixelMac', '/Users/test/Desktop/mcserver/plugins')
 registerCustomOutputTaskUnix('CrazyDev22LT', '/home/julian/Desktop/server/plugins')
 // ==============================================================
 
-def MIN_HEAP_SIZE = "2G"
-def MAX_HEAP_SIZE = "8G"
-//Valid values are: none, truecolor, indexed256, indexed16, indexed8
-def COLOR = "truecolor"
-
 def NMS_BINDINGS = Map.of(
         "v1_21_R3", "1.21.4-R0.1-SNAPSHOT",
         "v1_21_R2", "1.21.3-R0.1-SNAPSHOT",
@@ -70,34 +62,21 @@ def NMS_BINDINGS = Map.of(
         "v1_20_R2", "1.20.2-R0.1-SNAPSHOT",
         "v1_20_R1", "1.20.1-R0.1-SNAPSHOT",
 )
-def JVM_VERSION = Map.<String, Integer>of()
-NMS_BINDINGS.forEach { key, value ->
-    project(":nms:$key") {
+def JVM_VERSION = Map.of()
+NMS_BINDINGS.each { nms ->
+    project(":nms:${nms.key}") {
         apply plugin: 'java'
         apply plugin: 'com.volmit.nmstools'
 
         nmsTools {
-            it.jvm = JVM_VERSION.getOrDefault(key, 21)
-            it.version = value
+            it.jvm = JVM_VERSION.getOrDefault(nms.key, 21)
+            it.version = nms.value
         }
 
         dependencies {
             implementation project(":core")
         }
     }
-
-    tasks.register("runServer-$key", RunServer) {
-        group("servers")
-        minecraftVersion(value.split("-")[0])
-        minHeapSize(MIN_HEAP_SIZE)
-        maxHeapSize(MAX_HEAP_SIZE)
-        pluginJars(tasks.shadowJar.archiveFile)
-        javaLauncher = javaToolchains.launcherFor { it.languageVersion = JavaLanguageVersion.of(JVM_VERSION.getOrDefault(key, 21))}
-        runDirectory.convention(layout.buildDirectory.dir("run/$key"))
-        systemProperty("disable.watchdog", "")
-        systemProperty("net.kyori.ansi.colorLevel", COLOR)
-        systemProperty("com.mojang.eula.agree", true)
-    }
 }
 
 shadowJar {
@@ -113,6 +92,11 @@ shadowJar {
     relocate 'net.kyori', 'com.volmit.iris.util.kyori'
     relocate 'org.bstats', 'com.volmit.util.metrics'
     archiveFileName.set("Iris-${project.version}.jar")
+
+    dependencies {
+        exclude(dependency("org.ow2.asm:asm:"))
+        exclude(dependency("org.jetbrains:"))
+    }
 }
 
 dependencies {

core/src/main/java/com/volmit/iris/core/commands/CommandDeveloper.java

@@ -22,11 +22,14 @@ import com.volmit.iris.Iris;
 import com.volmit.iris.core.ServerConfigurator;
 import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.pregenerator.PregenTask;
+import com.volmit.iris.core.pregenerator.methods.HeadlessPregenMethod;
+import com.volmit.iris.core.service.IrisEngineSVC;
 import com.volmit.iris.core.tools.IrisPackBenchmarking;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.engine.object.IrisDimension;
-import com.volmit.iris.engine.service.EngineStatusSVC;
+import com.volmit.iris.engine.platform.PlatformChunkGenerator;
 import com.volmit.iris.util.decree.DecreeExecutor;
 import com.volmit.iris.util.decree.DecreeOrigin;
 import com.volmit.iris.util.decree.annotations.Decree;
@@ -36,6 +39,7 @@ import com.volmit.iris.util.format.Form;
 import com.volmit.iris.util.io.CountingDataInputStream;
 import com.volmit.iris.util.io.IO;
 import com.volmit.iris.util.mantle.TectonicPlate;
+import com.volmit.iris.util.math.Position2;
 import com.volmit.iris.util.nbt.mca.MCAFile;
 import com.volmit.iris.util.nbt.mca.MCAUtil;
 import com.volmit.iris.util.parallel.MultiBurst;
@@ -48,6 +52,7 @@ import org.apache.commons.lang.RandomStringUtils;
 import org.bukkit.Bukkit;
 import org.bukkit.Chunk;
 import org.bukkit.World;
+import org.bukkit.util.Vector;
 
 import java.io.*;
 import java.net.InetAddress;
@@ -66,20 +71,53 @@ public class CommandDeveloper implements DecreeExecutor {
 
     @Decree(description = "Get Loaded TectonicPlates Count", origin = DecreeOrigin.BOTH, sync = true)
     public void EngineStatus() {
-        var status = EngineStatusSVC.getStatus();
+        List<World> IrisWorlds = new ArrayList<>();
+        int TotalLoadedChunks = 0;
+        int TotalQueuedTectonicPlates = 0;
+        int TotalNotQueuedTectonicPlates = 0;
+        int TotalTectonicPlates = 0;
 
-        sender().sendMessage("-------------------------");
-        sender().sendMessage(C.DARK_PURPLE + "Engine Status");
-        sender().sendMessage(C.DARK_PURPLE + "Total Engines: " + C.LIGHT_PURPLE + status.engineCount());
-        sender().sendMessage(C.DARK_PURPLE + "Total Loaded Chunks: " + C.LIGHT_PURPLE + status.loadedChunks());
-        sender().sendMessage(C.DARK_PURPLE + "Tectonic Limit: " + C.LIGHT_PURPLE + status.tectonicLimit());
-        sender().sendMessage(C.DARK_PURPLE + "Tectonic Total Plates: " + C.LIGHT_PURPLE + status.tectonicPlates());
-        sender().sendMessage(C.DARK_PURPLE + "Tectonic Active Plates: " + C.LIGHT_PURPLE + status.activeTectonicPlates());
-        sender().sendMessage(C.DARK_PURPLE + "Tectonic ToUnload: " + C.LIGHT_PURPLE + status.queuedTectonicPlates());
-        sender().sendMessage(C.DARK_PURPLE + "Lowest Tectonic Unload Duration: " + C.LIGHT_PURPLE + Form.duration(status.minTectonicUnloadDuration()));
-        sender().sendMessage(C.DARK_PURPLE + "Highest Tectonic Unload Duration: " + C.LIGHT_PURPLE + Form.duration(status.maxTectonicUnloadDuration()));
-        sender().sendMessage(C.DARK_PURPLE + "Cache Size: " + C.LIGHT_PURPLE + Form.f(IrisData.cacheSize()));
-        sender().sendMessage("-------------------------");
+        long lowestUnloadDuration = 0;
+        long highestUnloadDuration = 0;
+
+        for (World world : Bukkit.getWorlds()) {
+            try {
+                if (IrisToolbelt.access(world).getEngine() != null) {
+                    IrisWorlds.add(world);
+                }
+            } catch (Exception e) {
+                // no
+            }
+        }
+
+        for (World world : IrisWorlds) {
+            Engine engine = IrisToolbelt.access(world).getEngine();
+            TotalQueuedTectonicPlates += (int) engine.getMantle().getToUnload();
+            TotalNotQueuedTectonicPlates += (int) engine.getMantle().getNotQueuedLoadedRegions();
+            TotalTectonicPlates += engine.getMantle().getLoadedRegionCount();
+            if (highestUnloadDuration <= (long) engine.getMantle().getTectonicDuration()) {
+                highestUnloadDuration = (long) engine.getMantle().getTectonicDuration();
+            }
+            if (lowestUnloadDuration >= (long) engine.getMantle().getTectonicDuration()) {
+                lowestUnloadDuration = (long) engine.getMantle().getTectonicDuration();
+            }
+            for (Chunk chunk : world.getLoadedChunks()) {
+                if (chunk.isLoaded()) {
+                    TotalLoadedChunks++;
+                }
+            }
+        }
+        Iris.info("-------------------------");
+        Iris.info(C.DARK_PURPLE + "Engine Status");
+        Iris.info(C.DARK_PURPLE + "Total Loaded Chunks: " + C.LIGHT_PURPLE + TotalLoadedChunks);
+        Iris.info(C.DARK_PURPLE + "Tectonic Limit: " + C.LIGHT_PURPLE + IrisEngineSVC.getTectonicLimit());
+        Iris.info(C.DARK_PURPLE + "Tectonic Total Plates: " + C.LIGHT_PURPLE + TotalTectonicPlates);
+        Iris.info(C.DARK_PURPLE + "Tectonic Active Plates: " + C.LIGHT_PURPLE + TotalNotQueuedTectonicPlates);
+        Iris.info(C.DARK_PURPLE + "Tectonic ToUnload: " + C.LIGHT_PURPLE + TotalQueuedTectonicPlates);
+        Iris.info(C.DARK_PURPLE + "Lowest Tectonic Unload Duration: " + C.LIGHT_PURPLE + Form.duration(lowestUnloadDuration));
+        Iris.info(C.DARK_PURPLE + "Highest Tectonic Unload Duration: " + C.LIGHT_PURPLE + Form.duration(highestUnloadDuration));
+        Iris.info(C.DARK_PURPLE + "Cache Size: " + C.LIGHT_PURPLE + Form.f(IrisData.cacheSize()));
+        Iris.info("-------------------------");
     }
 
     @Decree(description = "Test")
@@ -107,12 +145,16 @@ public class CommandDeveloper implements DecreeExecutor {
     public void packBenchmark(
             @Param(description = "The pack to bench", aliases = {"pack"}, defaultValue = "overworld")
             IrisDimension dimension,
-            @Param(description = "Radius in regions", defaultValue = "2048")
-            int radius,
+            @Param(description = "Diameter in regions", defaultValue = "2048")
+            int diameter,
+            @Param(description = "Headless", defaultValue = "true")
+            boolean headless,
             @Param(description = "Open GUI while benchmarking", defaultValue = "false")
             boolean gui
     ) {
-        new IrisPackBenchmarking(dimension, radius, gui);
+        int rb = diameter << 9;
+        Iris.info("Benchmarking pack " + dimension.getName() + " with diameter: " + rb + "(" + diameter + ")");
+        new IrisPackBenchmarking(dimension, diameter, headless, gui);
     }
 
     @Decree(description = "Upgrade to another Minecraft version")
@@ -180,6 +222,42 @@ public class CommandDeveloper implements DecreeExecutor {
         sender.sendMessage(C.RED + "Failed to load " + failed.get() + " of " + keys.length + " objects");
     }
 
+    @Decree(description = "Pregenerate a world")
+    public void headless(
+            @Param(description = "The radius of the pregen in blocks", aliases = "size")
+            int radius,
+            @Param(description = "The world to pregen", contextual = true)
+            World world,
+            @Param(aliases = "middle", description = "The center location of the pregen. Use \"me\" for your current location", defaultValue = "0,0")
+            Vector center
+    ) {
+        try {
+            var engine = Optional.ofNullable(IrisToolbelt.access(world))
+                    .map(PlatformChunkGenerator::getEngine)
+                    .orElse(null);
+
+            if (engine == null) {
+                sender().sendMessage(C.RED + "The engine access for this world is null!");
+                sender().sendMessage(C.RED + "Please make sure the world is loaded & the engine is initialized. Generate a new chunk, for example.");
+            }
+            radius = Math.max(radius, 1024);
+            IrisToolbelt.pregenerate(PregenTask
+                    .builder()
+                    .center(new Position2(center.getBlockX(), center.getBlockZ()))
+                    .gui(true)
+                    .radiusX(radius)
+                    .radiusZ(radius)
+                    .build(), new HeadlessPregenMethod(engine), engine);
+            String msg = C.GREEN + "Headless Pregen started in " + C.GOLD + world.getName() + C.GREEN + " of " + C.GOLD + (radius * 2) + C.GREEN + " by " + C.GOLD + (radius * 2) + C.GREEN + " blocks from " + C.GOLD + center.getX() + "," + center.getZ();
+            sender().sendMessage(msg);
+            Iris.info(msg);
+        } catch (Throwable e) {
+            sender().sendMessage(C.RED + "Epic fail. See console.");
+            Iris.reportError(e);
+            e.printStackTrace();
+        }
+    }
+
     @Decree(description = "Test", aliases = {"ip"})
     public void network() {
         try {

core/src/main/java/com/volmit/iris/core/commands/CommandSupport.java

@@ -21,6 +21,7 @@ package com.volmit.iris.core.commands;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.pregenerator.ChunkUpdater;
+import com.volmit.iris.core.service.IrisEngineSVC;
 import com.volmit.iris.core.tools.IrisPackBenchmarking;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import com.volmit.iris.engine.framework.Engine;

core/src/main/java/com/volmit/iris/core/loader/ResourceLoader.java

@@ -44,7 +44,6 @@ import lombok.EqualsAndHashCode;
 import lombok.ToString;
 
 import java.io.*;
-import java.util.Arrays;
 import java.util.Locale;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
@@ -220,10 +219,6 @@ public class ResourceLoader<T extends IrisRegistrant> implements MeteredCache {
         return s.map(this::load);
     }
 
-    public Stream<T> streamAllPossible() {
-        return streamAll(Arrays.stream(getPossibleKeys()));
-    }
-
     public KList<T> loadAll(KList<String> s) {
         KList<T> m = new KList<>();
 

core/src/main/java/com/volmit/iris/core/nms/INMSBinding.java

@@ -20,7 +20,9 @@ package com.volmit.iris.core.nms;
 
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.container.Pair;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
@@ -93,7 +95,6 @@ public interface INMSBinding {
             throw new IllegalStateException("Missing dimenstion types to create world");
 
         try (var ignored = injectLevelStems()) {
-            ignored.storeContext();
             return c.createWorld();
         }
     }
@@ -128,15 +129,13 @@ public interface INMSBinding {
         return 441;
     }
 
+    IRegionStorage createRegionStorage(Engine engine);
+
     KList<String> getStructureKeys();
 
     AutoClosing injectLevelStems();
 
-    default AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
-        return null;
-    }
+    Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end);
 
     boolean missingDimensionTypes(boolean overworld, boolean nether, boolean end);
-
-    void removeCustomDimensions(World world);
 }

core/src/main/java/com/volmit/iris/core/nms/container/AutoClosing.java

@@ -1,6 +1,5 @@
 package com.volmit.iris.core.nms.container;
 
-import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.function.NastyRunnable;
 import lombok.AllArgsConstructor;
 
@@ -8,7 +7,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 
 @AllArgsConstructor
 public class AutoClosing implements AutoCloseable {
-    private static final KMap<Thread, AutoClosing> CONTEXTS = new KMap<>();
     private final AtomicBoolean closed = new AtomicBoolean();
     private final NastyRunnable action;
 
@@ -16,24 +14,9 @@ public class AutoClosing implements AutoCloseable {
     public void close() {
         if (closed.getAndSet(true)) return;
         try {
-            removeContext();
             action.run();
         } catch (Throwable e) {
             throw new RuntimeException(e);
         }
     }
-
-    public void storeContext() {
-        CONTEXTS.put(Thread.currentThread(), this);
-    }
-
-    public void removeContext() {
-        CONTEXTS.values().removeIf(c -> c == this);
-    }
-
-    public static void closeContext() {
-        AutoClosing closing = CONTEXTS.remove(Thread.currentThread());
-        if (closing == null) return;
-        closing.close();
-    }
 }

core/src/main/java/com/volmit/iris/core/nms/headless/IRegion.java

@@ -0,0 +1,17 @@
+package com.volmit.iris.core.nms.headless;
+
+import com.volmit.iris.util.documentation.ChunkCoordinates;
+import lombok.NonNull;
+
+import java.io.IOException;
+
+public interface IRegion extends AutoCloseable {
+
+    @ChunkCoordinates
+    boolean exists(int x, int z);
+
+    void write(@NonNull SerializableChunk chunk) throws IOException;
+
+    @Override
+    void close();
+}

core/src/main/java/com/volmit/iris/core/nms/headless/IRegionStorage.java

@@ -0,0 +1,27 @@
+package com.volmit.iris.core.nms.headless;
+
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.documentation.ChunkCoordinates;
+import com.volmit.iris.util.documentation.RegionCoordinates;
+import lombok.NonNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.IOException;
+
+public interface IRegionStorage {
+
+    @ChunkCoordinates
+    boolean exists(int x, int z);
+
+    @Nullable
+    @RegionCoordinates
+    IRegion getRegion(int x, int z, boolean existingOnly) throws IOException;
+
+    @NonNull
+    @ChunkCoordinates
+    SerializableChunk createChunk(int x, int z);
+
+    void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx);
+
+    void close();
+}

core/src/main/java/com/volmit/iris/core/nms/headless/SerializableChunk.java

@@ -0,0 +1,12 @@
+package com.volmit.iris.core.nms.headless;
+
+import com.volmit.iris.engine.data.chunk.TerrainChunk;
+import com.volmit.iris.util.math.Position2;
+
+public interface SerializableChunk extends TerrainChunk {
+    Position2 getPos();
+
+    Object serialize();
+
+    void mark();
+}

core/src/main/java/com/volmit/iris/core/nms/v1X/NMSBinding1X.java

@@ -22,6 +22,7 @@ import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
 import com.volmit.iris.core.nms.container.Pair;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.util.collection.KList;
@@ -111,6 +112,11 @@ public class NMSBinding1X implements INMSBinding {
         return Color.GREEN;
     }
 
+    @Override
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return null;
+    }
+
     @Override
     public KList<String> getStructureKeys() {
         var list = StreamSupport.stream(Registry.STRUCTURE.spliterator(), false)
@@ -126,8 +132,8 @@ public class NMSBinding1X implements INMSBinding {
     }
 
     @Override
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
-        return injectLevelStems();
+    public Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
+        return new Pair<>(0, new AutoClosing(() -> {}));
     }
 
     @Override
@@ -135,11 +141,6 @@ public class NMSBinding1X implements INMSBinding {
         return false;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-
-    }
-
     @Override
     public CompoundTag serializeEntity(Entity location) {
         return null;

core/src/main/java/com/volmit/iris/core/pregenerator/EmptyListener.java

@@ -0,0 +1,80 @@
+package com.volmit.iris.core.pregenerator;
+
+public class EmptyListener implements PregenListener {
+    public static PregenListener INSTANCE = new EmptyListener();
+
+    @Override
+    public void onTick(double chunksPerSecond, double chunksPerMinute, double regionsPerMinute, double percent, int generated, int totalChunks, int chunksRemaining, long eta, long elapsed, String method) {
+
+    }
+
+    @Override
+    public void onChunkGenerating(int x, int z) {
+
+    }
+
+    @Override
+    public void onChunkGenerated(int x, int z) {
+
+    }
+
+    @Override
+    public void onRegionGenerated(int x, int z) {
+
+    }
+
+    @Override
+    public void onRegionGenerating(int x, int z) {
+
+    }
+
+    @Override
+    public void onChunkCleaned(int x, int z) {
+
+    }
+
+    @Override
+    public void onRegionSkipped(int x, int z) {
+
+    }
+
+    @Override
+    public void onNetworkStarted(int x, int z) {
+
+    }
+
+    @Override
+    public void onNetworkFailed(int x, int z) {
+
+    }
+
+    @Override
+    public void onNetworkReclaim(int revert) {
+
+    }
+
+    @Override
+    public void onNetworkGeneratedChunk(int x, int z) {
+
+    }
+
+    @Override
+    public void onNetworkDownloaded(int x, int z) {
+
+    }
+
+    @Override
+    public void onClose() {
+
+    }
+
+    @Override
+    public void onSaving() {
+
+    }
+
+    @Override
+    public void onChunkExistsInRegionGen(int x, int z) {
+
+    }
+}

core/src/main/java/com/volmit/iris/core/pregenerator/methods/HeadlessPregenMethod.java

@@ -0,0 +1,112 @@
+/*
+ *  Iris is a World Generator for Minecraft Bukkit Servers
+ *  Copyright (c) 2024 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.core.pregenerator.methods;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.core.pregenerator.PregenListener;
+import com.volmit.iris.core.pregenerator.PregeneratorMethod;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisHeadless;
+import com.volmit.iris.util.mantle.Mantle;
+import com.volmit.iris.util.parallel.MultiBurst;
+
+import java.io.IOException;
+import java.util.concurrent.Semaphore;
+
+public class HeadlessPregenMethod implements PregeneratorMethod {
+    private final Engine engine;
+    private final IrisHeadless headless;
+    private final Semaphore semaphore;
+    private final int max;
+    private final MultiBurst burst;
+
+    public HeadlessPregenMethod(Engine engine) {
+        this(engine, IrisSettings.getThreadCount(IrisSettings.get().getConcurrency().getParallelism()));
+    }
+
+    public HeadlessPregenMethod(Engine engine, int threads) {
+        this.max = Math.max(threads, 4);
+        this.engine = engine;
+        this.headless = new IrisHeadless(engine);
+        burst = new MultiBurst("HeadlessPregen", 8);
+        this.semaphore = new Semaphore(max);
+    }
+
+    @Override
+    public void init() {
+    }
+
+    @Override
+    public void close() {
+        try {
+            semaphore.acquire(max);
+        } catch (InterruptedException ignored) {
+        }
+        try {
+            headless.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close headless");
+            e.printStackTrace();
+        }
+        burst.close();
+    }
+
+    @Override
+    public void save() {
+    }
+
+    @Override
+    public boolean supportsRegions(int x, int z, PregenListener listener) {
+        return false;
+    }
+
+    @Override
+    public String getMethod(int x, int z) {
+        return "Headless";
+    }
+
+    @Override
+    public void generateRegion(int x, int z, PregenListener listener) {
+    }
+
+    @Override
+    public void generateChunk(int x, int z, PregenListener listener) {
+        try {
+            semaphore.acquire();
+        } catch (InterruptedException ignored) {
+            return;
+        }
+
+        burst.complete(() -> {
+            try {
+                listener.onChunkGenerating(x, z);
+                headless.generateChunk(x, z);
+                listener.onChunkGenerated(x, z);
+            } finally {
+                semaphore.release();
+            }
+        });
+    }
+
+    @Override
+    public Mantle getMantle() {
+        return engine.getMantle().getMantle();
+    }
+}

core/src/main/java/com/volmit/iris/core/service/IrisEngineSVC.java

@@ -0,0 +1,317 @@
+package com.volmit.iris.core.service;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.core.tools.IrisToolbelt;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.platform.PlatformChunkGenerator;
+import com.volmit.iris.util.collection.KList;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.format.C;
+import com.volmit.iris.util.format.Form;
+import com.volmit.iris.util.mantle.TectonicPlate;
+import com.volmit.iris.util.misc.getHardware;
+import com.volmit.iris.util.plugin.IrisService;
+import com.volmit.iris.util.scheduling.ChronoLatch;
+import com.volmit.iris.util.scheduling.Looper;
+import com.volmit.iris.util.scheduling.PrecisionStopwatch;
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.server.PluginDisableEvent;
+import org.bukkit.event.server.ServerLoadEvent;
+import org.bukkit.event.world.WorldLoadEvent;
+import org.bukkit.event.world.WorldUnloadEvent;
+import org.checkerframework.checker.units.qual.A;
+
+import java.util.*;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Supplier;
+
+public class IrisEngineSVC implements IrisService {
+    public static IrisEngineSVC instance;
+    public boolean isServerShuttingDown = false;
+    public boolean isServerLoaded = false;
+    private static final AtomicInteger tectonicLimit = new AtomicInteger(30);
+    private ReentrantLock lastUseLock;
+    private KMap<World, Long> lastUse;
+    private List<World> IrisWorlds;
+    private Looper cacheTicker;
+    private Looper trimTicker;
+    private Looper unloadTicker;
+    private Looper updateTicker;
+    private PrecisionStopwatch trimAlive;
+    private PrecisionStopwatch unloadAlive;
+    public PrecisionStopwatch trimActiveAlive;
+    public PrecisionStopwatch unloadActiveAlive;
+    private AtomicInteger TotalTectonicPlates;
+    private AtomicInteger TotalQueuedTectonicPlates;
+    private AtomicInteger TotalNotQueuedTectonicPlates;
+    private AtomicBoolean IsUnloadAlive;
+    private AtomicBoolean IsTrimAlive;
+    ChronoLatch cl;
+
+    public List<World> corruptedIrisWorlds = new ArrayList<>();
+
+    @Override
+    public void onEnable() {
+        this.cl = new ChronoLatch(5000);
+        lastUse = new KMap<>();
+        lastUseLock = new ReentrantLock();
+        IrisWorlds = new ArrayList<>();
+        IsUnloadAlive = new AtomicBoolean(true);
+        IsTrimAlive = new AtomicBoolean(true);
+        trimActiveAlive = new PrecisionStopwatch();
+        unloadActiveAlive = new PrecisionStopwatch();
+        trimAlive = new PrecisionStopwatch();
+        unloadAlive = new PrecisionStopwatch();
+        TotalTectonicPlates = new AtomicInteger();
+        TotalQueuedTectonicPlates = new AtomicInteger();
+        TotalNotQueuedTectonicPlates = new AtomicInteger();
+        tectonicLimit.set(2);
+        long t = getHardware.getProcessMemory();
+        while (t > 200) {
+            tectonicLimit.getAndAdd(1);
+            t = t - 200;
+        }
+        this.setup();
+        this.TrimLogic();
+        this.UnloadLogic();
+
+        trimAlive.begin();
+        unloadAlive.begin();
+        trimActiveAlive.begin();
+        unloadActiveAlive.begin();
+
+        updateTicker.start();
+        cacheTicker.start();
+        //trimTicker.start();
+        //unloadTicker.start();
+        instance = this;
+
+    }
+
+    public void engineStatus() {
+        boolean trimAlive = trimTicker.isAlive();
+        boolean unloadAlive = unloadTicker.isAlive();
+        Iris.info("Status:");
+        Iris.info("- Trim: " + trimAlive);
+        Iris.info("- Unload: " + unloadAlive);
+
+    }
+
+    public static int getTectonicLimit() {
+        return tectonicLimit.get();
+    }
+
+    @EventHandler
+    public void onWorldUnload(WorldUnloadEvent event) {
+        updateWorlds();
+    }
+
+    @EventHandler
+    public void onWorldLoad(WorldLoadEvent event) {
+        updateWorlds();
+    }
+
+    @EventHandler
+    public void onServerBoot(ServerLoadEvent event) {
+        isServerLoaded = true;
+    }
+
+    @EventHandler
+    public void onPluginDisable(PluginDisableEvent event) {
+        if (event.getPlugin().equals(Iris.instance)) {
+            isServerShuttingDown = true;
+        }
+    }
+
+    public void updateWorlds() {
+        for (World world : Bukkit.getWorlds()) {
+            try {
+                if (IrisToolbelt.access(world).getEngine() != null) {
+                    IrisWorlds.add(world);
+                }
+            } catch (Exception e) {
+                // no
+            }
+        }
+    }
+
+    private void setup() {
+        cacheTicker = new Looper() {
+            @Override
+            protected long loop() {
+                long now = System.currentTimeMillis();
+                lastUseLock.lock();
+                try {
+                    for (World key : new ArrayList<>(lastUse.keySet())) {
+                        Long last = lastUse.get(key);
+                        if (last == null)
+                            continue;
+                        if (now - last > 60000) {
+                            lastUse.remove(key);
+                        }
+                    }
+                } finally {
+                    lastUseLock.unlock();
+                }
+                return 1000;
+            }
+        };
+
+        updateTicker = new Looper() {
+            @Override
+            protected long loop() {
+                try {
+                    TotalQueuedTectonicPlates.set(0);
+                    TotalNotQueuedTectonicPlates.set(0);
+                    TotalTectonicPlates.set(0);
+                    for (World world : IrisWorlds) {
+                        Engine engine = Objects.requireNonNull(IrisToolbelt.access(world)).getEngine();
+                        TotalQueuedTectonicPlates.addAndGet((int) engine.getMantle().getToUnload());
+                        TotalNotQueuedTectonicPlates.addAndGet((int) engine.getMantle().getNotQueuedLoadedRegions());
+                        TotalTectonicPlates.addAndGet(engine.getMantle().getLoadedRegionCount());
+                    }
+                    if (!isServerShuttingDown && isServerLoaded) {
+                        if (!trimTicker.isAlive()) {
+                            Iris.info(C.RED + "TrimTicker found dead! Booting it up!");
+                            try {
+                                TrimLogic();
+                            } catch (Exception e) {
+                                Iris.error("What happened?");
+                                e.printStackTrace();
+                            }
+                        }
+
+                        if (!unloadTicker.isAlive()) {
+                            Iris.info(C.RED + "UnloadTicker found dead! Booting it up!");
+                            try {
+                               UnloadLogic();
+                            } catch (Exception e) {
+                                Iris.error("What happened?");
+                                e.printStackTrace();
+                            }
+                        }
+                    }
+
+                } catch (Exception e) {
+                    return -1;
+                }
+                return 1000;
+            }
+        };
+    }
+    public void TrimLogic() {
+        if (trimTicker == null || !trimTicker.isAlive()) {
+            trimTicker = new Looper() {
+                private final Supplier<Engine> supplier = createSupplier();
+
+                @Override
+                protected long loop() {
+                    long start = System.currentTimeMillis();
+                    trimAlive.reset();
+                    try {
+                        Engine engine = supplier.get();
+                        if (engine != null) {
+                            engine.getMantle().trim(tectonicLimit.get() / lastUse.size());
+                        }
+                    } catch (Throwable e) {
+                        Iris.reportError(e);
+                        Iris.info(C.RED + "EngineSVC: Failed to trim.");
+                        e.printStackTrace();
+                        return -1;
+                    }
+
+                    int size = lastUse.size();
+                    long time = (size > 0 ? 1000 / size : 1000) - (System.currentTimeMillis() - start);
+                    if (time <= 0)
+                        return 0;
+                    return time;
+                }
+            };
+            trimTicker.start();
+        }
+    }
+    public void UnloadLogic() {
+        if (unloadTicker == null || !unloadTicker.isAlive()) {
+            unloadTicker = new Looper() {
+                private final Supplier<Engine> supplier = createSupplier();
+
+                @Override
+                protected long loop() {
+                    long start = System.currentTimeMillis();
+                    unloadAlive.reset();
+                    try {
+                        Engine engine = supplier.get();
+                        if (engine != null) {
+                            long unloadStart = System.currentTimeMillis();
+                            int count = engine.getMantle().unloadTectonicPlate(tectonicLimit.get() / lastUse.size());
+                            if (count > 0) {
+                                Iris.debug(C.GOLD + "Unloaded " + C.YELLOW + count + " TectonicPlates in " + C.RED + Form.duration(System.currentTimeMillis() - unloadStart, 2));
+                            }
+                        }
+                    } catch (Throwable e) {
+                        Iris.reportError(e);
+                        Iris.info(C.RED + "EngineSVC: Failed to unload.");
+                        e.printStackTrace();
+                        return -1;
+                    }
+
+                    int size = lastUse.size();
+                    long time = (size > 0 ? 1000 / size : 1000) - (System.currentTimeMillis() - start);
+                    if (time <= 0)
+                        return 0;
+                    return time;
+                }
+            };
+            unloadTicker.start();
+        }
+    }
+
+    private Supplier<Engine> createSupplier() {
+        AtomicInteger i = new AtomicInteger();
+        return () -> {
+            List<World> worlds = Bukkit.getWorlds();
+            if (i.get() >= worlds.size()) {
+                i.set(0);
+            }
+            try {
+                for (int j = 0; j < worlds.size(); j++) {
+                    World world = worlds.get(i.getAndIncrement());
+                    PlatformChunkGenerator generator = IrisToolbelt.access(world);
+                    if (i.get() >= worlds.size()) {
+                        i.set(0);
+                    }
+
+                    if (generator != null) {
+                        Engine engine = generator.getEngine();
+                        boolean closed = engine.getMantle().getData().isClosed();
+                        if (engine != null && !engine.isStudio() && !closed) {
+                            lastUseLock.lock();
+                            lastUse.put(world, System.currentTimeMillis());
+                            lastUseLock.unlock();
+                            return engine;
+                        }
+                    }
+                }
+            } catch (Throwable e) {
+                Iris.info(C.RED + "EngineSVC: Failed to create supplier.");
+                e.printStackTrace();
+                Iris.reportError(e);
+            }
+            return null;
+        };
+    }
+
+    @Override
+    public void onDisable() {
+        cacheTicker.interrupt();
+        trimTicker.interrupt();
+        unloadTicker.interrupt();
+        lastUse.clear();
+    }
+}

core/src/main/java/com/volmit/iris/core/tools/IrisCreator.java

@@ -84,6 +84,11 @@ public class IrisCreator {
      * Benchmark mode
      */
     private boolean benchmark = false;
+    /**
+     * Radius of chunks to pregenerate in the headless mode
+     * if set to -1, headless mode is disabled
+     */
+    private int headlessRadius = 10;
 
     public static boolean removeFromBukkitYml(String name) throws IOException {
         YamlConfiguration yml = YamlConfiguration.loadConfiguration(BUKKIT_YML);
@@ -127,7 +132,6 @@ public class IrisCreator {
             Iris.service(StudioSVC.class).installIntoWorld(sender, d.getLoadKey(), new File(Bukkit.getWorldContainer(), name()));
         }
 
-        PlatformChunkGenerator access;
         AtomicReference<World> world = new AtomicReference<>();
         AtomicDouble pp = new AtomicDouble(0);
         O<Boolean> done = new O<>();
@@ -140,30 +144,56 @@ public class IrisCreator {
                 .create();
         ServerConfigurator.installDataPacks(false);
 
-        access = (PlatformChunkGenerator) wc.generator();
-        PlatformChunkGenerator finalAccess1 = access;
+        PlatformChunkGenerator access = (PlatformChunkGenerator) wc.generator();
+        if (access == null) {
+            throw new IrisException("Access is null. Something bad happened.");
+        }
 
-        J.a(() ->
-        {
-            Supplier<Integer> g = () -> {
-                if (finalAccess1 == null || finalAccess1.getEngine() == null) {
-                    return 0;
+        if (headlessRadius > 0 && !benchmark) {
+            AtomicBoolean failed = new AtomicBoolean(false);
+            J.a(() -> {
+                int generated = access.getGenerated();
+                double total = Math.pow(headlessRadius * 2 + 1, 2);
+
+                while (generated < total) {
+                    if (failed.get()) return;
+
+                    double v = (double) generated / total;
+                    if (sender.isPlayer()) {
+                        sender.sendProgress(v, "Generating headless chunks");
+                        J.sleep(16);
+                    } else {
+                        sender.sendMessage(C.WHITE + "Generating headless chunks " + Form.pc(v) + ((C.GRAY + " (" + ((int) total - generated) + " Left)")));
+                        J.sleep(1000);
+                    }
+                    generated = access.getGenerated();
                 }
-                return finalAccess1.getEngine().getGenerated();
-            };
-            if(!benchmark) {
-                if (finalAccess1 == null) return;
-                int req = finalAccess1.getSpawnChunks().join();
+            });
 
-                while (g.get() < req) {
-                    double v = (double) g.get() / (double) req;
+            try {
+                access.prepareSpawnChunks(seed, headlessRadius);
+            } catch (Throwable e) {
+                Iris.error("Failed to prepare spawn chunks for " + name);
+                e.printStackTrace();
+                failed.set(true);
+            }
+        }
+
+        J.a(() -> {
+            if(!benchmark) {
+                int req = access.getSpawnChunks().join();
+
+                int generated = access.getGenerated();
+                while (generated < req) {
+                    double v = (double) generated / (double) req;
                     if (sender.isPlayer()) {
                         sender.sendProgress(v, "Generating");
                         J.sleep(16);
                     } else {
-                        sender.sendMessage(C.WHITE + "Generating " + Form.pc(v) + ((C.GRAY + " (" + (req - g.get()) + " Left)")));
+                        sender.sendMessage(C.WHITE + "Generating " + Form.pc(v) + ((C.GRAY + " (" + (req - generated) + " Left)")));
                         J.sleep(1000);
                     }
+                    generated = access.getGenerated();
                 }
             }
         });

core/src/main/java/com/volmit/iris/core/tools/IrisPackBenchmarking.java

@@ -2,13 +2,22 @@ package com.volmit.iris.core.tools;
 
 
 import com.volmit.iris.Iris;
+import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.pregenerator.PregenTask;
+import com.volmit.iris.core.pregenerator.methods.HeadlessPregenMethod;
+import com.volmit.iris.core.pregenerator.methods.HybridPregenMethod;
+import com.volmit.iris.core.service.StudioSVC;
+import com.volmit.iris.engine.IrisEngine;
 import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.framework.EngineTarget;
 import com.volmit.iris.engine.object.IrisDimension;
+import com.volmit.iris.engine.object.IrisWorld;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.exceptions.IrisException;
 import com.volmit.iris.util.format.Form;
+import com.volmit.iris.util.io.IO;
 import com.volmit.iris.util.scheduling.J;
 import com.volmit.iris.util.scheduling.PrecisionStopwatch;
 import lombok.Getter;
@@ -17,11 +26,6 @@ import org.bukkit.Bukkit;
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
-import java.nio.file.FileVisitResult;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.SimpleFileVisitor;
-import java.nio.file.attribute.BasicFileAttributes;
 import java.time.Clock;
 import java.time.LocalDateTime;
 import java.util.Collections;
@@ -33,13 +37,16 @@ public class IrisPackBenchmarking {
     public static boolean benchmarkInProgress = false;
     private final PrecisionStopwatch stopwatch = new PrecisionStopwatch();
     private final IrisDimension dimension;
-    private final int radius;
+    private final int diameter;
     private final boolean gui;
+    private final boolean headless;
+    private transient Engine engine;
 
-    public IrisPackBenchmarking(IrisDimension dimension, int radius, boolean gui) {
+    public IrisPackBenchmarking(IrisDimension dimension, int diameter, boolean headless, boolean gui) {
         instance = this;
         this.dimension = dimension;
-        this.radius = radius;
+        this.diameter = diameter;
+        this.headless = headless;
         this.gui = gui;
         runBenchmark();
     }
@@ -50,12 +57,9 @@ public class IrisPackBenchmarking {
                 .start(() -> {
                     Iris.info("Setting up benchmark environment ");
                     benchmarkInProgress = true;
-                    File file = new File("benchmark");
-                    if (file.exists()) {
-                        deleteDirectory(file.toPath());
-                    }
+                    IO.delete(new File(Bukkit.getWorldContainer(), "benchmark"));
                     createBenchmark();
-                    while (!IrisToolbelt.isIrisWorld(Bukkit.getWorld("benchmark"))) {
+                    while (!headless && !IrisToolbelt.isIrisWorld(Bukkit.getWorld("benchmark"))) {
                         J.sleep(1000);
                         Iris.debug("Iris PackBenchmark: Waiting...");
                     }
@@ -73,7 +77,6 @@ public class IrisPackBenchmarking {
     public void finishedBenchmark(KList<Integer> cps) {
         try {
             String time = Form.duration(stopwatch.getMillis());
-            Engine engine = IrisToolbelt.access(Bukkit.getWorld("benchmark")).getEngine();
             Iris.info("-----------------");
             Iris.info("Results:");
             Iris.info("- Total time: " + time);
@@ -114,12 +117,16 @@ public class IrisPackBenchmarking {
                 e.printStackTrace();
             }
 
-            J.s(() -> {
-                var world = Bukkit.getWorld("benchmark");
-                if (world == null) return;
-                IrisToolbelt.evacuate(world);
-                Bukkit.unloadWorld(world, true);
-            });
+            if (headless) {
+                engine.close();
+            } else {
+                J.s(() -> {
+                    var world = Bukkit.getWorld("benchmark");
+                    if (world == null) return;
+                    IrisToolbelt.evacuate(world);
+                    Bukkit.unloadWorld(world, true);
+                });
+            }
 
             stopwatch.end();
         } catch (Exception e) {
@@ -130,13 +137,34 @@ public class IrisPackBenchmarking {
 
     private void createBenchmark() {
         try {
-            IrisToolbelt.createWorld()
+            if (headless) {
+                Iris.info("Using headless benchmark!");
+                IrisWorld world = IrisWorld.builder()
+                        .name("benchmark")
+                        .minHeight(dimension.getMinHeight())
+                        .maxHeight(dimension.getMaxHeight())
+                        .seed(1337)
+                        .worldFolder(new File(Bukkit.getWorldContainer(), "benchmark"))
+                        .environment(dimension.getEnvironment())
+                        .build();
+                Iris.service(StudioSVC.class).installIntoWorld(
+                        Iris.getSender(),
+                        dimension.getLoadKey(),
+                        world.worldFolder());
+                var data = IrisData.get(new File(world.worldFolder(), "iris/pack"));
+                var dim = data.getDimensionLoader().load(dimension.getLoadKey());
+                engine = new IrisEngine(new EngineTarget(world, dim, data), false);
+                return;
+            }
+
+            engine = IrisToolbelt.access(IrisToolbelt.createWorld()
                     .dimension(dimension.getLoadKey())
                     .name("benchmark")
                     .seed(1337)
                     .studio(false)
                     .benchmark(true)
-                    .create();
+                    .create())
+                    .getEngine();
         } catch (IrisException e) {
             throw new RuntimeException(e);
         }
@@ -146,9 +174,15 @@ public class IrisPackBenchmarking {
         IrisToolbelt.pregenerate(PregenTask
                 .builder()
                 .gui(gui)
-                .radiusX(radius)
-                .radiusZ(radius)
-                .build(), Bukkit.getWorld("benchmark")
+                .radiusX(diameter)
+                .radiusZ(diameter)
+                .build(), headless ?
+                new HeadlessPregenMethod(engine) :
+                new HybridPregenMethod(
+                        engine.getWorld().realWorld(),
+                        IrisSettings.getThreadCount(IrisSettings.get().getConcurrency().getParallelism())
+                ),
+                engine
         );
     }
 
@@ -178,26 +212,4 @@ public class IrisPackBenchmarking {
     private int findHighest(KList<Integer> list) {
         return Collections.max(list);
     }
-
-    private boolean deleteDirectory(Path dir) {
-        try {
-            Files.walkFileTree(dir, new SimpleFileVisitor<>() {
-                @Override
-                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
-                    Files.delete(file);
-                    return FileVisitResult.CONTINUE;
-                }
-
-                @Override
-                public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
-                    Files.delete(dir);
-                    return FileVisitResult.CONTINUE;
-                }
-            });
-            return true;
-        } catch (IOException e) {
-            e.printStackTrace();
-            return false;
-        }
-    }
 }

core/src/main/java/com/volmit/iris/engine/IrisEngine.java

@@ -43,7 +43,6 @@ import com.volmit.iris.util.format.C;
 import com.volmit.iris.util.format.Form;
 import com.volmit.iris.util.hunk.Hunk;
 import com.volmit.iris.util.io.IO;
-import com.volmit.iris.util.io.JarScanner;
 import com.volmit.iris.util.mantle.MantleFlag;
 import com.volmit.iris.util.math.M;
 import com.volmit.iris.util.math.RNG;
@@ -61,11 +60,7 @@ import org.bukkit.command.CommandSender;
 
 import java.io.File;
 import java.io.IOException;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.InvocationTargetException;
-import java.util.Collections;
 import java.util.HashSet;
-import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -76,8 +71,6 @@ import java.util.concurrent.atomic.AtomicLong;
 @EqualsAndHashCode(exclude = "context")
 @ToString(exclude = "context")
 public class IrisEngine implements Engine {
-    private static final Map<Class<? extends IrisEngineService>, Constructor<? extends IrisEngineService>> SERVICES = scanServices();
-    private final KMap<Class<? extends IrisEngineService>, IrisEngineService> services;
     private final AtomicInteger bud;
     private final AtomicInteger buds;
     private final AtomicInteger generated;
@@ -118,7 +111,6 @@ public class IrisEngine implements Engine {
         getEngineData();
         verifySeed();
         this.seedManager = new SeedManager(target.getWorld().getRawWorldSeed());
-        services = new KMap<>();
         bud = new AtomicInteger(0);
         buds = new AtomicInteger(0);
         metrics = new EngineMetrics(32);
@@ -145,26 +137,6 @@ public class IrisEngine implements Engine {
         Iris.debug("Engine Initialized " + getCacheID());
     }
 
-    @SuppressWarnings("unchecked")
-    private static Map<Class<? extends IrisEngineService>, Constructor<? extends IrisEngineService>> scanServices() {
-        JarScanner js = new JarScanner(Iris.instance.getJarFile(), "com.volmit.iris.engine.service");
-        J.attempt(js::scan);
-        KMap<Class<? extends IrisEngineService>, Constructor<? extends IrisEngineService>> map = new KMap<>();
-        js.getClasses()
-                .stream()
-                .filter(IrisEngineService.class::isAssignableFrom)
-                .map(c -> (Class<? extends IrisEngineService>) c)
-                .forEach(c -> {
-                    try {
-                        map.put(c, c.getConstructor(Engine.class));
-                    } catch (NoSuchMethodException e) {
-                        Iris.warn("Failed to load service " + c.getName() + " due to missing constructor");
-                    }
-                });
-
-        return Collections.unmodifiableMap(map);
-    }
-
     private void verifySeed() {
         if (getEngineData().getSeed() != null && getEngineData().getSeed() != target.getWorld().getRawWorldSeed()) {
             target.getWorld().setRawWorldSeed(getEngineData().getSeed());
@@ -189,8 +161,6 @@ public class IrisEngine implements Engine {
         execution.close();
         effects.close();
         mode.close();
-        services.values().forEach(s -> s.onDisable(true));
-        services.values().forEach(Iris.instance::unregisterListener);
 
         J.a(() -> new IrisProject(getData().getDataFolder()).updateWorkspace());
     }
@@ -199,24 +169,6 @@ public class IrisEngine implements Engine {
         try {
             Iris.debug("Setup Engine " + getCacheID());
             cacheId = RNG.r.nextInt();
-            boolean hotload = true;
-            if (services.isEmpty()) {
-                SERVICES.forEach((s, c) -> {
-                    try {
-                        services.put(s, c.newInstance(this));
-                    } catch (InstantiationException | IllegalAccessException |
-                             InvocationTargetException e) {
-                        Iris.error("Failed to create service " + s.getName());
-                        e.printStackTrace();
-                    }
-                });
-                hotload = false;
-            }
-            for (var service : services.values()) {
-                service.onEnable(hotload);
-                Iris.instance.registerListener(service);
-            }
-
             worldManager = new IrisWorldManager(this);
             complex = new IrisComplex(this);
             execution = new IrisExecutionEnvironment(this);
@@ -352,6 +304,11 @@ public class IrisEngine implements Engine {
         return generated.get();
     }
 
+    @Override
+    public void addGenerated(int x, int z) {
+        generated.incrementAndGet();
+    }
+
     @Override
     public double getGeneratedPerSecond() {
         if (perSecondLatch.flip()) {
@@ -466,7 +423,6 @@ public class IrisEngine implements Engine {
         PregeneratorJob.shutdownInstance();
         closed = true;
         J.car(art);
-        services.values().forEach(s -> s.onDisable(false));
         getWorldManager().close();
         getTarget().close();
         saveEngineData();

core/src/main/java/com/volmit/iris/engine/IrisWorldManager.java

@@ -27,6 +27,7 @@ import com.volmit.iris.engine.object.*;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.collection.KMap;
 import com.volmit.iris.util.collection.KSet;
+import com.volmit.iris.util.format.Form;
 import com.volmit.iris.util.mantle.Mantle;
 import com.volmit.iris.util.mantle.MantleFlag;
 import com.volmit.iris.util.math.M;
@@ -71,6 +72,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
     private final Looper looper;
     private final int id;
     private final KList<Runnable> updateQueue = new KList<>();
+    private final ChronoLatch cl;
     private final ChronoLatch clw;
     private final ChronoLatch ecl;
     private final ChronoLatch cln;
@@ -81,10 +83,12 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
     private long charge = 0;
     private int actuallySpawned = 0;
     private int cooldown = 0;
+    private List<Entity> precount = new KList<>();
     private KSet<Position2> injectBiomes = new KSet<>();
 
     public IrisWorldManager() {
         super(null);
+        cl = null;
         ecl = null;
         cln = null;
         clw = null;
@@ -99,6 +103,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
         chunkUpdater = new ChronoLatch(3000);
         chunkDiscovery = new ChronoLatch(5000);
         cln = new ChronoLatch(60000);
+        cl = new ChronoLatch(3000);
         ecl = new ChronoLatch(250);
         clw = new ChronoLatch(1000, true);
         id = engine.getCacheID();
@@ -146,12 +151,27 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
                         engine.getEngineData().cleanup(getEngine());
                     }
 
+                    if (precount != null) {
+                        entityCount = 0;
+                        for (Entity i : precount) {
+                            if (i instanceof LivingEntity) {
+                                if (!i.isDead()) {
+                                    entityCount++;
+                                }
+                            }
+                        }
+
+                        precount = null;
+                    }
+
                     if (energy < 650) {
                         if (ecl.flip()) {
                             energy *= 1 + (0.02 * M.clip((1D - getEntitySaturation()), 0D, 1D));
                             fixEnergy();
                         }
                     }
+
+                    onAsyncTick();
                 }
 
                 return IrisSettings.get().getWorld().getAsyncTickIntervalMS();
@@ -194,7 +214,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
                             int finalZ = c.getZ() + z;
                             J.a(() -> getMantle().raiseFlag(finalX, finalZ, MantleFlag.INITIAL_SPAWNED_MARKER,
                                     () -> {
-                                        J.a(() -> spawnIn(cx), RNG.r.i(5, 200));
+                                        J.a(() -> spawnIn(cx, true), RNG.r.i(5, 200));
                                         getSpawnersFromMarkers(cx).forEach((blockf, spawners) -> {
                                             if (spawners.isEmpty()) {
                                                 return;
@@ -202,7 +222,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
 
                                             IrisPosition block = new IrisPosition(blockf.getX(), blockf.getY() + getEngine().getWorld().minHeight(), blockf.getZ());
                                             IrisSpawner s = new KList<>(spawners).getRandom();
-                                            spawn(block, s);
+                                            spawn(block, s, true);
                                         });
                                     }));
                         }
@@ -212,16 +232,73 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
         }
     }
 
+    private boolean onAsyncTick() {
+        if (getEngine().isClosed()) {
+            return false;
+        }
+
+        actuallySpawned = 0;
+
+        if (energy < 100) {
+            J.sleep(200);
+            return false;
+        }
+
+        if (!getEngine().getWorld().hasRealWorld()) {
+            Iris.debug("Can't spawn. No real world");
+            J.sleep(5000);
+            return false;
+        }
+
+        double epx = getEntitySaturation();
+        if (epx > IrisSettings.get().getWorld().getTargetSpawnEntitiesPerChunk()) {
+            Iris.debug("Can't spawn. The entity per chunk ratio is at " + Form.pc(epx, 2) + " > 100% (total entities " + entityCount + ")");
+            J.sleep(5000);
+            return false;
+        }
+
+        if (cl.flip()) {
+            try {
+                J.s(() -> precount = getEngine().getWorld().realWorld().getEntities());
+            } catch (Throwable e) {
+                close();
+            }
+        }
+
+        int spawnBuffer = RNG.r.i(2, 12);
+
+        Chunk[] cc = getEngine().getWorld().realWorld().getLoadedChunks();
+        while (spawnBuffer-- > 0) {
+            if (cc.length == 0) {
+                Iris.debug("Can't spawn. No chunks!");
+                return false;
+            }
+
+            Chunk c = cc[RNG.r.nextInt(cc.length)];
+
+            if (!c.isLoaded() || !Chunks.isSafe(c.getWorld(), c.getX(), c.getZ())) {
+                continue;
+            }
+
+            spawnIn(c, false);
+        }
+
+        energy -= (actuallySpawned / 2D);
+        return actuallySpawned > 0;
+    }
+
     private void fixEnergy() {
         energy = M.clip(energy, 1D, getDimension().getMaximumEnergy());
     }
 
-    private void spawnIn(Chunk c) {
+    private void spawnIn(Chunk c, boolean initial) {
         if (getEngine().isClosed()) {
             return;
         }
 
-        energy += 1.2;
+        if (initial) {
+            energy += 1.2;
+        }
 
         if (IrisSettings.get().getWorld().isMarkerEntitySpawningSystem()) {
             getSpawnersFromMarkers(c).forEach((blockf, spawners) -> {
@@ -231,8 +308,9 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
 
                 IrisPosition block = new IrisPosition(blockf.getX(), blockf.getY() + getEngine().getWorld().minHeight(), blockf.getZ());
                 IrisSpawner s = new KList<>(spawners).getRandom();
+                spawn(block, s, false);
                 J.a(() -> getMantle().raiseFlag(c.getX(), c.getZ(), MantleFlag.INITIAL_SPAWNED_MARKER,
-                        () -> spawn(block, s)));
+                        () -> spawn(block, s, true)));
             });
         }
 
@@ -263,7 +341,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
                                         .stream()
                                         .filter(filter)))
                 .filter(counter)
-                .flatMap(this::stream)
+                .flatMap((i) -> stream(i, initial))
                 .collect(Collectors.toList()))
                 .getRandom();
         //@done
@@ -300,13 +378,13 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
         }
     }
 
-    private Stream<IrisEntitySpawn> stream(IrisSpawner s) {
-        for (IrisEntitySpawn i : s.getInitialSpawns()) {
+    private Stream<IrisEntitySpawn> stream(IrisSpawner s, boolean initial) {
+        for (IrisEntitySpawn i : initial ? s.getInitialSpawns() : s.getSpawns()) {
             i.setReferenceSpawner(s);
             i.setReferenceMarker(s.getReferenceMarker());
         }
 
-        return (s.getInitialSpawns()).stream();
+        return (initial ? s.getInitialSpawns() : s.getSpawns()).stream();
     }
 
     private KList<IrisEntitySpawn> spawnRandomly(List<IrisEntitySpawn> types) {
@@ -353,7 +431,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
         }
     }
 
-    private void spawn(IrisPosition block, IrisSpawner spawner) {
+    private void spawn(IrisPosition block, IrisSpawner spawner, boolean initial) {
         if (getEngine().isClosed()) {
             return;
         }
@@ -362,7 +440,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
             return;
         }
 
-        KList<IrisEntitySpawn> s = spawner.getInitialSpawns();
+        KList<IrisEntitySpawn> s = initial ? spawner.getInitialSpawns() : spawner.getSpawns();
         if (s.isEmpty()) {
             return;
         }

core/src/main/java/com/volmit/iris/engine/framework/Engine.java

@@ -610,6 +610,9 @@ public interface Engine extends DataProvider, Fallible, LootProvider, BlockUpdat
 
     int getGenerated();
 
+    @ChunkCoordinates
+    void addGenerated(int x, int z);
+
     CompletableFuture<Long> getHash32();
 
     default <T> IrisPosition lookForStreamResult(T find, ProceduralStream<T> stream, Function2<T, T, Boolean> matcher, long timeout) {

core/src/main/java/com/volmit/iris/engine/object/IrisContextInjector.java

@@ -2,15 +2,12 @@ package com.volmit.iris.engine.object;
 
 import com.volmit.iris.core.nms.INMS;
 import com.volmit.iris.core.nms.container.AutoClosing;
-import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.misc.ServerProperties;
 import lombok.Getter;
 import org.bukkit.Bukkit;
-import org.bukkit.NamespacedKey;
 import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.bukkit.event.EventHandler;
-import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.world.WorldInitEvent;
 
@@ -22,9 +19,14 @@ public class IrisContextInjector implements Listener {
     @Getter
     private static boolean missingDimensionTypes = false;
     private AutoClosing autoClosing = null;
+    private final int totalWorlds;
+    private int worldCounter = 0;
 
     public IrisContextInjector() {
-        if (!Bukkit.getWorlds().isEmpty()) return;
+        if (!Bukkit.getWorlds().isEmpty()) {
+            totalWorlds = 0;
+            return;
+        }
 
         String levelName = ServerProperties.LEVEL_NAME;
         List<String> irisWorlds = irisWorlds();
@@ -32,20 +34,29 @@ public class IrisContextInjector implements Listener {
         boolean nether = irisWorlds.contains(levelName + "_nether");
         boolean end = irisWorlds.contains(levelName + "_end");
 
+        int i = 1;
+        if (Bukkit.getAllowNether()) i++;
+        if (Bukkit.getAllowEnd()) i++;
+
         if (INMS.get().missingDimensionTypes(overworld, nether, end)) {
             missingDimensionTypes = true;
+            totalWorlds = 0;
             return;
         }
 
         if (overworld || nether || end) {
-            autoClosing = INMS.get().injectUncached(overworld, nether, end);
+            var pair = INMS.get().injectUncached(overworld, nether, end);
+            i += pair.getA() - 3;
+            autoClosing = pair.getB();
         }
 
+        totalWorlds = i;
         instance.registerListener(this);
     }
 
-    @EventHandler(priority = EventPriority.LOWEST)
+    @EventHandler
     public void on(WorldInitEvent event) {
+        if (++worldCounter < totalWorlds) return;
         if (autoClosing != null) {
             autoClosing.close();
             autoClosing = null;

core/src/main/java/com/volmit/iris/engine/object/IrisEngineService.java

@@ -1,19 +0,0 @@
-package com.volmit.iris.engine.object;
-
-import com.volmit.iris.Iris;
-import com.volmit.iris.engine.framework.Engine;
-import lombok.RequiredArgsConstructor;
-import org.bukkit.event.Listener;
-
-@RequiredArgsConstructor
-public abstract class IrisEngineService implements Listener {
-    protected final Engine engine;
-
-    public abstract void onEnable(boolean hotload);
-
-    public abstract void onDisable(boolean hotload);
-
-    public final void postShutdown(Runnable r) {
-        Iris.instance.postShutdown(r);
-    }
-}

core/src/main/java/com/volmit/iris/engine/object/IrisEntity.java

@@ -404,7 +404,7 @@ public class IrisEntity extends IrisRegistrant {
         });
 
 
-        return e.isValid() ? e : null;
+        return e;
     }
 
     private int surfaceY(Location l) {

core/src/main/java/com/volmit/iris/engine/object/IrisEntitySpawn.java

@@ -28,12 +28,19 @@ import com.volmit.iris.util.math.RNG;
 import com.volmit.iris.util.math.Vector3d;
 import com.volmit.iris.util.matter.MatterMarker;
 import com.volmit.iris.util.matter.slices.MarkerMatter;
+import io.lumine.mythic.bukkit.adapters.BukkitEntity;
 import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
 import lombok.experimental.Accessors;
-import org.bukkit.*;
+import org.bukkit.Chunk;
+import org.bukkit.Location;
+import org.bukkit.Material;
+import org.bukkit.World;
 import org.bukkit.entity.Entity;
+import org.bukkit.entity.EntityType;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.util.BoundingBox;
 
 @Snippet("entity-spawn")
 @Accessors(chain = true)
@@ -62,10 +69,6 @@ public class IrisEntitySpawn implements IRare {
     private transient IrisSpawner referenceSpawner;
     private transient IrisMarker referenceMarker;
 
-    public boolean check(Engine eng, IrisPosition c, ChunkSnapshot snapshot) {
-        return getRealEntity(eng).getSurface().matches(snapshot.getBlockData(c.getX() & 15, c.getY(), c.getZ() & 15));
-    }
-
     public int spawn(Engine gen, Chunk c, RNG rng) {
         int spawns = minSpawns == maxSpawns ? minSpawns : rng.i(Math.min(minSpawns, maxSpawns), Math.max(minSpawns, maxSpawns));
         int s = 0;
@@ -165,7 +168,7 @@ public class IrisEntitySpawn implements IRare {
                 return null;
             }
 
-            if (!ignoreSurfaces && !irisEntity.getSurface().matches(at.clone().subtract(0, 1, 0).getBlock().getBlockData())) {
+            if (!ignoreSurfaces && !irisEntity.getSurface().matches(at.clone().subtract(0, 1, 0).getBlock())) {
                 return null;
             }
 
@@ -180,10 +183,6 @@ public class IrisEntitySpawn implements IRare {
             Entity e = irisEntity.spawn(g, at.add(0.5, 0.5, 0.5), rng.aquire(() -> new RNG(g.getSeedManager().getEntity())));
             if (e != null) {
                 Iris.debug("Spawned " + C.DARK_AQUA + "Entity<" + getEntity() + "> " + C.GREEN + e.getType() + C.LIGHT_PURPLE + " @ " + C.GRAY + e.getLocation().getX() + ", " + e.getLocation().getY() + ", " + e.getLocation().getZ());
-
-                if (referenceSpawner != null) {
-                    referenceSpawner.getConditions().apply(e);
-                }
             }
 
             return e;

core/src/main/java/com/volmit/iris/engine/object/IrisHeadless.java

@@ -0,0 +1,325 @@
+/*
+ *  Iris is a World Generator for Minecraft Bukkit Servers
+ *  Copyright (c) 2024 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.engine.object;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.INMS;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.core.pregenerator.PregenListener;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.framework.EngineStage;
+import com.volmit.iris.engine.framework.WrongEngineBroException;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.context.IrisContext;
+import com.volmit.iris.util.documentation.BlockCoordinates;
+import com.volmit.iris.util.documentation.RegionCoordinates;
+import com.volmit.iris.util.hunk.Hunk;
+import com.volmit.iris.util.hunk.view.BiomeGridHunkHolder;
+import com.volmit.iris.util.hunk.view.SyncChunkDataHunkHolder;
+import com.volmit.iris.util.mantle.MantleFlag;
+import com.volmit.iris.util.math.M;
+import com.volmit.iris.util.math.Position2;
+import com.volmit.iris.util.parallel.MultiBurst;
+import com.volmit.iris.util.scheduling.J;
+import com.volmit.iris.util.scheduling.Looper;
+import com.volmit.iris.util.scheduling.PrecisionStopwatch;
+import org.bukkit.Material;
+import org.bukkit.block.data.BlockData;
+
+import java.io.IOException;
+import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.atomic.AtomicReferenceArray;
+import java.util.function.Consumer;
+
+public class IrisHeadless {
+    private final long KEEP_ALIVE = TimeUnit.SECONDS.toMillis(10L);
+    private final Engine engine;
+    private final IRegionStorage storage;
+    private final ExecutorService executor = Executors.newCachedThreadPool();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final AtomicInteger loadedChunks = new AtomicInteger();
+    private transient CompletingThread regionThread;
+    private transient boolean closed = false;
+
+    public IrisHeadless(Engine engine) {
+        this.engine = engine;
+        this.storage = INMS.get().createRegionStorage(engine);
+        if (storage == null) throw new IllegalStateException("Failed to create region storage!");
+        engine.getWorld().headless(this);
+        startRegionCleaner();
+    }
+
+    private void startRegionCleaner() {
+        var cleaner = new Looper() {
+            @Override
+            protected long loop() {
+                if (closed) return -1;
+                long time = M.ms() - KEEP_ALIVE;
+                regions.values()
+                        .stream()
+                        .filter(r -> r.lastEntry < time)
+                        .forEach(Region::submit);
+                return closed ? -1 : 1000;
+            }
+        };
+        cleaner.setName("Iris Region Cleaner - " + engine.getWorld().name());
+        cleaner.setPriority(Thread.MIN_PRIORITY);
+        cleaner.start();
+    }
+
+    public int getLoadedChunks() {
+        return loadedChunks.get();
+    }
+
+    /**
+     * Checks if the mca plate is fully generated or not.
+     *
+     * @param x coord of the chunk
+     * @param z coord of the chunk
+     * @return true if the chunk exists in .mca
+     */
+    public boolean exists(int x, int z) {
+        if (closed) return false;
+        if (engine.getWorld().hasRealWorld() && engine.getWorld().realWorld().isChunkLoaded(x, z))
+            return true;
+        return storage.exists(x, z);
+    }
+
+    public synchronized CompletableFuture<Void> generateRegion(MultiBurst burst, int x, int z, int maxConcurrent, PregenListener listener) {
+        if (closed) return CompletableFuture.completedFuture(null);
+        if (regionThread != null && !regionThread.future.isDone())
+            throw new IllegalStateException("Region generation already in progress");
+
+        regionThread = new CompletingThread(() -> {
+            boolean listening = listener != null;
+            Semaphore semaphore = new Semaphore(maxConcurrent);
+            CountDownLatch latch = new CountDownLatch(1024);
+
+            iterateRegion(x, z, pos -> {
+                try {
+                    semaphore.acquire();
+                } catch (InterruptedException e) {
+                    semaphore.release();
+                    return;
+                }
+
+                burst.complete(() -> {
+                    try {
+                        if (listening) listener.onChunkGenerating(pos.getX(), pos.getZ());
+                        generateChunk(pos.getX(), pos.getZ());
+                        if (listening) listener.onChunkGenerated(pos.getX(), pos.getZ());
+                    } finally {
+                        semaphore.release();
+                        latch.countDown();
+                    }
+                });
+            });
+            try {
+                latch.await();
+            } catch (InterruptedException ignored) {}
+            if (listening) listener.onRegionGenerated(x, z);
+        }, "Region Generator - " + x + "," + z, Thread.MAX_PRIORITY);
+
+        return regionThread.future;
+    }
+
+    @RegionCoordinates
+    private static void iterateRegion(int x, int z, Consumer<Position2> chunkPos) {
+        int cX = x << 5;
+        int cZ = z << 5;
+        for (int xx = 0; xx < 32; xx++) {
+            for (int zz = 0; zz < 32; zz++) {
+                chunkPos.accept(new Position2(cX + xx, cZ + zz));
+            }
+        }
+    }
+
+    public void generateChunk(int x, int z) {
+        if (closed || exists(x, z)) return;
+        try {
+            var chunk = storage.createChunk(x, z);
+            loadedChunks.incrementAndGet();
+
+            SyncChunkDataHunkHolder blocks = new SyncChunkDataHunkHolder(chunk);
+            BiomeGridHunkHolder biomes = new BiomeGridHunkHolder(chunk, chunk.getMinHeight(), chunk.getMaxHeight());
+            ChunkContext ctx = generate(engine, x << 4, z << 4, blocks, biomes);
+            blocks.apply();
+            biomes.apply();
+
+            storage.fillBiomes(chunk, ctx);
+            chunk.mark();
+
+            long key = Cache.key(x >> 5, z >> 5);
+            regions.computeIfAbsent(key, Region::new)
+                    .add(chunk);
+        } catch (Throwable e) {
+            loadedChunks.decrementAndGet();
+            Iris.error("Failed to generate " + x + ", " + z);
+            e.printStackTrace();
+        }
+    }
+
+    @BlockCoordinates
+    private ChunkContext generate(Engine engine, int x, int z, Hunk<BlockData> vblocks, Hunk<org.bukkit.block.Biome> vbiomes) throws WrongEngineBroException {
+        if (engine.isClosed()) {
+            throw new WrongEngineBroException();
+        }
+
+        engine.getContext().touch();
+        engine.getEngineData().getStatistics().generatedChunk();
+        ChunkContext ctx = null;
+        try {
+            PrecisionStopwatch p = PrecisionStopwatch.start();
+            Hunk<BlockData> blocks = vblocks.listen((xx, y, zz, t) -> engine.catchBlockUpdates(x + xx, y + engine.getMinHeight(), z + zz, t));
+
+            var dimension = engine.getDimension();
+            if (dimension.isDebugChunkCrossSections() && ((x >> 4) % dimension.getDebugCrossSectionsMod() == 0 || (z >> 4) % dimension.getDebugCrossSectionsMod() == 0)) {
+                for (int i = 0; i < 16; i++) {
+                    for (int j = 0; j < 16; j++) {
+                        blocks.set(i, 0, j, Material.CRYING_OBSIDIAN.createBlockData());
+                    }
+                }
+            } else {
+                ctx = new ChunkContext(x, z, engine.getComplex());
+                IrisContext.getOr(engine).setChunkContext(ctx);
+
+                for (EngineStage i : engine.getMode().getStages()) {
+                    i.generate(x, z, blocks, vbiomes, false, ctx);
+                }
+            }
+
+            engine.getMantle().getMantle().flag(x >> 4, z >> 4, MantleFlag.REAL, true);
+            engine.getMetrics().getTotal().put(p.getMilliseconds());
+            engine.addGenerated(x,z);
+        } catch (Throwable e) {
+            Iris.reportError(e);
+            engine.fail("Failed to generate " + x + ", " + z, e);
+        }
+        return ctx;
+    }
+
+    public void close() throws IOException {
+        if (closed) return;
+        try {
+            if (regionThread != null) {
+                regionThread.future.join();
+                regionThread = null;
+            }
+
+            regions.v().forEach(Region::submit);
+            Iris.info("Waiting for " + loadedChunks.get() + " chunks to unload...");
+            while (loadedChunks.get() > 0)
+                J.sleep(1);
+            Iris.info("All chunks unloaded");
+            executor.shutdown();
+            storage.close();
+            engine.getWorld().headless(null);
+        } finally {
+            closed = true;
+        }
+    }
+
+    private class Region implements Runnable {
+        private final int x, z;
+        private final long key;
+        private final AtomicReferenceArray<SerializableChunk> chunks = new AtomicReferenceArray<>(1024);
+        private final AtomicReference<Future<?>> full = new AtomicReference<>();
+        private transient int size;
+        private transient long lastEntry = M.ms();
+
+        public Region(long key) {
+            this.x = Cache.keyX(key);
+            this.z = Cache.keyZ(key);
+            this.key = key;
+        }
+
+        @Override
+        public void run() {
+            try (IRegion region = storage.getRegion(x, z, false)) {
+                assert region != null;
+
+                for (int i = 0; i < 1024; i++) {
+                    SerializableChunk chunk = chunks.get(i);
+                    if (chunk == null)
+                        continue;
+
+                    try {
+                        region.write(chunk);
+                    } catch (Throwable e) {
+                        Iris.error("Failed to save chunk " + chunk.getPos());
+                        e.printStackTrace();
+                    }
+                    loadedChunks.decrementAndGet();
+                }
+            } catch (Throwable e) {
+                Iris.error("Failed to load region file " + x + ", " + z);
+                e.printStackTrace();
+                loadedChunks.addAndGet(-size);
+            }
+        }
+
+        public synchronized void add(SerializableChunk chunk) {
+            lastEntry = M.ms();
+            if (chunks.getAndSet(index(chunk.getPos()), chunk) != null)
+                throw new IllegalStateException("Chunk " + chunk.getPos() + " already exists");
+            if (++size < 1024)
+                return;
+            submit();
+        }
+
+        public void submit() {
+            regions.remove(key);
+            full.getAndUpdate(future -> {
+                if (future != null) return future;
+                return executor.submit(this);
+            });
+        }
+
+        private int index(Position2 chunk) {
+            int x = chunk.getX() & 31;
+            int z = chunk.getZ() & 31;
+            return z * 32 + x;
+        }
+    }
+
+    private static class CompletingThread extends Thread {
+        private final CompletableFuture<Void> future = new CompletableFuture<>();
+
+        private CompletingThread(Runnable task, String name, int priority) {
+            super(task, name);
+            setPriority(priority);
+            start();
+        }
+
+        @Override
+        public void run() {
+            try {
+                super.run();
+            } finally {
+                future.complete(null);
+            }
+        }
+    }
+}

core/src/main/java/com/volmit/iris/engine/object/IrisSpawnCondition.java

@@ -1,58 +0,0 @@
-package com.volmit.iris.engine.object;
-
-import com.volmit.iris.Iris;
-import com.volmit.iris.engine.object.annotations.Desc;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import lombok.experimental.Accessors;
-import org.bukkit.NamespacedKey;
-import org.bukkit.entity.Entity;
-import org.bukkit.entity.SpawnCategory;
-import org.bukkit.persistence.PersistentDataType;
-
-import java.util.UUID;
-import java.util.function.BooleanSupplier;
-
-@Accessors(chain = true)
-@NoArgsConstructor
-@AllArgsConstructor
-@Desc("Conditions for a spawner to be triggered")
-@Data
-public class IrisSpawnCondition {
-    private static final NamespacedKey CATEGORY_KEY = new NamespacedKey(Iris.instance, "spawn_category");
-
-    private SpawnCategory category = SpawnCategory.AMBIENT;
-    private int maxEntities = 60;
-
-    public boolean check(KMap<UUID, KMap<String, Boolean>> cache, KList<Entity> entities) {
-        int entityCount = 0;
-        for (Entity entity : entities) {
-            var map = cache.computeIfAbsent(entity.getUniqueId(), k -> new KMap<>());
-            if (check(map, "category_" + category.name(), () -> checkCategory(entity, category)) && ++entityCount >= maxEntities)
-                return false;
-        }
-        return true;
-    }
-
-    public void apply(Entity entity) {
-        var pdc = entity.getPersistentDataContainer();
-        pdc.set(CATEGORY_KEY, PersistentDataType.STRING, category.name());
-    }
-
-    private static boolean check(KMap<String, Boolean> cache, String key, BooleanSupplier predicate) {
-        return cache.computeIfAbsent(key, k -> predicate.getAsBoolean()) == Boolean.TRUE;
-    }
-
-    private static boolean checkCategory(Entity entity, SpawnCategory category) {
-        if (entity.getSpawnCategory() == category)
-            return true;
-
-        var pdc = entity.getPersistentDataContainer();
-        if (!pdc.has(CATEGORY_KEY, PersistentDataType.STRING))
-            return false;
-        return category.name().equals(pdc.get(CATEGORY_KEY, PersistentDataType.STRING));
-    }
-}

core/src/main/java/com/volmit/iris/engine/object/IrisSpawner.java

@@ -74,9 +74,6 @@ public class IrisSpawner extends IrisRegistrant {
     @Desc("Where should these spawns be placed")
     private IrisSpawnGroup group = IrisSpawnGroup.NORMAL;
 
-    @Desc("Conditions for this spawner to be triggered")
-    private IrisSpawnCondition conditions = new IrisSpawnCondition();
-
     public boolean isValid(IrisBiome biome) {
         return switch (group) {
             case NORMAL -> switch (biome.getInferredType()) {

core/src/main/java/com/volmit/iris/engine/object/IrisSurface.java

@@ -20,7 +20,7 @@ package com.volmit.iris.engine.object;
 
 import com.volmit.iris.engine.object.annotations.Desc;
 import org.bukkit.Material;
-import org.bukkit.block.data.BlockData;
+import org.bukkit.block.Block;
 import org.bukkit.block.data.Waterlogged;
 
 @Desc("The type of surface entities should spawn on")
@@ -47,8 +47,8 @@ public enum IrisSurface {
      * @param state The blockstate
      * @return True if it matches
      */
-    public boolean matches(BlockData state) {
-        Material type = state.getMaterial();
+    public boolean matches(Block state) {
+        Material type = state.getType();
         if (type.isSolid()) {
             return this == LAND || this == OVERWORLD || (this == ANIMAL
                     && (type == Material.GRASS_BLOCK || type == Material.DIRT

core/src/main/java/com/volmit/iris/engine/object/IrisWorld.java

@@ -48,6 +48,7 @@ public class IrisWorld {
     private long seed;
     private World.Environment environment;
     private World realWorld;
+    private IrisHeadless headless;
     private int minHeight;
     private int maxHeight;
 

core/src/main/java/com/volmit/iris/engine/platform/BukkitChunkGenerator.java

@@ -21,7 +21,8 @@ package com.volmit.iris.engine.platform;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.loader.IrisData;
 import com.volmit.iris.core.nms.INMS;
-import com.volmit.iris.core.nms.container.AutoClosing;
+import com.volmit.iris.core.pregenerator.EmptyListener;
+import com.volmit.iris.core.pregenerator.methods.HeadlessPregenMethod;
 import com.volmit.iris.core.service.StudioSVC;
 import com.volmit.iris.engine.IrisEngine;
 import com.volmit.iris.engine.data.chunk.TerrainChunk;
@@ -33,10 +34,13 @@ import com.volmit.iris.engine.object.StudioMode;
 import com.volmit.iris.engine.platform.studio.StudioGenerator;
 import com.volmit.iris.util.collection.KList;
 import com.volmit.iris.util.data.IrisBiomeStorage;
+import com.volmit.iris.util.format.C;
+import com.volmit.iris.util.format.Form;
 import com.volmit.iris.util.hunk.Hunk;
 import com.volmit.iris.util.hunk.view.BiomeGridHunkHolder;
 import com.volmit.iris.util.hunk.view.ChunkDataHunkHolder;
 import com.volmit.iris.util.io.ReactiveFolder;
+import com.volmit.iris.util.plugin.VolmitSender;
 import com.volmit.iris.util.scheduling.ChronoLatch;
 import com.volmit.iris.util.scheduling.J;
 import com.volmit.iris.util.scheduling.Looper;
@@ -49,7 +53,6 @@ import org.bukkit.block.data.BlockData;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
-import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.world.WorldInitEvent;
 import org.bukkit.generator.BiomeProvider;
@@ -124,13 +127,11 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
         }
     }
 
-    @EventHandler(priority = EventPriority.LOWEST)
+    @EventHandler
     public void onWorldInit(WorldInitEvent event) {
         try {
             if (initialized || !world.name().equals(event.getWorld().getName()))
                 return;
-            AutoClosing.closeContext();
-            INMS.get().removeCustomDimensions(event.getWorld());
             world.setRawWorldSeed(event.getWorld().getSeed());
             Engine engine = getEngine(event.getWorld());
             if (engine == null) {
@@ -256,6 +257,10 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
     }
 
     private Engine getEngine(WorldInfo world) {
+        return getEngine(world.getSeed());
+    }
+
+    private Engine getEngine(long seed) {
         if (setup.get()) {
             return getEngine();
         }
@@ -268,7 +273,7 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
             }
 
 
-            getWorld().setRawWorldSeed(world.getSeed());
+            getWorld().setRawWorldSeed(seed);
             setupEngine();
             setup.set(true);
             this.hotloader = studio ? new Looper() {
@@ -339,6 +344,21 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
         getEngine(world);
     }
 
+    @Override
+    public void prepareSpawnChunks(long seed, int radius) {
+        if (radius < 0 || new File(world.worldFolder(), "level.dat").exists())
+            return;
+        var engine = getEngine(seed);
+        var headless = new HeadlessPregenMethod(engine, 4);
+
+        for (int x = -radius; x <= radius; x++) {
+            for (int z = -radius; z <= radius; z++) {
+                headless.generateChunk(x, z, EmptyListener.INSTANCE);
+            }
+        }
+        headless.close();
+    }
+
     @Override
     public void generateNoise(@NotNull WorldInfo world, @NotNull Random random, int x, int z, @NotNull ChunkGenerator.ChunkData d) {
         try {

core/src/main/java/com/volmit/iris/engine/platform/PlatformChunkGenerator.java

@@ -49,4 +49,12 @@ public interface PlatformChunkGenerator extends Hotloadable, DataProvider {
     void touch(World world);
 
     CompletableFuture<Integer> getSpawnChunks();
+
+    void prepareSpawnChunks(long seed, int radius);
+
+    default int getGenerated() {
+        Engine engine = getEngine();
+        if (engine == null) return 0;
+        return engine.getGenerated();
+    }
 }

core/src/main/java/com/volmit/iris/engine/service/EngineMobHandlerSVC.java

@@ -1,340 +0,0 @@
-package com.volmit.iris.engine.service;
-
-import com.google.common.util.concurrent.AtomicDouble;
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.IrisSettings;
-import com.volmit.iris.core.loader.IrisData;
-import com.volmit.iris.core.nms.container.Pair;
-import com.volmit.iris.engine.IrisWorldManager;
-import com.volmit.iris.engine.framework.Engine;
-import com.volmit.iris.engine.object.*;
-import com.volmit.iris.util.collection.KList;
-import com.volmit.iris.util.collection.KMap;
-import com.volmit.iris.util.collection.KSet;
-import com.volmit.iris.util.format.Form;
-import com.volmit.iris.util.mantle.Mantle;
-import com.volmit.iris.util.math.BlockPosition;
-import com.volmit.iris.util.math.Position2;
-import com.volmit.iris.util.math.RNG;
-import com.volmit.iris.util.matter.MatterMarker;
-import com.volmit.iris.util.parallel.Sync;
-import com.volmit.iris.util.scheduling.J;
-import com.volmit.iris.util.scheduling.PrecisionStopwatch;
-import io.papermc.lib.PaperLib;
-import lombok.SneakyThrows;
-import org.bukkit.ChunkSnapshot;
-import org.bukkit.GameRule;
-import org.bukkit.World;
-import org.bukkit.entity.Entity;
-import org.bukkit.entity.Player;
-import org.bukkit.event.EventHandler;
-import org.bukkit.event.EventPriority;
-import org.bukkit.event.player.PlayerChangedWorldEvent;
-import org.bukkit.event.player.PlayerJoinEvent;
-import org.bukkit.event.player.PlayerQuitEvent;
-
-import java.util.List;
-import java.util.Objects;
-import java.util.Set;
-import java.util.UUID;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicLong;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
-public class EngineMobHandlerSVC extends IrisEngineService {
-    private static final List<String> CAVE_TAGS = List.of("cave_floor", "cave_ceiling");
-    private static final int SAFE_RADIUS = 16;
-    private static final int MAX_RADIUS = 128;
-
-    private final AtomicLong currentTick = new AtomicLong();
-    private final Sync<Long> sync = new Sync<>();
-    private final Set<Player> players = ConcurrentHashMap.newKeySet();
-    private final AtomicBoolean running = new AtomicBoolean(false);
-    private transient KList<Entity> entities = new KList<>();
-    private transient Thread asyncTicker = null;
-    private transient Thread entityCollector = null;
-    private transient boolean charge = false;
-    private transient int task = -1;
-
-    public EngineMobHandlerSVC(Engine engine) {
-        super(engine);
-    }
-
-    @Override
-    public void onEnable(boolean hotload) {
-        if (running.get()) {
-            running.set(false);
-            cancel(asyncTicker);
-            cancel(entityCollector);
-        }
-
-        running.set(true);
-        charge = hotload;
-        asyncTicker = Thread.ofPlatform()
-                .name("Iris Async Mob Spawning - " + engine.getWorld().name())
-                .priority(9)
-                .start(() -> {
-                    while (mayLoop()) {
-                        try {
-                            asyncTick();
-                        } catch (Throwable e) {
-                            if (isInterrupted(e))
-                                return;
-                            Iris.error("Error in async tick for " + engine.getWorld().name());
-                            e.printStackTrace();
-
-                            J.sleep(100);
-                        }
-                    }
-                });
-        entityCollector = Thread.ofVirtual()
-                .name("Iris Async Entity Collector - " + engine.getWorld().name())
-                .start(() -> {
-                    while (mayLoop()) {
-                        try {
-                            sync.next().get();
-                            var world = engine.getWorld().realWorld();
-                            if (world == null) continue;
-                            J.s(() -> entities = new KList<>(world.getEntities()));
-                        } catch (Throwable e) {
-                            if (isInterrupted(e))
-                                return;
-
-                            Iris.error("Error in async tick for " + engine.getWorld().name());
-                            e.printStackTrace();
-
-                            J.sleep(100);
-                        }
-                    }
-                });
-        if (task != -1) J.csr(task);
-        task = J.sr(() -> sync.advance(currentTick.getAndIncrement()), 0);
-    }
-
-    @Override
-    public void onDisable(boolean hotload) {
-        running.set(false);
-        cancel(asyncTicker);
-        cancel(entityCollector);
-        if (!hotload) J.csr(task);
-    }
-
-    private void asyncTick() throws Throwable {
-        long tick = sync.next().get();
-        var manager = (IrisWorldManager) engine.getWorldManager();
-        if (charge) {
-            manager.chargeEnergy();
-            charge = false;
-        }
-
-        var world = engine.getWorld().realWorld();
-        if (world == null
-                || noSpawning()
-                || Boolean.FALSE.equals(world.getGameRuleValue(GameRule.DO_MOB_SPAWNING))
-                || players.isEmpty()
-                || manager.getEnergy() < 100)
-            return;
-
-        var p = PrecisionStopwatch.start();
-        var entities = new KList<>(this.entities);
-
-        var conditionCache = new KMap<UUID, KMap<String, Boolean>>();
-        var data = engine.getData();
-        var invalid = data.getSpawnerLoader()
-                .streamAllPossible()
-                .filter(Predicate.not(spawner -> spawner.canSpawn(engine)
-                        && spawner.getConditions().check(conditionCache, entities)))
-                .map(IrisSpawner::getLoadKey)
-                .collect(Collectors.toSet());
-
-        var centers = players.stream()
-                .filter(Objects::nonNull)
-                .filter(Player::isOnline)
-                .map(Player::getLocation)
-                .map(BlockPosition::fromLocation)
-                .collect(KList.collector())
-                .shuffle();
-
-        if (centers.isEmpty())
-            return;
-
-        AtomicDouble delta = new AtomicDouble();
-        int actuallySpawned = 0;
-
-        KMap<Position2, Pair<Entity[], ChunkSnapshot>> cache = new KMap<>();
-        while (centers.isNotEmpty()) {
-            var center = centers.pop();
-            var spawned = trySpawn(world, invalid, cache, center, delta);
-            if (spawned == 0 && p.getMilliseconds() < 1000)
-                centers.add(center);
-            actuallySpawned += spawned;
-        }
-        manager.setEnergy(manager.getEnergy() - delta.get());
-        if (actuallySpawned > 0) {
-            Iris.info("Async Mob Spawning " + world.getName() + " used " + delta + " energy and took " + Form.duration((long) p.getMilliseconds()));
-        }
-    }
-
-    private int trySpawn(
-            World world,
-            Set<String> invalid,
-            KMap<Position2, Pair<Entity[], ChunkSnapshot>> cache,
-            BlockPosition center,
-            AtomicDouble delta
-    ) {
-        var pos = center.randomPoint(MAX_RADIUS, SAFE_RADIUS);
-        if (pos.getY() < world.getMinHeight() || pos.getY() >= world.getMaxHeight())
-            return 0;
-
-        var chunkPos = new Position2(center.getX() >> 4, center.getZ() >> 4);
-        var pair = cache.computeIfAbsent(chunkPos, cPos -> {
-            try {
-                return PaperLib.getChunkAtAsync(world, cPos.getX(), cPos.getZ(), false)
-                        .thenApply(c -> c != null ? new Pair<>(c.getEntities(), c.getChunkSnapshot(false, false, false)) : null)
-                        .get();
-            } catch (InterruptedException | ExecutionException e) {
-                throw new RuntimeException(e);
-            }
-        });
-        if (pair == null)
-            return 0;
-
-        var spawners = spawnersAt(pair.getB(), pos, invalid);
-        spawners.removeIf(i -> !i.canSpawn(engine, chunkPos.getX(), chunkPos.getZ()));
-
-        if (spawners.isEmpty())
-            return 0;
-
-        IrisPosition irisPos = new IrisPosition(pos.getX(), pos.getY(), pos.getZ());
-        for (var spawner : spawners) {
-            var spawns = spawner.getSpawns().copy();
-            spawns.removeIf(spawn -> !spawn.check(engine, irisPos, pair.getB()));
-
-            var entity = IRare.pick(spawns, RNG.r.nextDouble());
-            if (entity == null)
-                continue;
-
-            entity.setReferenceSpawner(spawner);
-            entity.setReferenceMarker(spawner.getReferenceMarker());
-            int spawned = entity.spawn(engine, irisPos, RNG.r);
-            if (spawned == 0)
-                continue;
-
-            delta.addAndGet(spawned * ((entity.getEnergyMultiplier() * spawner.getEnergyMultiplier() * 1)));
-            spawner.spawn(engine, chunkPos.getX(), chunkPos.getZ());
-            if (!spawner.canSpawn(engine))
-                invalid.add(spawner.getLoadKey());
-            return spawned;
-        }
-        return 0;
-    }
-
-    private KSet<IrisSpawner> spawnersAt(ChunkSnapshot chunk, BlockPosition pos, Set<String> invalid) {
-        KSet<IrisSpawner> spawners = markerAt(chunk, pos, invalid);
-
-        var loader = engine.getData().getSpawnerLoader();
-        int y = pos.getY() - engine.getWorld().minHeight();
-        Stream.concat(engine.getRegion(pos.getX(), pos.getZ())
-                                .getEntitySpawners()
-                                .stream(),
-                        engine.getBiomeOrMantle(pos.getX(), y, pos.getZ())
-                                .getEntitySpawners()
-                                .stream())
-                .filter(Predicate.not(invalid::contains))
-                .map(loader::load)
-                .forEach(spawners::add);
-
-        return spawners;
-    }
-
-    private KSet<IrisSpawner> markerAt(ChunkSnapshot chunk, BlockPosition pos, Set<String> invalid) {
-        if (!IrisSettings.get().getWorld().isMarkerEntitySpawningSystem())
-            return new KSet<>();
-
-        int y = pos.getY() - engine.getWorld().minHeight();
-        Mantle mantle = engine.getMantle().getMantle();
-        MatterMarker matter = mantle.get(pos.getX(), y, pos.getZ(), MatterMarker.class);
-        if (matter == null || CAVE_TAGS.contains(matter.getTag()))
-            return new KSet<>();
-        IrisData data = engine.getData();
-        IrisMarker mark = data.getMarkerLoader().load(matter.getTag());
-        if (mark == null)
-            return new KSet<>();
-
-        if (mark.isEmptyAbove()) {
-            int x = pos.getX() & 15, z = pos.getZ() & 15;
-            boolean remove = chunk.getBlockData(x, pos.getY() + 1, z).getMaterial().isSolid() || chunk.getBlockData(x, pos.getY() + 2, z).getMaterial().isSolid();
-            if (remove) {
-                mantle.remove(pos.getX(), y, pos.getZ(), MatterMarker.class);
-                return new KSet<>();
-            }
-        }
-
-        KSet<IrisSpawner> spawners = new KSet<>();
-        for (String key : mark.getSpawners()) {
-            if (invalid.contains(key))
-                continue;
-
-            IrisSpawner spawner = data.getSpawnerLoader().load(key);
-            if (spawner == null) {
-                Iris.error("Cannot load spawner: " + key + " for marker " + matter.getTag());
-                continue;
-            }
-
-            spawner.setReferenceMarker(mark);
-            spawners.add(spawner);
-        }
-        return spawners;
-    }
-
-    @EventHandler(priority = EventPriority.LOWEST)
-    public void on(PlayerJoinEvent event) {
-        var player = event.getPlayer();
-        if (player.getWorld() != engine.getWorld().realWorld())
-            return;
-        players.add(player);
-    }
-
-    @EventHandler(priority = EventPriority.LOWEST)
-    public void on(PlayerQuitEvent event) {
-        players.remove(event.getPlayer());
-    }
-
-    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
-    public void on(PlayerChangedWorldEvent event) {
-        var player = event.getPlayer();
-        if (player.getWorld() == engine.getWorld().realWorld())
-            players.add(player);
-        else
-            players.remove(player);
-    }
-
-    @SneakyThrows
-    private static void cancel(Thread thread) {
-        if (thread == null || !thread.isAlive()) return;
-        thread.interrupt();
-        thread.join();
-    }
-
-    private static boolean noSpawning() {
-        var world = IrisSettings.get().getWorld();
-        return !world.isMarkerEntitySpawningSystem() && !world.isAnbientEntitySpawningSystem();
-    }
-
-    private boolean mayLoop() {
-        return !engine.isClosed() && running.get() && !Thread.interrupted();
-    }
-
-    private static boolean isInterrupted(Throwable e) {
-        while (e != null) {
-            if (e instanceof InterruptedException)
-                return true;
-            e = e.getCause();
-        }
-        return false;
-    }
-}

core/src/main/java/com/volmit/iris/engine/service/EngineStatusSVC.java

@@ -1,65 +0,0 @@
-package com.volmit.iris.engine.service;
-
-import com.volmit.iris.engine.framework.Engine;
-import com.volmit.iris.engine.object.IrisEngineService;
-import com.volmit.iris.util.collection.KList;
-
-public class EngineStatusSVC extends IrisEngineService {
-    private static final KList<EngineStatusSVC> INSTANCES = new KList<>();
-
-    public EngineStatusSVC(Engine engine) {
-        super(engine);
-    }
-
-    @Override
-    public void onEnable(boolean hotload) {
-        if (hotload) return;
-        synchronized (INSTANCES) {
-            INSTANCES.add(this);
-        }
-    }
-
-    @Override
-    public void onDisable(boolean hotload) {
-        if (hotload) return;
-
-        synchronized (INSTANCES) {
-            INSTANCES.remove(this);
-        }
-    }
-
-    public static int getEngineCount() {
-        return INSTANCES.size();
-    }
-
-    public static Status getStatus() {
-        synchronized (INSTANCES) {
-            long loadedChunks = 0;
-            long tectonicPlates = 0;
-            long activeTectonicPlates = 0;
-            long queuedTectonicPlates = 0;
-            long minTectonicUnloadDuration = Long.MAX_VALUE;
-            long maxTectonicUnloadDuration = Long.MIN_VALUE;
-
-            for (var service : INSTANCES) {
-                var world = service.engine.getWorld();
-                if (world.hasRealWorld())
-                    loadedChunks += world.realWorld().getLoadedChunks().length;
-
-                tectonicPlates += service.engine.getMantle().getLoadedRegionCount();
-                activeTectonicPlates += service.engine.getMantle().getNotQueuedLoadedRegions();
-                queuedTectonicPlates += service.engine.getMantle().getToUnload();
-                minTectonicUnloadDuration = Math.min(minTectonicUnloadDuration, (long) service.engine.getMantle().getTectonicDuration());
-                maxTectonicUnloadDuration = Math.max(maxTectonicUnloadDuration, (long) service.engine.getMantle().getTectonicDuration());
-            }
-            return new Status(INSTANCES.size(), loadedChunks, MantleCleanerSVC.getTectonicLimit(), tectonicPlates, activeTectonicPlates, queuedTectonicPlates, minTectonicUnloadDuration, maxTectonicUnloadDuration);
-        }
-    }
-
-    public record Status(int engineCount, long loadedChunks, int tectonicLimit,
-                         long tectonicPlates, long activeTectonicPlates,
-                         long queuedTectonicPlates,
-                         long minTectonicUnloadDuration,
-                         long maxTectonicUnloadDuration) {
-    }
-}

core/src/main/java/com/volmit/iris/engine/service/MantleCleanerSVC.java

@@ -1,127 +0,0 @@
-package com.volmit.iris.engine.service;
-
-import com.volmit.iris.Iris;
-import com.volmit.iris.core.IrisSettings;
-import com.volmit.iris.engine.framework.Engine;
-import com.volmit.iris.engine.object.IrisEngineService;
-import com.volmit.iris.util.format.C;
-import com.volmit.iris.util.math.M;
-import com.volmit.iris.util.misc.getHardware;
-import com.volmit.iris.util.scheduling.Looper;
-import lombok.SneakyThrows;
-
-import java.io.PrintWriter;
-import java.io.StringWriter;
-import java.util.concurrent.atomic.AtomicInteger;
-import java.util.function.LongSupplier;
-
-public class MantleCleanerSVC extends IrisEngineService {
-    private static final AtomicInteger tectonicLimit = new AtomicInteger(30);
-
-    static {
-        // todo: Redo this
-        tectonicLimit.set(2);
-        long t = getHardware.getProcessMemory();
-        while (t > 200) {
-            tectonicLimit.incrementAndGet();
-            t = t - 200;
-        }
-    }
-
-    private Ticker trimmer;
-    private Ticker unloader;
-
-    public MantleCleanerSVC(Engine engine) {
-        super(engine);
-    }
-
-    public static int getTectonicLimit() {
-        return tectonicLimit.get();
-    }
-
-    private static Ticker createTrimmer(Engine engine) {
-        return new Ticker(() -> {
-            if (engine.isClosed()) return -1;
-            long start = M.ms();
-            try {
-                engine.getMantle().trim(tectonicLimit.get() / getEngineCount());
-            } catch (Throwable e) {
-                Iris.debug(C.RED + "Mantle: Failed to trim.");
-                Iris.reportError(e);
-                e.printStackTrace();
-            }
-
-            if (engine.isClosed()) return -1;
-            int size = getEngineCount();
-            return Math.max(1000 / size - (M.ms() - start), 0);
-        }, "Iris Mantle Trimmer - " + engine.getWorld().name());
-    }
-
-    private static Ticker createUnloader(Engine engine) {
-        return new Ticker(() -> {
-            if (engine.isClosed()) return -1;
-            long start = M.ms();
-            try {
-                engine.getMantle().unloadTectonicPlate(tectonicLimit.get() / getEngineCount());
-            } catch (Throwable e) {
-                Iris.debug(C.RED + "Mantle: Failed to unload.");
-                Iris.reportError(e);
-                e.printStackTrace();
-            }
-
-            if (engine.isClosed()) return -1;
-            int size = getEngineCount();
-            return Math.max(1000 / size - (M.ms() - start), 0);
-        }, "Iris Mantle Unloader - " + engine.getWorld().name());
-    }
-
-    private static int getEngineCount() {
-        return Math.max(EngineStatusSVC.getEngineCount(), 1);
-    }
-
-    @Override
-    public void onEnable(boolean hotload) {
-        if (engine.isStudio() && !IrisSettings.get().getPerformance().trimMantleInStudio)
-            return;
-        if (trimmer == null || !trimmer.isAlive())
-            trimmer = createTrimmer(engine);
-        if (unloader == null || !unloader.isAlive())
-            unloader = createUnloader(engine);
-    }
-
-    @Override
-    public void onDisable(boolean hotload) {
-        if (hotload) return;
-        if (trimmer != null) trimmer.await();
-        if (unloader != null) unloader.await();
-    }
-
-    private static class Ticker extends Looper {
-        private final LongSupplier supplier;
-
-        private Ticker(LongSupplier supplier, String name) {
-            this.supplier = supplier;
-            setPriority(Thread.MIN_PRIORITY);
-            setName(name);
-            start();
-        }
-
-        @Override
-        protected long loop() {
-            try {
-                return supplier.getAsLong();
-            } catch (Throwable e) {
-                Iris.error("Exception in Looper " + getName());
-                StringWriter sw = new StringWriter();
-                e.printStackTrace(new PrintWriter(sw));
-                Iris.error(sw.toString());
-                return 3000;
-            }
-        }
-
-        @SneakyThrows
-        public void await() {
-            join();
-        }
-    }
-}

core/src/main/java/com/volmit/iris/util/collection/KList.java

@@ -26,8 +26,6 @@ import com.volmit.iris.util.math.RNG;
 import java.util.*;
 import java.util.function.Function;
 import java.util.function.Predicate;
-import java.util.stream.Collector;
-import java.util.stream.Collectors;
 
 @SuppressWarnings("ALL")
 public class KList<T> extends ArrayList<T> implements List<T> {
@@ -67,10 +65,6 @@ public class KList<T> extends ArrayList<T> implements List<T> {
         return s;
     }
 
-    public static <T> Collector<T, ?, KList<T>> collector() {
-        return Collectors.toCollection(KList::new);
-    }
-
     public static KList<String> asStringList(List<?> oo) {
         KList<String> s = new KList<String>();
 

core/src/main/java/com/volmit/iris/util/hunk/view/SyncChunkDataHunkHolder.java

@@ -0,0 +1,48 @@
+package com.volmit.iris.util.hunk.view;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.util.hunk.storage.ArrayHunk;
+import org.bukkit.Material;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.generator.ChunkGenerator;
+
+public class SyncChunkDataHunkHolder extends ArrayHunk<BlockData> {
+    private static final BlockData AIR = Material.AIR.createBlockData();
+    private final ChunkGenerator.ChunkData chunk;
+    private final Thread mainThread = Thread.currentThread();
+
+    public SyncChunkDataHunkHolder(ChunkGenerator.ChunkData chunk) {
+        super(16, chunk.getMaxHeight() - chunk.getMinHeight(), 16);
+        this.chunk = chunk;
+    }
+
+    @Override
+    public void setRaw(int x, int y, int z, BlockData data) {
+        if (Thread.currentThread() != mainThread)
+            Iris.warn("SyncChunkDataHunkHolder is not on the main thread");
+        super.setRaw(x, y, z, data);
+    }
+
+    @Override
+    public BlockData getRaw(int x, int y, int z) {
+        if (Thread.currentThread() != mainThread)
+            Iris.warn("SyncChunkDataHunkHolder is not on the main thread");
+        BlockData b = super.getRaw(x, y, z);
+
+        return b != null ? b : AIR;
+    }
+
+    public void apply() {
+        for (int i = getHeight()-1; i >= 0; i--) {
+            for (int j = 0; j < getWidth(); j++) {
+                for (int k = 0; k < getDepth(); k++) {
+                    BlockData b = super.getRaw(j, i, k);
+
+                    if (b != null) {
+                        chunk.setBlock(j, i + chunk.getMinHeight(), k, b);
+                    }
+                }
+            }
+        }
+    }
+}

core/src/main/java/com/volmit/iris/util/mantle/Mantle.java

@@ -21,6 +21,7 @@ package com.volmit.iris.util.mantle;
 import com.google.common.util.concurrent.AtomicDouble;
 import com.volmit.iris.Iris;
 import com.volmit.iris.core.IrisSettings;
+import com.volmit.iris.core.service.IrisEngineSVC;
 import com.volmit.iris.core.tools.IrisToolbelt;
 import com.volmit.iris.engine.data.cache.Cache;
 import com.volmit.iris.engine.framework.Engine;
@@ -424,7 +425,7 @@ public class Mantle {
         ioTrim.set(true);
         unloadLock.lock();
         try {
-            if (lastUse != null) {
+            if (lastUse != null && IrisEngineSVC.instance != null) {
                 if (!lastUse.isEmpty()) {
                     Iris.debug("Trimming Tectonic Plates older than " + Form.duration(adjustedIdleDuration.get(), 0));
                     for (long i : new ArrayList<>(lastUse.keySet())) {
@@ -434,6 +435,7 @@ public class Mantle {
                             if (lastUseTime != null && M.ms() - lastUseTime >= finalAdjustedIdleDuration) {
                                 toUnload.add(i);
                                 Iris.debug("Tectonic Region added to unload");
+                                IrisEngineSVC.instance.trimActiveAlive.reset();
                             }
                         });
                     }
@@ -452,49 +454,53 @@ public class Mantle {
         AtomicInteger i = new AtomicInteger();
         unloadLock.lock();
         BurstExecutor burst = null;
-        try {
-            KList<Long> copy = toUnload.copy();
-            if (!disableClear) toUnload.clear();
-            burst = MultiBurst.burst.burst(copy.size());
-            burst.setMulticore(copy.size() > tectonicLimit);
-            for (int j = 0; j < copy.size(); j++) {
-                Long id = copy.get(j);
-                if (id == null) {
-                    Iris.error("Null id in unloadTectonicPlate at index " + j);
-                    continue;
-                }
+        if (IrisEngineSVC.instance != null) {
+            try {
+                KList<Long> copy = toUnload.copy();
+                if (!disableClear) toUnload.clear();
+                burst = MultiBurst.burst.burst(copy.size());
+                burst.setMulticore(copy.size() > tectonicLimit);
+                for (int j = 0; j < copy.size(); j++) {
+                    Long id = copy.get(j);
+                    if (id == null) {
+                        Iris.error("Null id in unloadTectonicPlate at index " + j);
+                        continue;
+                    }
 
-                burst.queue(() ->
-                        hyperLock.withLong(id, () -> {
-                            TectonicPlate m = loadedRegions.get(id);
-                            if (m != null) {
-                                if (m.inUse()) {
-                                    Iris.debug("Tectonic Plate was added to unload while in use " + C.DARK_GREEN + m.getX() + " " + m.getZ());
-                                    if (disableClear) toUnload.remove(id);
-                                    lastUse.put(id, M.ms());
-                                    return;
+                    burst.queue(() ->
+                            hyperLock.withLong(id, () -> {
+                                TectonicPlate m = loadedRegions.get(id);
+                                if (m != null) {
+                                    if (m.inUse()) {
+                                        Iris.debug("Tectonic Plate was added to unload while in use " + C.DARK_GREEN + m.getX() + " " + m.getZ());
+                                        if (disableClear) toUnload.remove(id);
+                                        lastUse.put(id, M.ms());
+                                        return;
+                                    }
+                                    try {
+                                        m.write(fileForRegion(dataFolder, id));
+                                        loadedRegions.remove(id);
+                                        lastUse.remove(id);
+                                        if (disableClear) toUnload.remove(id);
+                                        i.incrementAndGet();
+                                        Iris.debug("Unloaded Tectonic Plate " + C.DARK_GREEN + Cache.keyX(id) + " " + Cache.keyZ(id));
+                                        IrisEngineSVC.instance.unloadActiveAlive.reset();
+                                    } catch (IOException e) {
+                                        Iris.reportError(e);
+                                    }
                                 }
-                                try {
-                                    m.write(fileForRegion(dataFolder, id));
-                                    loadedRegions.remove(id);
-                                    lastUse.remove(id);
-                                    if (disableClear) toUnload.remove(id);
-                                    i.incrementAndGet();
-                                    Iris.debug("Unloaded Tectonic Plate " + C.DARK_GREEN + Cache.keyX(id) + " " + Cache.keyZ(id));
-                                } catch (IOException e) {
-                                    Iris.reportError(e);
-                                }
-                            }
-                        }));
-            }
-            burst.complete();
-        } catch (Throwable e) {
-            e.printStackTrace();
-            if (burst != null)
+                            }));
+                }
                 burst.complete();
-        } finally {
-            unloadLock.unlock();
-            ioTectonicUnload.set(true);
+            } catch (Throwable e) {
+                e.printStackTrace();
+                if (burst != null)
+                    burst.complete();
+            } finally {
+                unloadLock.unlock();
+                ioTectonicUnload.set(true);
+            }
+            return i.get();
         }
         return i.get();
     }

core/src/main/java/com/volmit/iris/util/math/BlockPosition.java

@@ -19,14 +19,11 @@
 package com.volmit.iris.util.math;
 
 import lombok.Data;
-import org.bukkit.Location;
 import org.bukkit.World;
 import org.bukkit.block.Block;
 
 import java.util.Objects;
 
-import static com.volmit.iris.util.math.RNG.r;
-
 @Data
 public class BlockPosition {
     //Magic numbers
@@ -46,10 +43,6 @@ public class BlockPosition {
         this.z = z;
     }
 
-    public static BlockPosition fromLocation(Location loc) {
-        return new BlockPosition(loc.getBlockX(), loc.getBlockY(), loc.getBlockZ());
-    }
-
     public static long toLong(int x, int y, int z) {
         long var3 = 0L;
         var3 |= (x & m4) << m3;
@@ -115,18 +108,4 @@ public class BlockPosition {
         setY(Math.max(i.getY(), getY()));
         setZ(Math.max(i.getZ(), getZ()));
     }
-
-    public BlockPosition randomPoint(int radius, int innerRadius) {
-        int max = radius * radius;
-        int min = innerRadius * innerRadius;
-
-        while (true) {
-            int x = r.nextInt(-radius, radius + 1);
-            int y = r.nextInt(-radius, radius + 1);
-            int z = r.nextInt(-radius, radius + 1);
-            double dist = x * x + y * y + z * z;
-            if (dist < min || dist > max) continue;
-            return add(x, y, z);
-        }
-    }
 }

core/src/main/java/com/volmit/iris/util/math/Position2.java

@@ -21,6 +21,8 @@ package com.volmit.iris.util.math;
 import com.volmit.iris.engine.object.IrisPosition;
 import org.bukkit.util.Vector;
 
+import java.util.function.BiFunction;
+
 public class Position2 {
     private int x;
     private int z;
@@ -94,4 +96,8 @@ public class Position2 {
     public IrisPosition toIris() {
         return new IrisPosition(x, 23, z);
     }
+
+    public <T> T convert(BiFunction<Integer, Integer, T> constructor) {
+        return constructor.apply(x, z);
+    }
 }

core/src/main/java/com/volmit/iris/util/parallel/Sync.java

@@ -1,20 +0,0 @@
-package com.volmit.iris.util.parallel;
-
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.atomic.AtomicReference;
-
-public class Sync<T> {
-    private final AtomicReference<CompletableFuture<T>> tick = new AtomicReference<>(new CompletableFuture<>());
-
-    public void cancel(boolean mayInterruptIfRunning) {
-        tick.getAndSet(new CompletableFuture<>()).cancel(mayInterruptIfRunning);
-    }
-
-    public CompletableFuture<T> next() {
-        return tick.get();
-    }
-
-    public void advance(T value) {
-        tick.getAndSet(new CompletableFuture<>()).complete(value);
-    }
-}

nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/NMSBinding.java

@@ -7,6 +7,8 @@ import com.volmit.iris.Iris;
 import com.volmit.iris.core.nms.INMSBinding;
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_20_R1.headless.RegionStorage;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.util.collection.KList;
@@ -645,44 +647,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public com.volmit.iris.core.nms.container.Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.registryOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                        old.resources(),
+                        old.dataConfiguration(),
+                        old.datapackWorldgen(),
+                        createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().registryOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new com.volmit.iris.core.nms.container.Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -694,9 +694,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().K.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -720,7 +742,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.registryOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/headless/DirectTerrainChunk.java

@@ -0,0 +1,215 @@
+package com.volmit.iris.core.nms.v1_20_R1.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Registry;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_20_R1.block.CraftBlock;
+import org.bukkit.craftbukkit.v1_20_R1.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_20_R1.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+import static com.volmit.iris.core.nms.v1_20_R1.headless.RegionStorage.registryAccess;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+    private final Registry<net.minecraft.world.level.biome.Biome> biomes;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinBuildHeight();
+        this.maxHeight = access.getMaxBuildHeight();
+        this.biomes = registryAccess().registryOrThrow(net.minecraft.core.registries.Registries.BIOME);
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBlock.biomeBaseToBiome(biomes, access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBlock.biomeToBiomeBase(biomes, bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/headless/Region.java

@@ -0,0 +1,72 @@
+package com.volmit.iris.core.nms.v1_20_R1.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_20_R1/src/main/java/com/volmit/iris/core/nms/v1_20_R1/headless/RegionStorage.java

@@ -0,0 +1,312 @@
+package com.volmit.iris.core.nms.v1_20_R1.headless;
+
+import com.mojang.logging.LogUtils;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.*;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.Biomes;
+import net.minecraft.world.level.chunk.*;
+import net.minecraft.world.level.levelgen.BelowZeroRetrogen;
+import net.minecraft.world.level.levelgen.GenerationStep;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_20_R1.CraftServer;
+import org.bukkit.craftbukkit.v1_20_R1.block.CraftBlock;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.BLOCK_STATE_CODEC;
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.packOffsets;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minBuildHeight;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minBuildHeight = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minBuildHeight;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        Registry<Biome> registry = registryAccess().registryOrThrow(Registries.BIOME);
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .filter(biome -> biome != org.bukkit.block.Biome.CUSTOM)
+                .collect(Collectors.toMap(Function.identity(), b -> CraftBlock.biomeToBiomeBase(registry, b))));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().registryOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().registryOrThrow(Registries.BIOME).getHolder(ResourceKey.create(Registries.BIOME, new ResourceLocation(namespace, path)));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        ChunkPos chunkPos = chunk.getPos();
+        CompoundTag tag = NbtUtils.addCurrentDataVersion(new CompoundTag());
+        tag.putInt("xPos", chunkPos.x);
+        tag.putInt("yPos", chunk.getMinSection());
+        tag.putInt("zPos", chunkPos.z);
+        tag.putLong("LastUpdate", 0);
+        tag.putLong("InhabitedTime", chunk.getInhabitedTime());
+        tag.putString("Status", BuiltInRegistries.CHUNK_STATUS.getKey(chunk.getStatus()).toString());
+        BlendingData blendingdata = chunk.getBlendingData();
+        if (blendingdata != null) {
+            DataResult<Tag> dataresult = BlendingData.CODEC.encodeStart(NbtOps.INSTANCE, blendingdata);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("blending_data", nbt));
+        }
+
+        BelowZeroRetrogen retrogen = chunk.getBelowZeroRetrogen();
+        if (retrogen != null) {
+            DataResult<Tag> dataresult = BelowZeroRetrogen.CODEC.encodeStart(NbtOps.INSTANCE, retrogen);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("below_zero_retrogen", nbt));
+        }
+
+        UpgradeData upgradeData = chunk.getUpgradeData();
+        if (!upgradeData.isEmpty()) {
+            tag.put("UpgradeData", upgradeData.write());
+        }
+
+        LevelChunkSection[] sections = chunk.getSections();
+        ListTag sectionsTag = new ListTag();
+        Registry<Biome> biomeRegistry = registryAccess().registryOrThrow(Registries.BIOME);
+        Codec<PalettedContainerRO<Holder<Biome>>> codec = PalettedContainer.codecRO(biomeRegistry.asHolderIdMap(), biomeRegistry.holderByNameCodec(), PalettedContainer.Strategy.SECTION_BIOMES, biomeRegistry.getHolderOrThrow(Biomes.PLAINS));
+        boolean flag = chunk.isLightCorrect();
+
+        int minLightSection = chunk.getMinSection() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int j = chunk.getSectionIndexFromSectionY(y);
+            if (j < 0 || j >= sections.length)
+                continue;
+            CompoundTag sectionTag = new CompoundTag();
+            LevelChunkSection section = sections[j];
+            sectionTag.put("block_states", BLOCK_STATE_CODEC.encodeStart(NbtOps.INSTANCE, section.getStates()).getOrThrow(false, LogUtils.getLogger()::error));
+            sectionTag.put("biomes", codec.encodeStart(NbtOps.INSTANCE, section.getBiomes()).getOrThrow(false, LogUtils.getLogger()::error));
+
+            if (!sectionTag.isEmpty()) {
+                sectionTag.putByte("Y", (byte) y);
+                sectionsTag.add(sectionTag);
+            }
+        }
+
+        tag.put("sections", sectionsTag);
+        if (flag) {
+            tag.putBoolean("isLightOn", true);
+        }
+
+        ListTag blockEntities = new ListTag();
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag entityNbt = chunk.getBlockEntityNbtForSaving(blockPos);
+            if (entityNbt != null) {
+                blockEntities.add(entityNbt);
+            }
+        }
+
+        tag.put("block_entities", blockEntities);
+        if (chunk.getStatus().getChunkType() == ChunkStatus.ChunkType.PROTOCHUNK) {
+            ProtoChunk protochunk = (ProtoChunk)chunk;
+            ListTag entities = new ListTag();
+            entities.addAll(protochunk.getEntities());
+            tag.put("entities", entities);
+            CompoundTag carvingMasks = new CompoundTag();
+
+            for(GenerationStep.Carving carving : GenerationStep.Carving.values()) {
+                CarvingMask mask = protochunk.getCarvingMask(carving);
+                if (mask != null) {
+                    carvingMasks.putLongArray(carving.toString(), mask.toArray());
+                }
+            }
+
+            tag.put("CarvingMasks", carvingMasks);
+        }
+
+        saveTicks(tag, chunk.getTicksForSerialization());
+        tag.put("PostProcessing", packOffsets(chunk.getPostProcessing()));
+        CompoundTag heightMaps = new CompoundTag();
+
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMaps.put(entry.getKey().getSerializationKey(), new LongArrayTag(entry.getValue().getRawData()));
+            }
+        }
+
+        tag.put("Heightmaps", heightMaps);
+
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+        tag.put("structures", structureData);
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            tag.put("ChunkBukkitValues", chunk.persistentDataContainer.toTagCompound());
+        }
+
+        return tag;
+    }
+
+    private static void saveTicks(CompoundTag tag, ChunkAccess.TicksToSave ticks) {
+        tag.put("block_ticks", ticks.blocks().save(0, (block) -> BuiltInRegistries.BLOCK.getKey(block).toString()));
+        tag.put("fluid_ticks", ticks.fluids().save(0, (fluid) -> BuiltInRegistries.FLUID.getKey(fluid).toString()));
+    }
+}

nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/NMSBinding.java

@@ -17,6 +17,8 @@ import com.mojang.datafixers.util.Pair;
 import com.mojang.serialization.Lifecycle;
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_20_R2.headless.RegionStorage;
 import com.volmit.iris.util.scheduling.J;
 import lombok.SneakyThrows;
 import net.minecraft.core.*;
@@ -646,44 +648,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public com.volmit.iris.core.nms.container.Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.registryOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                        old.resources(),
+                        old.dataConfiguration(),
+                        old.datapackWorldgen(),
+                        createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().registryOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new com.volmit.iris.core.nms.container.Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -695,9 +695,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().K.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -721,7 +743,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.registryOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/headless/DirectTerrainChunk.java

@@ -0,0 +1,210 @@
+package com.volmit.iris.core.nms.v1_20_R2.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_20_R2.block.CraftBiome;
+import org.bukkit.craftbukkit.v1_20_R2.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_20_R2.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinBuildHeight();
+        this.maxHeight = access.getMaxBuildHeight();
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBiome.minecraftHolderToBukkit(access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBiome.bukkitToMinecraftHolder(bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/headless/Region.java

@@ -0,0 +1,72 @@
+package com.volmit.iris.core.nms.v1_20_R2.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_20_R2/src/main/java/com/volmit/iris/core/nms/v1_20_R2/headless/RegionStorage.java

@@ -0,0 +1,311 @@
+package com.volmit.iris.core.nms.v1_20_R2.headless;
+
+import com.mojang.logging.LogUtils;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.*;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.Biomes;
+import net.minecraft.world.level.chunk.*;
+import net.minecraft.world.level.levelgen.BelowZeroRetrogen;
+import net.minecraft.world.level.levelgen.GenerationStep;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_20_R2.CraftServer;
+import org.bukkit.craftbukkit.v1_20_R2.block.CraftBiome;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.BLOCK_STATE_CODEC;
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.packOffsets;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minBuildHeight;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minBuildHeight = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minBuildHeight;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .filter(biome -> biome != org.bukkit.block.Biome.CUSTOM)
+                .collect(Collectors.toMap(Function.identity(), CraftBiome::bukkitToMinecraftHolder)));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().registryOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    private static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().registryOrThrow(Registries.BIOME).getHolder(ResourceKey.create(Registries.BIOME, new ResourceLocation(namespace, path)));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        ChunkPos chunkPos = chunk.getPos();
+        CompoundTag tag = NbtUtils.addCurrentDataVersion(new CompoundTag());
+        tag.putInt("xPos", chunkPos.x);
+        tag.putInt("yPos", chunk.getMinSection());
+        tag.putInt("zPos", chunkPos.z);
+        tag.putLong("LastUpdate", 0);
+        tag.putLong("InhabitedTime", chunk.getInhabitedTime());
+        tag.putString("Status", BuiltInRegistries.CHUNK_STATUS.getKey(chunk.getStatus()).toString());
+        BlendingData blendingdata = chunk.getBlendingData();
+        if (blendingdata != null) {
+            DataResult<Tag> dataresult = BlendingData.CODEC.encodeStart(NbtOps.INSTANCE, blendingdata);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("blending_data", nbt));
+        }
+
+        BelowZeroRetrogen retrogen = chunk.getBelowZeroRetrogen();
+        if (retrogen != null) {
+            DataResult<Tag> dataresult = BelowZeroRetrogen.CODEC.encodeStart(NbtOps.INSTANCE, retrogen);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("below_zero_retrogen", nbt));
+        }
+
+        UpgradeData upgradeData = chunk.getUpgradeData();
+        if (!upgradeData.isEmpty()) {
+            tag.put("UpgradeData", upgradeData.write());
+        }
+
+        LevelChunkSection[] sections = chunk.getSections();
+        ListTag sectionsTag = new ListTag();
+        Registry<Biome> biomeRegistry = registryAccess().registryOrThrow(Registries.BIOME);
+        Codec<PalettedContainerRO<Holder<Biome>>> codec = PalettedContainer.codecRO(biomeRegistry.asHolderIdMap(), biomeRegistry.holderByNameCodec(), PalettedContainer.Strategy.SECTION_BIOMES, biomeRegistry.getHolderOrThrow(Biomes.PLAINS));
+        boolean flag = chunk.isLightCorrect();
+
+        int minLightSection = chunk.getMinSection() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int j = chunk.getSectionIndexFromSectionY(y);
+            if (j < 0 || j >= sections.length)
+                continue;
+            CompoundTag sectionTag = new CompoundTag();
+            LevelChunkSection section = sections[j];
+            sectionTag.put("block_states", BLOCK_STATE_CODEC.encodeStart(NbtOps.INSTANCE, section.getStates()).getOrThrow(false, LogUtils.getLogger()::error));
+            sectionTag.put("biomes", codec.encodeStart(NbtOps.INSTANCE, section.getBiomes()).getOrThrow(false, LogUtils.getLogger()::error));
+
+            if (!sectionTag.isEmpty()) {
+                sectionTag.putByte("Y", (byte) y);
+                sectionsTag.add(sectionTag);
+            }
+        }
+
+        tag.put("sections", sectionsTag);
+        if (flag) {
+            tag.putBoolean("isLightOn", true);
+        }
+
+        ListTag blockEntities = new ListTag();
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag entityNbt = chunk.getBlockEntityNbtForSaving(blockPos);
+            if (entityNbt != null) {
+                blockEntities.add(entityNbt);
+            }
+        }
+
+        tag.put("block_entities", blockEntities);
+        if (chunk.getStatus().getChunkType() == ChunkStatus.ChunkType.PROTOCHUNK) {
+            ProtoChunk protochunk = (ProtoChunk)chunk;
+            ListTag entities = new ListTag();
+            entities.addAll(protochunk.getEntities());
+            tag.put("entities", entities);
+            CompoundTag carvingMasks = new CompoundTag();
+
+            for(GenerationStep.Carving carving : GenerationStep.Carving.values()) {
+                CarvingMask mask = protochunk.getCarvingMask(carving);
+                if (mask != null) {
+                    carvingMasks.putLongArray(carving.toString(), mask.toArray());
+                }
+            }
+
+            tag.put("CarvingMasks", carvingMasks);
+        }
+
+        saveTicks(tag, chunk.getTicksForSerialization());
+        tag.put("PostProcessing", packOffsets(chunk.getPostProcessing()));
+        CompoundTag heightMaps = new CompoundTag();
+
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMaps.put(entry.getKey().getSerializationKey(), new LongArrayTag(entry.getValue().getRawData()));
+            }
+        }
+
+        tag.put("Heightmaps", heightMaps);
+
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+        tag.put("structures", structureData);
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            tag.put("ChunkBukkitValues", chunk.persistentDataContainer.toTagCompound());
+        }
+
+        return tag;
+    }
+
+    private static void saveTicks(CompoundTag tag, ChunkAccess.TicksToSave ticks) {
+        tag.put("block_ticks", ticks.blocks().save(0, (block) -> BuiltInRegistries.BLOCK.getKey(block).toString()));
+        tag.put("fluid_ticks", ticks.fluids().save(0, (fluid) -> BuiltInRegistries.FLUID.getKey(fluid).toString()));
+    }
+}

nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/NMSBinding.java

@@ -17,6 +17,8 @@ import com.mojang.datafixers.util.Pair;
 import com.mojang.serialization.Lifecycle;
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_20_R3.headless.RegionStorage;
 import com.volmit.iris.util.scheduling.J;
 import lombok.SneakyThrows;
 import net.minecraft.core.*;
@@ -647,44 +649,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public com.volmit.iris.core.nms.container.Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.registryOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                        old.resources(),
+                        old.dataConfiguration(),
+                        old.datapackWorldgen(),
+                        createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().registryOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new com.volmit.iris.core.nms.container.Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -696,9 +696,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().K.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -722,7 +744,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.registryOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/headless/DirectTerrainChunk.java

@@ -0,0 +1,211 @@
+package com.volmit.iris.core.nms.v1_20_R3.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ChunkStatus;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_20_R3.block.CraftBiome;
+import org.bukkit.craftbukkit.v1_20_R3.block.CraftBlockType;
+import org.bukkit.craftbukkit.v1_20_R3.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_20_R3.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinBuildHeight();
+        this.maxHeight = access.getMaxBuildHeight();
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBiome.minecraftHolderToBukkit(access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBiome.bukkitToMinecraftHolder(bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftBlockType.minecraftToBukkit(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/headless/Region.java

@@ -0,0 +1,72 @@
+package com.volmit.iris.core.nms.v1_20_R3.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_20_R3/src/main/java/com/volmit/iris/core/nms/v1_20_R3/headless/RegionStorage.java

@@ -0,0 +1,311 @@
+package com.volmit.iris.core.nms.v1_20_R3.headless;
+
+import com.mojang.logging.LogUtils;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.*;
+import net.minecraft.resources.ResourceKey;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.Biomes;
+import net.minecraft.world.level.chunk.*;
+import net.minecraft.world.level.levelgen.BelowZeroRetrogen;
+import net.minecraft.world.level.levelgen.GenerationStep;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_20_R3.CraftServer;
+import org.bukkit.craftbukkit.v1_20_R3.block.CraftBiome;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.BLOCK_STATE_CODEC;
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.packOffsets;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minBuildHeight;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minBuildHeight = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minBuildHeight;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .filter(biome -> biome != org.bukkit.block.Biome.CUSTOM)
+                .collect(Collectors.toMap(Function.identity(), CraftBiome::bukkitToMinecraftHolder)));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().registryOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    private static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().registryOrThrow(Registries.BIOME).getHolder(ResourceKey.create(Registries.BIOME, new ResourceLocation(namespace, path)));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        ChunkPos chunkPos = chunk.getPos();
+        CompoundTag tag = NbtUtils.addCurrentDataVersion(new CompoundTag());
+        tag.putInt("xPos", chunkPos.x);
+        tag.putInt("yPos", chunk.getMinSection());
+        tag.putInt("zPos", chunkPos.z);
+        tag.putLong("LastUpdate", 0);
+        tag.putLong("InhabitedTime", chunk.getInhabitedTime());
+        tag.putString("Status", BuiltInRegistries.CHUNK_STATUS.getKey(chunk.getStatus()).toString());
+        BlendingData blendingdata = chunk.getBlendingData();
+        if (blendingdata != null) {
+            DataResult<Tag> dataresult = BlendingData.CODEC.encodeStart(NbtOps.INSTANCE, blendingdata);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("blending_data", nbt));
+        }
+
+        BelowZeroRetrogen retrogen = chunk.getBelowZeroRetrogen();
+        if (retrogen != null) {
+            DataResult<Tag> dataresult = BelowZeroRetrogen.CODEC.encodeStart(NbtOps.INSTANCE, retrogen);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("below_zero_retrogen", nbt));
+        }
+
+        UpgradeData upgradeData = chunk.getUpgradeData();
+        if (!upgradeData.isEmpty()) {
+            tag.put("UpgradeData", upgradeData.write());
+        }
+
+        LevelChunkSection[] sections = chunk.getSections();
+        ListTag sectionsTag = new ListTag();
+        Registry<Biome> biomeRegistry = registryAccess().registryOrThrow(Registries.BIOME);
+        Codec<PalettedContainerRO<Holder<Biome>>> codec = PalettedContainer.codecRO(biomeRegistry.asHolderIdMap(), biomeRegistry.holderByNameCodec(), PalettedContainer.Strategy.SECTION_BIOMES, biomeRegistry.getHolderOrThrow(Biomes.PLAINS));
+        boolean flag = chunk.isLightCorrect();
+
+        int minLightSection = chunk.getMinSection() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int j = chunk.getSectionIndexFromSectionY(y);
+            if (j < 0 || j >= sections.length)
+                continue;
+            CompoundTag sectionTag = new CompoundTag();
+            LevelChunkSection section = sections[j];
+            sectionTag.put("block_states", BLOCK_STATE_CODEC.encodeStart(NbtOps.INSTANCE, section.getStates()).getOrThrow(false, LogUtils.getLogger()::error));
+            sectionTag.put("biomes", codec.encodeStart(NbtOps.INSTANCE, section.getBiomes()).getOrThrow(false, LogUtils.getLogger()::error));
+
+            if (!sectionTag.isEmpty()) {
+                sectionTag.putByte("Y", (byte) y);
+                sectionsTag.add(sectionTag);
+            }
+        }
+
+        tag.put("sections", sectionsTag);
+        if (flag) {
+            tag.putBoolean("isLightOn", true);
+        }
+
+        ListTag blockEntities = new ListTag();
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag entityNbt = chunk.getBlockEntityNbtForSaving(blockPos);
+            if (entityNbt != null) {
+                blockEntities.add(entityNbt);
+            }
+        }
+
+        tag.put("block_entities", blockEntities);
+        if (chunk.getStatus().getChunkType() == ChunkStatus.ChunkType.PROTOCHUNK) {
+            ProtoChunk protochunk = (ProtoChunk)chunk;
+            ListTag entities = new ListTag();
+            entities.addAll(protochunk.getEntities());
+            tag.put("entities", entities);
+            CompoundTag carvingMasks = new CompoundTag();
+
+            for(GenerationStep.Carving carving : GenerationStep.Carving.values()) {
+                CarvingMask mask = protochunk.getCarvingMask(carving);
+                if (mask != null) {
+                    carvingMasks.putLongArray(carving.toString(), mask.toArray());
+                }
+            }
+
+            tag.put("CarvingMasks", carvingMasks);
+        }
+
+        saveTicks(tag, chunk.getTicksForSerialization());
+        tag.put("PostProcessing", packOffsets(chunk.getPostProcessing()));
+        CompoundTag heightMaps = new CompoundTag();
+
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMaps.put(entry.getKey().getSerializationKey(), new LongArrayTag(entry.getValue().getRawData()));
+            }
+        }
+
+        tag.put("Heightmaps", heightMaps);
+
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+        tag.put("structures", structureData);
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            tag.put("ChunkBukkitValues", chunk.persistentDataContainer.toTagCompound());
+        }
+
+        return tag;
+    }
+
+    private static void saveTicks(CompoundTag tag, ChunkAccess.TicksToSave ticks) {
+        tag.put("block_ticks", ticks.blocks().save(0, (block) -> BuiltInRegistries.BLOCK.getKey(block).toString()));
+        tag.put("fluid_ticks", ticks.fluids().save(0, (fluid) -> BuiltInRegistries.FLUID.getKey(fluid).toString()));
+    }
+}

nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/NMSBinding.java

@@ -14,6 +14,8 @@ import com.mojang.serialization.Lifecycle;
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_20_R4.headless.RegionStorage;
 import com.volmit.iris.util.nbt.tag.CompoundTag;
 import com.volmit.iris.util.scheduling.J;
 import lombok.SneakyThrows;
@@ -672,44 +674,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public com.volmit.iris.core.nms.container.Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.registryOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                        old.resources(),
+                        old.dataConfiguration(),
+                        old.datapackWorldgen(),
+                        createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().registryOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new com.volmit.iris.core.nms.container.Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -721,9 +721,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().K.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -747,7 +769,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.registryOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/headless/DirectTerrainChunk.java

@@ -0,0 +1,211 @@
+package com.volmit.iris.core.nms.v1_20_R4.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_20_R4.block.CraftBiome;
+import org.bukkit.craftbukkit.v1_20_R4.block.CraftBlockType;
+import org.bukkit.craftbukkit.v1_20_R4.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_20_R4.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinBuildHeight();
+        this.maxHeight = access.getMaxBuildHeight();
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBiome.minecraftHolderToBukkit(access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBiome.bukkitToMinecraftHolder(bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftBlockType.minecraftToBukkit(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/headless/Region.java

@@ -0,0 +1,75 @@
+package com.volmit.iris.core.nms.v1_20_R4.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+import net.minecraft.world.level.chunk.storage.RegionStorageInfo;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private static final RegionStorageInfo info = new RegionStorageInfo("headless", Level.OVERWORLD, "headless");
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(info, path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_20_R4/src/main/java/com/volmit/iris/core/nms/v1_20_R4/headless/RegionStorage.java

@@ -0,0 +1,311 @@
+package com.volmit.iris.core.nms.v1_20_R4.headless;
+
+import com.mojang.logging.LogUtils;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.*;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.Biomes;
+import net.minecraft.world.level.chunk.*;
+import net.minecraft.world.level.chunk.status.ChunkType;
+import net.minecraft.world.level.levelgen.BelowZeroRetrogen;
+import net.minecraft.world.level.levelgen.GenerationStep;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_20_R4.CraftServer;
+import org.bukkit.craftbukkit.v1_20_R4.block.CraftBiome;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.BLOCK_STATE_CODEC;
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.packOffsets;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minBuildHeight;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minBuildHeight = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minBuildHeight;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .filter(biome -> biome != org.bukkit.block.Biome.CUSTOM)
+                .collect(Collectors.toMap(Function.identity(), CraftBiome::bukkitToMinecraftHolder)));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().registryOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    private static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().registryOrThrow(Registries.BIOME).getHolder(new ResourceLocation(namespace, path));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        ChunkPos chunkPos = chunk.getPos();
+        CompoundTag tag = NbtUtils.addCurrentDataVersion(new CompoundTag());
+        tag.putInt("xPos", chunkPos.x);
+        tag.putInt("yPos", chunk.getMinSection());
+        tag.putInt("zPos", chunkPos.z);
+        tag.putLong("LastUpdate", 0);
+        tag.putLong("InhabitedTime", chunk.getInhabitedTime());
+        tag.putString("Status", BuiltInRegistries.CHUNK_STATUS.getKey(chunk.getStatus()).toString());
+        BlendingData blendingdata = chunk.getBlendingData();
+        if (blendingdata != null) {
+            DataResult<Tag> dataresult = BlendingData.CODEC.encodeStart(NbtOps.INSTANCE, blendingdata);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("blending_data", nbt));
+        }
+
+        BelowZeroRetrogen retrogen = chunk.getBelowZeroRetrogen();
+        if (retrogen != null) {
+            DataResult<Tag> dataresult = BelowZeroRetrogen.CODEC.encodeStart(NbtOps.INSTANCE, retrogen);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("below_zero_retrogen", nbt));
+        }
+
+        UpgradeData upgradeData = chunk.getUpgradeData();
+        if (!upgradeData.isEmpty()) {
+            tag.put("UpgradeData", upgradeData.write());
+        }
+
+        LevelChunkSection[] sections = chunk.getSections();
+        ListTag sectionsTag = new ListTag();
+        Registry<Biome> biomeRegistry = registryAccess().registryOrThrow(Registries.BIOME);
+        Codec<PalettedContainerRO<Holder<Biome>>> codec = PalettedContainer.codecRO(biomeRegistry.asHolderIdMap(), biomeRegistry.holderByNameCodec(), PalettedContainer.Strategy.SECTION_BIOMES, biomeRegistry.getHolderOrThrow(Biomes.PLAINS));
+        boolean flag = chunk.isLightCorrect();
+
+        int minLightSection = chunk.getMinSection() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int j = chunk.getSectionIndexFromSectionY(y);
+            if (j < 0 || j >= sections.length)
+                continue;
+            CompoundTag sectionTag = new CompoundTag();
+            LevelChunkSection section = sections[j];
+            sectionTag.put("block_states", BLOCK_STATE_CODEC.encodeStart(NbtOps.INSTANCE, section.getStates()).getOrThrow());
+            sectionTag.put("biomes", codec.encodeStart(NbtOps.INSTANCE, section.getBiomes()).getOrThrow());
+
+            if (!sectionTag.isEmpty()) {
+                sectionTag.putByte("Y", (byte) y);
+                sectionsTag.add(sectionTag);
+            }
+        }
+
+        tag.put("sections", sectionsTag);
+        if (flag) {
+            tag.putBoolean("isLightOn", true);
+        }
+
+        ListTag blockEntities = new ListTag();
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag entityNbt = chunk.getBlockEntityNbtForSaving(blockPos, registryAccess());
+            if (entityNbt != null) {
+                blockEntities.add(entityNbt);
+            }
+        }
+
+        tag.put("block_entities", blockEntities);
+        if (chunk.getStatus().getChunkType() == ChunkType.PROTOCHUNK) {
+            ProtoChunk protochunk = (ProtoChunk)chunk;
+            ListTag entities = new ListTag();
+            entities.addAll(protochunk.getEntities());
+            tag.put("entities", entities);
+            CompoundTag carvingMasks = new CompoundTag();
+
+            for(GenerationStep.Carving carving : GenerationStep.Carving.values()) {
+                CarvingMask mask = protochunk.getCarvingMask(carving);
+                if (mask != null) {
+                    carvingMasks.putLongArray(carving.toString(), mask.toArray());
+                }
+            }
+
+            tag.put("CarvingMasks", carvingMasks);
+        }
+
+        saveTicks(tag, chunk.getTicksForSerialization());
+        tag.put("PostProcessing", packOffsets(chunk.getPostProcessing()));
+        CompoundTag heightMaps = new CompoundTag();
+
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMaps.put(entry.getKey().getSerializationKey(), new LongArrayTag(entry.getValue().getRawData()));
+            }
+        }
+
+        tag.put("Heightmaps", heightMaps);
+
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+        tag.put("structures", structureData);
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            tag.put("ChunkBukkitValues", chunk.persistentDataContainer.toTagCompound());
+        }
+
+        return tag;
+    }
+
+    private static void saveTicks(CompoundTag tag, ChunkAccess.TicksToSave ticks) {
+        tag.put("block_ticks", ticks.blocks().save(0, (block) -> BuiltInRegistries.BLOCK.getKey(block).toString()));
+        tag.put("fluid_ticks", ticks.fluids().save(0, (fluid) -> BuiltInRegistries.FLUID.getKey(fluid).toString()));
+    }
+}

nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/NMSBinding.java

@@ -18,6 +18,8 @@ import com.mojang.serialization.Lifecycle;
 import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_21_R1.headless.RegionStorage;
 import com.volmit.iris.util.scheduling.J;
 import lombok.SneakyThrows;
 import net.minecraft.core.*;
@@ -676,44 +678,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public com.volmit.iris.core.nms.container.Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.registryOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                        old.resources(),
+                        old.dataConfiguration(),
+                        old.datapackWorldgen(),
+                        createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().registryOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new com.volmit.iris.core.nms.container.Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -725,9 +725,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().K.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -751,7 +773,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.registryOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/headless/DirectTerrainChunk.java

@@ -0,0 +1,211 @@
+package com.volmit.iris.core.nms.v1_21_R1.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_21_R1.block.CraftBiome;
+import org.bukkit.craftbukkit.v1_21_R1.block.CraftBlockType;
+import org.bukkit.craftbukkit.v1_21_R1.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_21_R1.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinBuildHeight();
+        this.maxHeight = access.getMaxBuildHeight();
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBiome.minecraftHolderToBukkit(access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBiome.bukkitToMinecraftHolder(bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftBlockType.minecraftToBukkit(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setPersistedStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/headless/Region.java

@@ -0,0 +1,75 @@
+package com.volmit.iris.core.nms.v1_21_R1.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+import net.minecraft.world.level.chunk.storage.RegionStorageInfo;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private static final RegionStorageInfo info = new RegionStorageInfo("headless", Level.OVERWORLD, "headless");
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(info, path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_21_R1/src/main/java/com/volmit/iris/core/nms/v1_21_R1/headless/RegionStorage.java

@@ -0,0 +1,307 @@
+package com.volmit.iris.core.nms.v1_21_R1.headless;
+
+import com.mojang.logging.LogUtils;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.DataResult;
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.core.*;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.*;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.biome.Biomes;
+import net.minecraft.world.level.chunk.*;
+import net.minecraft.world.level.chunk.status.ChunkType;
+import net.minecraft.world.level.levelgen.BelowZeroRetrogen;
+import net.minecraft.world.level.levelgen.GenerationStep;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_21_R1.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R1.block.CraftBiome;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.BLOCK_STATE_CODEC;
+import static net.minecraft.world.level.chunk.storage.ChunkSerializer.packOffsets;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minBuildHeight;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minBuildHeight = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minBuildHeight;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .filter(biome -> biome != org.bukkit.block.Biome.CUSTOM)
+                .collect(Collectors.toMap(Function.identity(), CraftBiome::bukkitToMinecraftHolder)));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().registryOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    private static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().registryOrThrow(Registries.BIOME).getHolder(ResourceLocation.fromNamespaceAndPath(namespace, path));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        ChunkPos chunkPos = chunk.getPos();
+        CompoundTag tag = NbtUtils.addCurrentDataVersion(new CompoundTag());
+        tag.putInt("xPos", chunkPos.x);
+        tag.putInt("yPos", chunk.getMinSection());
+        tag.putInt("zPos", chunkPos.z);
+        tag.putLong("LastUpdate", 0);
+        tag.putLong("InhabitedTime", chunk.getInhabitedTime());
+        tag.putString("Status", BuiltInRegistries.CHUNK_STATUS.getKey(chunk.getPersistedStatus()).toString());
+        BlendingData blendingdata = chunk.getBlendingData();
+        if (blendingdata != null) {
+            DataResult<Tag> dataresult = BlendingData.CODEC.encodeStart(NbtOps.INSTANCE, blendingdata);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("blending_data", nbt));
+        }
+
+        BelowZeroRetrogen retrogen = chunk.getBelowZeroRetrogen();
+        if (retrogen != null) {
+            DataResult<Tag> dataresult = BelowZeroRetrogen.CODEC.encodeStart(NbtOps.INSTANCE, retrogen);
+            dataresult.resultOrPartial(LogUtils.getLogger()::error).ifPresent((nbt) -> tag.put("below_zero_retrogen", nbt));
+        }
+
+        UpgradeData upgradeData = chunk.getUpgradeData();
+        if (!upgradeData.isEmpty()) {
+            tag.put("UpgradeData", upgradeData.write());
+        }
+
+        LevelChunkSection[] sections = chunk.getSections();
+        ListTag sectionsTag = new ListTag();
+        Registry<Biome> biomeRegistry = registryAccess().registryOrThrow(Registries.BIOME);
+        Codec<PalettedContainerRO<Holder<Biome>>> codec = PalettedContainer.codecRO(biomeRegistry.asHolderIdMap(), biomeRegistry.holderByNameCodec(), PalettedContainer.Strategy.SECTION_BIOMES, biomeRegistry.getHolderOrThrow(Biomes.PLAINS));
+        boolean flag = chunk.isLightCorrect();
+
+        int minLightSection = chunk.getMinSection() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int j = chunk.getSectionIndexFromSectionY(y);
+            if (j < 0 || j >= sections.length)
+                continue;
+            CompoundTag sectionTag = new CompoundTag();
+            LevelChunkSection section = sections[j];
+            sectionTag.put("block_states", BLOCK_STATE_CODEC.encodeStart(NbtOps.INSTANCE, section.getStates()).getOrThrow());
+            sectionTag.put("biomes", codec.encodeStart(NbtOps.INSTANCE, section.getBiomes()).getOrThrow());
+
+            if (!sectionTag.isEmpty()) {
+                sectionTag.putByte("Y", (byte) y);
+                sectionsTag.add(sectionTag);
+            }
+        }
+
+        tag.put("sections", sectionsTag);
+        if (flag) {
+            tag.putBoolean("isLightOn", true);
+        }
+
+        ListTag blockEntities = new ListTag();
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag entityNbt = chunk.getBlockEntityNbtForSaving(blockPos, registryAccess());
+            if (entityNbt != null) {
+                blockEntities.add(entityNbt);
+            }
+        }
+
+        tag.put("block_entities", blockEntities);
+        if (chunk.getPersistedStatus().getChunkType() == ChunkType.PROTOCHUNK) {
+            ProtoChunk protochunk = (ProtoChunk)chunk;
+            ListTag entities = new ListTag();
+            entities.addAll(protochunk.getEntities());
+            tag.put("entities", entities);
+            CompoundTag carvingMasks = new CompoundTag();
+
+            for(GenerationStep.Carving carving : GenerationStep.Carving.values()) {
+                CarvingMask mask = protochunk.getCarvingMask(carving);
+                if (mask != null) {
+                    carvingMasks.putLongArray(carving.toString(), mask.toArray());
+                }
+            }
+
+            tag.put("CarvingMasks", carvingMasks);
+        }
+
+        saveTicks(tag, chunk.getTicksForSerialization());
+        tag.put("PostProcessing", packOffsets(chunk.getPostProcessing()));
+        CompoundTag heightMaps = new CompoundTag();
+
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getPersistedStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMaps.put(entry.getKey().getSerializationKey(), new LongArrayTag(entry.getValue().getRawData()));
+            }
+        }
+
+        tag.put("Heightmaps", heightMaps);
+
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+        tag.put("structures", structureData);
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            tag.put("ChunkBukkitValues", chunk.persistentDataContainer.toTagCompound());
+        }
+
+        return tag;
+    }
+
+    private static void saveTicks(CompoundTag tag, ChunkAccess.TicksToSave ticks) {
+        tag.put("block_ticks", ticks.blocks().save(0, (block) -> BuiltInRegistries.BLOCK.getKey(block).toString()));
+        tag.put("fluid_ticks", ticks.fluids().save(0, (fluid) -> BuiltInRegistries.FLUID.getKey(fluid).toString()));
+    }
+}

nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/NMSBinding.java

@@ -14,6 +14,8 @@ import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.Pair;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_21_R2.headless.RegionStorage;
 import com.volmit.iris.util.scheduling.J;
 import lombok.SneakyThrows;
 import net.minecraft.core.*;
@@ -666,44 +668,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.lookupOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                        old.resources(),
+                        old.dataConfiguration(),
+                        old.datapackWorldgen(),
+                        createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().lookupOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -715,9 +715,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().L.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -741,7 +763,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.lookupOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/headless/DirectTerrainChunk.java

@@ -0,0 +1,211 @@
+package com.volmit.iris.core.nms.v1_21_R2.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_21_R2.block.CraftBiome;
+import org.bukkit.craftbukkit.v1_21_R2.block.CraftBlockType;
+import org.bukkit.craftbukkit.v1_21_R2.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_21_R2.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinY();
+        this.maxHeight = access.getMaxY();
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBiome.minecraftHolderToBukkit(access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBiome.bukkitToMinecraftHolder(bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftBlockType.minecraftToBukkit(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setPersistedStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/headless/Region.java

@@ -0,0 +1,75 @@
+package com.volmit.iris.core.nms.v1_21_R2.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+import net.minecraft.world.level.chunk.storage.RegionStorageInfo;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private static final RegionStorageInfo info = new RegionStorageInfo("headless", Level.OVERWORLD, "headless");
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(info, path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_21_R2/src/main/java/com/volmit/iris/core/nms/v1_21_R2/headless/RegionStorage.java

@@ -0,0 +1,244 @@
+package com.volmit.iris.core.nms.v1_21_R2.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import it.unimi.dsi.fastutil.shorts.ShortArrayList;
+import it.unimi.dsi.fastutil.shorts.ShortList;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.Optionull;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.LevelChunkSection;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.chunk.UpgradeData;
+import net.minecraft.world.level.chunk.storage.SerializableChunkData;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_21_R2.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R2.block.CraftBiome;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minY;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minY = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minY;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .collect(Collectors.toMap(Function.identity(), CraftBiome::bukkitToMinecraftHolder)));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().lookupOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    private static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().lookupOrThrow(Registries.BIOME).get(ResourceLocation.fromNamespaceAndPath(namespace, path));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        RegistryAccess access = registryAccess();
+        List<SerializableChunkData.SectionData> list = new ArrayList<>();
+        LevelChunkSection[] sections = chunk.getSections();
+
+        int minLightSection = chunk.getMinSectionY() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int index = chunk.getSectionIndexFromSectionY(y);
+            if (index < 0 || index >= sections.length) continue;
+            LevelChunkSection section = sections[index].copy();
+            list.add(new SerializableChunkData.SectionData(y, section, null, null));
+        }
+
+        List<CompoundTag> blockEntities = new ArrayList<>(chunk.getBlockEntitiesPos().size());
+
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag nbt = chunk.getBlockEntityNbtForSaving(blockPos, access);
+            if (nbt != null) {
+                blockEntities.add(nbt);
+            }
+        }
+        Map<Heightmap.Types, long[]> heightMap = new EnumMap<>(Heightmap.Types.class);
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getPersistedStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMap.put(entry.getKey(), entry.getValue().getRawData().clone());
+            }
+        }
+
+        ChunkAccess.PackedTicks packedTicks = chunk.getTicksForSerialization(0);
+        ShortList[] postProcessing = Arrays.stream(chunk.getPostProcessing()).map((shortlist) -> shortlist != null ? new ShortArrayList(shortlist) : null).toArray(ShortList[]::new);
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+
+        CompoundTag persistentDataContainer = null;
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            persistentDataContainer = chunk.persistentDataContainer.toTagCompound();
+        }
+
+        return new SerializableChunkData(access.lookupOrThrow(Registries.BIOME), chunk.getPos(),
+                chunk.getMinSectionY(), 0, chunk.getInhabitedTime(), chunk.getPersistedStatus(),
+                Optionull.map(chunk.getBlendingData(), BlendingData::pack), chunk.getBelowZeroRetrogen(),
+                chunk.getUpgradeData().copy(), null, heightMap, packedTicks, postProcessing,
+                chunk.isLightCorrect(), list, new ArrayList<>(), blockEntities, structureData, persistentDataContainer)
+                .write();
+    }
+}

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/IrisChunkGenerator.java

@@ -209,7 +209,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     @Override
     public WeightedRandomList<MobSpawnSettings.SpawnerData> getMobsAt(Holder<Biome> holder, StructureManager structuremanager, MobCategory enumcreaturetype, BlockPos blockposition) {
-        return WeightedRandomList.create();
+        return delegate.getMobsAt(holder, structuremanager, enumcreaturetype, blockposition);
     }
 
     @Override

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/NMSBinding.java

@@ -8,6 +8,8 @@ import com.volmit.iris.core.nms.container.AutoClosing;
 import com.volmit.iris.core.nms.container.BiomeColor;
 import com.volmit.iris.core.nms.container.Pair;
 import com.volmit.iris.core.nms.datapack.DataVersion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.v1_21_R3.headless.RegionStorage;
 import com.volmit.iris.engine.data.cache.AtomicCache;
 import com.volmit.iris.engine.framework.Engine;
 import com.volmit.iris.util.collection.KList;
@@ -665,44 +667,42 @@ public class NMSBinding implements INMSBinding {
     }
 
     @Override
-    @SneakyThrows
+    public IRegionStorage createRegionStorage(Engine engine) {
+        return new RegionStorage(engine);
+    }
+
+    @Override
     public AutoClosing injectLevelStems() {
-        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
-
-        var server = ((CraftServer) Bukkit.getServer());
-        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
-        var nmsServer = server.getServer();
-        var old = nmsServer.worldLoader;
-
-        field.setAccessible(true);
-        field.set(nmsServer, dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
-                old.resources(),
-                old.dataConfiguration(),
-                old.datapackWorldgen(),
-                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
-        )));
-
-        return new AutoClosing(() -> {
-            field.set(nmsServer, old);
-            dataContextLock.unlock();
-        });
+        return inject(this::supplier);
     }
 
     @Override
     @SneakyThrows
-    public AutoClosing injectUncached(boolean overworld, boolean nether, boolean end) {
+    public Pair<Integer, AutoClosing> injectUncached(boolean overworld, boolean nether, boolean end) {
         var reg = registry();
         var field = getField(RegistryAccess.ImmutableRegistryAccess.class, Map.class);
         field.setAccessible(true);
 
-        var access = createRegistryAccess(((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions(), true, overworld, nether, end);
-        var injected = access.lookupOrThrow(Registries.LEVEL_STEM);
+        AutoClosing closing = inject(old -> new WorldLoader.DataLoadContext(
+                    old.resources(),
+                    old.dataConfiguration(),
+                    old.datapackWorldgen(),
+                    createRegistryAccess(old.datapackDimensions(), true, overworld, nether, end)
+                )
+        );
+
+        var injected = ((CraftServer) Bukkit.getServer()).getServer().worldLoader.datapackDimensions().lookupOrThrow(Registries.LEVEL_STEM);
         var old = (Map<ResourceKey<? extends Registry<?>>, Registry<?>>) field.get(reg);
         var fake = new HashMap<>(old);
         fake.put(Registries.LEVEL_STEM, injected);
         field.set(reg, fake);
 
-        return new AutoClosing(() -> field.set(reg, old));
+        return new Pair<>(
+                injected.size(),
+                new AutoClosing(() -> {
+                    closing.close();
+                    field.set(reg, old);
+                }));
     }
 
     @Override
@@ -714,9 +714,31 @@ public class NMSBinding implements INMSBinding {
         return overworld || nether || end;
     }
 
-    @Override
-    public void removeCustomDimensions(World world) {
-        ((CraftWorld) world).getHandle().L.customDimensions = null;
+    private WorldLoader.DataLoadContext supplier(WorldLoader.DataLoadContext old) {
+        return dataLoadContext.aquire(() -> new WorldLoader.DataLoadContext(
+                old.resources(),
+                old.dataConfiguration(),
+                old.datapackWorldgen(),
+                createRegistryAccess(old.datapackDimensions(), false, true, true, true)
+        ));
+    }
+
+    @SneakyThrows
+    private AutoClosing inject(Function<WorldLoader.DataLoadContext, WorldLoader.DataLoadContext> transformer) {
+        if (!dataContextLock.tryLock()) throw new IllegalStateException("Failed to inject data context!");
+
+        var server = ((CraftServer) Bukkit.getServer());
+        var field = getField(MinecraftServer.class, WorldLoader.DataLoadContext.class);
+        var nmsServer = server.getServer();
+        var old = nmsServer.worldLoader;
+
+        field.setAccessible(true);
+        field.set(nmsServer, transformer.apply(old));
+
+        return new AutoClosing(() -> {
+            field.set(nmsServer, old);
+            dataContextLock.unlock();
+        });
     }
 
     private RegistryAccess.Frozen createRegistryAccess(RegistryAccess.Frozen datapack, boolean copy, boolean overworld, boolean nether, boolean end) {
@@ -740,7 +762,7 @@ public class NMSBinding implements INMSBinding {
 
         if (copy) copy(fake, access.lookupOrThrow(Registries.LEVEL_STEM));
 
-        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake)).freeze();
+        return new RegistryAccess.Frozen.ImmutableRegistryAccess(List.of(fake.freeze())).freeze();
     }
 
     private void register(MappedRegistry<LevelStem> target, Registry<DimensionType> dimensions, FlatLevelSource source, ResourceKey<LevelStem> key) {

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/headless/DirectTerrainChunk.java

@@ -0,0 +1,211 @@
+package com.volmit.iris.core.nms.v1_21_R3.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.BiomeBaseInjector;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.data.IrisCustomData;
+import com.volmit.iris.util.math.Position2;
+import lombok.Data;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.EntityBlock;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.chunk.status.ChunkStatus;
+import org.bukkit.Material;
+import org.bukkit.block.Biome;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.craftbukkit.v1_21_R3.block.CraftBiome;
+import org.bukkit.craftbukkit.v1_21_R3.block.CraftBlockType;
+import org.bukkit.craftbukkit.v1_21_R3.block.data.CraftBlockData;
+import org.bukkit.craftbukkit.v1_21_R3.util.CraftMagicNumbers;
+import org.bukkit.generator.ChunkGenerator;
+import org.bukkit.material.MaterialData;
+import org.jetbrains.annotations.NotNull;
+
+@Data
+public final class DirectTerrainChunk implements SerializableChunk {
+    private final ProtoChunk access;
+    private final int minHeight, maxHeight;
+
+    public DirectTerrainChunk(ProtoChunk access) {
+        this.access = access;
+        this.minHeight = access.getMinY();
+        this.maxHeight = access.getMaxY();
+    }
+
+    @Override
+    public BiomeBaseInjector getBiomeBaseInjector() {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int z) {
+        return getBiome(x, 0, z);
+    }
+
+    @NotNull
+    @Override
+    public Biome getBiome(int x, int y, int z) {
+        if (y < minHeight || y > maxHeight) return Biome.PLAINS;
+        return CraftBiome.minecraftHolderToBukkit(access.getNoiseBiome(x >> 2, y >> 2, z >> 2));
+    }
+
+    @Override
+    public void setBiome(int x, int z, Biome bio) {
+        for (int y = minHeight; y < maxHeight; y += 4) {
+            setBiome(x, y, z, bio);
+        }
+    }
+
+    @Override
+    public void setBiome(int x, int y, int z, Biome bio) {
+        if (y < minHeight || y > maxHeight) return;
+        access.setBiome(x & 15, y, z & 15, CraftBiome.bukkitToMinecraftHolder(bio));
+    }
+
+    public void setBlock(int x, int y, int z, Material material) {
+        this.setBlock(x, y, z, material.createBlockData());
+    }
+
+    public void setBlock(int x, int y, int z, MaterialData material) {
+        this.setBlock(x, y, z, CraftMagicNumbers.getBlock(material));
+    }
+
+    @Override
+    public void setBlock(int x, int y, int z, BlockData blockData) {
+        if (blockData == null) {
+            Iris.error("NULL BD");
+        }
+        if (blockData instanceof IrisCustomData data)
+            blockData = data.getBase();
+        if (!(blockData instanceof CraftBlockData craftBlockData))
+            throw new IllegalArgumentException("Expected CraftBlockData, got " + blockData.getClass().getSimpleName() + " instead");
+        access.setBlockState(new BlockPos(x & 15, y, z & 15), craftBlockData.getState(), false);
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, Material material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, material.createBlockData());
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, MaterialData material) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, CraftMagicNumbers.getBlock(material));
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockData blockData) {
+        this.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, ((CraftBlockData) blockData).getState());
+    }
+
+    public Material getType(int x, int y, int z) {
+        return CraftBlockType.minecraftToBukkit(this.getTypeId(x, y, z).getBlock());
+    }
+
+    public MaterialData getTypeAndData(int x, int y, int z) {
+        return CraftMagicNumbers.getMaterial(this.getTypeId(x, y, z));
+    }
+
+    public BlockData getBlockData(int x, int y, int z) {
+        return CraftBlockData.fromData(this.getTypeId(x, y, z));
+    }
+
+    @Override
+    public ChunkGenerator.ChunkData getRaw() {
+        return null;
+    }
+
+    @Override
+    public void setRaw(ChunkGenerator.ChunkData data) {
+
+    }
+
+    @Override
+    public void inject(ChunkGenerator.BiomeGrid biome) {
+
+    }
+
+    public void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, BlockState type) {
+        if (xMin > 15 || yMin >= this.maxHeight || zMin > 15)
+            return;
+
+        if (xMin < 0) {
+            xMin = 0;
+        }
+
+        if (yMin < this.minHeight) {
+            yMin = this.minHeight;
+        }
+
+        if (zMin < 0) {
+            zMin = 0;
+        }
+
+        if (xMax > 16) {
+            xMax = 16;
+        }
+
+        if (yMax > this.maxHeight) {
+            yMax = this.maxHeight;
+        }
+
+        if (zMax > 16) {
+            zMax = 16;
+        }
+
+        if (xMin >= xMax || yMin >= yMax || zMin >= zMax)
+            return;
+
+        for (int y = yMin; y < yMax; ++y) {
+            for (int x = xMin; x < xMax; ++x) {
+                for (int z = zMin; z < zMax; ++z) {
+                    this.setBlock(x, y, z, type);
+                }
+            }
+        }
+
+    }
+
+    public BlockState getTypeId(int x, int y, int z) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return Blocks.AIR.defaultBlockState();
+        return access.getBlockState(new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z));
+    }
+
+    public byte getData(int x, int y, int z) {
+        return CraftMagicNumbers.toLegacyData(this.getTypeId(x, y, z));
+    }
+
+    private void setBlock(int x, int y, int z, BlockState type) {
+        if (x != (x & 15) || y < this.minHeight || y >= this.maxHeight || z != (z & 15))
+            return;
+        BlockPos blockPosition = new BlockPos(access.getPos().getMinBlockX() + x, y, access.getPos().getMinBlockZ() + z);
+        BlockState oldBlockData = access.setBlockState(blockPosition, type, false);
+        if (type.hasBlockEntity()) {
+            BlockEntity tileEntity = ((EntityBlock) type.getBlock()).newBlockEntity(blockPosition, type);
+            if (tileEntity == null) {
+                access.removeBlockEntity(blockPosition);
+            } else {
+                access.setBlockEntity(tileEntity);
+            }
+        } else if (oldBlockData != null && oldBlockData.hasBlockEntity()) {
+            access.removeBlockEntity(blockPosition);
+        }
+
+    }
+
+    @Override
+    public Position2 getPos() {
+        return new Position2(access.getPos().x, access.getPos().z);
+    }
+
+    @Override
+    public Object serialize() {
+        return RegionStorage.serialize(access);
+    }
+
+    @Override
+    public void mark() {
+        access.setPersistedStatus(ChunkStatus.FULL);
+    }
+}

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/headless/Region.java

@@ -0,0 +1,75 @@
+package com.volmit.iris.core.nms.v1_21_R3.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.util.math.M;
+import lombok.NonNull;
+import lombok.Synchronized;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.chunk.storage.RegionFile;
+import net.minecraft.world.level.chunk.storage.RegionStorageInfo;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.file.Path;
+
+class Region implements IRegion, Comparable<Region> {
+    private static final RegionStorageInfo info = new RegionStorageInfo("headless", Level.OVERWORLD, "headless");
+    private final RegionFile regionFile;
+    transient long references;
+    transient long lastUsed;
+
+    Region(Path path, Path folder) throws IOException {
+        this.regionFile = new RegionFile(info, path, folder, false);
+    }
+
+    @Override
+    @Synchronized
+    public boolean exists(int x, int z) {
+        try (DataInputStream din = regionFile.getChunkDataInputStream(new ChunkPos(x, z))) {
+            if (din == null) return false;
+            return !"empty".equals(NbtIo.read(din).getString("Status"));
+        } catch (IOException e) {
+            return false;
+        }
+    }
+
+    @Override
+    @Synchronized
+    public void write(@NonNull SerializableChunk chunk) throws IOException {
+        try (DataOutputStream dos = regionFile.getChunkDataOutputStream(chunk.getPos().convert(ChunkPos::new))) {
+            NbtIo.write((CompoundTag) chunk.serialize(), dos);
+        }
+    }
+
+    @Override
+    public void close() {
+        --references;
+        lastUsed = M.ms();
+    }
+
+    public boolean unused() {
+        return references <= 0;
+    }
+
+    public boolean remove() {
+        if (!unused()) return false;
+        try {
+            regionFile.close();
+        } catch (IOException e) {
+            Iris.error("Failed to close region file");
+            e.printStackTrace();
+        }
+        return true;
+    }
+
+    @Override
+    public int compareTo(Region o) {
+        return Long.compare(lastUsed, o.lastUsed);
+    }
+}

nms/v1_21_R3/src/main/java/com/volmit/iris/core/nms/v1_21_R3/headless/RegionStorage.java

@@ -0,0 +1,244 @@
+package com.volmit.iris.core.nms.v1_21_R3.headless;
+
+import com.volmit.iris.Iris;
+import com.volmit.iris.core.nms.headless.IRegion;
+import com.volmit.iris.core.nms.headless.IRegionStorage;
+import com.volmit.iris.core.nms.headless.SerializableChunk;
+import com.volmit.iris.engine.data.cache.AtomicCache;
+import com.volmit.iris.engine.data.cache.Cache;
+import com.volmit.iris.engine.framework.Engine;
+import com.volmit.iris.engine.object.IrisBiome;
+import com.volmit.iris.util.collection.KMap;
+import com.volmit.iris.util.context.ChunkContext;
+import com.volmit.iris.util.math.RNG;
+import com.volmit.iris.util.scheduling.J;
+import it.unimi.dsi.fastutil.shorts.ShortArrayList;
+import it.unimi.dsi.fastutil.shorts.ShortList;
+import lombok.Getter;
+import lombok.NonNull;
+import net.minecraft.FileUtil;
+import net.minecraft.Optionull;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.ChunkPos;
+import net.minecraft.world.level.LevelHeightAccessor;
+import net.minecraft.world.level.biome.Biome;
+import net.minecraft.world.level.chunk.ChunkAccess;
+import net.minecraft.world.level.chunk.LevelChunkSection;
+import net.minecraft.world.level.chunk.ProtoChunk;
+import net.minecraft.world.level.chunk.UpgradeData;
+import net.minecraft.world.level.chunk.storage.SerializableChunkData;
+import net.minecraft.world.level.levelgen.Heightmap;
+import net.minecraft.world.level.levelgen.blending.BlendingData;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_21_R3.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R3.block.CraftBiome;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+public class RegionStorage implements IRegionStorage, LevelHeightAccessor {
+    private static final AtomicCache<RegistryAccess> CACHE = new AtomicCache<>();
+    private final KMap<Long, Region> regions = new KMap<>();
+    private final Path folder;
+
+    private final Engine engine;
+    private final KMap<String, Holder<Biome>> customBiomes = new KMap<>();
+    private final KMap<org.bukkit.block.Biome, Holder<Biome>> minecraftBiomes;
+    private final RNG biomeRng;
+    private final @Getter int minY;
+    private final @Getter int height;
+
+    private transient boolean closed = false;
+
+    public RegionStorage(Engine engine) {
+        this.engine = engine;
+        this.folder = new File(engine.getWorld().worldFolder(), "region").toPath();
+        this.biomeRng = new RNG(engine.getSeedManager().getBiome());
+
+        this.minY = engine.getDimension().getMinHeight();
+        this.height = engine.getDimension().getMaxHeight() - minY;
+
+        AtomicInteger failed = new AtomicInteger();
+        var dimKey = engine.getDimension().getLoadKey();
+        for (var biome : engine.getAllBiomes()) {
+            if (!biome.isCustom()) continue;
+            for (var custom : biome.getCustomDerivitives()) {
+                biomeHolder(dimKey, custom.getId()).ifPresentOrElse(holder -> customBiomes.put(custom.getId(), holder), () -> {
+                    Iris.error("Failed to load custom biome " + dimKey + " " + custom.getId());
+                    failed.incrementAndGet();
+                });
+            }
+        }
+        if (failed.get() > 0) {
+            throw new IllegalStateException("Failed to load " + failed.get() + " custom biomes");
+        }
+
+        minecraftBiomes = new KMap<>(org.bukkit.Registry.BIOME.stream()
+                .collect(Collectors.toMap(Function.identity(), CraftBiome::bukkitToMinecraftHolder)));
+        minecraftBiomes.values().removeAll(customBiomes.values());
+    }
+
+    @Override
+    public boolean exists(int x, int z) {
+        try (IRegion region = getRegion(x >> 5, z >> 5, true)) {
+            return region != null && region.exists(x, z);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public IRegion getRegion(int x, int z, boolean existingOnly) throws IOException {
+        AtomicReference<IOException> exception = new AtomicReference<>();
+        Region region = regions.computeIfAbsent(Cache.key(x, z), k -> {
+            trim();
+
+            try {
+                FileUtil.createDirectoriesSafe(this.folder);
+                Path path = folder.resolve("r." + x + "." + z + ".mca");
+                if (existingOnly && !Files.exists(path)) {
+                    return null;
+                } else {
+                    return new Region(path, this.folder);
+                }
+            } catch (IOException e) {
+                exception.set(e);
+                return null;
+            }
+        });
+
+        if (region == null) {
+            if (exception.get() != null)
+                throw exception.get();
+            return null;
+        }
+        region.references++;
+        return region;
+    }
+
+    @NotNull
+    @Override
+    public SerializableChunk createChunk(int x, int z) {
+        return new DirectTerrainChunk(new ProtoChunk(new ChunkPos(x, z), UpgradeData.EMPTY, this, registryAccess().lookupOrThrow(Registries.BIOME), null));
+    }
+
+    @Override
+    public void fillBiomes(@NonNull SerializableChunk chunk, @Nullable ChunkContext ctx) {
+        if (!(chunk instanceof DirectTerrainChunk tc))
+            return;
+        tc.getAccess().fillBiomesFromNoise((qX, qY, qZ, sampler) -> getNoiseBiome(engine, ctx, qX << 2, qY << 2, qZ << 2), null);
+    }
+
+    @Override
+    public synchronized void close() {
+        if (closed) return;
+
+        while (!regions.isEmpty()) {
+            regions.values().removeIf(Region::remove);
+            J.sleep(1);
+        }
+
+        closed = true;
+        customBiomes.clear();
+        minecraftBiomes.clear();
+    }
+
+    private void trim() {
+        int size = regions.size();
+        if (size < 256) return;
+        int remove = size - 255;
+
+        var list = regions.values()
+                .stream()
+                .filter(Region::unused)
+                .sorted()
+                .collect(Collectors.toList())
+                .reversed();
+
+        int skip = list.size() - remove;
+        if (skip > 0) list.subList(0, skip).clear();
+
+        if (list.isEmpty()) return;
+        regions.values().removeIf(r -> list.contains(r) && r.remove());
+    }
+
+    private Holder<Biome> getNoiseBiome(Engine engine, ChunkContext ctx, int x, int y, int z) {
+        int m = y - engine.getMinHeight();
+        IrisBiome ib = ctx == null ? engine.getSurfaceBiome(x, z) : ctx.getBiome().get(x & 15, z & 15);
+        if (ib.isCustom()) {
+            return customBiomes.get(ib.getCustomBiome(biomeRng, x, m, z).getId());
+        } else {
+            return minecraftBiomes.get(ib.getSkyBiome(biomeRng, x, m, z));
+        }
+    }
+
+    private static RegistryAccess registryAccess() {
+        return CACHE.aquire(() -> ((CraftServer) Bukkit.getServer()).getServer().registryAccess());
+    }
+
+    private static Optional<Holder.Reference<Biome>> biomeHolder(String namespace, String path) {
+        return registryAccess().lookupOrThrow(Registries.BIOME).get(ResourceLocation.fromNamespaceAndPath(namespace, path));
+    }
+
+    static CompoundTag serialize(ChunkAccess chunk) {
+        RegistryAccess access = registryAccess();
+        List<SerializableChunkData.SectionData> list = new ArrayList<>();
+        LevelChunkSection[] sections = chunk.getSections();
+
+        int minLightSection = chunk.getMinSectionY() - 1;
+        int maxLightSection = minLightSection + chunk.getSectionsCount() + 2;
+        for(int y = minLightSection; y < maxLightSection; ++y) {
+            int index = chunk.getSectionIndexFromSectionY(y);
+            if (index < 0 || index >= sections.length) continue;
+            LevelChunkSection section = sections[index].copy();
+            list.add(new SerializableChunkData.SectionData(y, section, null, null));
+        }
+
+        List<CompoundTag> blockEntities = new ArrayList<>(chunk.getBlockEntitiesPos().size());
+
+        for(BlockPos blockPos : chunk.getBlockEntitiesPos()) {
+            CompoundTag nbt = chunk.getBlockEntityNbtForSaving(blockPos, access);
+            if (nbt != null) {
+                blockEntities.add(nbt);
+            }
+        }
+        Map<Heightmap.Types, long[]> heightMap = new EnumMap<>(Heightmap.Types.class);
+        for(Map.Entry<Heightmap.Types, Heightmap> entry : chunk.getHeightmaps()) {
+            if (chunk.getPersistedStatus().heightmapsAfter().contains(entry.getKey())) {
+                heightMap.put(entry.getKey(), entry.getValue().getRawData().clone());
+            }
+        }
+
+        ChunkAccess.PackedTicks packedTicks = chunk.getTicksForSerialization(0);
+        ShortList[] postProcessing = Arrays.stream(chunk.getPostProcessing()).map((shortlist) -> shortlist != null ? new ShortArrayList(shortlist) : null).toArray(ShortList[]::new);
+        CompoundTag structureData = new CompoundTag();
+        structureData.put("starts", new CompoundTag());
+        structureData.put("References", new CompoundTag());
+
+        CompoundTag persistentDataContainer = null;
+        if (!chunk.persistentDataContainer.isEmpty()) {
+            persistentDataContainer = chunk.persistentDataContainer.toTagCompound();
+        }
+
+        return new SerializableChunkData(access.lookupOrThrow(Registries.BIOME), chunk.getPos(),
+                chunk.getMinSectionY(), 0, chunk.getInhabitedTime(), chunk.getPersistedStatus(),
+                Optionull.map(chunk.getBlendingData(), BlendingData::pack), chunk.getBelowZeroRetrogen(),
+                chunk.getUpgradeData().copy(), null, heightMap, packedTicks, postProcessing,
+                chunk.isLightCorrect(), list, new ArrayList<>(), blockEntities, structureData, persistentDataContainer)
+                .write();
+    }
+}