feat: implement command to fix block connections (#2746)

* feat: implement command to fix block connections
 - closes #313

* set SETUP to true on setup

* Add (untested) processing capability and second passes where appropriate

* Minor refactor, add various javadocs

* Minor adjustments

* Better chest handling

* Utilise thread extends when able

* Add strings, changes to fastmode/side effect handling

* Cleanup

* Add for 1.21

* Adjustment for tall flowers - add capability to forcefully override block updates

* Move to Fawe/LinTag

* fix: adjustments, fix certain upside-down blocks

* Add for 1.21.3

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_20_R2/PaperweightAdapter.java

@@ -857,12 +857,12 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
     }
 
     private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
-        SideEffect.NEIGHBORS,
+            //FAWE start - FAWE-supported side effects
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
             SideEffect.LIGHTING,
-        SideEffect.VALIDATION,
+            SideEffect.NEIGHBORS
-        SideEffect.ENTITY_AI,
+            //FAWE end
-        SideEffect.EVENTS,
-        SideEffect.UPDATE
     );
 
     @Override

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_20_R2/PaperweightServerLevelDelegateProxy.java

@@ -0,0 +1,237 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * 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.sk89q.worldedit.bukkit.adapter.ext.fawe.v1_20_R2;
+
+import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.bukkit.adapter.Refraction;
+import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R2.PaperweightFaweAdapter;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class PaperweightServerLevelDelegateProxy implements InvocationHandler {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    // FAWE start - extent not EditSession
+    private final Extent editSession;
+    //FAWE end
+    private final ServerLevel serverLevel;
+    //FAWE start - use FAWE adapter
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    //FAWE end
+    //FAWE start - force error if method not caught by this instance
+    private final boolean errorOnPassthrough;
+    //FAWE end
+
+    private PaperweightServerLevelDelegateProxy(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        this.editSession = editSession;
+        this.serverLevel = serverLevel;
+        //FAWE start
+        this.errorOnPassthrough = false;
+        //FAWE end
+    }
+
+    public static WorldGenLevel newInstance(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(editSession, serverLevel, adapter)
+        );
+    }
+
+    //FAWE start - force error if method not caught by this instance
+    private PaperweightServerLevelDelegateProxy(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        this.editSession = extent;
+        this.serverLevel = serverLevel;
+        this.errorOnPassthrough = errorOnPassthrough;
+    }
+
+    public static WorldGenLevel newInstance(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(extent, serverLevel, errorOnPassthrough)
+        );
+    }
+    //FAWE end
+
+    @Nullable
+    private BlockEntity getBlockEntity(BlockPos blockPos) {
+        BlockEntity tileEntity = this.serverLevel.getChunkAt(blockPos).getBlockEntity(blockPos);
+        if (tileEntity == null) {
+            return null;
+        }
+        BlockEntity newEntity = tileEntity.getType().create(blockPos, getBlockState(blockPos));
+        newEntity.load((CompoundTag) adapter.fromNativeLin(this.editSession.getFullBlock(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        ).getNbtReference().getValue()));
+
+        return newEntity;
+    }
+
+    private BlockState getBlockState(BlockPos blockPos) {
+        return adapter.adapt(this.editSession.getBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+    }
+
+    private boolean setBlock(BlockPos blockPos, BlockState blockState) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), adapter.adapt(blockState));
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private boolean removeBlock(BlockPos blockPos, boolean bl) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), BlockTypes.AIR.getDefaultState());
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private FluidState getFluidState(BlockPos pos) {
+        return getBlockState(pos).getFluidState();
+    }
+
+    private boolean isWaterAt(BlockPos pos) {
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        //FAWE start - cannot use switch where method names are equal
+        String methodName = method.getName();
+        if (Refraction.pickName("getBlockState", "a_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockState
+                return getBlockState(blockPos);
+            }
+        }
+        if (Refraction.pickName("getBlockEntity", "c_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockEntity
+                return getBlockEntity(blockPos);
+            }
+        }
+        if ("a".equals(methodName) || "setBlock".equals(methodName) || "removeBlock".equals(methodName) || "destroyBlock".equals(
+                methodName)) {
+            if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof BlockState blockState) {
+                // setBlock
+                return setBlock(blockPos, blockState);
+            } else if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof Boolean bl) {
+                // removeBlock (and also matches destroyBlock)
+                return removeBlock(blockPos, bl);
+            }
+        }
+        //FAWE start
+        if (Refraction.pickName("getFluidState", "b_").equals(methodName)) { //net.minecraft.world.level.BlockGetter
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return getFluidState(blockPos);
+            }
+        }
+        if (Refraction.pickName("isWaterAt", "z").equals(methodName)) { //net.minecraft.world.level.LevelReader
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return isWaterAt(blockPos);
+            }
+        }
+        if (Refraction.pickName("getEntities", "a_").equals(methodName)) { //net.minecraft.world.level.EntityGetter
+            if (args.length == 2 && args[0] instanceof Entity && args[1] instanceof AABB) {
+                return new ArrayList<>();
+            }
+        }
+        // Specific passthroughs that we want to allow
+        // net.minecraft.world.level.BlockAndTintGetter
+        if (Refraction.pickName("getRawBrightness", "b").equals(methodName)) {
+            return method.invoke(this.serverLevel, args);
+        }
+        // net.minecraft.world.level.LevelHeightAccessor
+        if (Refraction.pickName("getMaxBuildHeight", "al").equals(methodName)) {
+            if (args.length == 0) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        // net.minecraft.world.level.SignalGetter
+        if (Refraction.pickName("hasNeighborSignal", "C").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getSignal", "c").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getControlInputSignal", "a").equals(methodName)) {
+            if (args.length == 3 && args[0] instanceof BlockPos && args[1] instanceof Direction && args[2] instanceof Boolean) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getDirectSignal", "a").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        //FAWE start - force error if method not caught by this instance
+        if (errorOnPassthrough) {
+            LOGGER.error(
+                    """
+                            Attempted passthough of method {}.
+                            Method argument types: {}
+                            Method argument values: {}
+                            """,
+                    method.getName(),
+                    Arrays.stream(args).map(a -> a.getClass().getName()).toList(),
+                    Arrays.stream(args).map(Object::toString).toList()
+            );
+            throw new FaweException("Method required passthrough.");
+        }
+        //FAWE end
+
+        return method.invoke(this.serverLevel, args);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R2/PaperweightFaweAdapter.java

@@ -4,6 +4,7 @@ import com.fastasyncworldedit.bukkit.adapter.FaweAdapter;
 import com.fastasyncworldedit.bukkit.adapter.NMSRelighterFactory;
 import com.fastasyncworldedit.core.FaweCache;
 import com.fastasyncworldedit.core.entity.LazyBaseEntity;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
@@ -13,6 +14,7 @@ import com.fastasyncworldedit.core.util.NbtUtils;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Sets;
 import com.sk89q.jnbt.Tag;
 import com.sk89q.worldedit.blocks.BaseItemStack;
 import com.sk89q.worldedit.bukkit.BukkitAdapter;
@@ -21,6 +23,7 @@ import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R2.nbt.PaperweightLazy
 import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R2.regen.PaperweightRegen;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.block.BlockStateIdAccess;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.internal.wna.WorldNativeAccess;
@@ -33,7 +36,6 @@ import com.sk89q.worldedit.registry.state.IntegerProperty;
 import com.sk89q.worldedit.registry.state.Property;
 import com.sk89q.worldedit.util.Direction;
 import com.sk89q.worldedit.util.SideEffect;
-import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.RegenOptions;
 import com.sk89q.worldedit.world.biome.BiomeType;
@@ -284,9 +286,16 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return state.toBaseBlock();
     }
 
+    private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
+            SideEffect.LIGHTING,
+            SideEffect.NEIGHBORS
+    );
+
     @Override
     public Set<SideEffect> getSupportedSideEffects() {
-        return SideEffectSet.defaults().getSideEffectsToApply();
+        return SUPPORTED_SIDE_EFFECTS;
     }
 
     @Override
@@ -434,6 +443,10 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return material.getCraftBlockData();
     }
 
+    public net.minecraft.world.level.block.state.BlockState adapt(BlockState blockState) {
+        return Block.stateById(getOrdinalToIbdID()[blockState.getOrdinal()]);
+    }
+
     @Override
     public void sendFakeChunk(org.bukkit.World world, Player player, ChunkPacket chunkPacket) {
         ServerLevel nmsWorld = getServerLevel(world);
@@ -602,6 +615,11 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return new PaperweightPostProcessor();
     }
 
+    @Override
+    public PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return new PaperweightPlacementStateProcessor(extent, mask, region);
+    }
+
     private boolean wasAccessibleSinceLastSave(ChunkHolder holder) {
         if (!PaperLib.isPaper() || !PaperweightPlatformAdapter.POST_CHUNK_REWRITE) {
             try {

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R2/PaperweightFaweMutableBlockPlaceContext.java

@@ -0,0 +1,142 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R2;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightFaweMutableBlockPlaceContext extends BlockPlaceContext {
+
+    private static final BlockHitResult DEFAULT_BLOCK_HIT = new BlockHitResult(
+            new Vec3(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            Direction.NORTH,
+            new BlockPos(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            false
+    );
+    private final ServerLevel level;
+    private BlockHitResult hitResult = null;
+    private Direction direction = null;
+    private BlockPos relativePos;
+
+    @SuppressWarnings("DataFlowIssue")
+    public PaperweightFaweMutableBlockPlaceContext(ServerLevel level) {
+        super(
+                level,
+                null,
+                null,
+                null,
+                DEFAULT_BLOCK_HIT
+
+        );
+        this.level = level;
+        this.replaceClicked = false;
+    }
+
+    public PaperweightFaweMutableBlockPlaceContext withSetting(BlockHitResult hitResult, Direction direction) {
+        this.hitResult = hitResult;
+        this.direction = direction;
+        this.relativePos = hitResult.getBlockPos().relative(hitResult.getDirection());
+        return this;
+    }
+
+    @Override
+    @Nonnull
+    public BlockPos getClickedPos() {
+        return this.relativePos;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getClickedFace() {
+        return this.hitResult.getDirection();
+    }
+
+    @Override
+    @Nonnull
+    public Vec3 getClickLocation() {
+        return this.hitResult.getLocation();
+    }
+
+    @Override
+    public boolean isInside() {
+        return this.hitResult.isInside();
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public ItemStack getItemInHand() {
+        return ItemStack.EMPTY;
+    }
+
+    @Nullable
+    @Override
+    public Player getPlayer() {
+        return null;
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public InteractionHand getHand() {
+        return null;
+    }
+
+    @Override
+    @Nonnull
+    public Level getLevel() {
+        return this.level;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getHorizontalDirection() {
+        return this.direction.getAxis() == Direction.Axis.Y ? Direction.NORTH : this.direction;
+    }
+
+    @Override
+    public boolean isSecondaryUseActive() {
+        return false;
+    }
+
+    @Override
+    public float getRotation() {
+        return (float) (this.direction.get2DDataValue() * 90);
+    }
+
+    @Override
+    public boolean canPlace() {
+        return this.getLevel().getBlockState(this.getClickedPos()).canBeReplaced(this);
+    }
+
+    @Override
+    public boolean replacingClickedOnBlock() {
+        return false;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingDirection() {
+        return direction;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingVerticalDirection() {
+        return direction.getAxis() == Direction.Axis.Y ? Direction.UP : Direction.DOWN;
+    }
+
+    @Override
+    @Nonnull
+    public Direction[] getNearestLookingDirections() {
+        return new Direction[]{direction};
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R2/PaperweightGetBlocks.java

@@ -21,6 +21,7 @@ import com.sk89q.worldedit.bukkit.WorldEditPlugin;
 import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.biome.BiomeTypes;
 import com.sk89q.worldedit.world.block.BlockTypesCache;
@@ -840,7 +841,9 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                         nmsChunk.mustNotSave = false;
                         nmsChunk.setUnsaved(true);
                         // send to player
-                        if (Settings.settings().LIGHTING.MODE == 0 || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
+                        if (!set
+                                .getSideEffectSet()
+                                .shouldApply(SideEffect.LIGHTING) || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
                             this.send();
                         }
                         if (finalizer != null) {

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R2/PaperweightLevelProxy.java

@@ -0,0 +1,116 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R2;
+
+import com.fastasyncworldedit.core.util.ReflectionUtils;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import net.minecraft.core.BlockPos;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+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.border.WorldBorder;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.level.material.Fluids;
+import org.enginehub.linbus.tree.LinCompoundTag;
+import sun.misc.Unsafe;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightLevelProxy extends ServerLevel {
+
+    protected ServerLevel serverLevel;
+    private PaperweightFaweAdapter adapter;
+    private PaperweightPlacementStateProcessor processor;
+
+    @SuppressWarnings("DataFlowIssue")
+    private PaperweightLevelProxy() {
+        super(null, null, null, null, null, null, null, true, 0L, null, true, null, null, null, null);
+        throw new IllegalStateException("Cannot be instantiated");
+    }
+
+    public static PaperweightLevelProxy getInstance(ServerLevel serverLevel, PaperweightPlacementStateProcessor processor) {
+        Unsafe unsafe = ReflectionUtils.getUnsafe();
+
+        PaperweightLevelProxy newLevel;
+        try {
+            newLevel = (PaperweightLevelProxy) unsafe.allocateInstance(PaperweightLevelProxy.class);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        }
+        newLevel.processor = processor;
+        newLevel.adapter = ((PaperweightFaweAdapter) WorldEditPlugin.getInstance().getBukkitImplAdapter());
+        newLevel.serverLevel = serverLevel;
+        return newLevel;
+    }
+
+    @Nullable
+    @Override
+    public BlockEntity getBlockEntity(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return null;
+        }
+        LinCompoundTag tag = processor.getTileAt(blockPos.getX(), blockPos.getY(), blockPos.getZ());
+        if (tag == null) {
+            return null;
+        }
+        BlockState state = adapter.adapt(processor.getBlockStateAt(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+        if (!(state.getBlock() instanceof EntityBlock entityBlock)) {
+            return null;
+        }
+        BlockEntity tileEntity = entityBlock.newBlockEntity(blockPos, state);
+        tileEntity.load((CompoundTag) adapter.fromNativeLin(tag));
+        return tileEntity;
+    }
+
+    @Override
+    @Nonnull
+    public BlockState getBlockState(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return Blocks.AIR.defaultBlockState();
+        }
+        com.sk89q.worldedit.world.block.BlockState state = processor.getBlockStateAt(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        );
+        return adapter.adapt(state);
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    @Nonnull
+    public FluidState getFluidState(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return Fluids.EMPTY.defaultFluidState();
+        }
+        return getBlockState(pos).getFluidState();
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    public boolean isWaterAt(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return false;
+        }
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public int getHeight() {
+        return serverLevel.getHeight();
+    }
+
+    @Override
+    public int getMinBuildHeight() {
+        return serverLevel.getMinBuildHeight();
+    }
+
+    @Override
+    public WorldBorder getWorldBorder() {
+        return serverLevel.getWorldBorder();
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R2/PaperweightPlacementStateProcessor.java

@@ -0,0 +1,112 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R2;
+
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
+import com.fastasyncworldedit.core.wrappers.WorldWrapper;
+import com.sk89q.worldedit.bukkit.BukkitWorld;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.Direction;
+import com.sk89q.worldedit.world.World;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+import org.bukkit.craftbukkit.v1_20_R2.CraftWorld;
+
+import javax.annotation.Nullable;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class PaperweightPlacementStateProcessor extends PlacementStateProcessor {
+
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    private final PaperweightFaweMutableBlockPlaceContext mutableBlockPlaceContext;
+    private final PaperweightLevelProxy proxyLevel;
+
+    public PaperweightPlacementStateProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        super(extent, mask, region);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    private PaperweightPlacementStateProcessor(
+            Extent extent,
+            BlockTypeMask mask,
+            Map<SecondPass, Character> crossChunkSecondPasses,
+            ThreadLocal<PlacementStateProcessor> threadProcessors,
+            Region region,
+            AtomicBoolean finished
+    ) {
+        super(extent, mask, crossChunkSecondPasses, threadProcessors, region, finished);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    @Override
+    protected char getStateAtFor(
+            int x,
+            int y,
+            int z,
+            BlockState state,
+            Vector3 clickPos,
+            Direction clickedFaceDirection,
+            BlockVector3 clickedBlock
+    ) {
+        Block block = ((PaperweightBlockMaterial) state.getMaterial()).getBlock();
+        Vec3 pos = new Vec3(clickPos.x(), clickPos.y(), clickPos.z());
+        net.minecraft.core.Direction side = net.minecraft.core.Direction.valueOf(clickedFaceDirection.toString());
+        BlockPos blockPos = new BlockPos(clickedBlock.x(), clickedBlock.y(), clickedBlock.z());
+        net.minecraft.world.level.block.state.BlockState newState = block.getStateForPlacement(mutableBlockPlaceContext.withSetting(
+                new BlockHitResult(pos, side, blockPos, false),
+                side.getOpposite()
+        ));
+        return newState == null ? BlockTypesCache.ReservedIDs.AIR : adapter.ibdIDToOrdinal(Block.BLOCK_STATE_REGISTRY.getId(
+                newState));
+    }
+
+    @Override
+    @Nullable
+    public Extent construct(Extent child) {
+        if (child == getExtent()) {
+            return this;
+        }
+        return new PaperweightPlacementStateProcessor(child, mask, region);
+    }
+
+    @Override
+    public PlacementStateProcessor fork() {
+        return new PaperweightPlacementStateProcessor(extent, mask, postCompleteSecondPasses, threadProcessors, region, finished);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext.fawe/v1_20_R3/PaperweightAdapter.java

@@ -856,12 +856,12 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
     }
 
     private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
-        SideEffect.NEIGHBORS,
+            //FAWE start - FAWE-supported side effects
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
             SideEffect.LIGHTING,
-        SideEffect.VALIDATION,
+            SideEffect.NEIGHBORS
-        SideEffect.ENTITY_AI,
+            //FAWE end
-        SideEffect.EVENTS,
-        SideEffect.UPDATE
     );
 
     @Override

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext.fawe/v1_20_R3/PaperweightServerLevelDelegateProxy.java

@@ -0,0 +1,237 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * 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.sk89q.worldedit.bukkit.adapter.ext.fawe.v1_20_R3;
+
+import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.bukkit.adapter.Refraction;
+import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R3.PaperweightFaweAdapter;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class PaperweightServerLevelDelegateProxy implements InvocationHandler {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    // FAWE start - extent not EditSession
+    private final Extent editSession;
+    //FAWE end
+    private final ServerLevel serverLevel;
+    //FAWE start - use FAWE adapter
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    //FAWE end
+    //FAWE start - force error if method not caught by this instance
+    private final boolean errorOnPassthrough;
+    //FAWE end
+
+    private PaperweightServerLevelDelegateProxy(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        this.editSession = editSession;
+        this.serverLevel = serverLevel;
+        //FAWE start
+        this.errorOnPassthrough = false;
+        //FAWE end
+    }
+
+    public static WorldGenLevel newInstance(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(editSession, serverLevel, adapter)
+        );
+    }
+
+    //FAWE start - force error if method not caught by this instance
+    private PaperweightServerLevelDelegateProxy(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        this.editSession = extent;
+        this.serverLevel = serverLevel;
+        this.errorOnPassthrough = errorOnPassthrough;
+    }
+
+    public static WorldGenLevel newInstance(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(extent, serverLevel, errorOnPassthrough)
+        );
+    }
+    //FAWE end
+
+    @Nullable
+    private BlockEntity getBlockEntity(BlockPos blockPos) {
+        BlockEntity tileEntity = this.serverLevel.getChunkAt(blockPos).getBlockEntity(blockPos);
+        if (tileEntity == null) {
+            return null;
+        }
+        BlockEntity newEntity = tileEntity.getType().create(blockPos, getBlockState(blockPos));
+        newEntity.load((CompoundTag) adapter.fromNativeLin(this.editSession.getFullBlock(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        ).getNbtReference().getValue()));
+
+        return newEntity;
+    }
+
+    private BlockState getBlockState(BlockPos blockPos) {
+        return adapter.adapt(this.editSession.getBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+    }
+
+    private boolean setBlock(BlockPos blockPos, BlockState blockState) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), adapter.adapt(blockState));
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private boolean removeBlock(BlockPos blockPos, boolean bl) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), BlockTypes.AIR.getDefaultState());
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private FluidState getFluidState(BlockPos pos) {
+        return getBlockState(pos).getFluidState();
+    }
+
+    private boolean isWaterAt(BlockPos pos) {
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        //FAWE start - cannot use switch where method names are equal
+        String methodName = method.getName();
+        if (Refraction.pickName("getBlockState", "a_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockState
+                return getBlockState(blockPos);
+            }
+        }
+        if (Refraction.pickName("getBlockEntity", "c_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockEntity
+                return getBlockEntity(blockPos);
+            }
+        }
+        if ("a".equals(methodName) || "setBlock".equals(methodName) || "removeBlock".equals(methodName) || "destroyBlock".equals(
+                methodName)) {
+            if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof BlockState blockState) {
+                // setBlock
+                return setBlock(blockPos, blockState);
+            } else if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof Boolean bl) {
+                // removeBlock (and also matches destroyBlock)
+                return removeBlock(blockPos, bl);
+            }
+        }
+        //FAWE start
+        if (Refraction.pickName("getFluidState", "b_").equals(methodName)) { //net.minecraft.world.level.BlockGetter
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return getFluidState(blockPos);
+            }
+        }
+        if (Refraction.pickName("isWaterAt", "z").equals(methodName)) { //net.minecraft.world.level.LevelReader
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return isWaterAt(blockPos);
+            }
+        }
+        if (Refraction.pickName("getEntities", "a_").equals(methodName)) { //net.minecraft.world.level.EntityGetter
+            if (args.length == 2 && args[0] instanceof Entity && args[1] instanceof AABB) {
+                return new ArrayList<>();
+            }
+        }
+        // Specific passthroughs that we want to allow
+        // net.minecraft.world.level.BlockAndTintGetter
+        if (Refraction.pickName("getRawBrightness", "b").equals(methodName)) {
+            return method.invoke(this.serverLevel, args);
+        }
+        // net.minecraft.world.level.LevelHeightAccessor
+        if (Refraction.pickName("getMaxBuildHeight", "al").equals(methodName)) {
+            if (args.length == 0) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        // net.minecraft.world.level.SignalGetter
+        if (Refraction.pickName("hasNeighborSignal", "C").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getSignal", "c").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getControlInputSignal", "a").equals(methodName)) {
+            if (args.length == 3 && args[0] instanceof BlockPos && args[1] instanceof Direction && args[2] instanceof Boolean) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getDirectSignal", "a").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        //FAWE start - force error if method not caught by this instance
+        if (errorOnPassthrough) {
+            LOGGER.error(
+                    """
+                            Attempted passthough of method {}.
+                            Method argument types: {}
+                            Method argument values: {}
+                            """,
+                    method.getName(),
+                    Arrays.stream(args).map(a -> a.getClass().getName()).toList(),
+                    Arrays.stream(args).map(Object::toString).toList()
+            );
+            throw new FaweException("Method required passthrough.");
+        }
+        //FAWE end
+
+        return method.invoke(this.serverLevel, args);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R3/PaperweightFaweAdapter.java

@@ -4,6 +4,7 @@ import com.fastasyncworldedit.bukkit.adapter.FaweAdapter;
 import com.fastasyncworldedit.bukkit.adapter.NMSRelighterFactory;
 import com.fastasyncworldedit.core.FaweCache;
 import com.fastasyncworldedit.core.entity.LazyBaseEntity;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
@@ -13,6 +14,7 @@ import com.fastasyncworldedit.core.util.NbtUtils;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Sets;
 import com.sk89q.jnbt.Tag;
 import com.sk89q.worldedit.blocks.BaseItemStack;
 import com.sk89q.worldedit.bukkit.BukkitAdapter;
@@ -21,7 +23,7 @@ import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R3.nbt.PaperweightLazy
 import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R3.regen.PaperweightRegen;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.Extent;
-import com.sk89q.worldedit.internal.block.BlockStateIdAccess;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.internal.wna.WorldNativeAccess;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -33,7 +35,6 @@ import com.sk89q.worldedit.registry.state.IntegerProperty;
 import com.sk89q.worldedit.registry.state.Property;
 import com.sk89q.worldedit.util.Direction;
 import com.sk89q.worldedit.util.SideEffect;
-import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.RegenOptions;
 import com.sk89q.worldedit.world.biome.BiomeType;
@@ -284,9 +285,16 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return state.toBaseBlock();
     }
 
+    private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
+            SideEffect.LIGHTING,
+            SideEffect.NEIGHBORS
+    );
+
     @Override
     public Set<SideEffect> getSupportedSideEffects() {
-        return SideEffectSet.defaults().getSideEffectsToApply();
+        return SUPPORTED_SIDE_EFFECTS;
     }
 
     @Override
@@ -434,6 +442,10 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return material.getCraftBlockData();
     }
 
+    public net.minecraft.world.level.block.state.BlockState adapt(BlockState blockState) {
+        return Block.stateById(getOrdinalToIbdID()[blockState.getOrdinal()]);
+    }
+
     @Override
     public void sendFakeChunk(org.bukkit.World world, Player player, ChunkPacket chunkPacket) {
         ServerLevel nmsWorld = getServerLevel(world);
@@ -471,8 +483,7 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
 
     @Override
     public boolean canPlaceAt(org.bukkit.World world, BlockVector3 blockVector3, BlockState blockState) {
-        int internalId = BlockStateIdAccess.getBlockStateId(blockState);
+        net.minecraft.world.level.block.state.BlockState blockState1 = Block.stateById(getOrdinalToIbdID()[blockState.getOrdinal()]);
-        net.minecraft.world.level.block.state.BlockState blockState1 = Block.stateById(internalId);
         return blockState1.hasPostProcess(
                 getServerLevel(world),
                 new BlockPos(blockVector3.x(), blockVector3.y(), blockVector3.z())
@@ -602,6 +613,11 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return new PaperweightPostProcessor();
     }
 
+    @Override
+    public PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return new PaperweightPlacementStateProcessor(extent, mask, region);
+    }
+
     private boolean wasAccessibleSinceLastSave(ChunkHolder holder) {
         if (!PaperLib.isPaper() || !PaperweightPlatformAdapter.POST_CHUNK_REWRITE) {
             try {

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R3/PaperweightFaweMutableBlockPlaceContext.java

@@ -0,0 +1,137 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R3;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightFaweMutableBlockPlaceContext extends BlockPlaceContext {
+
+    private static final BlockHitResult DEFAULT_BLOCK_HIT = new BlockHitResult(
+            new Vec3(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            Direction.NORTH,
+            new BlockPos(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            false
+    );
+    private final ServerLevel level;
+    private BlockHitResult hitResult = null;
+    private Direction direction = null;
+    private BlockPos relativePos;
+
+    @SuppressWarnings("DataFlowIssue")
+    public PaperweightFaweMutableBlockPlaceContext(ServerLevel level) {
+        super(level, null, null, null, DEFAULT_BLOCK_HIT
+
+        );
+        this.level = level;
+        this.replaceClicked = false;
+    }
+
+    public PaperweightFaweMutableBlockPlaceContext withSetting(BlockHitResult hitResult, Direction direction) {
+        this.hitResult = hitResult;
+        this.direction = direction;
+        this.relativePos = hitResult.getBlockPos().relative(hitResult.getDirection());
+        return this;
+    }
+
+    @Override
+    @Nonnull
+    public BlockPos getClickedPos() {
+        return this.relativePos;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getClickedFace() {
+        return this.hitResult.getDirection();
+    }
+
+    @Override
+    @Nonnull
+    public Vec3 getClickLocation() {
+        return this.hitResult.getLocation();
+    }
+
+    @Override
+    public boolean isInside() {
+        return this.hitResult.isInside();
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public ItemStack getItemInHand() {
+        return ItemStack.EMPTY;
+    }
+
+    @Nullable
+    @Override
+    public Player getPlayer() {
+        return null;
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public InteractionHand getHand() {
+        return null;
+    }
+
+    @Override
+    @Nonnull
+    public Level getLevel() {
+        return this.level;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getHorizontalDirection() {
+        return this.direction.getAxis() == Direction.Axis.Y ? Direction.NORTH : this.direction;
+    }
+
+    @Override
+    public boolean isSecondaryUseActive() {
+        return false;
+    }
+
+    @Override
+    public float getRotation() {
+        return (float) (this.direction.get2DDataValue() * 90);
+    }
+
+    @Override
+    public boolean canPlace() {
+        return this.getLevel().getBlockState(this.getClickedPos()).canBeReplaced(this);
+    }
+
+    @Override
+    public boolean replacingClickedOnBlock() {
+        return false;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingDirection() {
+        return direction;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingVerticalDirection() {
+        return direction.getAxis() == Direction.Axis.Y ? Direction.UP : Direction.DOWN;
+    }
+
+    @Override
+    @Nonnull
+    public Direction[] getNearestLookingDirections() {
+        return new Direction[]{direction};
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R3/PaperweightGetBlocks.java

@@ -21,6 +21,7 @@ import com.sk89q.worldedit.bukkit.WorldEditPlugin;
 import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.biome.BiomeTypes;
 import com.sk89q.worldedit.world.block.BlockTypesCache;
@@ -840,7 +841,9 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                         nmsChunk.mustNotSave = false;
                         nmsChunk.setUnsaved(true);
                         // send to player
-                        if (Settings.settings().LIGHTING.MODE == 0 || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
+                        if (!set
+                                .getSideEffectSet()
+                                .shouldApply(SideEffect.LIGHTING) || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
                             this.send();
                         }
                         if (finalizer != null) {

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R3/PaperweightLevelProxy.java

@@ -0,0 +1,116 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R3;
+
+import com.fastasyncworldedit.core.util.ReflectionUtils;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import net.minecraft.core.BlockPos;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+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.border.WorldBorder;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.level.material.Fluids;
+import org.enginehub.linbus.tree.LinCompoundTag;
+import sun.misc.Unsafe;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightLevelProxy extends ServerLevel {
+
+    protected ServerLevel serverLevel;
+    private PaperweightFaweAdapter adapter;
+    private PaperweightPlacementStateProcessor processor;
+
+    @SuppressWarnings("DataFlowIssue")
+    private PaperweightLevelProxy() {
+        super(null, null, null, null, null, null, null, true, 0L, null, true, null, null, null, null);
+        throw new IllegalStateException("Cannot be instantiated");
+    }
+
+    public static PaperweightLevelProxy getInstance(ServerLevel serverLevel, PaperweightPlacementStateProcessor processor) {
+        Unsafe unsafe = ReflectionUtils.getUnsafe();
+
+        PaperweightLevelProxy newLevel;
+        try {
+            newLevel = (PaperweightLevelProxy) unsafe.allocateInstance(PaperweightLevelProxy.class);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        }
+        newLevel.processor = processor;
+        newLevel.adapter = ((PaperweightFaweAdapter) WorldEditPlugin.getInstance().getBukkitImplAdapter());
+        newLevel.serverLevel = serverLevel;
+        return newLevel;
+    }
+
+    @Nullable
+    @Override
+    public BlockEntity getBlockEntity(@Nonnull BlockPos blockPos) {
+        if (blockPos.getY() == Integer.MAX_VALUE) {
+            return null;
+        }
+        LinCompoundTag tag = processor.getTileAt(blockPos.getX(), blockPos.getY(), blockPos.getZ());
+        if (tag == null) {
+            return null;
+        }
+        BlockState state = adapter.adapt(processor.getBlockStateAt(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+        if (!(state.getBlock() instanceof EntityBlock entityBlock)) {
+            return null;
+        }
+        BlockEntity tileEntity = entityBlock.newBlockEntity(blockPos, state);
+        tileEntity.load((CompoundTag) adapter.fromNativeLin(tag));
+        return tileEntity;
+    }
+
+    @Override
+    @Nonnull
+    public BlockState getBlockState(@Nonnull BlockPos blockPos) {
+        if (blockPos.getY() == Integer.MAX_VALUE) {
+            return Blocks.AIR.defaultBlockState();
+        }
+        com.sk89q.worldedit.world.block.BlockState state = processor.getBlockStateAt(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        );
+        return adapter.adapt(state);
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    @Nonnull
+    public FluidState getFluidState(@Nonnull BlockPos pos) {
+        if (pos.getY() == Integer.MAX_VALUE) {
+            return Fluids.EMPTY.defaultFluidState();
+        }
+        return getBlockState(pos).getFluidState();
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    public boolean isWaterAt(@Nonnull BlockPos pos) {
+        if (pos.getY() == Integer.MAX_VALUE) {
+            return false;
+        }
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public int getHeight() {
+        return serverLevel.getHeight();
+    }
+
+    @Override
+    public int getMinBuildHeight() {
+        return serverLevel.getMinBuildHeight();
+    }
+
+    @Override
+    public WorldBorder getWorldBorder() {
+        return serverLevel.getWorldBorder();
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R3/PaperweightPlacementStateProcessor.java

@@ -0,0 +1,112 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R3;
+
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
+import com.fastasyncworldedit.core.wrappers.WorldWrapper;
+import com.sk89q.worldedit.bukkit.BukkitWorld;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.Direction;
+import com.sk89q.worldedit.world.World;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import net.minecraft.core.BlockPos;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+import org.bukkit.craftbukkit.v1_20_R3.CraftWorld;
+
+import javax.annotation.Nullable;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class PaperweightPlacementStateProcessor extends PlacementStateProcessor {
+
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    private final PaperweightFaweMutableBlockPlaceContext mutableBlockPlaceContext;
+    private final PaperweightLevelProxy proxyLevel;
+
+    public PaperweightPlacementStateProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        super(extent, mask, region);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    private PaperweightPlacementStateProcessor(
+            Extent extent,
+            BlockTypeMask mask,
+            Map<SecondPass, Character> crossChunkSecondPasses,
+            ThreadLocal<PlacementStateProcessor> threadProcessors,
+            Region region,
+            AtomicBoolean finished
+    ) {
+        super(extent, mask, crossChunkSecondPasses, threadProcessors, region, finished);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    @Override
+    protected char getStateAtFor(
+            int x,
+            int y,
+            int z,
+            BlockState state,
+            Vector3 clickPos,
+            Direction clickedFaceDirection,
+            BlockVector3 clickedBlock
+    ) {
+        Block block = ((PaperweightBlockMaterial) state.getMaterial()).getBlock();
+        Vec3 pos = new Vec3(clickPos.x(), clickPos.y(), clickPos.z());
+        net.minecraft.core.Direction side = net.minecraft.core.Direction.valueOf(clickedFaceDirection.toString());
+        BlockPos blockPos = new BlockPos(clickedBlock.x(), clickedBlock.y(), clickedBlock.z());
+        net.minecraft.world.level.block.state.BlockState newState = block.getStateForPlacement(mutableBlockPlaceContext.withSetting(
+                new BlockHitResult(pos, side, blockPos, false),
+                side.getOpposite()
+        ));
+        return newState == null ? BlockTypesCache.ReservedIDs.AIR : adapter.ibdIDToOrdinal(Block.BLOCK_STATE_REGISTRY.getId(
+                newState));
+    }
+
+    @Override
+    @Nullable
+    public Extent construct(Extent child) {
+        if (child == getExtent()) {
+            return this;
+        }
+        return new PaperweightPlacementStateProcessor(child, mask, region);
+    }
+
+    @Override
+    public PlacementStateProcessor fork() {
+        return new PaperweightPlacementStateProcessor(extent, mask, postCompleteSecondPasses, threadProcessors, region, finished);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext.fawe/v1_20_R4/PaperweightAdapter.java

@@ -880,12 +880,12 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
     }
 
     private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
-        SideEffect.NEIGHBORS,
+            //FAWE start - FAWE-supported side effects
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
             SideEffect.LIGHTING,
-        SideEffect.VALIDATION,
+            SideEffect.NEIGHBORS
-        SideEffect.ENTITY_AI,
+            //FAWE end
-        SideEffect.EVENTS,
-        SideEffect.UPDATE
     );
 
     @Override

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext.fawe/v1_20_R4/PaperweightServerLevelDelegateProxy.java

@@ -0,0 +1,240 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * 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.sk89q.worldedit.bukkit.adapter.ext.fawe.v1_20_R4;
+
+import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.bukkit.adapter.Refraction;
+import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R4.PaperweightFaweAdapter;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class PaperweightServerLevelDelegateProxy implements InvocationHandler {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    // FAWE start - extent not EditSession
+    private final Extent editSession;
+    //FAWE end
+    private final ServerLevel serverLevel;
+    //FAWE start - use FAWE adapter
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    //FAWE end
+    //FAWE start - force error if method not caught by this instance
+    private final boolean errorOnPassthrough;
+    //FAWE end
+
+    private PaperweightServerLevelDelegateProxy(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        this.editSession = editSession;
+        this.serverLevel = serverLevel;
+        //FAWE start
+        this.errorOnPassthrough = false;
+        //FAWE end
+    }
+
+    public static WorldGenLevel newInstance(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(editSession, serverLevel, adapter)
+        );
+    }
+
+    //FAWE start - force error if method not caught by this instance
+    private PaperweightServerLevelDelegateProxy(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        this.editSession = extent;
+        this.serverLevel = serverLevel;
+        this.errorOnPassthrough = errorOnPassthrough;
+    }
+
+    public static WorldGenLevel newInstance(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(extent, serverLevel, errorOnPassthrough)
+        );
+    }
+    //FAWE end
+
+    @Nullable
+    private BlockEntity getBlockEntity(BlockPos blockPos) {
+        BlockEntity tileEntity = this.serverLevel.getChunkAt(blockPos).getBlockEntity(blockPos);
+        if (tileEntity == null) {
+            return null;
+        }
+        BlockEntity newEntity = tileEntity.getType().create(blockPos, getBlockState(blockPos));
+        newEntity.loadWithComponents(
+                (CompoundTag) adapter.fromNativeLin(this.editSession.getFullBlock(
+                        blockPos.getX(),
+                        blockPos.getY(),
+                        blockPos.getZ()
+                ).getNbtReference().getValue()),
+                this.serverLevel.registryAccess()
+        );
+
+        return newEntity;
+    }
+
+    private BlockState getBlockState(BlockPos blockPos) {
+        return adapter.adapt(this.editSession.getBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+    }
+
+    private boolean setBlock(BlockPos blockPos, BlockState blockState) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), adapter.adapt(blockState));
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private boolean removeBlock(BlockPos blockPos, boolean bl) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), BlockTypes.AIR.getDefaultState());
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private FluidState getFluidState(BlockPos pos) {
+        return getBlockState(pos).getFluidState();
+    }
+
+    private boolean isWaterAt(BlockPos pos) {
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        //FAWE start - cannot use switch where method names are equal
+        String methodName = method.getName();
+        if (Refraction.pickName("getBlockState", "a_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockState
+                return getBlockState(blockPos);
+            }
+        }
+        if (Refraction.pickName("getBlockEntity", "c_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockEntity
+                return getBlockEntity(blockPos);
+            }
+        }
+        if ("a".equals(methodName) || "setBlock".equals(methodName) || "removeBlock".equals(methodName) || "destroyBlock".equals(
+                methodName)) {
+            if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof BlockState blockState) {
+                // setBlock
+                return setBlock(blockPos, blockState);
+            } else if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof Boolean bl) {
+                // removeBlock (and also matches destroyBlock)
+                return removeBlock(blockPos, bl);
+            }
+        }
+        //FAWE start
+        if (Refraction.pickName("getFluidState", "b_").equals(methodName)) { //net.minecraft.world.level.BlockGetter
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return getFluidState(blockPos);
+            }
+        }
+        if (Refraction.pickName("isWaterAt", "z").equals(methodName)) { //net.minecraft.world.level.LevelReader
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return isWaterAt(blockPos);
+            }
+        }
+        if (Refraction.pickName("getEntities", "a_").equals(methodName)) { //net.minecraft.world.level.EntityGetter
+            if (args.length == 2 && args[0] instanceof Entity && args[1] instanceof AABB) {
+                return new ArrayList<>();
+            }
+        }
+        // Specific passthroughs that we want to allow
+        // net.minecraft.world.level.BlockAndTintGetter
+        if (Refraction.pickName("getRawBrightness", "b").equals(methodName)) {
+            return method.invoke(this.serverLevel, args);
+        }
+        // net.minecraft.world.level.LevelHeightAccessor
+        if (Refraction.pickName("getMaxBuildHeight", "al").equals(methodName)) {
+            if (args.length == 0) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        // net.minecraft.world.level.SignalGetter
+        if (Refraction.pickName("hasNeighborSignal", "C").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getSignal", "c").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getControlInputSignal", "a").equals(methodName)) {
+            if (args.length == 3 && args[0] instanceof BlockPos && args[1] instanceof Direction && args[2] instanceof Boolean) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getDirectSignal", "a").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        //FAWE start - force error if method not caught by this instance
+        if (errorOnPassthrough) {
+            LOGGER.error(
+                    """
+                            Attempted passthough of method {}.
+                            Method argument types: {}
+                            Method argument values: {}
+                            """,
+                    method.getName(),
+                    Arrays.stream(args).map(a -> a.getClass().getName()).toList(),
+                    Arrays.stream(args).map(Object::toString).toList()
+            );
+            throw new FaweException("Method required passthrough.");
+        }
+        //FAWE end
+
+        return method.invoke(this.serverLevel, args);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R4/PaperweightFaweAdapter.java

@@ -4,6 +4,7 @@ import com.fastasyncworldedit.bukkit.adapter.FaweAdapter;
 import com.fastasyncworldedit.bukkit.adapter.NMSRelighterFactory;
 import com.fastasyncworldedit.core.FaweCache;
 import com.fastasyncworldedit.core.entity.LazyBaseEntity;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
@@ -13,6 +14,7 @@ import com.fastasyncworldedit.core.util.NbtUtils;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Sets;
 import com.mojang.serialization.Codec;
 import com.sk89q.jnbt.Tag;
 import com.sk89q.worldedit.blocks.BaseItemStack;
@@ -22,6 +24,7 @@ import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R4.nbt.PaperweightLazy
 import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R4.regen.PaperweightRegen;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.block.BlockStateIdAccess;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.internal.wna.WorldNativeAccess;
@@ -34,7 +37,6 @@ import com.sk89q.worldedit.registry.state.IntegerProperty;
 import com.sk89q.worldedit.registry.state.Property;
 import com.sk89q.worldedit.util.Direction;
 import com.sk89q.worldedit.util.SideEffect;
-import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.concurrency.LazyReference;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.RegenOptions;
@@ -293,9 +295,16 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return state.toBaseBlock();
     }
 
+    private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
+            SideEffect.LIGHTING,
+            SideEffect.NEIGHBORS
+    );
+
     @Override
     public Set<SideEffect> getSupportedSideEffects() {
-        return SideEffectSet.defaults().getSideEffectsToApply();
+        return SUPPORTED_SIDE_EFFECTS;
     }
 
     @Override
@@ -443,6 +452,10 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return material.getCraftBlockData();
     }
 
+    public net.minecraft.world.level.block.state.BlockState adapt(BlockState blockState) {
+        return Block.stateById(getOrdinalToIbdID()[blockState.getOrdinal()]);
+    }
+
     @Override
     public void sendFakeChunk(org.bukkit.World world, Player player, ChunkPacket chunkPacket) {
         ServerLevel nmsWorld = getServerLevel(world);
@@ -624,6 +637,11 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return new PaperweightPostProcessor();
     }
 
+    @Override
+    public PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return new PaperweightPlacementStateProcessor(extent, mask, region);
+    }
+
     private boolean wasAccessibleSinceLastSave(ChunkHolder holder) {
         if (!PaperLib.isPaper() || !PaperweightPlatformAdapter.POST_CHUNK_REWRITE) {
             try {

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R4/PaperweightFaweMutableBlockPlaceContext.java

@@ -0,0 +1,143 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R4;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightFaweMutableBlockPlaceContext extends BlockPlaceContext {
+
+    private static final BlockHitResult DEFAULT_BLOCK_HIT = new BlockHitResult(
+            new Vec3(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            Direction.NORTH,
+            new BlockPos(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            false
+    );
+    private final ServerLevel level;
+    private BlockHitResult hitResult = null;
+    private Direction direction = null;
+    private BlockPos relativePos;
+
+    @SuppressWarnings("DataFlowIssue")
+    public PaperweightFaweMutableBlockPlaceContext(ServerLevel level) {
+        super(
+                level,
+                null,
+                null,
+                null,
+                DEFAULT_BLOCK_HIT
+
+        );
+        this.level = level;
+        this.replaceClicked = false;
+    }
+
+    public PaperweightFaweMutableBlockPlaceContext withSetting(BlockHitResult hitResult, Direction direction) {
+        this.hitResult = hitResult;
+        this.direction = direction;
+        this.relativePos = hitResult.getBlockPos().relative(hitResult.getDirection());
+        return this;
+    }
+
+    @Override
+    @Nonnull
+    public BlockPos getClickedPos() {
+        return this.relativePos;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getClickedFace() {
+        return this.hitResult.getDirection();
+    }
+
+    @Override
+    @Nonnull
+    public Vec3 getClickLocation() {
+        return this.hitResult.getLocation();
+    }
+
+    @Override
+    public boolean isInside() {
+        return this.hitResult.isInside();
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public ItemStack getItemInHand() {
+        return ItemStack.EMPTY;
+    }
+
+    @Nullable
+    @Override
+    public Player getPlayer() {
+        return null;
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public InteractionHand getHand() {
+        return null;
+    }
+
+    @Override
+    @Nonnull
+    public Level getLevel() {
+        return this.level;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getHorizontalDirection() {
+        return this.direction.getAxis() == Direction.Axis.Y ? Direction.NORTH : this.direction;
+    }
+
+    @Override
+    public boolean isSecondaryUseActive() {
+        return false;
+    }
+
+    @Override
+    public float getRotation() {
+        return (float) (this.direction.get2DDataValue() * 90);
+    }
+
+    @Override
+    public boolean canPlace() {
+        return this.getLevel().getBlockState(this.getClickedPos()).canBeReplaced(this);
+    }
+
+    @Override
+    public boolean replacingClickedOnBlock() {
+        return false;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingDirection() {
+        return direction;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingVerticalDirection() {
+        return direction.getAxis() == Direction.Axis.Y ? Direction.UP : Direction.DOWN;
+    }
+
+    @Override
+    @Nonnull
+    public Direction[] getNearestLookingDirections() {
+        return new Direction[]{direction};
+    }
+
+}
+

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R4/PaperweightGetBlocks.java

@@ -21,6 +21,7 @@ import com.sk89q.worldedit.bukkit.WorldEditPlugin;
 import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.biome.BiomeTypes;
 import com.sk89q.worldedit.world.block.BlockTypesCache;
@@ -841,7 +842,9 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                         nmsChunk.mustNotSave = false;
                         nmsChunk.setUnsaved(true);
                         // send to player
-                        if (Settings.settings().LIGHTING.MODE == 0 || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
+                        if (!set
+                                .getSideEffectSet()
+                                .shouldApply(SideEffect.LIGHTING) || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
                             this.send();
                         }
                         if (finalizer != null) {

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R4/PaperweightLevelProxy.java

@@ -0,0 +1,116 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R4;
+
+import com.fastasyncworldedit.core.util.ReflectionUtils;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import net.minecraft.core.BlockPos;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+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.border.WorldBorder;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.level.material.Fluids;
+import org.enginehub.linbus.tree.LinCompoundTag;
+import sun.misc.Unsafe;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightLevelProxy extends ServerLevel {
+
+    protected ServerLevel serverLevel;
+    private PaperweightPlacementStateProcessor processor;
+    private PaperweightFaweAdapter adapter;
+
+    @SuppressWarnings("DataFlowIssue")
+    private PaperweightLevelProxy() {
+        super(null, null, null, null, null, null, null, true, 0L, null, true, null, null, null, null);
+        throw new IllegalStateException("Cannot be instantiated");
+    }
+
+    public static PaperweightLevelProxy getInstance(ServerLevel serverLevel, PaperweightPlacementStateProcessor processor) {
+        Unsafe unsafe = ReflectionUtils.getUnsafe();
+
+        PaperweightLevelProxy newLevel;
+        try {
+            newLevel = (PaperweightLevelProxy) unsafe.allocateInstance(PaperweightLevelProxy.class);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        }
+        newLevel.processor = processor;
+        newLevel.adapter = ((PaperweightFaweAdapter) WorldEditPlugin.getInstance().getBukkitImplAdapter());
+        newLevel.serverLevel = serverLevel;
+        return newLevel;
+    }
+
+    @Nullable
+    @Override
+    public BlockEntity getBlockEntity(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return null;
+        }
+        LinCompoundTag tag = processor.getTileAt(blockPos.getX(), blockPos.getY(), blockPos.getZ());
+        if (tag == null) {
+            return null;
+        }
+        BlockState state = adapter.adapt(processor.getBlockStateAt(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+        if (!(state.getBlock() instanceof EntityBlock entityBlock)) {
+            return null;
+        }
+        BlockEntity tileEntity = entityBlock.newBlockEntity(blockPos, state);
+        tileEntity.loadWithComponents((CompoundTag) adapter.fromNativeLin(tag), serverLevel.registryAccess());
+        return tileEntity;
+    }
+
+    @Override
+    @Nonnull
+    public BlockState getBlockState(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return Blocks.AIR.defaultBlockState();
+        }
+        com.sk89q.worldedit.world.block.BlockState state = processor.getBlockStateAt(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        );
+        return adapter.adapt(state);
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    @Nonnull
+    public FluidState getFluidState(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return Fluids.EMPTY.defaultFluidState();
+        }
+        return getBlockState(pos).getFluidState();
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    public boolean isWaterAt(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return false;
+        }
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public int getHeight() {
+        return serverLevel.getHeight();
+    }
+
+    @Override
+    public int getMinBuildHeight() {
+        return serverLevel.getMinBuildHeight();
+    }
+
+    @Override
+    public WorldBorder getWorldBorder() {
+        return serverLevel.getWorldBorder();
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_20_R4/PaperweightPlacementStateProcessor.java

@@ -0,0 +1,111 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_20_R4;
+
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
+import com.fastasyncworldedit.core.wrappers.WorldWrapper;
+import com.sk89q.worldedit.bukkit.BukkitWorld;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.Direction;
+import com.sk89q.worldedit.world.World;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+import org.bukkit.craftbukkit.CraftWorld;
+
+import javax.annotation.Nullable;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class PaperweightPlacementStateProcessor extends PlacementStateProcessor {
+
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    private final PaperweightLevelProxy proxyLevel;
+    private final PaperweightFaweMutableBlockPlaceContext mutableBlockPlaceContext;
+
+    public PaperweightPlacementStateProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        super(extent, mask, region);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    private PaperweightPlacementStateProcessor(
+            Extent extent,
+            BlockTypeMask mask,
+            Map<SecondPass, Character> crossChunkSecondPasses,
+            ServerLevel serverLevel,
+            ThreadLocal<PlacementStateProcessor> threadProcessors,
+            Region region,
+            AtomicBoolean finished
+    ) {
+        super(extent, mask, crossChunkSecondPasses, threadProcessors, region, finished);
+        this.proxyLevel = PaperweightLevelProxy.getInstance(serverLevel, this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    @Override
+    protected char getStateAtFor(
+            int x,
+            int y,
+            int z,
+            BlockState state,
+            Vector3 clickPos,
+            Direction clickedFaceDirection,
+            BlockVector3 clickedBlock
+    ) {
+        Block block = ((PaperweightBlockMaterial) state.getMaterial()).getBlock();
+        Vec3 pos = new Vec3(clickPos.x(), clickPos.y(), clickPos.z());
+        net.minecraft.core.Direction side = net.minecraft.core.Direction.valueOf(clickedFaceDirection.toString());
+        BlockPos blockPos = new BlockPos(clickedBlock.x(), clickedBlock.y(), clickedBlock.z());
+        net.minecraft.world.level.block.state.BlockState newState = block.getStateForPlacement(mutableBlockPlaceContext.withSetting(
+                new BlockHitResult(pos, side, blockPos, false),
+                side.getOpposite()
+        ));
+        return newState == null ? BlockTypesCache.ReservedIDs.AIR : adapter.ibdIDToOrdinal(Block.BLOCK_STATE_REGISTRY.getId(
+                newState));
+    }
+
+    @Override
+    @Nullable
+    public Extent construct(Extent child) {
+        if (child == getExtent()) {
+            return this;
+        }
+        return new PaperweightPlacementStateProcessor(child, mask, region);
+    }
+
+    @Override
+    public PlacementStateProcessor fork() {
+        return new PaperweightPlacementStateProcessor(
+                extent,
+                mask,
+                postCompleteSecondPasses,
+                proxyLevel.serverLevel,
+                threadProcessors,
+                region,
+                finished
+        );
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_21_R1/PaperweightAdapter.java

@@ -886,12 +886,12 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
     }
 
     private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
-        SideEffect.NEIGHBORS,
+            //FAWE start - FAWE-supported side effects
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
             SideEffect.LIGHTING,
-        SideEffect.VALIDATION,
+            SideEffect.NEIGHBORS
-        SideEffect.ENTITY_AI,
+            //FAWE end
-        SideEffect.EVENTS,
-        SideEffect.UPDATE
     );
 
     @Override

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_21_R1/PaperweightServerLevelDelegateProxy.java

@@ -0,0 +1,240 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * 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.sk89q.worldedit.bukkit.adapter.ext.fawe.v1_21_R1;
+
+import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.bukkit.adapter.Refraction;
+import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_R1.PaperweightFaweAdapter;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class PaperweightServerLevelDelegateProxy implements InvocationHandler {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    // FAWE start - extent not EditSession
+    private final Extent editSession;
+    //FAWE end
+    private final ServerLevel serverLevel;
+    //FAWE start - use FAWE adapter
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    //FAWE end
+    //FAWE start - force error if method not caught by this instance
+    private final boolean errorOnPassthrough;
+    //FAWE end
+
+    private PaperweightServerLevelDelegateProxy(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        this.editSession = editSession;
+        this.serverLevel = serverLevel;
+        //FAWE start
+        this.errorOnPassthrough = false;
+        //FAWE end
+    }
+
+    public static WorldGenLevel newInstance(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(editSession, serverLevel, adapter)
+        );
+    }
+
+    //FAWE start - force error if method not caught by this instance
+    private PaperweightServerLevelDelegateProxy(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        this.editSession = extent;
+        this.serverLevel = serverLevel;
+        this.errorOnPassthrough = errorOnPassthrough;
+    }
+
+    public static WorldGenLevel newInstance(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(extent, serverLevel, errorOnPassthrough)
+        );
+    }
+    //FAWE end
+
+    @Nullable
+    private BlockEntity getBlockEntity(BlockPos blockPos) {
+        BlockEntity tileEntity = this.serverLevel.getChunkAt(blockPos).getBlockEntity(blockPos);
+        if (tileEntity == null) {
+            return null;
+        }
+        BlockEntity newEntity = tileEntity.getType().create(blockPos, getBlockState(blockPos));
+        newEntity.loadWithComponents(
+                (CompoundTag) adapter.fromNativeLin(this.editSession.getFullBlock(
+                        blockPos.getX(),
+                        blockPos.getY(),
+                        blockPos.getZ()
+                ).getNbtReference().getValue()),
+                this.serverLevel.registryAccess()
+        );
+
+        return newEntity;
+    }
+
+    private BlockState getBlockState(BlockPos blockPos) {
+        return adapter.adapt(this.editSession.getBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+    }
+
+    private boolean setBlock(BlockPos blockPos, BlockState blockState) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), adapter.adapt(blockState));
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private boolean removeBlock(BlockPos blockPos, boolean bl) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), BlockTypes.AIR.getDefaultState());
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private FluidState getFluidState(BlockPos pos) {
+        return getBlockState(pos).getFluidState();
+    }
+
+    private boolean isWaterAt(BlockPos pos) {
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        //FAWE start - cannot use switch where method names are equal
+        String methodName = method.getName();
+        if (Refraction.pickName("getBlockState", "a_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockState
+                return getBlockState(blockPos);
+            }
+        }
+        if (Refraction.pickName("getBlockEntity", "c_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockEntity
+                return getBlockEntity(blockPos);
+            }
+        }
+        if ("a".equals(methodName) || "setBlock".equals(methodName) || "removeBlock".equals(methodName) || "destroyBlock".equals(
+                methodName)) {
+            if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof BlockState blockState) {
+                // setBlock
+                return setBlock(blockPos, blockState);
+            } else if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof Boolean bl) {
+                // removeBlock (and also matches destroyBlock)
+                return removeBlock(blockPos, bl);
+            }
+        }
+        //FAWE start
+        if (Refraction.pickName("getFluidState", "b_").equals(methodName)) { //net.minecraft.world.level.BlockGetter
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return getFluidState(blockPos);
+            }
+        }
+        if (Refraction.pickName("isWaterAt", "z").equals(methodName)) { //net.minecraft.world.level.LevelReader
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return isWaterAt(blockPos);
+            }
+        }
+        if (Refraction.pickName("getEntities", "a_").equals(methodName)) { //net.minecraft.world.level.EntityGetter
+            if (args.length == 2 && args[0] instanceof Entity && args[1] instanceof AABB) {
+                return new ArrayList<>();
+            }
+        }
+        // Specific passthroughs that we want to allow
+        // net.minecraft.world.level.BlockAndTintGetter
+        if (Refraction.pickName("getRawBrightness", "b").equals(methodName)) {
+            return method.invoke(this.serverLevel, args);
+        }
+        // net.minecraft.world.level.LevelHeightAccessor
+        if (Refraction.pickName("getMaxBuildHeight", "al").equals(methodName)) {
+            if (args.length == 0) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        // net.minecraft.world.level.SignalGetter
+        if (Refraction.pickName("hasNeighborSignal", "C").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getSignal", "c").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getControlInputSignal", "a").equals(methodName)) {
+            if (args.length == 3 && args[0] instanceof BlockPos && args[1] instanceof Direction && args[2] instanceof Boolean) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getDirectSignal", "a").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        //FAWE start - force error if method not caught by this instance
+        if (errorOnPassthrough) {
+            LOGGER.error(
+                    """
+                            Attempted passthough of method {}.
+                            Method argument types: {}
+                            Method argument values: {}
+                            """,
+                    method.getName(),
+                    Arrays.stream(args).map(a -> a.getClass().getName()).toList(),
+                    Arrays.stream(args).map(Object::toString).toList()
+            );
+            throw new FaweException("Method required passthrough.");
+        }
+        //FAWE end
+
+        return method.invoke(this.serverLevel, args);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_R1/PaperweightFaweAdapter.java

@@ -4,6 +4,7 @@ import com.fastasyncworldedit.bukkit.adapter.FaweAdapter;
 import com.fastasyncworldedit.bukkit.adapter.NMSRelighterFactory;
 import com.fastasyncworldedit.core.FaweCache;
 import com.fastasyncworldedit.core.entity.LazyBaseEntity;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
@@ -13,6 +14,7 @@ import com.fastasyncworldedit.core.util.NbtUtils;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Sets;
 import com.mojang.serialization.Codec;
 import com.sk89q.jnbt.Tag;
 import com.sk89q.worldedit.blocks.BaseItemStack;
@@ -22,6 +24,7 @@ import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_R1.nbt.PaperweightLazy
 import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_R1.regen.PaperweightRegen;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.block.BlockStateIdAccess;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.internal.wna.WorldNativeAccess;
@@ -34,7 +37,6 @@ import com.sk89q.worldedit.registry.state.IntegerProperty;
 import com.sk89q.worldedit.registry.state.Property;
 import com.sk89q.worldedit.util.Direction;
 import com.sk89q.worldedit.util.SideEffect;
-import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.concurrency.LazyReference;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.RegenOptions;
@@ -293,9 +295,16 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return state.toBaseBlock();
     }
 
+    private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
+            SideEffect.LIGHTING,
+            SideEffect.NEIGHBORS
+    );
+
     @Override
     public Set<SideEffect> getSupportedSideEffects() {
-        return SideEffectSet.defaults().getSideEffectsToApply();
+        return SUPPORTED_SIDE_EFFECTS;
     }
 
     @Override
@@ -443,6 +452,10 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return material.getCraftBlockData();
     }
 
+    public net.minecraft.world.level.block.state.BlockState adapt(BlockState blockState) {
+        return Block.stateById(getOrdinalToIbdID()[blockState.getOrdinal()]);
+    }
+
     @Override
     public void sendFakeChunk(org.bukkit.World world, Player player, ChunkPacket chunkPacket) {
         ServerLevel nmsWorld = getServerLevel(world);
@@ -624,6 +637,11 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return new PaperweightPostProcessor();
     }
 
+    @Override
+    public PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return new PaperweightPlacementStateProcessor(extent, mask, region);
+    }
+
     private boolean wasAccessibleSinceLastSave(ChunkHolder holder) {
         if (PaperLib.isPaper()) { // Papers new chunk system has no related replacement - therefor we assume true.
             return true;

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_R1/PaperweightFaweMutableBlockPlaceContext.java

@@ -0,0 +1,143 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_R1;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightFaweMutableBlockPlaceContext extends BlockPlaceContext {
+
+    private static final BlockHitResult DEFAULT_BLOCK_HIT = new BlockHitResult(
+            new Vec3(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            Direction.NORTH,
+            new BlockPos(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            false
+    );
+    private final ServerLevel level;
+    private BlockHitResult hitResult = null;
+    private Direction direction = null;
+    private BlockPos relativePos;
+
+    @SuppressWarnings("DataFlowIssue")
+    public PaperweightFaweMutableBlockPlaceContext(ServerLevel level) {
+        super(
+                level,
+                null,
+                null,
+                null,
+                DEFAULT_BLOCK_HIT
+
+        );
+        this.level = level;
+        this.replaceClicked = false;
+    }
+
+    public PaperweightFaweMutableBlockPlaceContext withSetting(BlockHitResult hitResult, Direction direction) {
+        this.hitResult = hitResult;
+        this.direction = direction;
+        this.relativePos = hitResult.getBlockPos().relative(hitResult.getDirection());
+        return this;
+    }
+
+    @Override
+    @Nonnull
+    public BlockPos getClickedPos() {
+        return this.relativePos;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getClickedFace() {
+        return this.hitResult.getDirection();
+    }
+
+    @Override
+    @Nonnull
+    public Vec3 getClickLocation() {
+        return this.hitResult.getLocation();
+    }
+
+    @Override
+    public boolean isInside() {
+        return this.hitResult.isInside();
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public ItemStack getItemInHand() {
+        return ItemStack.EMPTY;
+    }
+
+    @Nullable
+    @Override
+    public Player getPlayer() {
+        return null;
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public InteractionHand getHand() {
+        return null;
+    }
+
+    @Override
+    @Nonnull
+    public Level getLevel() {
+        return this.level;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getHorizontalDirection() {
+        return this.direction.getAxis() == Direction.Axis.Y ? Direction.NORTH : this.direction;
+    }
+
+    @Override
+    public boolean isSecondaryUseActive() {
+        return false;
+    }
+
+    @Override
+    public float getRotation() {
+        return (float) (this.direction.get2DDataValue() * 90);
+    }
+
+    @Override
+    public boolean canPlace() {
+        return this.getLevel().getBlockState(this.getClickedPos()).canBeReplaced(this);
+    }
+
+    @Override
+    public boolean replacingClickedOnBlock() {
+        return false;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingDirection() {
+        return direction;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingVerticalDirection() {
+        return direction.getAxis() == Direction.Axis.Y ? Direction.UP : Direction.DOWN;
+    }
+
+    @Override
+    @Nonnull
+    public Direction[] getNearestLookingDirections() {
+        return new Direction[]{direction};
+    }
+
+}
+

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_R1/PaperweightGetBlocks.java

@@ -21,6 +21,7 @@ import com.sk89q.worldedit.bukkit.WorldEditPlugin;
 import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.biome.BiomeTypes;
 import com.sk89q.worldedit.world.block.BlockTypesCache;
@@ -836,7 +837,9 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                         nmsChunk.mustNotSave = false;
                         nmsChunk.setUnsaved(true);
                         // send to player
-                        if (Settings.settings().LIGHTING.MODE == 0 || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
+                        if (!set
+                                .getSideEffectSet()
+                                .shouldApply(SideEffect.LIGHTING) || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
                             this.send();
                         }
                         if (finalizer != null) {

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_R1/PaperweightLevelProxy.java

@@ -0,0 +1,115 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_R1;
+
+import com.fastasyncworldedit.core.util.ReflectionUtils;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import net.minecraft.core.BlockPos;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+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.border.WorldBorder;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.level.material.Fluids;
+import org.enginehub.linbus.tree.LinCompoundTag;
+import sun.misc.Unsafe;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightLevelProxy extends ServerLevel {
+
+    protected ServerLevel serverLevel;
+    private PaperweightPlacementStateProcessor processor;
+    private PaperweightFaweAdapter adapter;
+
+    @SuppressWarnings("DataFlowIssue")
+    private PaperweightLevelProxy() {
+        super(null, null, null, null, null, null, null, true, 0L, null, true, null, null, null, null);
+        throw new IllegalStateException("Cannot be instantiated");
+    }
+
+    public static PaperweightLevelProxy getInstance(ServerLevel serverLevel, PaperweightPlacementStateProcessor processor) {
+        Unsafe unsafe = ReflectionUtils.getUnsafe();
+
+        PaperweightLevelProxy newLevel;
+        try {
+            newLevel = (PaperweightLevelProxy) unsafe.allocateInstance(PaperweightLevelProxy.class);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        }
+        newLevel.processor = processor;
+        newLevel.adapter = ((PaperweightFaweAdapter) WorldEditPlugin.getInstance().getBukkitImplAdapter());
+        newLevel.serverLevel = serverLevel;
+        return newLevel;
+    }
+
+    @Nullable
+    @Override
+    public BlockEntity getBlockEntity(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return null;
+        }
+        LinCompoundTag tag = processor.getTileAt(blockPos.getX(), blockPos.getY(), blockPos.getZ());
+        if (tag == null) {
+            return null;
+        }
+        BlockState state = adapter.adapt(processor.getBlockStateAt(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+        if (!(state.getBlock() instanceof EntityBlock entityBlock)) {
+            return null;
+        }
+        BlockEntity tileEntity = entityBlock.newBlockEntity(blockPos, state);
+        tileEntity.loadWithComponents((CompoundTag) adapter.fromNativeLin(tag), serverLevel.registryAccess());
+        return tileEntity;
+    }
+
+    @Override
+    @Nonnull
+    public BlockState getBlockState(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return Blocks.AIR.defaultBlockState();
+        }
+        com.sk89q.worldedit.world.block.BlockState state = processor.getBlockStateAt(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        );
+        return adapter.adapt(state);
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    @Nonnull
+    public FluidState getFluidState(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return Fluids.EMPTY.defaultFluidState();
+        }
+        return getBlockState(pos).getFluidState();
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    public boolean isWaterAt(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return false;
+        }
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public int getHeight() {
+        return serverLevel.getHeight();
+    }
+
+    @Override
+    public int getMinBuildHeight() {
+        return serverLevel.getMinBuildHeight();
+    }
+
+    @Override
+    public WorldBorder getWorldBorder() {
+        return serverLevel.getWorldBorder();
+    }
+}

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_R1/PaperweightPlacementStateProcessor.java

@@ -0,0 +1,111 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_R1;
+
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
+import com.fastasyncworldedit.core.wrappers.WorldWrapper;
+import com.sk89q.worldedit.bukkit.BukkitWorld;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.Direction;
+import com.sk89q.worldedit.world.World;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+import org.bukkit.craftbukkit.CraftWorld;
+
+import javax.annotation.Nullable;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class PaperweightPlacementStateProcessor extends PlacementStateProcessor {
+
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    private final PaperweightFaweMutableBlockPlaceContext mutableBlockPlaceContext;
+    private final PaperweightLevelProxy proxyLevel;
+
+    public PaperweightPlacementStateProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        super(extent, mask, region);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    private PaperweightPlacementStateProcessor(
+            Extent extent,
+            BlockTypeMask mask,
+            Map<SecondPass, Character> crossChunkSecondPasses,
+            ServerLevel serverLevel,
+            ThreadLocal<PlacementStateProcessor> threadProcessors,
+            Region region,
+            AtomicBoolean finished
+    ) {
+        super(extent, mask, crossChunkSecondPasses, threadProcessors, region, finished);
+        this.proxyLevel = PaperweightLevelProxy.getInstance(serverLevel, this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    @Override
+    protected char getStateAtFor(
+            int x,
+            int y,
+            int z,
+            BlockState state,
+            Vector3 clickPos,
+            Direction clickedFaceDirection,
+            BlockVector3 clickedBlock
+    ) {
+        Block block = ((PaperweightBlockMaterial) state.getMaterial()).getBlock();
+        Vec3 pos = new Vec3(clickPos.x(), clickPos.y(), clickPos.z());
+        net.minecraft.core.Direction side = net.minecraft.core.Direction.valueOf(clickedFaceDirection.toString());
+        BlockPos blockPos = new BlockPos(clickedBlock.x(), clickedBlock.y(), clickedBlock.z());
+        net.minecraft.world.level.block.state.BlockState newState = block.getStateForPlacement(mutableBlockPlaceContext.withSetting(
+                new BlockHitResult(pos, side, blockPos, false),
+                side.getOpposite()
+        ));
+        return newState == null ? BlockTypesCache.ReservedIDs.AIR : adapter.ibdIDToOrdinal(Block.BLOCK_STATE_REGISTRY.getId(
+                newState));
+    }
+
+    @Override
+    @Nullable
+    public Extent construct(Extent child) {
+        if (child == getExtent()) {
+            return this;
+        }
+        return new PaperweightPlacementStateProcessor(child, mask, region);
+    }
+
+    @Override
+    public PlacementStateProcessor fork() {
+        return new PaperweightPlacementStateProcessor(
+                extent,
+                mask,
+                postCompleteSecondPasses,
+                proxyLevel.serverLevel,
+                threadProcessors,
+                region,
+                finished
+        );
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_21_3/PaperweightAdapter.java

@@ -849,12 +849,12 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
     }
 
     private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
-        SideEffect.NEIGHBORS,
+        //FAWE start - FAWE-supported side effects
+        SideEffect.HISTORY,
+        SideEffect.HEIGHTMAPS,
         SideEffect.LIGHTING,
-        SideEffect.VALIDATION,
+        SideEffect.NEIGHBORS
-        SideEffect.ENTITY_AI,
+        //FAWE end
-        SideEffect.EVENTS,
-        SideEffect.UPDATE
     );
 
     @Override

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_21_3/PaperweightServerLevelDelegateProxy.java

@@ -0,0 +1,240 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * 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.sk89q.worldedit.bukkit.adapter.ext.fawe.v1_21_3;
+
+import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.bukkit.adapter.Refraction;
+import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_3.PaperweightFaweAdapter;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.block.entity.BlockEntity;
+import net.minecraft.world.level.block.state.BlockState;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.phys.AABB;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class PaperweightServerLevelDelegateProxy implements InvocationHandler {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    // FAWE start - extent not EditSession
+    private final Extent editSession;
+    //FAWE end
+    private final ServerLevel serverLevel;
+    //FAWE start - use FAWE adapter
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    //FAWE end
+    //FAWE start - force error if method not caught by this instance
+    private final boolean errorOnPassthrough;
+    //FAWE end
+
+    private PaperweightServerLevelDelegateProxy(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        this.editSession = editSession;
+        this.serverLevel = serverLevel;
+        //FAWE start
+        this.errorOnPassthrough = false;
+        //FAWE end
+    }
+
+    public static WorldGenLevel newInstance(EditSession editSession, ServerLevel serverLevel, PaperweightAdapter adapter) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(editSession, serverLevel, adapter)
+        );
+    }
+
+    //FAWE start - force error if method not caught by this instance
+    private PaperweightServerLevelDelegateProxy(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        this.editSession = extent;
+        this.serverLevel = serverLevel;
+        this.errorOnPassthrough = errorOnPassthrough;
+    }
+
+    public static WorldGenLevel newInstance(Extent extent, ServerLevel serverLevel, boolean errorOnPassthrough) {
+        return (WorldGenLevel) Proxy.newProxyInstance(
+                serverLevel.getClass().getClassLoader(),
+                serverLevel.getClass().getInterfaces(),
+                new PaperweightServerLevelDelegateProxy(extent, serverLevel, errorOnPassthrough)
+        );
+    }
+    //FAWE end
+
+    @Nullable
+    private BlockEntity getBlockEntity(BlockPos blockPos) {
+        BlockEntity tileEntity = this.serverLevel.getChunkAt(blockPos).getBlockEntity(blockPos);
+        if (tileEntity == null) {
+            return null;
+        }
+        BlockEntity newEntity = tileEntity.getType().create(blockPos, getBlockState(blockPos));
+        newEntity.loadWithComponents(
+                (CompoundTag) adapter.fromNativeLin(this.editSession.getFullBlock(
+                        blockPos.getX(),
+                        blockPos.getY(),
+                        blockPos.getZ()
+                ).getNbtReference().getValue()),
+                this.serverLevel.registryAccess()
+        );
+
+        return newEntity;
+    }
+
+    private BlockState getBlockState(BlockPos blockPos) {
+        return adapter.adapt(this.editSession.getBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+    }
+
+    private boolean setBlock(BlockPos blockPos, BlockState blockState) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), adapter.adapt(blockState));
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private boolean removeBlock(BlockPos blockPos, boolean bl) {
+        try {
+            return editSession.setBlock(blockPos.getX(), blockPos.getY(), blockPos.getZ(), BlockTypes.AIR.getDefaultState());
+        } catch (MaxChangedBlocksException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private FluidState getFluidState(BlockPos pos) {
+        return getBlockState(pos).getFluidState();
+    }
+
+    private boolean isWaterAt(BlockPos pos) {
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+        //FAWE start - cannot use switch where method names are equal
+        String methodName = method.getName();
+        if (Refraction.pickName("getBlockState", "a_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockState
+                return getBlockState(blockPos);
+            }
+        }
+        if (Refraction.pickName("getBlockEntity", "c_").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                // getBlockEntity
+                return getBlockEntity(blockPos);
+            }
+        }
+        if ("a".equals(methodName) || "setBlock".equals(methodName) || "removeBlock".equals(methodName) || "destroyBlock".equals(
+                methodName)) {
+            if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof BlockState blockState) {
+                // setBlock
+                return setBlock(blockPos, blockState);
+            } else if (args.length >= 2 && args[0] instanceof BlockPos blockPos && args[1] instanceof Boolean bl) {
+                // removeBlock (and also matches destroyBlock)
+                return removeBlock(blockPos, bl);
+            }
+        }
+        //FAWE start
+        if (Refraction.pickName("getFluidState", "b_").equals(methodName)) { //net.minecraft.world.level.BlockGetter
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return getFluidState(blockPos);
+            }
+        }
+        if (Refraction.pickName("isWaterAt", "z").equals(methodName)) { //net.minecraft.world.level.LevelReader
+            if (args.length == 1 && args[0] instanceof BlockPos blockPos) {
+                return isWaterAt(blockPos);
+            }
+        }
+        if (Refraction.pickName("getEntities", "a_").equals(methodName)) { //net.minecraft.world.level.EntityGetter
+            if (args.length == 2 && args[0] instanceof Entity && args[1] instanceof AABB) {
+                return new ArrayList<>();
+            }
+        }
+        // Specific passthroughs that we want to allow
+        // net.minecraft.world.level.BlockAndTintGetter
+        if (Refraction.pickName("getRawBrightness", "b").equals(methodName)) {
+            return method.invoke(this.serverLevel, args);
+        }
+        // net.minecraft.world.level.LevelHeightAccessor
+        if (Refraction.pickName("getMaxBuildHeight", "al").equals(methodName)) {
+            if (args.length == 0) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        // net.minecraft.world.level.SignalGetter
+        if (Refraction.pickName("hasNeighborSignal", "C").equals(methodName)) {
+            if (args.length == 1 && args[0] instanceof BlockPos) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getSignal", "c").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getControlInputSignal", "a").equals(methodName)) {
+            if (args.length == 3 && args[0] instanceof BlockPos && args[1] instanceof Direction && args[2] instanceof Boolean) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        if (Refraction.pickName("getDirectSignal", "a").equals(methodName)) {
+            if (args.length == 2 && args[0] instanceof BlockPos && args[1] instanceof Direction) {
+                return method.invoke(this.serverLevel, args);
+            }
+        }
+        //FAWE start - force error if method not caught by this instance
+        if (errorOnPassthrough) {
+            LOGGER.error(
+                    """
+                            Attempted passthough of method {}.
+                            Method argument types: {}
+                            Method argument values: {}
+                            """,
+                    method.getName(),
+                    Arrays.stream(args).map(a -> a.getClass().getName()).toList(),
+                    Arrays.stream(args).map(Object::toString).toList()
+            );
+            throw new FaweException("Method required passthrough.");
+        }
+        //FAWE end
+
+        return method.invoke(this.serverLevel, args);
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_3/PaperweightFaweAdapter.java

@@ -4,6 +4,7 @@ import com.fastasyncworldedit.bukkit.adapter.FaweAdapter;
 import com.fastasyncworldedit.bukkit.adapter.NMSRelighterFactory;
 import com.fastasyncworldedit.core.FaweCache;
 import com.fastasyncworldedit.core.entity.LazyBaseEntity;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
@@ -13,6 +14,7 @@ import com.fastasyncworldedit.core.util.NbtUtils;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Sets;
 import com.mojang.serialization.Codec;
 import com.sk89q.jnbt.Tag;
 import com.sk89q.worldedit.blocks.BaseItemStack;
@@ -22,6 +24,7 @@ import com.sk89q.worldedit.bukkit.adapter.ext.fawe.v1_21_3.PaperweightAdapter;
 import com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_3.regen.PaperweightRegen;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.block.BlockStateIdAccess;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.internal.wna.WorldNativeAccess;
@@ -34,7 +37,6 @@ import com.sk89q.worldedit.registry.state.IntegerProperty;
 import com.sk89q.worldedit.registry.state.Property;
 import com.sk89q.worldedit.util.Direction;
 import com.sk89q.worldedit.util.SideEffect;
-import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.concurrency.LazyReference;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.RegenOptions;
@@ -279,9 +281,16 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return state.toBaseBlock();
     }
 
+    private static final Set<SideEffect> SUPPORTED_SIDE_EFFECTS = Sets.immutableEnumSet(
+            SideEffect.HISTORY,
+            SideEffect.HEIGHTMAPS,
+            SideEffect.LIGHTING,
+            SideEffect.NEIGHBORS
+    );
+
     @Override
     public Set<SideEffect> getSupportedSideEffects() {
-        return SideEffectSet.defaults().getSideEffectsToApply();
+        return SUPPORTED_SIDE_EFFECTS;
     }
 
     @Override
@@ -425,6 +434,10 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return material.getCraftBlockData();
     }
 
+    public net.minecraft.world.level.block.state.BlockState adapt(BlockState blockState) {
+        return Block.stateById(getOrdinalToIbdID()[blockState.getOrdinal()]);
+    }
+
     @Override
     public void sendFakeChunk(org.bukkit.World world, Player player, ChunkPacket chunkPacket) {
         ServerLevel nmsWorld = getServerLevel(world);
@@ -605,6 +618,11 @@ public final class PaperweightFaweAdapter extends FaweAdapter<net.minecraft.nbt.
         return new PaperweightPostProcessor();
     }
 
+    @Override
+    public PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return new PaperweightPlacementStateProcessor(extent, mask, region);
+    }
+
     private boolean wasAccessibleSinceLastSave(ChunkHolder holder) {
         if (PaperLib.isPaper()) { // Papers new chunk system has no related replacement - therefor we assume true.
             return true;

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_3/PaperweightFaweMutableBlockPlaceContext.java

@@ -0,0 +1,143 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_3;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.context.BlockPlaceContext;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightFaweMutableBlockPlaceContext extends BlockPlaceContext {
+
+    private static final BlockHitResult DEFAULT_BLOCK_HIT = new BlockHitResult(
+            new Vec3(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            Direction.NORTH,
+            new BlockPos(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE),
+            false
+    );
+    private final ServerLevel level;
+    private BlockHitResult hitResult = null;
+    private Direction direction = null;
+    private BlockPos relativePos;
+
+    @SuppressWarnings("DataFlowIssue")
+    public PaperweightFaweMutableBlockPlaceContext(ServerLevel level) {
+        super(
+                level,
+                null,
+                null,
+                null,
+                DEFAULT_BLOCK_HIT
+
+        );
+        this.level = level;
+        this.replaceClicked = false;
+    }
+
+    public PaperweightFaweMutableBlockPlaceContext withSetting(BlockHitResult hitResult, Direction direction) {
+        this.hitResult = hitResult;
+        this.direction = direction;
+        this.relativePos = hitResult.getBlockPos().relative(hitResult.getDirection());
+        return this;
+    }
+
+    @Override
+    @Nonnull
+    public BlockPos getClickedPos() {
+        return this.relativePos;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getClickedFace() {
+        return this.hitResult.getDirection();
+    }
+
+    @Override
+    @Nonnull
+    public Vec3 getClickLocation() {
+        return this.hitResult.getLocation();
+    }
+
+    @Override
+    public boolean isInside() {
+        return this.hitResult.isInside();
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public ItemStack getItemInHand() {
+        return ItemStack.EMPTY;
+    }
+
+    @Nullable
+    @Override
+    public Player getPlayer() {
+        return null;
+    }
+
+    @Override
+    @SuppressWarnings("NullableProblems")
+    public InteractionHand getHand() {
+        return null;
+    }
+
+    @Override
+    @Nonnull
+    public Level getLevel() {
+        return this.level;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getHorizontalDirection() {
+        return this.direction.getAxis() == Direction.Axis.Y ? Direction.NORTH : this.direction;
+    }
+
+    @Override
+    public boolean isSecondaryUseActive() {
+        return false;
+    }
+
+    @Override
+    public float getRotation() {
+        return (float) (this.direction.get2DDataValue() * 90);
+    }
+
+    @Override
+    public boolean canPlace() {
+        return this.getLevel().getBlockState(this.getClickedPos()).canBeReplaced(this);
+    }
+
+    @Override
+    public boolean replacingClickedOnBlock() {
+        return false;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingDirection() {
+        return direction;
+    }
+
+    @Override
+    @Nonnull
+    public Direction getNearestLookingVerticalDirection() {
+        return direction.getAxis() == Direction.Axis.Y ? Direction.UP : Direction.DOWN;
+    }
+
+    @Override
+    @Nonnull
+    public Direction[] getNearestLookingDirections() {
+        return new Direction[]{direction};
+    }
+
+}
+

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_3/PaperweightGetBlocks.java

@@ -21,6 +21,7 @@ import com.sk89q.worldedit.bukkit.WorldEditPlugin;
 import com.sk89q.worldedit.internal.Constants;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.biome.BiomeTypes;
 import com.sk89q.worldedit.world.block.BlockTypesCache;
@@ -837,7 +838,9 @@ public class PaperweightGetBlocks extends CharGetBlocks implements BukkitGetBloc
                         nmsChunk.mustNotSave = false;
                         nmsChunk.markUnsaved();
                         // send to player
-                        if (Settings.settings().LIGHTING.MODE == 0 || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
+                        if (!set
+                                .getSideEffectSet()
+                                .shouldApply(SideEffect.LIGHTING) || !Settings.settings().LIGHTING.DELAY_PACKET_SENDING || finalMask == 0 && biomes != null) {
                             this.send();
                         }
                         if (finalizer != null) {

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_3/PaperweightLevelProxy.java

@@ -0,0 +1,136 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_3;
+
+import com.fastasyncworldedit.core.util.ReflectionUtils;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import net.minecraft.core.BlockPos;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.tags.FluidTags;
+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.border.WorldBorder;
+import net.minecraft.world.level.material.FluidState;
+import net.minecraft.world.level.material.Fluids;
+import org.enginehub.linbus.tree.LinCompoundTag;
+import sun.misc.Unsafe;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+public class PaperweightLevelProxy extends ServerLevel {
+
+    protected ServerLevel serverLevel;
+    private PaperweightPlacementStateProcessor processor;
+    private PaperweightFaweAdapter adapter;
+
+    @SuppressWarnings("DataFlowIssue")
+    private PaperweightLevelProxy() {
+        super(null, null, null, null, null, null, null, true, 0L, null, true, null, null, null, null);
+        throw new IllegalStateException("Cannot be instantiated");
+    }
+
+    public static PaperweightLevelProxy getInstance(ServerLevel serverLevel, PaperweightPlacementStateProcessor processor) {
+        Unsafe unsafe = ReflectionUtils.getUnsafe();
+
+        PaperweightLevelProxy newLevel;
+        try {
+            newLevel = (PaperweightLevelProxy) unsafe.allocateInstance(PaperweightLevelProxy.class);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        }
+        newLevel.processor = processor;
+        newLevel.adapter = ((PaperweightFaweAdapter) WorldEditPlugin.getInstance().getBukkitImplAdapter());
+        newLevel.serverLevel = serverLevel;
+        return newLevel;
+    }
+
+    @Nullable
+    @Override
+    public BlockEntity getBlockEntity(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return null;
+        }
+        LinCompoundTag tag = processor.getTileAt(blockPos.getX(), blockPos.getY(), blockPos.getZ());
+        if (tag == null) {
+            return null;
+        }
+        BlockState state = adapter.adapt(processor.getBlockStateAt(blockPos.getX(), blockPos.getY(), blockPos.getZ()));
+        if (!(state.getBlock() instanceof EntityBlock entityBlock)) {
+            return null;
+        }
+        BlockEntity tileEntity = entityBlock.newBlockEntity(blockPos, state);
+        tileEntity.loadWithComponents((CompoundTag) adapter.fromNativeLin(tag), serverLevel.registryAccess());
+        return tileEntity;
+    }
+
+    @Override
+    @Nonnull
+    public BlockState getBlockState(@Nonnull BlockPos blockPos) {
+        if (blockPos.getX() == Integer.MAX_VALUE) {
+            return Blocks.AIR.defaultBlockState();
+        }
+        com.sk89q.worldedit.world.block.BlockState state = processor.getBlockStateAt(
+                blockPos.getX(),
+                blockPos.getY(),
+                blockPos.getZ()
+        );
+        return adapter.adapt(state);
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    @Nonnull
+    public FluidState getFluidState(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return Fluids.EMPTY.defaultFluidState();
+        }
+        return getBlockState(pos).getFluidState();
+    }
+
+    @SuppressWarnings("unused")
+    @Override
+    public boolean isWaterAt(@Nonnull BlockPos pos) {
+        if (pos.getX() == Integer.MAX_VALUE) {
+            return false;
+        }
+        return getBlockState(pos).getFluidState().is(FluidTags.WATER);
+    }
+
+    @Override
+    public int getHeight() {
+        return serverLevel.getHeight();
+    }
+
+    @Override
+    public int getMinY() {
+        return serverLevel.getMinY();
+    }
+
+    @Override
+    public int getMaxY() {
+        return serverLevel.getMaxY();
+    }
+
+    @Override
+    public boolean isInsideBuildHeight(int blockY) {
+        return serverLevel.isInsideBuildHeight(blockY);
+    }
+
+    @Override
+    public boolean isOutsideBuildHeight(BlockPos pos) {
+        return serverLevel.isOutsideBuildHeight(pos);
+    }
+
+    @Override
+    public boolean isOutsideBuildHeight(int blockY) {
+        return serverLevel.isOutsideBuildHeight(blockY);
+    }
+
+    @Override
+    public WorldBorder getWorldBorder() {
+        return serverLevel.getWorldBorder();
+    }
+
+}

worldedit-bukkit/adapters/adapter-1_21_3/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_3/PaperweightPlacementStateProcessor.java

@@ -0,0 +1,111 @@
+package com.sk89q.worldedit.bukkit.adapter.impl.fawe.v1_21_3;
+
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
+import com.fastasyncworldedit.core.util.ExtentTraverser;
+import com.fastasyncworldedit.core.wrappers.WorldWrapper;
+import com.sk89q.worldedit.bukkit.BukkitWorld;
+import com.sk89q.worldedit.bukkit.WorldEditPlugin;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.Direction;
+import com.sk89q.worldedit.world.World;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import net.minecraft.core.BlockPos;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.block.Block;
+import net.minecraft.world.phys.BlockHitResult;
+import net.minecraft.world.phys.Vec3;
+import org.bukkit.craftbukkit.CraftWorld;
+
+import javax.annotation.Nullable;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class PaperweightPlacementStateProcessor extends PlacementStateProcessor {
+
+    private final PaperweightFaweAdapter adapter = ((PaperweightFaweAdapter) WorldEditPlugin
+            .getInstance()
+            .getBukkitImplAdapter());
+    private final PaperweightFaweMutableBlockPlaceContext mutableBlockPlaceContext;
+    private final PaperweightLevelProxy proxyLevel;
+
+    public PaperweightPlacementStateProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        super(extent, mask, region);
+        World world = ExtentTraverser.getWorldFromExtent(extent);
+        if (world == null) {
+            throw new UnsupportedOperationException(
+                    "World is required for PlacementStateProcessor but none found in given extent.");
+        }
+        BukkitWorld bukkitWorld;
+        if (world instanceof WorldWrapper wrapper) {
+            bukkitWorld = (BukkitWorld) wrapper.getParent();
+        } else {
+            bukkitWorld = (BukkitWorld) world;
+        }
+        this.proxyLevel = PaperweightLevelProxy.getInstance(((CraftWorld) bukkitWorld.getWorld()).getHandle(), this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    private PaperweightPlacementStateProcessor(
+            Extent extent,
+            BlockTypeMask mask,
+            Map<SecondPass, Character> crossChunkSecondPasses,
+            ServerLevel serverLevel,
+            ThreadLocal<PlacementStateProcessor> threadProcessors,
+            Region region,
+            AtomicBoolean finished
+    ) {
+        super(extent, mask, crossChunkSecondPasses, threadProcessors, region, finished);
+        this.proxyLevel = PaperweightLevelProxy.getInstance(serverLevel, this);
+        this.mutableBlockPlaceContext = new PaperweightFaweMutableBlockPlaceContext(proxyLevel);
+    }
+
+    @Override
+    protected char getStateAtFor(
+            int x,
+            int y,
+            int z,
+            BlockState state,
+            Vector3 clickPos,
+            Direction clickedFaceDirection,
+            BlockVector3 clickedBlock
+    ) {
+        Block block = ((PaperweightBlockMaterial) state.getMaterial()).getBlock();
+        Vec3 pos = new Vec3(clickPos.x(), clickPos.y(), clickPos.z());
+        net.minecraft.core.Direction side = net.minecraft.core.Direction.valueOf(clickedFaceDirection.toString());
+        BlockPos blockPos = new BlockPos(clickedBlock.x(), clickedBlock.y(), clickedBlock.z());
+        net.minecraft.world.level.block.state.BlockState newState = block.getStateForPlacement(mutableBlockPlaceContext.withSetting(
+                new BlockHitResult(pos, side, blockPos, false),
+                side.getOpposite()
+        ));
+        return newState == null ? BlockTypesCache.ReservedIDs.AIR : adapter.ibdIDToOrdinal(Block.BLOCK_STATE_REGISTRY.getId(
+                newState));
+    }
+
+    @Override
+    @Nullable
+    public Extent construct(Extent child) {
+        if (child == getExtent()) {
+            return this;
+        }
+        return new PaperweightPlacementStateProcessor(child, mask, region);
+    }
+
+    @Override
+    public PlacementStateProcessor fork() {
+        return new PaperweightPlacementStateProcessor(
+                extent,
+                mask,
+                postCompleteSecondPasses,
+                proxyLevel.serverLevel,
+                threadProcessors,
+                region,
+                finished
+        );
+    }
+
+}

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitServerInterface.java

@@ -21,6 +21,7 @@ package com.sk89q.worldedit.bukkit;
 
 import com.fastasyncworldedit.bukkit.util.MinecraftVersion;
 import com.fastasyncworldedit.core.configuration.Settings;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
 import com.google.common.collect.Sets;
@@ -37,7 +38,10 @@ import com.sk89q.worldedit.extension.platform.Capability;
 import com.sk89q.worldedit.extension.platform.MultiUserPlatform;
 import com.sk89q.worldedit.extension.platform.Preference;
 import com.sk89q.worldedit.extension.platform.Watchdog;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.util.lifecycle.Lifecycled;
 import com.sk89q.worldedit.world.DataFixer;
@@ -309,5 +313,10 @@ public class BukkitServerInterface extends AbstractPlatform implements MultiUser
         }
         return this.plugin.getBukkitImplAdapter().getTickingPostProcessor();
     }
+
+    @Override
+    public PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return this.plugin.getBukkitImplAdapter().getPlatformPlacementProcessor(extent, mask, region);
+    }
     //FAWE end
 }

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/adapter/BukkitImplAdapter.java

@@ -23,6 +23,7 @@ import com.fastasyncworldedit.bukkit.FaweBukkit;
 import com.fastasyncworldedit.bukkit.adapter.IBukkitAdapter;
 import com.fastasyncworldedit.bukkit.adapter.NMSRelighterFactory;
 import com.fastasyncworldedit.core.Fawe;
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
 import com.fastasyncworldedit.core.queue.IChunkGet;
@@ -34,6 +35,7 @@ import com.sk89q.worldedit.blocks.BaseItemStack;
 import com.sk89q.worldedit.bukkit.BukkitAdapter;
 import com.sk89q.worldedit.entity.BaseEntity;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.wna.WorldNativeAccess;
 import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
@@ -402,5 +404,13 @@ public interface BukkitImplAdapter<T> extends IBukkitAdapter {
     default IBatchProcessor getTickingPostProcessor() {
         return null;
     }
+
+    /**
+     * Returns an {@link PlacementStateProcessor} instance for processing placed blocks to "fix" them.
+     * @since TODO
+     */
+    default PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        return null;
+    }
     //FAWE end
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/FaweAPI.java

@@ -32,6 +32,8 @@ import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.util.Location;
+import com.sk89q.worldedit.util.SideEffect;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.world.World;
 import org.apache.logging.log4j.Logger;
@@ -355,8 +357,12 @@ public class FaweAPI {
             if (unwrapped instanceof IQueueExtent) {
                 queue = (IQueueExtent) unwrapped;
             } else if (Settings.settings().QUEUE.PARALLEL_THREADS > 1) {
-                ParallelQueueExtent parallel =
+                ParallelQueueExtent parallel = new ParallelQueueExtent(
-                        new ParallelQueueExtent(Fawe.instance().getQueueHandler(), world, true);
+                        Fawe.instance().getQueueHandler(),
+                        world,
+                        true,
+                        SideEffectSet.none().with(SideEffect.LIGHTING)
+                );
                 queue = parallel.getExtent();
             } else {
                 queue = Fawe.instance().getQueueHandler().getQueue(world);

worldedit-core/src/main/java/com/fastasyncworldedit/core/extension/factory/parser/mask/Adjacent2DMaskParser.java

@@ -0,0 +1,51 @@
+package com.fastasyncworldedit.core.extension.factory.parser.mask;
+
+import com.fastasyncworldedit.core.extension.factory.parser.RichParser;
+import com.fastasyncworldedit.core.function.mask.Adjacent2DMask;
+import com.fastasyncworldedit.core.function.mask.AdjacentAny2DMask;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.command.util.SuggestionHelper;
+import com.sk89q.worldedit.extension.input.InputParseException;
+import com.sk89q.worldedit.extension.input.ParserContext;
+import com.sk89q.worldedit.function.mask.Mask;
+
+import javax.annotation.Nonnull;
+import java.util.stream.Stream;
+
+public class Adjacent2DMaskParser extends RichParser<Mask> {
+
+    public Adjacent2DMaskParser(WorldEdit worldEdit) {
+        super(worldEdit, "~2d", "adjacent2d");
+    }
+
+    @Override
+    protected Stream<String> getSuggestions(String argumentInput, int index) {
+        if (index == 0) {
+            return worldEdit.getMaskFactory().getSuggestions(argumentInput).stream();
+        } else if (index == 1 || index == 2) {
+            return SuggestionHelper.suggestPositiveDoubles(argumentInput);
+        }
+        return Stream.empty();
+    }
+
+    @Override
+    protected Mask parseFromInput(@Nonnull String[] arguments, ParserContext context) throws InputParseException {
+        if (arguments.length == 0) {
+            return null;
+        }
+        Mask subMask = worldEdit.getMaskFactory().parseFromInput(arguments[0], context);
+        int min = arguments.length > 1 ? Integer.parseInt(arguments[1]) : -1;
+        int max = arguments.length > 2 ? Integer.parseInt(arguments[2]) : -1;
+        if (min == -1 && max == -1) {
+            min = 1;
+            max = 4;
+        } else if (max == -1) {
+            max = min;
+        }
+        if (max >= 4 && min == 1) {
+            return new AdjacentAny2DMask(subMask);
+        }
+        return new Adjacent2DMask(subMask, min, max);
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/PassthroughExtent.java

@@ -6,16 +6,18 @@ import com.fastasyncworldedit.core.queue.Filter;
 import com.sk89q.jnbt.CompoundTag;
 import com.sk89q.worldedit.MaxChangedBlocksException;
 import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.entity.BaseEntity;
+import com.sk89q.worldedit.entity.Entity;
 import com.sk89q.worldedit.extent.AbstractDelegateExtent;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.extent.clipboard.Clipboard;
 import com.sk89q.worldedit.function.mask.Mask;
-import com.sk89q.worldedit.function.operation.Operation;
 import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.session.ClipboardHolder;
 import com.sk89q.worldedit.util.Countable;
+import com.sk89q.worldedit.util.Location;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
@@ -25,6 +27,7 @@ import com.sk89q.worldedit.world.block.BlockType;
 import javax.annotation.Nullable;
 import java.util.List;
 import java.util.Set;
+import java.util.UUID;
 
 public class PassthroughExtent extends AbstractDelegateExtent {
 
@@ -194,17 +197,55 @@ public class PassthroughExtent extends AbstractDelegateExtent {
         return getExtent().getBlock(position);
     }
 
+    @Override
+    public BlockState getBlock(int x, int y, int z) {
+        return getExtent().getBlock(x, y, z);
+    }
+
     @Override
     public BaseBlock getFullBlock(BlockVector3 position) {
         return getExtent().getFullBlock(position);
     }
 
+    @Override
+    public BaseBlock getFullBlock(int x, int y, int z) {
+        return getExtent().getFullBlock(x, y, z);
+    }
+
+    @Override
+    public List<? extends Entity> getEntities(Region region) {
+        return getExtent().getEntities(region);
+    }
+
+    @Override
+    public List<? extends Entity> getEntities() {
+        return getExtent().getEntities();
+    }
+
+    @Nullable
+    @Override
+    public Entity createEntity(Location location, BaseEntity entity) {
+        return getExtent().createEntity(location, entity);
+    }
+
+    @Nullable
+    @Override
+    public Entity createEntity(Location location, BaseEntity entity, UUID uuid) {
+        return getExtent().createEntity(location, entity, uuid);
+    }
+
     @Override
     @Deprecated
     public <T extends BlockStateHolder<T>> boolean setBlock(BlockVector3 position, T block) throws WorldEditException {
         return getExtent().setBlock(position, block);
     }
 
+    @Override
+    public <T extends BlockStateHolder<T>> boolean setBlock(int x, int y, int z, T block) throws
+            WorldEditException {
+        return getExtent().setBlock(x, y, z, block);
+    }
+
     @Override
     public boolean setTile(int x, int y, int z, CompoundTag tile) throws WorldEditException {
         return getExtent().setTile(x, y, z, tile);
@@ -216,9 +257,8 @@ public class PassthroughExtent extends AbstractDelegateExtent {
     }
 
     @Override
-    @Nullable
+    public boolean setBiome(int x, int y, int z, BiomeType biome) {
-    public Operation commit() {
+        return getExtent().setBiome(x, y, z, biome);
-        return getExtent().commit();
     }
 
     @Override
@@ -226,6 +266,11 @@ public class PassthroughExtent extends AbstractDelegateExtent {
         return getExtent().cancel();
     }
 
+    @Override
+    public void removeEntity(int x, int y, int z, UUID uuid) {
+        getExtent().removeEntity(x, y, z, uuid);
+    }
+
     @Override
     public boolean isQueueEnabled() {
         return getExtent().isQueueEnabled();
@@ -251,6 +296,16 @@ public class PassthroughExtent extends AbstractDelegateExtent {
         return getExtent().apply(region, filter, full);
     }
 
+    @Override
+    public BiomeType getBiome(BlockVector3 position) {
+        return getExtent().getBiome(position);
+    }
+
+    @Override
+    public BiomeType getBiomeType(int x, int y, int z) {
+        return getExtent().getBiomeType(x, y, z);
+    }
+
     @Override
     public <T extends Filter> T apply(Iterable<BlockVector3> positions, T filter) {
         return getExtent().apply(positions, filter);

worldedit-core/src/main/java/com/fastasyncworldedit/core/extent/processor/PlacementStateProcessor.java

@@ -0,0 +1,545 @@
+package com.fastasyncworldedit.core.extent.processor;
+
+import com.fastasyncworldedit.core.configuration.Caption;
+import com.fastasyncworldedit.core.extent.NullExtent;
+import com.fastasyncworldedit.core.extent.filter.block.FilterBlock;
+import com.fastasyncworldedit.core.function.mask.AdjacentAny2DMask;
+import com.fastasyncworldedit.core.math.BlockVector3ChunkMap;
+import com.fastasyncworldedit.core.math.MutableBlockVector3;
+import com.fastasyncworldedit.core.math.MutableVector3;
+import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
+import com.fastasyncworldedit.core.queue.IBatchProcessor;
+import com.fastasyncworldedit.core.queue.IChunk;
+import com.fastasyncworldedit.core.queue.IChunkGet;
+import com.fastasyncworldedit.core.queue.IChunkSet;
+import com.fastasyncworldedit.core.registry.state.PropertyKey;
+import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.extent.AbstractDelegateExtent;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockCategoryMask;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
+import com.sk89q.worldedit.function.pattern.Pattern;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.registry.state.Property;
+import com.sk89q.worldedit.util.Direction;
+import com.sk89q.worldedit.world.block.BaseBlock;
+import com.sk89q.worldedit.world.block.BlockCategories;
+import com.sk89q.worldedit.world.block.BlockCategory;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockTypes;
+import com.sk89q.worldedit.world.block.BlockTypesCache;
+import org.enginehub.linbus.tree.LinCompoundTag;
+
+import java.util.EnumSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.stream.Collectors;
+
+/**
+ * Processor/pattern that uses Minecraft internal methods to determine the shape of blocks, e.g. stairs and fences
+ *
+ * @since TODO
+ */
+public abstract class PlacementStateProcessor extends AbstractDelegateExtent implements IBatchProcessor, Pattern {
+
+    private static final Direction[] NESW = new Direction[]{Direction.NORTH, Direction.EAST, Direction.SOUTH, Direction.WEST};
+    private static final int CHUNK_BLOCK_POS_MASK = -1 << 4;
+
+    private static volatile boolean SETUP = false;
+    private static BlockTypeMask DEFAULT_MASK = null;
+    private static BlockTypeMask IN_FIRST_PASS = null;
+    private static BlockTypeMask REQUIRES_SECOND_PASS = null;
+    private static BlockTypeMask IN_FIRST_PASS_WITHOUT_SECOND = null;
+    private static AdjacentAny2DMask ADJACENT_STAIR_MASK = null;
+
+    protected final Extent extent;
+    protected final BlockTypeMask mask;
+    protected final Region region;
+    protected final Map<SecondPass, Character> postCompleteSecondPasses;
+    protected final ThreadLocal<PlacementStateProcessor> threadProcessors;
+    protected final AtomicBoolean finished;
+    private final MutableVector3 clickPos = new MutableVector3();
+    private final MutableBlockVector3 clickedBlock = new MutableBlockVector3();
+    private final MutableBlockVector3 placedBlock = new MutableBlockVector3(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE);
+
+    private IChunkGet processChunkGet = null;
+    private IChunkSet processChunkSet = null;
+    private int processChunkX;
+    private int processChunkZ;
+
+    /**
+     * Processor/pattern for performing block updates, e.g. stair shape and glass pane connections
+     *
+     * @param extent Extent to use
+     * @param mask   Mask of blocks to perform updates on
+     * @since TODO
+     */
+    public PlacementStateProcessor(Extent extent, BlockTypeMask mask, Region region) {
+        super(extent);
+        // Required here as child classes are located within adapters and will therefore be statically accessed on startup,
+        // meaning we attempt to access BlockTypes class before it is correctly initialised.
+        if (!SETUP) {
+            synchronized (PlacementStateProcessor.class) {
+                if (!SETUP) {
+                    setup();
+                }
+            }
+        }
+        this.extent = extent;
+        this.mask = mask == null ? DEFAULT_MASK : mask;
+        this.region = region;
+        this.postCompleteSecondPasses = new ConcurrentHashMap<>();
+        this.threadProcessors = ThreadLocal.withInitial(this::fork);
+        this.finished = new AtomicBoolean();
+    }
+
+    protected PlacementStateProcessor(
+            Extent extent,
+            BlockTypeMask mask,
+            Map<SecondPass, Character> crossChunkSecondPasses,
+            ThreadLocal<PlacementStateProcessor> threadProcessors,
+            Region region,
+            AtomicBoolean finished
+    ) {
+        super(extent);
+        this.extent = extent;
+        this.mask = mask;
+        this.region = region;
+        this.postCompleteSecondPasses = crossChunkSecondPasses;
+        this.threadProcessors = threadProcessors;
+        this.finished = finished;
+    }
+
+    private static void setup() {
+        NullExtent nullExtent = new NullExtent(
+                com.sk89q.worldedit.extent.NullExtent.INSTANCE,
+                Caption.of("PlacementStateProcessor fell through to null extent")
+        );
+
+        IN_FIRST_PASS = new BlockTypeMask(nullExtent);
+        IN_FIRST_PASS.add(
+                BlockTypes.CHEST,
+                BlockTypes.TRAPPED_CHEST
+        );
+        IN_FIRST_PASS.add(BlockCategories.STAIRS.getAll());
+
+        IN_FIRST_PASS_WITHOUT_SECOND = new BlockTypeMask(nullExtent);
+        IN_FIRST_PASS_WITHOUT_SECOND.add(BlockCategories.STAIRS.getAll());
+
+        REQUIRES_SECOND_PASS = new BlockTypeMask(nullExtent);
+        REQUIRES_SECOND_PASS.add(
+                BlockTypes.IRON_BARS,
+                BlockTypes.GLASS_PANE,
+                BlockTypes.BLACK_STAINED_GLASS_PANE,
+                BlockTypes.BLUE_STAINED_GLASS_PANE,
+                BlockTypes.BROWN_STAINED_GLASS_PANE,
+                BlockTypes.LIGHT_BLUE_STAINED_GLASS_PANE,
+                BlockTypes.PINK_STAINED_GLASS_PANE,
+                BlockTypes.LIGHT_GRAY_STAINED_GLASS_PANE,
+                BlockTypes.GRAY_STAINED_GLASS_PANE,
+                BlockTypes.CYAN_STAINED_GLASS_PANE,
+                BlockTypes.PURPLE_STAINED_GLASS_PANE,
+                BlockTypes.GREEN_STAINED_GLASS_PANE,
+                BlockTypes.LIME_STAINED_GLASS_PANE,
+                BlockTypes.MAGENTA_STAINED_GLASS_PANE,
+                BlockTypes.YELLOW_STAINED_GLASS_PANE,
+                BlockTypes.ORANGE_STAINED_GLASS_PANE,
+                BlockTypes.RED_STAINED_GLASS_PANE,
+                BlockTypes.WHITE_STAINED_GLASS_PANE,
+                BlockTypes.TRIPWIRE,
+                BlockTypes.TWISTING_VINES_PLANT,
+                BlockTypes.CAVE_VINES_PLANT,
+                BlockTypes.WEEPING_VINES_PLANT,
+                BlockTypes.VINE,
+                BlockTypes.REDSTONE_WIRE
+        );
+        BlockCategory[] categories = new BlockCategory[]{BlockCategories.FENCES, BlockCategories.FENCE_GATES, BlockCategories.WALLS, BlockCategories.CAVE_VINES};
+        for (BlockCategory category : categories) {
+            if (category != null) {
+                REQUIRES_SECOND_PASS.add(category.getAll());
+            }
+        }
+
+        DEFAULT_MASK = REQUIRES_SECOND_PASS.copy();
+        DEFAULT_MASK.add(
+                BlockTypes.CHORUS_PLANT,
+                BlockTypes.DRIPSTONE_BLOCK,
+                BlockTypes.POINTED_DRIPSTONE,
+                BlockTypes.BIG_DRIPLEAF,
+                BlockTypes.BIG_DRIPLEAF_STEM,
+                BlockTypes.CAMPFIRE,
+                BlockTypes.CHEST,
+                BlockTypes.TRAPPED_CHEST,
+                BlockTypes.CRAFTER,
+                BlockTypes.MUSHROOM_STEM,
+                BlockTypes.BROWN_MUSHROOM_BLOCK,
+                BlockTypes.RED_MUSHROOM_BLOCK
+        );
+        categories = new BlockCategory[]{BlockCategories.STAIRS, BlockCategories.BAMBOO_BLOCKS, BlockCategories.TALL_FLOWERS};
+        for (BlockCategory category : categories) {
+            if (category != null) {
+                DEFAULT_MASK.add(category.getAll());
+            }
+        }
+
+        ADJACENT_STAIR_MASK = new AdjacentAny2DMask(new BlockCategoryMask(nullExtent, BlockCategories.STAIRS), false);
+        SETUP = true;
+    }
+
+    @Override
+    public IChunkSet processSet(IChunk iChunk, IChunkGet chunkGet, IChunkSet chunkSet) {
+        if (finished.get()) {
+            return chunkSet;
+        }
+        PlacementStateProcessor threadProcessor = threadProcessors.get();
+        try {
+            threadProcessor.initProcess(iChunk, chunkGet, chunkSet);
+            return threadProcessor.process();
+        } finally {
+            threadProcessor.uninit();
+        }
+    }
+
+    private void initProcess(IChunk iChunk, IChunkGet chunkGet, IChunkSet chunkSet) {
+        this.processChunkX = iChunk.getX() << 4;
+        this.processChunkZ = iChunk.getZ() << 4;
+        this.processChunkGet = chunkGet;
+        this.processChunkSet = chunkSet;
+    }
+
+    private void uninit() {
+        this.processChunkGet = null;
+        this.processChunkSet = null;
+    }
+
+    private IChunkSet process() {
+        Map<BlockVector3, FaweCompoundTag> setTiles = processChunkSet.tiles();
+        for (int layer = processChunkGet.getMinSectionPosition(); layer <= processChunkGet.getMaxSectionPosition(); layer++) {
+            int layerY = layer << 4;
+            char[] set = processChunkSet.loadIfPresent(layer);
+            if (set == null) {
+                continue;
+            }
+            for (int y = 0, i = 0; y < 16; y++, i += 256) {
+                int blockY = layerY + y;
+                checkAndPerformUpdate(setTiles, set, i, blockY, true);
+                checkAndPerformUpdate(setTiles, set, i, blockY, false);
+            }
+        }
+        return processChunkSet;
+    }
+
+    private void checkAndPerformUpdate(
+            Map<BlockVector3, FaweCompoundTag> setTiles,
+            char[] set,
+            int index,
+            int blockY,
+            boolean firstPass
+    ) {
+        for (int z = 0; z < 16; z++) {
+            int blockZ = processChunkZ + z;
+            for (int x = 0; x < 16; x++, index++) {
+                int blockX = processChunkX + x;
+                char ordinal = set[index];
+                BlockState state = BlockTypesCache.states[ordinal];
+                if (firstPass) {
+                    if (!IN_FIRST_PASS.test(state)) {
+                        continue;
+                    }
+                } else if (IN_FIRST_PASS_WITHOUT_SECOND.test(state)) {
+                    continue;
+                }
+                if (!mask.test(state)) {
+                    continue;
+                }
+                boolean atEdge = x == 0 || x == 15 || z == 0 || z == 15;
+                if (!firstPass && atEdge && REQUIRES_SECOND_PASS.test(state)) {
+                    postCompleteSecondPasses.put(new SecondPass(
+                            blockX,
+                            blockY,
+                            blockZ,
+                            setTiles.isEmpty() ? null : ((BlockVector3ChunkMap<FaweCompoundTag>) setTiles).remove(x, blockY, z)
+                    ), ordinal);
+                    set[index] = BlockTypesCache.ReservedIDs.__RESERVED__;
+                    continue;
+                }
+                if (state.getBlockType().equals(BlockTypes.CHEST) || state.getBlockType().equals(BlockTypes.TRAPPED_CHEST)) {
+                    placedBlock.setComponents(blockX, blockY, blockZ);
+                } else {
+                    placedBlock.setComponents(Integer.MAX_VALUE, Integer.MAX_VALUE, Integer.MAX_VALUE);
+                }
+                char newOrdinal = getBlockOrdinal(blockX, blockY, blockZ, state);
+                if (newOrdinal == ordinal) {
+                    continue;
+                }
+                set[index] = newOrdinal;
+            }
+        }
+    }
+
+    @Override
+    public ProcessorScope getScope() {
+        return ProcessorScope.CHANGING_BLOCKS;
+    }
+
+    @Override
+    public void finish() {
+        flush();
+    }
+
+    @Override
+    public void flush() {
+        finished.set(true);
+        for (Map.Entry<SecondPass, Character> entry : postCompleteSecondPasses.entrySet()) {
+            BlockState state;
+            char ordinal = entry.getValue();
+            SecondPass secondPass = entry.getKey();
+            if (ordinal != 0) {
+                state = BlockTypesCache.states[ordinal];
+            } else {
+                state = extent.getBlock(secondPass.x, secondPass.y, secondPass.z);
+            }
+            char newOrdinal = getBlockOrdinal(secondPass.x, secondPass.y, secondPass.z, state);
+            if (newOrdinal == state.getOrdinalChar() && ordinal == 0) {
+                continue;
+            }
+            if (secondPass.tile != null) {
+                extent.tile(secondPass.x, secondPass.y, secondPass.z, secondPass.tile);
+            }
+            extent.setBlock(secondPass.x, secondPass.y, secondPass.z, BlockTypesCache.states[newOrdinal]);
+        }
+        postCompleteSecondPasses.clear();
+    }
+
+    @Override
+    public abstract PlacementStateProcessor fork();
+
+    protected abstract char getStateAtFor(
+            int x,
+            int y,
+            int z,
+            BlockState state,
+            Vector3 clickPos,
+            Direction clickedFaceDirection,
+            BlockVector3 clickedBlock
+    );
+
+    public BlockState getBlockStateAt(int x, int y, int z) {
+        Character ord = postCompleteSecondPasses.get(new SecondPass(x, y, z, null));
+        if (ord != null && ord != 0) {
+            return BlockTypesCache.states[ord];
+        }
+        if (processChunkSet == null || (x & CHUNK_BLOCK_POS_MASK) != processChunkX || (z & CHUNK_BLOCK_POS_MASK) != processChunkZ) {
+            return extent.getBlock(x, y, z);
+        }
+        char[] set = processChunkSet.loadIfPresent(y >> 4);
+        if (set == null) {
+            return processChunkGet.getBlock(x & 15, y, z & 15);
+        }
+        char ordinal = set[(y & 15) << 8 | (z & 15) << 4 | (x & 15)];
+        if (ordinal == BlockTypesCache.ReservedIDs.__RESERVED__) {
+            return processChunkGet.getBlock(x & 15, y, z & 15);
+        }
+        BlockState state = BlockTypesCache.states[ordinal];
+        // "Hack" for chests as internal server methods will only accept "single" chests for joining
+        if (state.getBlockType().equals(BlockTypes.CHEST) || state.getBlockType().equals(BlockTypes.TRAPPED_CHEST)) {
+            String shape =  state.getState(PropertyKey.TYPE).toString();
+            if (shape.equals("right")) {
+                Direction facing = state.getState(PropertyKey.FACING);
+                Direction left = facing.getLeft();
+                int testX = x + left.getBlockX();
+                int testZ = z + left.getBlockZ();
+                if (placedBlock.isAt(testX, y, testZ)) {
+                    return state.with(PropertyKey.TYPE, "single");
+                }
+            } else if(shape.equals("left")) {
+                Direction facing = state.getState(PropertyKey.FACING);
+                Direction right = facing.getRight();
+                int testX = x + right.getBlockX();
+                int testZ = z + right.getBlockZ();
+                if (placedBlock.isAt(testX, y, testZ)) {
+                    return state.with(PropertyKey.TYPE, "single");
+                }
+            }
+        }
+        return state;
+    }
+
+    public LinCompoundTag getTileAt(int x, int y, int z) {
+        SecondPass secondPass = new SecondPass(x, y, z, null);
+        Character ord = postCompleteSecondPasses.get(secondPass);
+        if (ord != null && ord != 0) {
+            // This should be rare enough...
+            for (SecondPass pass : postCompleteSecondPasses.keySet()) {
+                if (pass.hashCode() == secondPass.hashCode()) {
+                    return pass.tile != null ? pass.tile.linTag() : BlockTypesCache.states[ord].getNbt();
+                }
+            }
+            return BlockTypesCache.states[ord].getNbt();
+        }
+        if (processChunkSet == null || (x & CHUNK_BLOCK_POS_MASK) != processChunkX || (z & CHUNK_BLOCK_POS_MASK) != processChunkZ) {
+            return extent.getFullBlock(x, y, z).getNbt();
+        }
+        FaweCompoundTag tile = processChunkSet.tile(x & 15, y, z & 15);
+        if (tile != null) {
+            return tile.linTag();
+        }
+        char[] set = processChunkSet.loadIfPresent(y >> 4);
+        if (set == null) {
+            return processChunkGet.getFullBlock(x & 15, y, z & 15).getNbt();
+        }
+        char ordinal = set[(y & 15) << 8 | (z & 15) << 4 | (x & 15)];
+        if (ordinal == BlockTypesCache.ReservedIDs.__RESERVED__) {
+            return processChunkGet.getFullBlock(x & 15, y, z & 15).getNbt();
+        }
+        return BlockTypesCache.states[ordinal].getNbt();
+    }
+
+    private char getBlockOrdinal(int blockX, int blockY, int blockZ, BlockState state) {
+        char override = getOverrideBlockOrdinal(blockX, blockY, blockZ, state);
+        if (override != BlockTypesCache.ReservedIDs.__RESERVED__) {
+            return override;
+        }
+        EnumSet<Direction> dirs = Direction.getDirections(state);
+        Direction clickedFaceDirection = null; // This should be always be set by the below.
+        Set<String> states = state.getStates().keySet().stream().map(Property::getName).collect(Collectors.toSet());
+        if (dirs.isEmpty() || states.contains("NORTH") && states.contains("EAST")) {
+            clickPos.setComponents(blockX + 0.5d, blockY, blockZ + 0.5d);
+            clickedFaceDirection = Direction.UP;
+            clickedBlock.setComponents(blockX, blockY - 1, blockZ);
+        } else {
+            boolean hadNesw = false;
+            for (Direction dir : NESW) {
+                if (dirs.contains(dir)) {
+                    clickedFaceDirection = dir.getLeft().getLeft();
+                    if (state.getBlockType() == BlockTypes.CHEST || state.getBlockType() == BlockTypes.TRAPPED_CHEST) {
+                        Direction tmp = clickedFaceDirection;
+                        clickedFaceDirection = dir;
+                        dir = tmp;
+                    }
+                    clickPos.setComponents(
+                            (double) blockX + 0.5 * (1 + dir.getBlockX()),
+                            (double) blockY + 0.2,
+                            (double) blockZ + 0.5 * (1 + dir.getBlockZ())
+                    );
+                    clickedBlock.setComponents(blockX, blockY, blockZ).add(dir.toBlockVector());
+                    hadNesw = true;
+                    break;
+                }
+            }
+            if (hadNesw) {
+                if (dirs.contains(Direction.UP)) {
+                    clickPos.mutY(blockY + 0.6);
+                }
+            } else if (dirs.contains(Direction.UP)) {
+                clickedFaceDirection = Direction.DOWN;
+                clickPos.setComponents(blockX + 0.5d, blockY + 1d, blockZ + 0.5d);
+                clickedBlock.setComponents(blockX, blockY + 1, blockZ);
+            } else if (dirs.contains(Direction.DOWN)) {
+                clickedFaceDirection = Direction.UP;
+                clickPos.setComponents(blockX + 0.5d, blockY - 1d, blockZ + 0.5d);
+                clickedBlock.setComponents(blockX, blockY - 1, blockZ);
+            }
+        }
+        return getStateAtFor(blockX, blockY, blockZ, state, clickPos, clickedFaceDirection, clickedBlock);
+    }
+
+    protected char getOverrideBlockOrdinal(int blockX, int blockY, int blockZ, BlockState state) {
+        if (BlockCategories.TALL_FLOWERS.contains(state)) {
+            PropertyKey propertyKey = PropertyKey.HALF;
+            BlockState plantState = extent.getBlock(blockX, blockY - 1, blockZ).getBlockType().equals(state.getBlockType())
+                    ? state.with(propertyKey, "upper")
+                    : state.with(propertyKey, "lower");
+            return plantState.getOrdinalChar();
+        }
+        return BlockTypesCache.ReservedIDs.__RESERVED__;
+    }
+
+    @Override
+    public void applyBlock(FilterBlock block) {
+        if (finished.get()) {
+            return;
+        }
+        BlockState state = BlockTypesCache.states[block.getOrdinal()];
+        if (!mask.test(state)) {
+            return;
+        }
+        if (REQUIRES_SECOND_PASS.test(block.getBlock()) && ADJACENT_STAIR_MASK.test(extent, block)) {
+            postCompleteSecondPasses.put(new SecondPass(block), (char) 0);
+        }
+        char ordinal = (char) block.getOrdinal();
+        char newOrdinal = getBlockOrdinal(block.x(), block.y(), block.z(), block.getBlock());
+        if (ordinal != newOrdinal) {
+            block.setBlock(BlockTypesCache.states[newOrdinal]);
+        }
+    }
+
+    @Override
+    public boolean apply(Extent orDefault, BlockVector3 get, BlockVector3 set) throws WorldEditException {
+        if (orDefault == null) {
+            orDefault = extent;
+        }
+        BaseBlock block = orDefault.getFullBlock(get);
+        if (!mask.test(block)) {
+            return false;
+        }
+        if (REQUIRES_SECOND_PASS.test(block) && ADJACENT_STAIR_MASK.test(extent, set)) {
+            postCompleteSecondPasses.put(new SecondPass(set), (char) 0);
+            return false;
+        }
+        char newOrdinal = getBlockOrdinal(set.x(), set.y(), set.z(), block.toBlockState());
+        if (block.getOrdinalChar() != newOrdinal) {
+            BlockState newState = BlockTypesCache.states[newOrdinal];
+            orDefault.setBlock(set.x(), set.y(), set.z(), newState);
+            LinCompoundTag nbt = block.getNbt();
+            if (nbt != null && newState.getBlockType() == block.getBlockType()) {
+                orDefault.tile(set.x(), set.y(), set.z(), FaweCompoundTag.of(nbt));
+            }
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public BaseBlock applyBlock(BlockVector3 position) {
+        if (finished.get()) {
+            return null;
+        }
+        BaseBlock block = extent.getFullBlock(position);
+        if (!mask.test(block)) {
+            return null;
+        }
+        if (REQUIRES_SECOND_PASS.test(block) && ADJACENT_STAIR_MASK.test(extent, position)) {
+            postCompleteSecondPasses.put(new SecondPass(position), (char) 0);
+            return null;
+        }
+        char newOrdinal = getBlockOrdinal(position.x(), position.y(), position.z(), block.toBlockState());
+        if (block.getOrdinalChar() != newOrdinal) {
+            BlockState state = BlockTypesCache.states[newOrdinal];
+            LinCompoundTag nbt = block.getNbt();
+            if (nbt != null && state.getBlockType() == block.getBlockType()) {
+                state.toBaseBlock(nbt);
+            }
+            return state.toBaseBlock();
+        }
+        return null;
+    }
+
+    protected record SecondPass(int x, int y, int z, FaweCompoundTag tile) {
+
+        private SecondPass(BlockVector3 pos) {
+            this(pos.x(), pos.y(), pos.z(), null);
+        }
+
+        @Override
+        public int hashCode() {
+            return (x ^ (z << 12)) ^ (y << 24);
+        }
+
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/mask/Adjacent2DMask.java

@@ -0,0 +1,66 @@
+package com.fastasyncworldedit.core.function.mask;
+
+import com.fastasyncworldedit.core.math.MutableBlockVector3;
+import com.sk89q.worldedit.function.mask.AbstractMask;
+import com.sk89q.worldedit.function.mask.Mask;
+import com.sk89q.worldedit.math.BlockVector3;
+
+/**
+ * Mask that tests adjacency only in 2D/the same y-level
+ *
+ * @since TODO
+ */
+public class Adjacent2DMask extends AbstractMask {
+
+    private final int min;
+    private final int max;
+    private final Mask mask;
+    private final MutableBlockVector3 vector;
+
+    /**
+     * Mask that tests adjacency only in 2D/the same y-level
+     *
+     * @param mask Mask required to be adjacent
+     * @param requiredMin Minimum number of positive adjacency matches required
+     * @param requiredMax Maximum number of positive adjacency matches  required
+     * @since TODO
+     */
+    public Adjacent2DMask(Mask mask, int requiredMin, int requiredMax) {
+        this.mask = mask;
+        this.min = requiredMin;
+        this.max = requiredMax;
+        this.vector = new MutableBlockVector3();
+    }
+
+    @Override
+    public boolean test(BlockVector3 bv) {
+        vector.setComponents(bv);
+        double x = bv.x();
+        double z = bv.z();
+        vector.mutX(x + 1);
+        int count = 0;
+        if (mask.test(vector) && ++count == min && max >= 4) {
+            return true;
+        }
+        vector.mutX(x - 1);
+        if (mask.test(vector) && ++count == min && max >= 4) {
+            return true;
+        }
+        vector.mutX(x);
+        vector.mutZ(z + 1);
+        if (mask.test(vector) && ++count == min && max >= 4) {
+            return true;
+        }
+        vector.mutZ(z - 1);
+        if (mask.test(vector) && ++count == min && max >= 4) {
+            return true;
+        }
+        return count >= min && count <= max;
+    }
+
+    @Override
+    public Mask copy() {
+        return new Adjacent2DMask(mask.copy(), min, max);
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/mask/AdjacentAny2DMask.java

@@ -0,0 +1,90 @@
+package com.fastasyncworldedit.core.function.mask;
+
+import com.fastasyncworldedit.core.math.MutableBlockVector3;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.AbstractExtentMask;
+import com.sk89q.worldedit.function.mask.AbstractMask;
+import com.sk89q.worldedit.function.mask.Mask;
+import com.sk89q.worldedit.math.BlockVector3;
+
+/**
+ * Optimized version of {@link Adjacent2DMask} for testing for any single adjacency
+ *
+ * @since TODO
+ */
+public class AdjacentAny2DMask extends AbstractMask {
+
+    private final Mask mask;
+    private final MutableBlockVector3 mutable;
+
+    /**
+     * Optimized version of {@link Adjacent2DMask} for testing for any single adjacency. Caches results of the adjacent mask
+     *
+     * @param mask Mask required to be adjacent
+     * @since TODO
+     */
+    public AdjacentAny2DMask(Mask mask) {
+        this(mask, true);
+    }
+
+    /**
+     * Optimized version of {@link Adjacent2DMask} for testing for any single adjacency
+     *
+     * @param mask  Mask required to be adjacent
+     * @param cache If the result of the adjacency mask should be cached
+     * @since TODO
+     */
+    public AdjacentAny2DMask(Mask mask, boolean cache) {
+        this.mask = cache ? CachedMask.cache(mask) : mask;
+        mutable = new MutableBlockVector3();
+    }
+
+    @Override
+    public boolean test(BlockVector3 v) {
+        int x = v.x();
+        int y = v.y();
+        int z = v.z();
+        if (mask.test(mutable.setComponents(x + 1, y, z))) {
+            return true;
+        }
+        if (mask.test(mutable.setComponents(x - 1, y, z))) {
+            return true;
+        }
+        if (mask.test(mutable.setComponents(x, y, z + 1))) {
+            return true;
+        }
+        return mask.test(mutable.setComponents(x, y, z - 1));
+    }
+
+    /**
+     * Test this mask for the given extent
+     *
+     * @param extent   extent to test in
+     * @param position position to test at
+     * @since TODO
+     */
+    public boolean test(Extent extent, BlockVector3 position) {
+        if (!(mask instanceof AbstractExtentMask extentMask)) {
+            throw new UnsupportedOperationException("Adjacency mask must inherit from AbstractExtentMask");
+        }
+        int x = position.x();
+        int y = position.y();
+        int z = position.z();
+        if (extentMask.test(extent, mutable.setComponents(x + 1, y, z))) {
+            return true;
+        }
+        if (extentMask.test(extent, mutable.setComponents(x - 1, y, z))) {
+            return true;
+        }
+        if (extentMask.test(extent, mutable.setComponents(x, y, z + 1))) {
+            return true;
+        }
+        return extentMask.test(extent, mutable.setComponents(x, y, z - 1));
+    }
+
+    @Override
+    public Mask copy() {
+        return new AdjacentAny2DMask(mask.copy(), false);
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/mask/AdjacentAnyMask.java

@@ -23,7 +23,7 @@ public class AdjacentAnyMask extends AbstractMask implements ResettableMask {
     }
 
     AdjacentAnyMask(CachedMask mask, int minY, int maxY) {
-        this.mask = CachedMask.cache(mask);
+        this.mask = mask;
         mutable = new MutableBlockVector3();
         this.minY = minY;
         this.maxY = maxY;

worldedit-core/src/main/java/com/fastasyncworldedit/core/history/changeset/FaweStreamChangeSet.java

@@ -461,7 +461,6 @@ public abstract class FaweStreamChangeSet extends AbstractChangeSet {
                 } catch (EOFException ignored) {
                 } catch (Exception e) {
                     e.printStackTrace();
-                    e.printStackTrace();
                 }
                 try {
                     is.close();

worldedit-core/src/main/java/com/fastasyncworldedit/core/math/MutableBlockVector3.java

@@ -62,7 +62,7 @@ public class MutableBlockVector3 extends BlockVector3 {
     }
 
     @Override
-    public BlockVector3 getMinimum(BlockVector3 v2) {
+    public MutableBlockVector3 getMinimum(BlockVector3 v2) {
         this.x = Math.min(v2.x(), x);
         this.y = Math.min(v2.y(), y);
         this.z = Math.min(v2.z(), z);
@@ -70,7 +70,7 @@ public class MutableBlockVector3 extends BlockVector3 {
     }
 
     @Override
-    public BlockVector3 getMaximum(BlockVector3 v2) {
+    public MutableBlockVector3 getMaximum(BlockVector3 v2) {
         this.x = Math.max(v2.x(), x);
         this.y = Math.max(v2.y(), y);
         this.z = Math.max(v2.z(), z);
@@ -113,4 +113,140 @@ public class MutableBlockVector3 extends BlockVector3 {
         return this;
     }
 
+    @Override
+    public final MutableBlockVector3 withX(int x) {
+        this.x = x;
+        return this;
+    }
+
+    @Override
+    public final MutableBlockVector3 withY(int y) {
+        this.y = y;
+        return this;
+    }
+
+    @Override
+    public final MutableBlockVector3 withZ(int z) {
+        this.z = z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 add(BlockVector3 other) {
+        return add(other.x(), other.y(), other.z());
+    }
+
+    @Override
+    public MutableBlockVector3 add(int x, int y, int z) {
+        this.x += x;
+        this.y += y;
+        this.z += z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 add(BlockVector3... others) {
+        for (BlockVector3 other : others) {
+            this.x += other.x();
+            this.y += other.y();
+            this.z += other.z();
+        }
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 subtract(BlockVector3 other) {
+        return subtract(other.x(), other.y(), other.z());
+    }
+
+    @Override
+    public MutableBlockVector3 subtract(int x, int y, int z) {
+        this.x -= x;
+        this.y -= y;
+        this.z -= z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 subtract(BlockVector3... others) {
+        for (BlockVector3 other : others) {
+            this.x -= other.x();
+            this.y -= other.y();
+            this.z -= other.z();
+        }
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 multiply(BlockVector3 other) {
+        return multiply(other.x(), other.y(), other.z());
+    }
+
+    @Override
+    public MutableBlockVector3 multiply(int x, int y, int z) {
+        this.x *= x;
+        this.y *= y;
+        this.z *= z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 multiply(BlockVector3... others) {
+        for (BlockVector3 other : others) {
+            this.x *= other.x();
+            this.y *= other.y();
+            this.z *= other.z();
+        }
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 multiply(int n) {
+        return multiply(n, n, n);
+    }
+
+    @Override
+    public MutableBlockVector3 divide(BlockVector3 other) {
+        return divide(other.x(), other.y(), other.z());
+    }
+
+    @Override
+    public MutableBlockVector3 divide(int x, int y, int z) {
+        this.x /= x;
+        this.y /= y;
+        this.z /= z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 divide(int n) {
+        return divide(n, n, n);
+    }
+
+    @Override
+    public MutableBlockVector3 shr(int x, int y, int z) {
+        this.x = this.x >> x;
+        this.y = this.y >> y;
+        this.z = this.z >> z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 shr(int n) {
+        return shr(n, n, n);
+    }
+
+    @Override
+    public MutableBlockVector3 shl(int x, int y, int z) {
+        this.x = this.x >> x;
+        this.y = this.y >> y;
+        this.z = this.z >> z;
+        return this;
+    }
+
+    @Override
+    public MutableBlockVector3 shl(int n) {
+        return shl(n, n, n);
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/Filter.java

@@ -62,4 +62,13 @@ public interface Filter {
 
     }
 
+    /**
+     * Signals to the filter the edit has concluded
+     *
+     * @since TODO
+     */
+    default void finish() {
+
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IChunkSet.java

@@ -7,6 +7,7 @@ import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.extent.OutputExtent;
 import com.sk89q.worldedit.function.operation.Operation;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
 
@@ -139,4 +140,19 @@ public interface IChunkSet extends IBlocks, OutputExtent {
         return this;
     }
 
+    /**
+     * Set the side effects to be used when settings these blocks
+     *
+     * @since TODO
+     */
+    void setSideEffectSet(@Nonnull SideEffectSet sideEffectSet);
+
+    /**
+     * Get the side effects to be used when settings these blocks
+     *
+     * @since TODO
+     */
+    @Nonnull
+    SideEffectSet getSideEffectSet();
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IDelegateFilter.java

@@ -38,6 +38,11 @@ public interface IDelegateFilter extends Filter {
         return this;
     }
 
+    @Override
+    default void finish() {
+        getParent().finish();
+    }
+
     Filter newInstance(Filter other);
 
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IQueueExtent.java

@@ -10,6 +10,7 @@ import com.sk89q.worldedit.function.operation.Operation;
 import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.SideEffectSet;
 
 import javax.annotation.Nullable;
 import java.io.Flushable;
@@ -81,6 +82,20 @@ public interface IQueueExtent<T extends IChunk> extends Flushable, Trimable, ICh
 
     boolean isFastMode();
 
+    /**
+     * Set the side effects to be used with this extent
+     *
+     * @since TODO
+     */
+    void setSideEffectSet(SideEffectSet sideEffectSet);
+
+    /**
+     * Get the side effects to be used with this extent
+     *
+     * @since TODO
+     */
+    SideEffectSet getSideEffectSet();
+
     /**
      * Create a new root IChunk object. Full chunks will be reused, so a more optimized chunk can be
      * returned in that case.

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/ParallelQueueExtent.java

@@ -20,11 +20,14 @@ import com.fastasyncworldedit.core.queue.Filter;
 import com.fastasyncworldedit.core.queue.IQueueChunk;
 import com.fastasyncworldedit.core.queue.IQueueExtent;
 import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.extent.clipboard.Clipboard;
 import com.sk89q.worldedit.function.mask.BlockMask;
 import com.sk89q.worldedit.function.mask.ExistingBlockMask;
 import com.sk89q.worldedit.function.mask.Mask;
+import com.sk89q.worldedit.function.operation.Operation;
+import com.sk89q.worldedit.function.operation.RunContext;
 import com.sk89q.worldedit.function.pattern.BlockPattern;
 import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
@@ -32,6 +35,7 @@ import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.util.Countable;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.World;
 import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
@@ -39,6 +43,7 @@ import com.sk89q.worldedit.world.block.BlockStateHolder;
 import com.sk89q.worldedit.world.block.BlockType;
 import org.apache.logging.log4j.Logger;
 
+import javax.annotation.Nullable;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
@@ -58,11 +63,12 @@ public class ParallelQueueExtent extends PassthroughExtent {
     // not very important)
     private final boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
     private final boolean fastmode;
+    private final SideEffectSet sideEffectSet;
     private int changes;
     private int lastException = Integer.MIN_VALUE;
     private int exceptionCount = 0;
 
-    public ParallelQueueExtent(QueueHandler handler, World world, boolean fastmode) {
+    public ParallelQueueExtent(QueueHandler handler, World world, boolean fastmode, @Nullable SideEffectSet sideEffectSet) {
         super(handler.getQueue(world, new BatchProcessorHolder(), new BatchProcessorHolder()));
         this.world = world;
         this.handler = handler;
@@ -75,6 +81,7 @@ public class ParallelQueueExtent extends PassthroughExtent {
             ((MultiBatchProcessor) this.postProcessor.getProcessor()).setFaweExceptionArray(faweExceptionReasonsUsed);
         }
         this.fastmode = fastmode;
+        this.sideEffectSet = sideEffectSet == null ? SideEffectSet.defaults() : sideEffectSet;
     }
 
     /**
@@ -121,7 +128,12 @@ public class ParallelQueueExtent extends PassthroughExtent {
 
     @SuppressWarnings("rawtypes")
     private IQueueExtent<IQueueChunk> getNewQueue() {
-        return handler.getQueue(world, this.processor, this.postProcessor);
+        SingleThreadQueueExtent queue = (SingleThreadQueueExtent) handler.getQueue(world, this.processor, this.postProcessor);
+        queue.setFastMode(fastmode);
+        queue.setSideEffectSet(sideEffectSet);
+        queue.setFaweExceptionArray(faweExceptionReasonsUsed);
+        enter(queue);
+        return queue;
     }
 
     @Override
@@ -140,6 +152,8 @@ public class ParallelQueueExtent extends PassthroughExtent {
                 BlockVector2 pos = chunksIter.next();
                 block = getExtent().apply(block, filter, region, pos.x(), pos.z(), full);
             }
+            getExtent().flush();
+            filter.finish();
         } else {
             final ForkJoinTask[] tasks = IntStream.range(0, size).mapToObj(i -> handler.submit(() -> {
                 try {
@@ -147,13 +161,9 @@ public class ParallelQueueExtent extends PassthroughExtent {
                     final Region newRegion = region.clone();
                     // Create a chunk that we will reuse/reset for each operation
                     final SingleThreadQueueExtent queue = (SingleThreadQueueExtent) getNewQueue();
-                    queue.setFastMode(fastmode);
-                    queue.setFaweExceptionArray(faweExceptionReasonsUsed);
-                    enter(queue);
                     synchronized (queue) {
                         try {
                             ChunkFilterBlock block = null;
-
                             while (true) {
                                 // Get the next chunk posWeakChunk
                                 final int chunkX;
@@ -169,6 +179,7 @@ public class ParallelQueueExtent extends PassthroughExtent {
                                 block = queue.apply(block, newFilter, newRegion, chunkX, chunkZ, full);
                             }
                             queue.flush();
+                            filter.finish();
                         } catch (Throwable t) {
                             if (t instanceof FaweException) {
                                 Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) t, LOGGER);
@@ -205,6 +216,24 @@ public class ParallelQueueExtent extends PassthroughExtent {
         return filter;
     }
 
+    @Override
+    protected Operation commitBefore() {
+        return new Operation() {
+            @Override
+            public Operation resume(final RunContext run) throws WorldEditException {
+                extent.commit();
+                processor.flush();
+                ((IQueueExtent<IQueueChunk<?>>) extent).flush();
+                return null;
+            }
+
+            @Override
+            public void cancel() {
+
+            }
+        };
+    }
+
     @Override
     public int countBlocks(Region region, Mask searchMask) {
         return

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/SingleThreadQueueExtent.java

@@ -27,6 +27,7 @@ import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector2;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.World;
 import it.unimi.dsi.fastutil.longs.Long2ObjectLinkedOpenHashMap;
 import org.apache.logging.log4j.Logger;
@@ -68,6 +69,7 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
     private boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
     private int lastException = Integer.MIN_VALUE;
     private int exceptionCount = 0;
+    private SideEffectSet sideEffectSet = SideEffectSet.defaults();
 
     public SingleThreadQueueExtent() {
     }
@@ -110,6 +112,16 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         this.fastmode = fastmode;
     }
 
+    @Override
+    public void setSideEffectSet(SideEffectSet sideEffectSet) {
+        this.sideEffectSet = sideEffectSet;
+    }
+
+    @Override
+    public SideEffectSet getSideEffectSet() {
+        return sideEffectSet;
+    }
+
     @Override
     public int getMinY() {
         return minY;
@@ -120,6 +132,10 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
         return maxY;
     }
 
+    public World getWorld() {
+        return world;
+    }
+
     /**
      * Sets the cached boolean array of length {@code FaweException.Type.values().length} that determines if a thrown
      * {@link FaweException} of type {@link FaweException.Type} should be output to console, rethrown to attempt to be visible
@@ -278,10 +294,16 @@ public class SingleThreadQueueExtent extends ExtentBatchProcessorHolder implemen
     private ChunkHolder poolOrCreate(int chunkX, int chunkZ) {
         ChunkHolder next = create(false);
         next.init(this, chunkX, chunkZ);
-        next.setFastMode(isFastMode());
         return next;
     }
 
+    @Override
+    public IQueueChunk wrap(IQueueChunk chunk) {
+        chunk.setFastMode(isFastMode());
+        chunk.setSideEffectSet(getSideEffectSet());
+        return chunk;
+    }
+
     @Override
     public final IQueueChunk getOrCreateChunk(int x, int z) {
         getChunkLock.lock();

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/BitSetBlocks.java

@@ -6,6 +6,7 @@ import com.fastasyncworldedit.core.nbt.FaweCompoundTag;
 import com.fastasyncworldedit.core.queue.IChunkSet;
 import com.fastasyncworldedit.core.util.collection.MemBlockSet;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockState;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
@@ -212,6 +213,16 @@ public class BitSetBlocks implements IChunkSet {
         return false;
     }
 
+    @Override
+    public void setSideEffectSet(SideEffectSet sideEffectSet) {
+
+    }
+
+    @Override
+    public SideEffectSet getSideEffectSet() {
+        return SideEffectSet.none();
+    }
+
     @Override
     public int getSectionCount() {
         return layers;

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/CharSetBlocks.java

@@ -9,6 +9,7 @@ import com.fastasyncworldedit.core.queue.IChunkSet;
 import com.fastasyncworldedit.core.queue.Pool;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
 import com.sk89q.worldedit.world.block.BlockTypesCache;
@@ -44,6 +45,7 @@ public class CharSetBlocks extends CharBlocks implements IChunkSet {
     public EnumMap<HeightMapType, int[]> heightMaps;
     private boolean fastMode = false;
     private int bitMask = -1;
+    private SideEffectSet sideEffectSet = SideEffectSet.defaults();
 
     private CharSetBlocks() {
         // Expand as we go
@@ -374,10 +376,21 @@ public class CharSetBlocks extends CharBlocks implements IChunkSet {
                 heightMaps != null ? new EnumMap<>(heightMaps) : null,
                 defaultOrdinal(),
                 fastMode,
-                bitMask
+                bitMask,
+                sideEffectSet
         );
     }
 
+    @Override
+    public void setSideEffectSet(SideEffectSet sideEffectSet) {
+        this.sideEffectSet = sideEffectSet;
+    }
+
+    @Override
+    public SideEffectSet getSideEffectSet() {
+        return sideEffectSet;
+    }
+
     static char[][] createLightCopy(char[][] lightArr, int sectionCount) {
         if (lightArr == null) {
             return null;

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/ThreadUnsafeCharBlocks.java

@@ -9,6 +9,7 @@ import com.fastasyncworldedit.core.queue.IBlocks;
 import com.fastasyncworldedit.core.queue.IChunkSet;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BlockState;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
@@ -51,6 +52,7 @@ public class ThreadUnsafeCharBlocks implements IChunkSet, IBlocks {
     private Map<HeightMapType, int[]> heightMaps;
     private boolean fastMode;
     private int bitMask;
+    private SideEffectSet sideEffectSet;
 
     /**
      * New instance given the data stored in a {@link CharSetBlocks} instance.
@@ -71,7 +73,8 @@ public class ThreadUnsafeCharBlocks implements IChunkSet, IBlocks {
             Map<HeightMapType, int[]> heightMaps,
             char defaultOrdinal,
             boolean fastMode,
-            int bitMask
+            int bitMask,
+            SideEffectSet sideEffectSet
     ) {
         this.blocks = blocks;
         this.minSectionPosition = minSectionPosition;
@@ -87,6 +90,7 @@ public class ThreadUnsafeCharBlocks implements IChunkSet, IBlocks {
         this.defaultOrdinal = defaultOrdinal;
         this.fastMode = fastMode;
         this.bitMask = bitMask;
+        this.sideEffectSet = sideEffectSet;
     }
 
     @Override
@@ -480,10 +484,21 @@ public class ThreadUnsafeCharBlocks implements IChunkSet, IBlocks {
                 heightMaps != null ? new HashMap<>(heightMaps) : null,
                 defaultOrdinal,
                 fastMode,
-                bitMask
+                bitMask,
+                sideEffectSet
         );
     }
 
+    @Override
+    public void setSideEffectSet(SideEffectSet sideEffectSet) {
+        this.sideEffectSet = sideEffectSet;
+    }
+
+    @Override
+    public SideEffectSet getSideEffectSet() {
+        return sideEffectSet;
+    }
+
     @Override
     public boolean trim(boolean aggressive) {
         return false;

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/chunk/ChunkHolder.java

@@ -15,6 +15,7 @@ import com.fastasyncworldedit.core.util.MemUtil;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
@@ -51,6 +52,7 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     private boolean isInit = false; // Lighting handles queue differently. It relies on the chunk cache and not doing init.
     private boolean createCopy = false;
     private long initTime = -1L;
+    private SideEffectSet sideEffectSet;
 
     private ChunkHolder() {
         this.delegate = NULL;
@@ -150,6 +152,16 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
         return chunkSet != null && chunkSet.hasBiomes(layer);
     }
 
+    @Override
+    public void setSideEffectSet(SideEffectSet sideEffectSet) {
+        this.sideEffectSet = sideEffectSet;
+    }
+
+    @Override
+    public SideEffectSet getSideEffectSet() {
+        return sideEffectSet;
+    }
+
     public boolean isInit() {
         return isInit;
     }
@@ -874,7 +886,6 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     public synchronized void filterBlocks(Filter filter, ChunkFilterBlock block, @Nullable Region region, boolean full) {
         final IChunkGet get = getOrCreateGet();
         final IChunkSet set = getOrCreateSet();
-        set.setFastMode(fastmode);
         try {
             block.filter(this, get, set, filter, region, full);
         } finally {
@@ -948,13 +959,21 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
         return chunkSet;
     }
 
+    public final IChunkSet getChunkSet() {
+        return chunkSet;
+    }
+
     /**
      * Create a wrapped set object
      * - The purpose of wrapping is to allow different extents to intercept / alter behavior
      * - e.g., caching, optimizations, filtering
      */
     private IChunkSet newWrappedSet() {
-        return extent.getCachedSet(chunkX, chunkZ);
+        IChunkSet set = extent.getCachedSet(chunkX, chunkZ);
+        set.setFastMode(fastmode);
+        set.setSideEffectSet(sideEffectSet);
+        set.setBitMask(bitMask);
+        return set;
     }
 
     /**
@@ -985,7 +1004,6 @@ public class ChunkHolder<T extends Future<T>> implements IQueueChunk<T> {
     @Override
     public synchronized T call() {
         if (chunkSet != null && !chunkSet.isEmpty()) {
-            chunkSet.setBitMask(bitMask);
             IChunkSet copy = chunkSet.createCopy();
             return this.call(copy, () -> {
                 // Do nothing

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/chunk/NullChunk.java

@@ -8,6 +8,7 @@ import com.fastasyncworldedit.core.queue.IChunkSet;
 import com.fastasyncworldedit.core.queue.IQueueChunk;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
@@ -86,6 +87,16 @@ public final class NullChunk implements IQueueChunk {
         return false;
     }
 
+    @Override
+    public void setSideEffectSet(SideEffectSet sideEffectSet) {
+
+    }
+
+    @Override
+    public SideEffectSet getSideEffectSet() {
+        return SideEffectSet.none();
+    }
+
     @Nonnull
     public int[] getHeightMap(@Nullable HeightMapType type) {
         return new int[256];

worldedit-core/src/main/java/com/fastasyncworldedit/core/util/ExtentTraverser.java

@@ -1,7 +1,11 @@
 package com.fastasyncworldedit.core.util;
 
+import com.fastasyncworldedit.core.queue.implementation.ParallelQueueExtent;
+import com.fastasyncworldedit.core.queue.implementation.SingleThreadQueueExtent;
+import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.extent.AbstractDelegateExtent;
 import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.world.World;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -21,6 +25,26 @@ public class ExtentTraverser<T extends Extent> {
         this.parent = parent;
     }
 
+    /**
+     * Get the world backing the given extent, if present, else null.
+     *
+     * @since TODO
+     */
+    @Nullable
+    public static World getWorldFromExtent(Extent extent) {
+        if (extent.isWorld()) {
+            return (World) extent;
+        } else if (extent instanceof EditSession session) {
+            return session.getWorld();
+        } else if (extent instanceof SingleThreadQueueExtent stqe) {
+            return stqe.getWorld();
+        } else if (extent instanceof ParallelQueueExtent pqe) {
+            return ((SingleThreadQueueExtent) pqe.getExtent()).getWorld();
+        } else {
+            return new ExtentTraverser<>(extent).findAndGet(World.class);
+        }
+    }
+
     public boolean exists() {
         return root != null;
     }

worldedit-core/src/main/java/com/sk89q/worldedit/EditSessionBuilder.java

@@ -64,7 +64,10 @@ import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.extent.inventory.BlockBag;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.regions.RegionIntersection;
 import com.sk89q.worldedit.util.Identifiable;
+import com.sk89q.worldedit.util.SideEffect;
+import com.sk89q.worldedit.util.SideEffectSet;
 import com.sk89q.worldedit.util.eventbus.EventBus;
 import com.sk89q.worldedit.util.formatting.text.Component;
 import com.sk89q.worldedit.util.formatting.text.TextComponent;
@@ -104,6 +107,7 @@ public final class EditSessionBuilder {
     private Extent extent;
     private boolean compiled;
     private boolean wrapped;
+    private SideEffectSet sideEffectSet = null;
 
     private @Nullable
     World world;
@@ -415,6 +419,16 @@ public final class EditSessionBuilder {
         return setDirty();
     }
 
+    /**
+     * Set the side effects to be used with this edit
+     *
+     * @since TODO
+     */
+    public EditSessionBuilder setSideEffectSet(@Nullable SideEffectSet sideEffectSet) {
+        this.sideEffectSet = sideEffectSet;
+        return setDirty();
+    }
+
     /**
      * Compile the builder to the settings given. Prepares history, limits, lighting, etc.
      */
@@ -445,6 +459,10 @@ public final class EditSessionBuilder {
                 fastMode = actor.getSession().hasFastMode();
             }
         }
+        if (sideEffectSet == null) {
+            // Keep heightmaps to maintain behaviour
+            sideEffectSet = fastMode ? SideEffectSet.none().with(SideEffect.HEIGHTMAPS) : SideEffectSet.defaults();
+        }
         if (checkMemory == null) {
             checkMemory = actor != null && !this.fastMode;
         }
@@ -470,12 +488,18 @@ public final class EditSessionBuilder {
                 if (unwrapped instanceof IQueueExtent) {
                     extent = queue = (IQueueExtent) unwrapped;
                 } else if (Settings.settings().QUEUE.PARALLEL_THREADS > 1 && !Fawe.isMainThread()) {
-                    ParallelQueueExtent parallel = new ParallelQueueExtent(Fawe.instance().getQueueHandler(), world, fastMode);
+                    ParallelQueueExtent parallel = new ParallelQueueExtent(
+                            Fawe.instance().getQueueHandler(),
+                            world,
+                            fastMode,
+                            sideEffectSet
+                    );
                     queue = parallel.getExtent();
                     extent = parallel;
                 } else {
                     extent = queue = Fawe.instance().getQueueHandler().getQueue(world);
                 }
+                queue.setSideEffectSet(sideEffectSet);
             } else {
                 wnaMode = true;
                 extent = world;
@@ -491,7 +515,7 @@ public final class EditSessionBuilder {
             }
             extent = this.bypassAll = wrapExtent(extent, eventBus, event, EditSession.Stage.BEFORE_CHANGE);
             this.bypassHistory = this.extent = wrapExtent(bypassAll, eventBus, event, EditSession.Stage.BEFORE_REORDER);
-            if (!this.fastMode || changeSet != null) {
+            if (!this.fastMode  || this.sideEffectSet.shouldApply(SideEffect.HISTORY) || changeSet != null) {
                 if (changeSet == null) {
                     if (Settings.settings().HISTORY.USE_DISK) {
                         UUID uuid = actor == null ? Identifiable.CONSOLE : actor.getUniqueId();
@@ -546,13 +570,28 @@ public final class EditSessionBuilder {
             }
             // There's no need to do the below (and it'll also just be a pain to implement) if we're not placing chunks
             if (placeChunks) {
-                if (((relightMode != null && relightMode != RelightMode.NONE) || (relightMode == null && Settings.settings().LIGHTING.MODE > 0))) {
+                if (this.sideEffectSet.shouldApply(SideEffect.LIGHTING) || (relightMode != null && relightMode != RelightMode.NONE)) {
-                    relighter = WorldEdit.getInstance().getPlatformManager()
+                    relighter = WorldEdit
+                            .getInstance()
+                            .getPlatformManager()
                             .queryCapability(Capability.WORLD_EDITING)
-                            .getRelighterFactory().createRelighter(relightMode, world, queue);
+                            .getRelighterFactory()
+                            .createRelighter(relightMode, world, queue);
                     queue.addProcessor(new RelightProcessor(relighter));
                 }
+                if (this.sideEffectSet.shouldApply(SideEffect.HEIGHTMAPS)) {
                     queue.addProcessor(new HeightmapProcessor(world.getMinY(), world.getMaxY()));
+                }
+                if (this.sideEffectSet.shouldApply(SideEffect.NEIGHBORS)) {
+                    Region region = allowedRegions == null || allowedRegions.length == 0
+                            ? null
+                            : allowedRegions.length == 1 ? allowedRegions[0] : new RegionIntersection(allowedRegions);
+                    queue.addProcessor(WorldEdit
+                            .getInstance()
+                            .getPlatformManager()
+                            .queryCapability(Capability.WORLD_EDITING)
+                            .getPlatformPlacementProcessor(extent, null, region));
+                }
 
                 if (!Settings.settings().EXPERIMENTAL.KEEP_ENTITIES_IN_BLOCKS) {
                     queue.addProcessor(new EntityInBlockRemovingProcessor());
@@ -714,6 +753,15 @@ public final class EditSessionBuilder {
         return changeSet;
     }
 
+    /**
+     * Get the SideEffectSet that will be used
+     *
+     * @since TODO
+     */
+    public SideEffectSet getSideEffectSet() {
+        return sideEffectSet;
+    }
+
     /**
      * Get the ultimate resultant extent
      */

worldedit-core/src/main/java/com/sk89q/worldedit/LocalSession.java

@@ -154,6 +154,7 @@ public class LocalSession implements TextureHolder {
     private transient TextureUtil texture;
     private transient ResettableExtent transform = null;
     private transient World currentWorld;
+    private transient boolean fastMode = false;
     //FAWE end
     private transient ClipboardHolder clipboard;
     private transient final Object clipboardLock = new Object();
@@ -1725,11 +1726,12 @@ public class LocalSession implements TextureHolder {
      * @return an edit session
      */
     public EditSession createEditSession(Actor actor) {
-        //FAWE start
+        //FAWE start - save command used
         return createEditSession(actor, null);
     }
 
     public EditSession createEditSession(Actor actor, String command) {
+        //FAWE end
         checkNotNull(actor);
 
         World world = null;
@@ -1740,17 +1742,18 @@ public class LocalSession implements TextureHolder {
         }
 
         // Create an edit session
-        EditSession editSession;
         EditSessionBuilder builder = WorldEdit.getInstance().newEditSessionBuilder().world(world);
         if (actor.isPlayer() && actor instanceof Player) {
             BlockBag blockBag = getBlockBag((Player) actor);
             builder.actor(actor);
             builder.blockBag(blockBag);
         }
+        //FAWE start
         builder.command(command);
-        builder.fastMode(!this.sideEffectSet.doesApplyAny());
+        builder.fastMode(this.fastMode);
+        builder.setSideEffectSet(this.sideEffectSet);
 
-        editSession = builder.build();
+        EditSession editSession = builder.build();
 
         if (mask != null) {
             editSession.setMask(mask);
@@ -1762,7 +1765,7 @@ public class LocalSession implements TextureHolder {
             editSession.addTransform(transform);
         }
         editSession.setTickingWatchdog(tickingWatchdog);
-
+        //FAWE end
         return editSession;
     }
     //FAWE end
@@ -1801,7 +1804,9 @@ public class LocalSession implements TextureHolder {
      */
     @Deprecated
     public boolean hasFastMode() {
-        return !this.sideEffectSet.doesApplyAny();
+        //FAWE start - use fastmode boolean not side effects
+        return this.fastMode;
+        //FAWE end
     }
 
     /**
@@ -1811,7 +1816,9 @@ public class LocalSession implements TextureHolder {
      */
     @Deprecated
     public void setFastMode(boolean fastMode) {
-        this.sideEffectSet = fastMode ? SideEffectSet.none() : SideEffectSet.defaults();
+        //FAWE start - use fastmode boolean not side effects
+        this.fastMode = fastMode;
+        //FAWE end
     }
 
     /**

worldedit-core/src/main/java/com/sk89q/worldedit/command/RegionCommands.java

@@ -29,6 +29,7 @@ import com.fastasyncworldedit.core.util.MaskTraverser;
 import com.sk89q.jnbt.CompoundTag;
 import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.command.util.CommandPermissions;
 import com.sk89q.worldedit.command.util.CommandPermissionsConditionGenerator;
@@ -38,6 +39,7 @@ import com.sk89q.worldedit.command.util.annotation.Preload;
 import com.sk89q.worldedit.command.util.annotation.SynchronousSettingExpected;
 import com.sk89q.worldedit.entity.Player;
 import com.sk89q.worldedit.extension.platform.Actor;
+import com.sk89q.worldedit.extension.platform.Capability;
 import com.sk89q.worldedit.function.GroundFunction;
 import com.sk89q.worldedit.function.generator.FloraGenerator;
 import com.sk89q.worldedit.function.mask.ExistingBlockMask;
@@ -915,4 +917,33 @@ public class RegionCommands {
         return affected;
     }
 
+    //FAWE start - block "fixing"
+    @Command(
+            name = "/fixblocks",
+            aliases = {"/updateblocks", "/fixconnect"},
+            desc = "\"Fixes\" all blocks in the region to the correct shape/connections based on surrounding blocks"
+    )
+    @CommandPermissions("worldedit.region.fixblocks")
+    @Logging(REGION)
+    @Confirm(Confirm.Processor.REGION)
+    @Preload(Preload.PreloadCheck.PRELOAD)
+    public int fixblocks(
+            Actor actor, EditSession editSession, @Selection Region region
+    ) {
+        int affected = editSession.setBlocks(
+                region,
+                WorldEdit
+                        .getInstance()
+                        .getPlatformManager()
+                        .queryCapability(Capability.WORLD_EDITING)
+                        .getPlatformPlacementProcessor(editSession, null, region)
+        );
+        if (affected != 0) {
+            actor.print(Caption.of("worldedit.set.done", TextComponent.of(affected)));
+
+        }
+        return affected;
+    }
+    //FAWE end
+
 }

worldedit-core/src/main/java/com/sk89q/worldedit/extension/platform/Platform.java

@@ -19,13 +19,16 @@
 
 package com.sk89q.worldedit.extension.platform;
 
+import com.fastasyncworldedit.core.extent.processor.PlacementStateProcessor;
 import com.fastasyncworldedit.core.extent.processor.lighting.Relighter;
 import com.fastasyncworldedit.core.extent.processor.lighting.RelighterFactory;
 import com.fastasyncworldedit.core.queue.IBatchProcessor;
 import com.sk89q.worldedit.LocalConfiguration;
-import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.entity.Player;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.function.mask.BlockTypeMask;
 import com.sk89q.worldedit.internal.util.NonAbstractForCompatibility;
+import com.sk89q.worldedit.regions.Region;
 import com.sk89q.worldedit.registry.Keyed;
 import com.sk89q.worldedit.util.SideEffect;
 import com.sk89q.worldedit.util.io.ResourceLoader;
@@ -276,5 +279,15 @@ public interface Platform extends Keyed {
     default IBatchProcessor getPlatformPostProcessor(boolean fastMode) {
         return null;
     }
+
+    /**
+     * Returns an {@link PlacementStateProcessor} instance for processing placed blocks to "fix" them. Optional region to
+     * prevent any changes outside of, as sometimes block neighbours will also be updated otherwise.
+     *
+     * @since TODO
+     */
+    default PlacementStateProcessor getPlatformPlacementProcessor(Extent extent, BlockTypeMask mask, @Nullable Region region) {
+        return null;
+    }
     //FAWE end
 }

worldedit-core/src/main/java/com/sk89q/worldedit/function/mask/BlockCategoryMask.java

@@ -22,6 +22,7 @@ package com.sk89q.worldedit.function.mask;
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.block.BlockCategory;
+import com.sk89q.worldedit.world.block.BlockStateHolder;
 import com.sk89q.worldedit.world.block.BlockTypes;
 
 import javax.annotation.Nullable;
@@ -54,6 +55,15 @@ public class BlockCategoryMask extends AbstractExtentMask {
     public boolean test(Extent extent, BlockVector3 vector) {
         return category.contains(extent.getBlock(vector));
     }
+
+    /**
+     * Test a specific block against this category mask
+     *
+     * @since TODO
+     */
+    public <B extends BlockStateHolder<B>> boolean test(B blockStateHolder) {
+        return category.contains(blockStateHolder);
+    }
     //FAWE end
 
     @Nullable

worldedit-core/src/main/java/com/sk89q/worldedit/function/mask/BlockTypeMask.java

@@ -21,6 +21,7 @@ package com.sk89q.worldedit.function.mask;
 
 import com.sk89q.worldedit.extent.Extent;
 import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.world.block.BlockStateHolder;
 import com.sk89q.worldedit.world.block.BlockType;
 import com.sk89q.worldedit.world.block.BlockTypes;
 
@@ -140,6 +141,15 @@ public class BlockTypeMask extends AbstractExtentMask {
     public boolean test(BlockType block) {
         return types[block.getInternalId()];
     }
+
+    /**
+     * Test a block state against this block type mask
+     *
+     * @since TODO
+     */
+    public <B extends BlockStateHolder<B>> boolean test(B blockStateHolder) {
+        return types[blockStateHolder.getBlockType().getInternalId()];
+    }
     //FAWE end
 
     @Nullable
@@ -149,7 +159,7 @@ public class BlockTypeMask extends AbstractExtentMask {
     }
 
     @Override
-    public Mask copy() {
+    public BlockTypeMask copy() {
         return new BlockTypeMask(getExtent(), types.clone(), hasAir);
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/math/BlockVector3.java

@@ -127,6 +127,10 @@ public abstract class BlockVector3 {
     }
 
     //FAWE start
+    public boolean isAt(int x, int y, int z) {
+        return x() == x && y() == y && z() == z;
+    }
+
     public MutableBlockVector3 setComponents(double x, double y, double z) {
         return new MutableBlockVector3((int) x, (int) y, (int) z);
     }

worldedit-core/src/main/java/com/sk89q/worldedit/util/Direction.java

@@ -21,9 +21,13 @@ package com.sk89q.worldedit.util;
 
 import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.registry.state.DirectionalProperty;
+import com.sk89q.worldedit.registry.state.Property;
+import com.sk89q.worldedit.world.block.BlockState;
 
 import javax.annotation.Nullable;
 import java.util.ArrayList;
+import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
@@ -36,32 +40,32 @@ import java.util.OptionalInt;
 public enum Direction {
 
     //FAWE start - left, right
-    NORTH(Vector3.at(0, 0, -1), Flag.CARDINAL, 3, 1),
+    NORTH(Vector3.at(0, 0, -1), Flag.CARDINAL, 3, 1), // 0
-    EAST(Vector3.at(1, 0, 0), Flag.CARDINAL, 0, 2),
+    EAST(Vector3.at(1, 0, 0), Flag.CARDINAL, 0, 2), // 1
-    SOUTH(Vector3.at(0, 0, 1), Flag.CARDINAL, 1, 3),
+    SOUTH(Vector3.at(0, 0, 1), Flag.CARDINAL, 1, 3), // 2
-    WEST(Vector3.at(-1, 0, 0), Flag.CARDINAL, 2, 0),
+    WEST(Vector3.at(-1, 0, 0), Flag.CARDINAL, 2, 0), // 3
 
-    UP(Vector3.at(0, 1, 0), Flag.UPRIGHT, -1, -1),
+    UP(Vector3.at(0, 1, 0), Flag.UPRIGHT, -1, -1), // 4
-    DOWN(Vector3.at(0, -1, 0), Flag.UPRIGHT, -1, -1),
+    DOWN(Vector3.at(0, -1, 0), Flag.UPRIGHT, -1, -1), // 5
 
-    NORTHEAST(Vector3.at(1, 0, -1), Flag.ORDINAL, 7, 8),
+    NORTHEAST(Vector3.at(1, 0, -1), Flag.ORDINAL, 7, 8), // 6
-    NORTHWEST(Vector3.at(-1, 0, -1), Flag.ORDINAL, 9, 6),
+    NORTHWEST(Vector3.at(-1, 0, -1), Flag.ORDINAL, 9, 6), // 7
-    SOUTHEAST(Vector3.at(1, 0, 1), Flag.ORDINAL, 6, 9),
+    SOUTHEAST(Vector3.at(1, 0, 1), Flag.ORDINAL, 6, 9), // 8
-    SOUTHWEST(Vector3.at(-1, 0, 1), Flag.ORDINAL, 8, 7),
+    SOUTHWEST(Vector3.at(-1, 0, 1), Flag.ORDINAL, 8, 7), // 9
 
-    WEST_NORTHWEST(Vector3.at(-Math.cos(Math.PI / 8), 0, -Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 9, 6),
+    WEST_NORTHWEST(Vector3.at(-Math.cos(Math.PI / 8), 0, -Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 18, 14), // 11
-    WEST_SOUTHWEST(Vector3.at(-Math.cos(Math.PI / 8), 0, Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 8, 7),
+    WEST_SOUTHWEST(Vector3.at(-Math.cos(Math.PI / 8), 0, Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 17, 13), // 12
-    NORTH_NORTHWEST(Vector3.at(-Math.sin(Math.PI / 8), 0, -Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 9, 6),
+    NORTH_NORTHWEST(Vector3.at(-Math.sin(Math.PI / 8), 0, -Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 12, 15), // 13
-    NORTH_NORTHEAST(Vector3.at(Math.sin(Math.PI / 8), 0, -Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 7, 8),
+    NORTH_NORTHEAST(Vector3.at(Math.sin(Math.PI / 8), 0, -Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 11, 16), // 14
-    EAST_NORTHEAST(Vector3.at(Math.cos(Math.PI / 8), 0, -Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 7, 8),
+    EAST_NORTHEAST(Vector3.at(Math.cos(Math.PI / 8), 0, -Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 13, 17), // 15
-    EAST_SOUTHEAST(Vector3.at(Math.cos(Math.PI / 8), 0, Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 6, 9),
+    EAST_SOUTHEAST(Vector3.at(Math.cos(Math.PI / 8), 0, Math.sin(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 14, 18), // 16
-    SOUTH_SOUTHEAST(Vector3.at(Math.sin(Math.PI / 8), 0, Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 6, 9),
+    SOUTH_SOUTHEAST(Vector3.at(Math.sin(Math.PI / 8), 0, Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 15, 12), // 17
-    SOUTH_SOUTHWEST(Vector3.at(-Math.sin(Math.PI / 8), 0, Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 8, 7),
+    SOUTH_SOUTHWEST(Vector3.at(-Math.sin(Math.PI / 8), 0, Math.cos(Math.PI / 8)), Flag.SECONDARY_ORDINAL, 16, 11), // 18
 
-    ASCENDING_NORTH(Vector3.at(0, 1, -1), Flag.ASCENDING_CARDINAL, 3 + 18, 1 + 18),
+    ASCENDING_NORTH(Vector3.at(0, 1, -1), Flag.ASCENDING_CARDINAL, 3 + 18, 1 + 18), // 19
-    ASCENDING_EAST(Vector3.at(1, 1, 0), Flag.ASCENDING_CARDINAL, 0 + 18, 2 + 18),
+    ASCENDING_EAST(Vector3.at(1, 1, 0), Flag.ASCENDING_CARDINAL, 0 + 18, 2 + 18), // 20
-    ASCENDING_SOUTH(Vector3.at(0, 1, 1), Flag.ASCENDING_CARDINAL, 1 + 18, 3 + 18),
+    ASCENDING_SOUTH(Vector3.at(0, 1, 1), Flag.ASCENDING_CARDINAL, 1 + 18, 3 + 18), // 21
-    ASCENDING_WEST(Vector3.at(-1, 1, 0), Flag.ASCENDING_CARDINAL, 2 + 18, 0 + 18),
+    ASCENDING_WEST(Vector3.at(-1, 1, 0), Flag.ASCENDING_CARDINAL, 2 + 18, 0 + 18), // 22
     ;
     //FAWE end
 
@@ -95,12 +99,18 @@ public enum Direction {
         return map.get(sequence);
     }
 
+    /**
+     * Get the direction 90 degrees left (anti-clockwise) of this direction if possible, else return this direction
+     */
     public Direction getLeft() {
-        return left != -1 ? values()[left] : null;
+        return left != -1 ? values()[left] : this;
     }
 
+    /**
+     * Get the direction 90 degrees right (clockwise) of this direction if possible, else return this direction
+     */
     public Direction getRight() {
-        return right != -1 ? values()[right] : null;
+        return right != -1 ? values()[right] : this;
     }
 
     public double getX() {
@@ -346,5 +356,46 @@ public enum Direction {
 
     }
 
-}
+    //FAWE start - utility methods for block states
 
+    /**
+     * Get the directions associated with the given block state, e.g. the connections a fence makes or the direction stairs face
+     *
+     * @since TODO
+     */
+    public static EnumSet<Direction> getDirections(BlockState state) {
+        EnumSet<Direction> directions = EnumSet.noneOf(Direction.class);
+        for (Property<?> property : state.getBlockType().getProperties()) {
+            if (property instanceof DirectionalProperty dirProp) {
+                directions.add(state.getState(dirProp));
+                continue;
+            }
+            Object value = state.getState(property);
+            if (!(value instanceof String str)) {
+                if (value instanceof Integer i) {
+                    fromRotationIndex(i).ifPresent(directions::add);
+                } else if (value instanceof Boolean b && b) {
+                    try {
+                        directions.add(Direction.valueOf(property.getName().toUpperCase(Locale.ROOT)));
+                    } catch (IllegalArgumentException ignored) {
+                    }
+                }
+                continue;
+            }
+            switch (str.toLowerCase(Locale.ROOT)) {
+                case "upper", "ceiling", "up", "top" -> directions.add(Direction.UP);
+                case "lower", "floor", "down", "bottom", "y" -> directions.add(Direction.DOWN);
+                case "double", "wall" -> {} // Do nothing
+                case "south" -> directions.add(Direction.SOUTH);
+                case "x", "east" -> directions.add(Direction.EAST);
+                case "z", "north" -> directions.add(Direction.NORTH);
+                case "west" -> directions.add(Direction.WEST);
+                case "hinge" -> {} // Do nothing for now
+                case "shape" -> {} // Do nothing for now
+            }
+        }
+        return directions;
+    }
+    //FAWE end
+
+}

worldedit-core/src/main/java/com/sk89q/worldedit/util/SideEffect.java

@@ -19,23 +19,30 @@
 
 package com.sk89q.worldedit.util;
 
+import com.fastasyncworldedit.core.configuration.Settings;
+
 import java.util.Locale;
 
 public enum SideEffect {
-    LIGHTING(State.ON, true),
+    //FAWE start - adjust defaults, add history and heightmaps
-    NEIGHBORS(State.ON, true),
+    HISTORY(State.ON, true),
-    UPDATE(State.ON, true),
+    HEIGHTMAPS(State.ON, true),
+    LIGHTING(Settings.settings().LIGHTING.MODE == 0 ? State.OFF : State.ON, true),
+    NEIGHBORS(State.OFF, true),
+    UPDATE(State.OFF, true),
+    //FAWE end
     VALIDATION(State.OFF, true),
     ENTITY_AI(State.OFF, true),
     EVENTS(State.OFF, true),
     /**
      * Internal use only.
      */
-    POI_UPDATE(State.ON, false),
+    POI_UPDATE(State.OFF, false),
     /**
      * Internal use only.
      */
-    NETWORK(State.ON, false);
+    NETWORK(State.OFF, false);
+    //FAWE end
 
     private final String displayName;
     private final String description;

worldedit-core/src/main/java/com/sk89q/worldedit/util/SideEffectSet.java

@@ -19,7 +19,6 @@
 
 package com.sk89q.worldedit.util;
 
-import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 
 import java.util.Arrays;
@@ -31,7 +30,12 @@ import java.util.stream.Collectors;
 
 public class SideEffectSet {
 
-    private static final SideEffectSet DEFAULT = new SideEffectSet();
+    //FAWE start - assign value map
+    private static final SideEffectSet DEFAULT = new SideEffectSet(
+            Arrays.stream(SideEffect.values())
+                    .filter(SideEffect::isExposed)
+                    .collect(Collectors.toMap(Function.identity(), SideEffect::getDefaultValue)));
+    //FAWE end
     private static final SideEffectSet NONE = new SideEffectSet(
         Arrays.stream(SideEffect.values())
             .filter(SideEffect::isExposed)
@@ -42,12 +46,6 @@ public class SideEffectSet {
     private final Set<SideEffect> appliedSideEffects;
     private final boolean appliesAny;
 
-    //FAWE start
-    private SideEffectSet() {
-        this(ImmutableMap.of());
-    }
-    //FAWE end
-
     public SideEffectSet(Map<SideEffect, SideEffect.State> sideEffects) {
         this.sideEffects = Maps.immutableEnumMap(sideEffects);
 
@@ -61,6 +59,27 @@ public class SideEffectSet {
         //FAWE end
     }
 
+    //FAWE start - simple overload method for setting side effects
+
+    /**
+     * Create a new {@link SideEffectSet} with the given side effect set to "on"
+     *
+     * @since TODO
+     */
+    public SideEffectSet with(SideEffect sideEffect) {
+        return with(sideEffect, SideEffect.State.ON);
+    }
+
+    /**
+     * Create a new {@link SideEffectSet} with the given side effect set to "off"
+     *
+     * @since TODO
+     */
+    public SideEffectSet without(SideEffect sideEffect) {
+        return with(sideEffect, SideEffect.State.OFF);
+    }
+    //FAWE end
+
     public SideEffectSet with(SideEffect sideEffect, SideEffect.State state) {
         Map<SideEffect, SideEffect.State> entries = this.sideEffects.isEmpty()
                 ? Maps.newEnumMap(SideEffect.class)
@@ -103,4 +122,23 @@ public class SideEffectSet {
         return NONE;
     }
 
+    //FAWE start
+
+    /**
+     * API-friendly side effect set.
+     * Sets:
+     *  - Heightmaps
+     *  - Lighting (if set to mode 1 or 2 in config)
+     * Does not set:
+     *  - History
+     *  - Neighbours
+     *  - Lighting (if set to mode 0 in config
+     *
+     * @since TODO
+     */
+    public static SideEffectSet api() {
+        return defaults().without(SideEffect.HISTORY);
+    }
+    //FAWE end
+
 }

worldedit-core/src/main/resources/lang/strings.json

@@ -627,10 +627,14 @@
   "worldedit.selection.polygon2d.explain.secondary": "Added point #{0} at {1}.",
   "worldedit.selection.sphere.explain.secondary": "Radius set to {0}.",
   "worldedit.selection.sphere.explain.secondary-defined": "Radius set to {0} ({1}).",
+  "worldedit.sideeffect.history": "History",
+  "worldedit.sideeffect.history.description": "Writes history of the change",
+  "worldedit.sideeffect.heightmaps": "Heightmaps",
+  "worldedit.sideeffect.heightmaps.description": "Updates heightmaps",
   "worldedit.sideeffect.lighting": "Lighting",
   "worldedit.sideeffect.lighting.description": "Updates block lighting",
   "worldedit.sideeffect.neighbors": "Neighbors",
-  "worldedit.sideeffect.neighbors.description": "Notifies nearby blocks of changes",
+  "worldedit.sideeffect.neighbors.description": "Updates shapes of blocks in the edit",
   "worldedit.sideeffect.update": "Update",
   "worldedit.sideeffect.update.description": "Notifies the changed block",
   "worldedit.sideeffect.validation": "Validation",