Way too much

.gitignore

@@ -53,6 +53,8 @@ service-account*.json
 
 .qa/
 .repro/
+.perf/
+.release-gate/
 
 # Throwaway worktree copies used by the API / PlaceholderAPI rebuild lanes. Generated, never source.
 .apiwt/

adapters/bukkit/nms/v26_2_R1/src/main/java/art/arcane/iris/core/nms/v26_2_R1/CustomBiomeSource.java

@@ -11,6 +11,7 @@ import art.arcane.iris.engine.framework.GenerationSessionLease;
 import art.arcane.iris.engine.object.IrisBiome;
 import art.arcane.iris.engine.object.IrisBiomeCustom;
 import art.arcane.iris.engine.object.IrisDimension;
+import art.arcane.iris.engine.object.IrisDimensionCarvingResolver;
 import art.arcane.iris.util.project.context.IrisContext;
 import art.arcane.volmlib.util.collection.KMap;
 import art.arcane.volmlib.util.math.RNG;
@@ -521,6 +522,16 @@ public class CustomBiomeSource extends BiomeSource {
             int y,
             int z,
             Climate.Sampler sampler
+    ) {
+        return getVisibleNoiseBiomeWithActiveGenerationLease(x, y, z, sampler, null);
+    }
+
+    Holder<Biome> getVisibleNoiseBiomeWithActiveGenerationLease(
+            int x,
+            int y,
+            int z,
+            Climate.Sampler sampler,
+            IrisDimensionCarvingResolver.State resolverState
     ) {
         long cacheKey = packNoiseKey(x, y, z);
         Holder<Biome> cachedHolder = noiseBiomeCache.get(cacheKey);
@@ -528,7 +539,7 @@ public class CustomBiomeSource extends BiomeSource {
             return cachedHolder;
         }
 
-        Holder<Biome> resolvedHolder = resolveVisibleBiomeHolder(x, y, z);
+        Holder<Biome> resolvedHolder = resolveVisibleBiomeHolder(x, y, z, resolverState);
         Holder<Biome> existingHolder = noiseBiomeCache.putIfAbsent(cacheKey, resolvedHolder);
         if (existingHolder != null) {
             return existingHolder;
@@ -602,8 +613,13 @@ public class CustomBiomeSource extends BiomeSource {
         return holder;
     }
 
-    private Holder<Biome> resolveVisibleBiomeHolder(int x, int y, int z) {
+    private Holder<Biome> resolveVisibleBiomeHolder(
-        BiomeResolution resolution = resolveBiomeResolution(x, y, z);
+            int x,
+            int y,
+            int z,
+            IrisDimensionCarvingResolver.State resolverState
+    ) {
+        BiomeResolution resolution = resolveBiomeResolution(x, y, z, resolverState);
         if (resolution == null) {
             return getFallbackBiome();
         }
@@ -636,6 +652,15 @@ public class CustomBiomeSource extends BiomeSource {
     }
 
     private BiomeResolution resolveBiomeResolution(int x, int y, int z) {
+        return resolveBiomeResolution(x, y, z, null);
+    }
+
+    private BiomeResolution resolveBiomeResolution(
+            int x,
+            int y,
+            int z,
+            IrisDimensionCarvingResolver.State resolverState
+    ) {
         if (engine == null || engine.isClosed()) {
             return null;
         }
@@ -657,7 +682,7 @@ public class CustomBiomeSource extends BiomeSource {
             int surfaceInternalY = engine.getComplex().getHeightStream().get(blockX, blockZ).intValue();
             underground = internalY <= surfaceInternalY - 8;
             irisBiome = underground
-                    ? engine.getCaveBiome(blockX, internalY, blockZ)
+                    ? engine.getCaveBiome(blockX, internalY, blockZ, resolverState)
                     : engine.getComplex().getTrueBiomeStream().get(blockX, blockZ);
         } else {
             irisBiome = engine.getComplex().getTrueBiomeStream().get(blockX, blockZ);

adapters/bukkit/nms/v26_2_R1/src/main/java/art/arcane/iris/core/nms/v26_2_R1/IrisChunkGenerator.java

@@ -10,6 +10,7 @@ import art.arcane.iris.engine.framework.NativeStructureGenerationPolicy;
 import art.arcane.iris.engine.IrisEngine;
 import art.arcane.iris.engine.platform.BukkitChunkGenerator;
 import art.arcane.iris.engine.object.IrisDimension;
+import art.arcane.iris.engine.object.IrisDimensionCarvingResolver;
 import art.arcane.iris.engine.object.IrisMaterialPalette;
 import art.arcane.iris.engine.object.IrisNativeStructureDecision;
 import art.arcane.iris.nativegen.NativeStructureGenerationException;
@@ -643,8 +644,10 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
              GenerationSessionLease lease = requireGenerationLease("bukkit_nms_create_biomes");
              IrisContext.Scope ignored = IrisContext.open(engine, lease.sessionId(), null)) {
             customBiomeSource.prepareVisibleBiomeBatch();
+            IrisDimensionCarvingResolver.State resolverState = new IrisDimensionCarvingResolver.State();
             ichunkaccess.fillBiomesFromNoise(
-                    customBiomeSource::getVisibleNoiseBiomeWithActiveGenerationLease,
+                    (x, y, z, sampler) -> customBiomeSource.getVisibleNoiseBiomeWithActiveGenerationLease(
+                            x, y, z, sampler, resolverState),
                     randomstate.sampler());
             return CompletableFuture.completedFuture(ichunkaccess);
         }

adapters/bukkit/nms/v26_2_R1/src/test/java/art/arcane/iris/core/nms/v26_2_R1/IrisChunkGeneratorFailureContractTest.java

@@ -258,7 +258,8 @@ public class IrisChunkGeneratorFailureContractTest {
 
         assertTrue(createBiomes.contains("requireGenerationStage(\"bukkit_nms_create_biomes\")"));
         assertTrue(createBiomes.contains("customBiomeSource.prepareVisibleBiomeBatch()"));
-        assertTrue(createBiomes.contains("customBiomeSource::getVisibleNoiseBiomeWithActiveGenerationLease"));
+        assertTrue(createBiomes.contains("new IrisDimensionCarvingResolver.State()"));
+        assertTrue(createBiomes.contains("sampler, resolverState"));
         assertTrue(buildSurface.contains("delegate.buildSurface("));
         assertTrue(carvers.contains("delegate.applyCarvers("));
         assertTrue(noise.contains("requireNoiseGenerationStage("));

adapters/bukkit/plugin/src/main/java/art/arcane/iris/Iris.java

@@ -573,7 +573,7 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
     }
 
     private static String logPrefix(Iris plugin) {
-        return plugin == null ? "[Iris] " : plugin.getTag();
+        return plugin == null ? ComponentLog.discriminator("Iris", "&a") : plugin.getTag();
     }
 
     /**

adapters/bukkit/plugin/src/main/java/art/arcane/iris/IrisBootstrap.java

@@ -9,6 +9,7 @@ import art.arcane.iris.core.lifecycle.WorldReplacementBootstrap;
 import art.arcane.iris.core.lifecycle.WorldReplacementBootstrapMarker;
 import art.arcane.iris.core.pack.DefaultPackBootstrapProvisioner;
 import art.arcane.iris.core.pack.DefaultPackBootstrapProvisioner.ProvisionResult;
+import art.arcane.iris.util.common.misc.SlimJar;
 import io.papermc.paper.plugin.bootstrap.BootstrapContext;
 import io.papermc.paper.plugin.bootstrap.PluginBootstrap;
 import io.papermc.paper.plugin.lifecycle.event.LifecycleEvent;
@@ -26,6 +27,7 @@ public final class IrisBootstrap implements PluginBootstrap {
     public void bootstrap(BootstrapContext context) {
         WorldReplacementBootstrapMarker.markBootstrapped();
         try {
+            loadRuntimeLibraries(context);
             BukkitStartupPaths startupPaths = BukkitStartupPaths.resolveCurrent();
             reconcilePendingWorldReplacements(context, startupPaths);
             quarantineWorthlessHusks(startupPaths, message -> context.getLogger().warn(message));
@@ -38,6 +40,27 @@ public final class IrisBootstrap implements PluginBootstrap {
         }
     }
 
+    private static void loadRuntimeLibraries(BootstrapContext context) {
+        SlimJar.loadBootstrap(
+                context.getDataDirectory().resolve("cache").resolve("libraries"),
+                new SlimJar.BootstrapLogger() {
+                    @Override
+                    public void info(String message) {
+                        context.getLogger().info(message);
+                    }
+
+                    @Override
+                    public void error(String message) {
+                        context.getLogger().error(message);
+                    }
+
+                    @Override
+                    public void debug(String message) {
+                        context.getLogger().debug(message);
+                    }
+                });
+    }
+
     private static void reconcilePendingWorldReplacements(
             BootstrapContext context,
             BukkitStartupPaths startupPaths

adapters/bukkit/plugin/src/main/java/art/arcane/iris/IrisPluginLoader.java

@@ -0,0 +1,69 @@
+package art.arcane.iris;
+
+import art.arcane.iris.util.common.misc.SlimJar;
+import io.papermc.paper.plugin.bootstrap.PluginProviderContext;
+import io.papermc.paper.plugin.loader.PluginClasspathBuilder;
+import io.papermc.paper.plugin.loader.PluginLoader;
+import io.papermc.paper.plugin.loader.library.impl.JarLibrary;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.stream.Stream;
+
+@SuppressWarnings("UnstableApiUsage")
+public final class IrisPluginLoader implements PluginLoader {
+    @Override
+    public void classloader(PluginClasspathBuilder classpathBuilder) {
+        PluginProviderContext context = classpathBuilder.getContext();
+        Path libraryRoot = context.getDataDirectory().resolve("cache").resolve("libraries");
+        SlimJar.loadBootstrap(libraryRoot, new SlimJar.BootstrapLogger() {
+            @Override
+            public void info(String message) {
+                context.getLogger().info(message);
+            }
+
+            @Override
+            public void error(String message) {
+                context.getLogger().error(message);
+            }
+
+            @Override
+            public void debug(String message) {
+                context.getLogger().debug(message);
+            }
+        });
+        for (Path library : relocatedLibraries(libraryRoot)) {
+            classpathBuilder.addLibrary(new JarLibrary(library));
+        }
+    }
+
+    static List<Path> relocatedLibraries(Path libraryRoot) {
+        try (Stream<Path> paths = Files.walk(libraryRoot)) {
+            List<Path> libraries = paths
+                    .filter(Files::isRegularFile)
+                    .filter(path -> path.getFileName().toString().endsWith(".jar"))
+                    .filter(IrisPluginLoader::isRelocatedLibrary)
+                    .sorted()
+                    .toList();
+            if (libraries.isEmpty()) {
+                throw new IllegalStateException("Iris runtime library provisioning produced no relocated libraries.");
+            }
+            return libraries;
+        } catch (IOException failure) {
+            throw new IllegalStateException("Unable to enumerate provisioned Iris runtime libraries.", failure);
+        }
+    }
+
+    private static boolean isRelocatedLibrary(Path path) {
+        int count = path.getNameCount();
+        for (int i = 0; i < count - 2; i++) {
+            if ("relocated".equals(path.getName(i).toString())
+                    && "Iris".equals(path.getName(i + 1).toString())) {
+                return true;
+            }
+        }
+        return false;
+    }
+}

adapters/bukkit/plugin/src/main/java/art/arcane/iris/core/commands/CommandStudio.java

@@ -96,6 +96,7 @@ import java.time.temporal.ChronoUnit;
 import java.util.Date;
 import java.util.List;
 import java.util.Objects;
+import java.util.UUID;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -412,7 +413,8 @@ public class CommandStudio implements DirectorExecutor {
             return;
         }
 
-        VisionGUI.launch(IrisToolbelt.access(world).getEngine());
+        UUID openerId = sender().isPlayer() ? player().getUniqueId() : null;
+        VisionGUI.launch(IrisToolbelt.access(world).getEngine(), openerId);
         sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_OPENING_MAP));
     }
 

adapters/bukkit/plugin/src/main/java/art/arcane/iris/core/gui/BukkitGuiHost.java

@@ -30,6 +30,7 @@ import org.bukkit.event.Listener;
 
 import java.util.ArrayList;
 import java.util.Map;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 
 public final class BukkitGuiHost implements GuiHost.Provider {
@@ -72,8 +73,8 @@ public final class BukkitGuiHost implements GuiHost.Provider {
     }
 
     @Override
-    public GuiOverlay overlayFor(Engine engine) {
+    public GuiOverlay overlayFor(Engine engine, UUID openerId) {
-        return engine == null ? null : new BukkitVisionOverlay(engine);
+        return engine == null ? null : new BukkitVisionOverlay(engine, openerId);
     }
 
     private static final class HotloadListener implements Listener {

adapters/bukkit/plugin/src/main/java/art/arcane/iris/core/gui/BukkitVisionOverlay.java

@@ -18,7 +18,6 @@
 
 package art.arcane.iris.core.gui;
 
-import art.arcane.iris.core.runtime.WorldRuntimeControlService;
 import art.arcane.iris.engine.IrisComplex;
 import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.framework.render.RenderType;
@@ -28,7 +27,6 @@ import art.arcane.iris.platform.bukkit.BukkitWorldBinding;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.iris.util.common.scheduling.J;
 import art.arcane.volmlib.util.format.Form;
-import org.bukkit.Chunk;
 import org.bukkit.Location;
 import org.bukkit.World;
 import org.bukkit.entity.LivingEntity;
@@ -39,6 +37,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
+import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -50,14 +49,16 @@ import static art.arcane.iris.util.common.data.registry.Attributes.MAX_HEALTH;
 
 public final class BukkitVisionOverlay implements GuiOverlay {
     private final Engine engine;
+    private final UUID openerId;
     private final AtomicBoolean nativeTeleportActive = new AtomicBoolean();
     private final AtomicBoolean playerRefreshQueued = new AtomicBoolean();
     private final AtomicLong teleportSequence = new AtomicLong();
     private final AtomicReference<VisionTeleportRequest> latestTeleport = new AtomicReference<>();
     private volatile List<GuiMarker> playerMarkers = List.of();
 
-    public BukkitVisionOverlay(Engine engine) {
+    public BukkitVisionOverlay(Engine engine, UUID openerId) {
         this.engine = engine;
+        this.openerId = openerId;
     }
 
     /**
@@ -177,67 +178,20 @@ public final class BukkitVisionOverlay implements GuiOverlay {
                 return;
             }
             List<Player> players = BukkitWorldBinding.players(target);
-            if (players.isEmpty()) {
+            Player player = selectPlayer(players);
+            if (player == null) {
                 finish(request);
                 return;
             }
-            Player player = players.get(0);
-            requestTeleportChunk(request, target, player, world);
-        });
-        if (!scheduled) {
-            finish(request);
-        }
-    }
-
-    private void requestTeleportChunk(
-            VisionTeleportRequest request,
-            IrisWorld target,
-            Player player,
-            World world
-    ) {
             int blockX = request.blockX;
             int blockZ = request.blockZ;
-        int chunkX = blockX >> 4;
-        int chunkZ = blockZ >> 4;
-        CompletableFuture<Chunk> requested;
             try {
-            requested = WorldRuntimeControlService.get().requestChunkAsync(
+                int blockY = engine.getMinHeight() + engine.getHeight(blockX, blockZ, false) + 2;
+                Location destination = new Location(
                         world,
-                    chunkX,
+                        blockX + 0.5D,
-                    chunkZ,
+                        blockY,
-                    true,
+                        blockZ + 0.5D);
-                    true
-            );
-        } catch (Throwable failure) {
-            fail(request, target, world, failure);
-            return;
-        }
-        if (requested == null) {
-            fail(request, target, world, new IllegalStateException(
-                    "Vision destination chunk request returned no future."));
-            return;
-        }
-        requested.whenComplete((chunk, failure) -> {
-            if (!isCurrent(request, target)) {
-                finish(request);
-                return;
-            }
-            if (failure != null) {
-                fail(request, target, world, failure);
-                return;
-            }
-            if (chunk == null || chunk.getWorld() != world) {
-                fail(request, target, world, new IllegalStateException(
-                        "Vision destination chunk request returned no chunk."));
-                return;
-            }
-            boolean scheduled = J.runRegion(world, chunkX, chunkZ, () -> {
-                if (!isCurrent(request, target)) {
-                    finish(request);
-                    return;
-                }
-                int yy = world.getHighestBlockYAt(blockX, blockZ) + 1;
-                Location destination = new Location(world, blockX, yy, blockZ);
                 if (!J.runEntity(player, () -> delegateTeleport(
                         request,
                         target,
@@ -247,12 +201,25 @@ public final class BukkitVisionOverlay implements GuiOverlay {
                     fail(request, target, world, new IllegalStateException(
                             "Failed to schedule the Vision teleport on the player entity."));
                 }
-            });
+            } catch (Throwable failure) {
-            if (!scheduled) {
+                fail(request, target, world, failure);
-                fail(request, target, world, new IllegalStateException(
-                        "Failed to schedule the Vision surface lookup on its owning region."));
             }
         });
+        if (!scheduled) {
+            finish(request);
+        }
+    }
+
+    private Player selectPlayer(List<Player> players) {
+        if (openerId == null) {
+            return players.isEmpty() ? null : players.get(0);
+        }
+        for (Player player : players) {
+            if (openerId.equals(player.getUniqueId())) {
+                return player;
+            }
+        }
+        return null;
     }
 
     private void delegateTeleport(

adapters/bukkit/plugin/src/main/resources/paper-plugin.yml

@@ -2,6 +2,7 @@ name: ${name}
 version: ${version}
 main: ${main}
 bootstrapper: ${bootstrapper}
+loader: art.arcane.iris.IrisPluginLoader
 folia-supported: true
 api-version: '${apiVersion}'
 load: STARTUP

adapters/bukkit/plugin/src/test/java/art/arcane/iris/IrisPluginLoaderTest.java

@@ -0,0 +1,34 @@
+package art.arcane.iris;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class IrisPluginLoaderTest {
+    @Rule
+    public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+    @Test
+    public void exposesOnlyRelocatedRuntimeLibrariesInStableOrder() throws Exception {
+        Path root = temporaryFolder.newFolder("libraries").toPath();
+        Path original = Files.createDirectories(root.resolve("gson/2.14.0"))
+                .resolve("gson.jar");
+        Path relocatedGson = Files.createDirectories(root.resolve("gson/2.14.0/relocated/Iris"))
+                .resolve("gson.jar");
+        Path relocatedCaffeine = Files.createDirectories(root.resolve("caffeine/3.2.4/relocated/Iris"))
+                .resolve("caffeine.jar");
+        Files.createFile(original);
+        Files.createFile(relocatedGson);
+        Files.createFile(relocatedCaffeine);
+
+        List<Path> libraries = IrisPluginLoader.relocatedLibraries(root);
+
+        assertEquals(List.of(relocatedCaffeine, relocatedGson), libraries);
+    }
+}

adapters/bukkit/plugin/src/test/java/art/arcane/iris/PaperPluginMetadataTest.java

@@ -53,6 +53,7 @@ public class PaperPluginMetadataTest {
         }
 
         assertTrue(metadata.contains("bootstrapper: " + IrisBootstrap.class.getName()));
+        assertTrue(metadata.contains("loader: " + IrisPluginLoader.class.getName()));
         assertTrue(metadata.contains("folia-supported: true"));
         assertTrue(metadata.contains("load: STARTUP"));
         assertFalse(metadata.contains("commands:"));

adapters/bukkit/plugin/src/test/java/art/arcane/iris/core/gui/BukkitVisionOverlayFoliaContractTest.java

@@ -1,108 +1,67 @@
 package art.arcane.iris.core.gui;
 
-import art.arcane.iris.core.runtime.WorldRuntimeControlService;
 import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.object.IrisWorld;
 import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.platform.bukkit.BukkitWorldBinding;
 import art.arcane.iris.util.common.scheduling.J;
-import org.bukkit.Chunk;
 import org.bukkit.Location;
 import org.bukkit.World;
 import org.bukkit.entity.Player;
 import org.junit.Test;
 import org.mockito.MockedStatic;
 
-import java.nio.file.Files;
-import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.ArgumentMatchers.same;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 public class BukkitVisionOverlayFoliaContractTest {
     @Test
-    public void teleportLoadsTheDestinationChunkBeforeItsOwningRegionReadsTheSurface() throws Exception {
+    public void teleportDelegatesImmediatelyToTheNativeAsyncPath() {
-        String source = Files.readString(Path.of(
-                "src/main/java/art/arcane/iris/core/gui/BukkitVisionOverlay.java"
-        )).replace("\r\n", "\n");
-        String request = method(source, "private void requestTeleportChunk(");
-
-        assertBefore(request, "requestChunkAsync(", "requested.whenComplete(");
-        assertBefore(request, "requested.whenComplete(", "J.runRegion(");
-        assertBefore(request, "J.runRegion(", "world.getHighestBlockYAt(");
-        assertBefore(request, "world.getHighestBlockYAt(", "J.runEntity(");
-        assertTrue(request.contains("chunkX,\n                    chunkZ,\n                    true,\n                    true"));
-        assertEquals(1, occurrences(request, "world.getHighestBlockYAt("));
-    }
-
-    @Test
-    public void teleportReportsAsyncAndSchedulingFailuresWithDestinationContext() throws Exception {
-        String source = Files.readString(Path.of(
-                "src/main/java/art/arcane/iris/core/gui/BukkitVisionOverlay.java"
-        )).replace("\r\n", "\n");
-        String request = method(source, "private void requestTeleportChunk(");
-        String reporter = method(source, "private void reportTeleportFailure(");
-
-        assertTrue(request.contains("if (requested == null)"));
-        assertTrue(request.contains("if (failure != null)"));
-        assertTrue(request.contains("if (chunk == null ||"));
-        assertTrue(request.contains("if (!J.runEntity("));
-        assertTrue(request.contains("if (!scheduled)"));
-        assertTrue(reporter.contains("IrisLogging.reportError("));
-        assertTrue(reporter.contains("world.getName()"));
-        assertTrue(reporter.contains("blockX + \",\" + blockZ"));
-    }
-
-    @Test
-    public void teleportObservesNativeCompletionAndRejectsFalseSettlement() throws Exception {
-        String source = Files.readString(Path.of(
-                "src/main/java/art/arcane/iris/core/gui/BukkitVisionOverlay.java"
-        )).replace("\r\n", "\n");
-        String delegate = method(source, "private void delegateTeleport(");
-
-        assertTrue(delegate.contains("teleport.whenComplete("));
-        assertTrue(delegate.contains("!Boolean.TRUE.equals(success)"));
-        assertTrue(delegate.contains("restartLatest(request)"));
-    }
-
-    @Test
-    public void staleChunkCompletionCannotTeleportOverTheLatestRequest() {
         VisionHarness harness = new VisionHarness();
-        CompletableFuture<Chunk> firstChunk = new CompletableFuture<>();
-        CompletableFuture<Chunk> secondChunk = new CompletableFuture<>();
-        harness.stubChunk(0, 0, firstChunk);
-        harness.stubChunk(2, 2, secondChunk);
 
         try (harness) {
-            harness.overlay.teleport(1.5D, 1.5D);
             harness.overlay.teleport(33.5D, 33.5D);
 
-            firstChunk.complete(harness.chunk);
+            assertEquals(1, harness.destinations.size());
-            assertEquals(0, harness.destinations.size());
+            Location destination = harness.destinations.get(0);
-            secondChunk.complete(harness.chunk);
+            assertEquals(33.5D, destination.getX(), 0D);
+            assertEquals(76D, destination.getY(), 0D);
+            assertEquals(33.5D, destination.getZ(), 0D);
+            verify(harness.engine).getHeight(33, 33, false);
+        }
+    }
+
+    @Test
+    public void teleportFloorsNegativeCoordinatesBeforeCenteringTheDestination() {
+        VisionHarness harness = new VisionHarness();
+
+        try (harness) {
+            harness.overlay.teleport(-0.25D, -16.01D);
 
             assertEquals(1, harness.destinations.size());
-            assertEquals(33, harness.destinations.get(0).getBlockX());
+            Location destination = harness.destinations.get(0);
-            assertEquals(33, harness.destinations.get(0).getBlockZ());
+            assertEquals(-0.5D, destination.getX(), 0D);
+            assertEquals(-16.5D, destination.getZ(), 0D);
+            verify(harness.engine).getHeight(-1, -17, false);
         }
     }
 
     @Test
     public void latestRequestRunsAfterAnOlderNativeTeleportSettles() {
         VisionHarness harness = new VisionHarness();
-        harness.stubChunk(0, 0, CompletableFuture.completedFuture(harness.chunk));
-        harness.stubChunk(2, 2, CompletableFuture.completedFuture(harness.chunk));
         CompletableFuture<Boolean> firstTeleport = new CompletableFuture<>();
         CompletableFuture<Boolean> secondTeleport = new CompletableFuture<>();
         harness.nativeTeleports.add(firstTeleport);
@@ -121,54 +80,28 @@ public class BukkitVisionOverlayFoliaContractTest {
         }
     }
 
-    private static void assertBefore(String source, String first, String second) {
+    @Test
-        int firstIndex = source.indexOf(first);
+    public void missingOpenerDoesNotTeleportAnotherPlayer() {
-        int secondIndex = source.indexOf(second);
+        VisionHarness harness = new VisionHarness();
-        assertTrue("Missing source contract token: " + first, firstIndex >= 0);
+        harness.binding.when(() -> BukkitWorldBinding.players(harness.target))
-        assertTrue("Missing source contract token: " + second, secondIndex >= 0);
+                .thenReturn(List.of(harness.otherPlayer));
-        assertTrue(first + " must occur before " + second, firstIndex < secondIndex);
-    }
 
-    private static int occurrences(String source, String match) {
+        try (harness) {
-        int count = 0;
+            harness.overlay.teleport(1.5D, 1.5D);
-        int offset = 0;
-        while ((offset = source.indexOf(match, offset)) >= 0) {
-            count++;
-            offset += match.length();
-        }
-        return count;
-    }
 
-    private static String method(String source, String signature) {
+            assertEquals(0, harness.destinations.size());
-        int start = source.indexOf(signature);
-        assertTrue("Missing source contract signature: " + signature, start >= 0);
-        int openBrace = source.indexOf('{', start);
-        assertTrue("Missing source contract method body: " + signature, openBrace >= 0);
-        int depth = 0;
-        for (int index = openBrace; index < source.length(); index++) {
-            char current = source.charAt(index);
-            if (current == '{') {
-                depth++;
-            } else if (current == '}') {
-                depth--;
-                if (depth == 0) {
-                    return source.substring(start, index + 1);
         }
     }
-        }
-        throw new IllegalArgumentException("Unclosed source contract method: " + signature);
-    }
 
     private static final class VisionHarness implements AutoCloseable {
         private final Engine engine;
         private final IrisWorld target;
         private final World world;
         private final Player player;
-        private final Chunk chunk;
+        private final Player otherPlayer;
-        private final WorldRuntimeControlService runtime;
+        private final UUID openerId;
         private final MockedStatic<J> scheduling;
         private final MockedStatic<BukkitWorldBinding> binding;
-        private final MockedStatic<WorldRuntimeControlService> runtimeAccess;
         private final MockedStatic<BukkitPlatform> platform;
         private final List<Location> destinations;
         private final List<CompletableFuture<Boolean>> nativeTeleports;
@@ -180,33 +113,26 @@ public class BukkitVisionOverlayFoliaContractTest {
             target = mock(IrisWorld.class);
             world = mock(World.class);
             player = mock(Player.class);
-            chunk = mock(Chunk.class);
+            otherPlayer = mock(Player.class);
-            runtime = mock(WorldRuntimeControlService.class);
+            openerId = UUID.randomUUID();
             destinations = new ArrayList<>();
             nativeTeleports = new ArrayList<>();
             nativeTeleportIndex = new AtomicInteger();
 
             when(engine.getWorld()).thenReturn(target);
+            when(engine.getMinHeight()).thenReturn(-64);
+            when(engine.getHeight(anyInt(), anyInt(), eq(false))).thenReturn(138);
             when(target.hasPlatformWorld()).thenReturn(true);
             when(player.isOnline()).thenReturn(true);
             when(player.getWorld()).thenReturn(world);
-            when(chunk.getWorld()).thenReturn(world);
+            when(player.getUniqueId()).thenReturn(openerId);
-            when(world.getHighestBlockYAt(anyInt(), anyInt())).thenReturn(70);
+            when(otherPlayer.getUniqueId()).thenReturn(UUID.randomUUID());
 
             scheduling = mockStatic(J.class);
             scheduling.when(() -> J.runGlobal(any(Runnable.class))).thenAnswer(invocation -> {
                 invocation.getArgument(0, Runnable.class).run();
                 return true;
             });
-            scheduling.when(() -> J.runRegion(
-                            same(world),
-                            anyInt(),
-                            anyInt(),
-                            any(Runnable.class)))
-                    .thenAnswer(invocation -> {
-                        invocation.getArgument(3, Runnable.class).run();
-                        return true;
-                    });
             scheduling.when(() -> J.runEntity(same(player), any(Runnable.class))).thenAnswer(invocation -> {
                 invocation.getArgument(1, Runnable.class).run();
                 return true;
@@ -214,10 +140,7 @@ public class BukkitVisionOverlayFoliaContractTest {
 
             binding = mockStatic(BukkitWorldBinding.class);
             binding.when(() -> BukkitWorldBinding.world(target)).thenReturn(world);
-            binding.when(() -> BukkitWorldBinding.players(target)).thenReturn(List.of(player));
+            binding.when(() -> BukkitWorldBinding.players(target)).thenReturn(List.of(otherPlayer, player));
-
-            runtimeAccess = mockStatic(WorldRuntimeControlService.class);
-            runtimeAccess.when(WorldRuntimeControlService::get).thenReturn(runtime);
 
             platform = mockStatic(BukkitPlatform.class);
             platform.when(() -> BukkitPlatform.teleportAsync(same(player), any(Location.class)))
@@ -228,26 +151,12 @@ public class BukkitVisionOverlayFoliaContractTest {
                                 ? nativeTeleports.get(index)
                                 : CompletableFuture.completedFuture(true);
                     });
-            overlay = new BukkitVisionOverlay(engine);
+            overlay = new BukkitVisionOverlay(engine, openerId);
-        }
-
-        private void stubChunk(
-                int chunkX,
-                int chunkZ,
-                CompletableFuture<Chunk> requested
-        ) {
-            when(runtime.requestChunkAsync(
-                    same(world),
-                    eq(chunkX),
-                    eq(chunkZ),
-                    eq(true),
-                    eq(true))).thenReturn(requested);
         }
 
         @Override
         public void close() {
             platform.close();
-            runtimeAccess.close();
             binding.close();
             scheduling.close();
         }

adapters/fabric/src/main/java/art/arcane/iris/fabric/FabricModdedLoader.java

@@ -21,6 +21,7 @@ package art.arcane.iris.fabric;
 import art.arcane.iris.modded.ModdedLoader;
 import art.arcane.iris.modded.service.ModdedTreeFellerService;
 import net.fabricmc.api.EnvType;
+import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLevelEvents;
 import net.fabricmc.fabric.api.event.player.PlayerBlockBreakEvents;
 import net.fabricmc.fabric.api.permission.v1.PermissionContextOwner;
 import net.fabricmc.loader.api.FabricLoader;
@@ -71,6 +72,16 @@ public final class FabricModdedLoader implements ModdedLoader {
         // map). Off-thread readers rely on the ModdedServerLevels snapshot, which the caller republishes.
     }
 
+    @Override
+    public void fireDynamicLevelLoad(MinecraftServer server, ServerLevel level) {
+        ServerLevelEvents.LOAD.invoker().onLevelLoad(server, level);
+    }
+
+    @Override
+    public void fireDynamicLevelUnload(MinecraftServer server, ServerLevel level) {
+        ServerLevelEvents.UNLOAD.invoker().onLevelUnload(server, level);
+    }
+
     @Override
     public boolean clientEnvironment() {
         return FabricLoader.getInstance().getEnvironmentType() == EnvType.CLIENT;

adapters/forge/src/main/java/art/arcane/iris/forge/ForgeModdedLoader.java

@@ -28,6 +28,7 @@ import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.level.block.state.BlockState;
 import net.minecraftforge.common.util.Result;
 import net.minecraftforge.event.level.BlockEvent;
+import net.minecraftforge.event.level.LevelEvent;
 import net.minecraftforge.fml.ModList;
 import net.minecraftforge.fml.loading.FMLEnvironment;
 import net.minecraftforge.fml.loading.FMLLoader;
@@ -77,6 +78,16 @@ public final class ForgeModdedLoader implements ModdedLoader {
         server.markWorldsDirty();
     }
 
+    @Override
+    public void fireDynamicLevelLoad(MinecraftServer server, ServerLevel level) {
+        LevelEvent.Load.BUS.post(new LevelEvent.Load(level));
+    }
+
+    @Override
+    public void fireDynamicLevelUnload(MinecraftServer server, ServerLevel level) {
+        LevelEvent.Unload.BUS.post(new LevelEvent.Unload(level));
+    }
+
     @Override
     public boolean clientEnvironment() {
         return FMLEnvironment.dist.isClient();

adapters/modded-common/src/main/java/art/arcane/iris/modded/ModdedDimensionManager.java

@@ -56,13 +56,16 @@ import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 public final class ModdedDimensionManager {
+    private static final int TELEPORT_WARM_RADIUS = 0;
     private static final Object LOCK = new Object();
     private static final ConcurrentHashMap<String, Handle> HANDLES = new ConcurrentHashMap<>();
     private static final TicketType TELEPORT_WARM_TICKET = new TicketType(TicketType.NO_TIMEOUT,
             TicketType.FLAG_LOADING | TicketType.FLAG_KEEP_DIMENSION_ACTIVE);
-    private static final long TELEPORT_WARM_TIMEOUT_SECONDS = 30L;
+    private static final long TELEPORT_TIMEOUT_SECONDS = 10L;
     private static volatile ModdedServerAccess access;
 
     private ModdedDimensionManager() {
@@ -213,15 +216,16 @@ public final class ModdedDimensionManager {
                     instanceof IrisModdedChunkGenerator irisGenerator
                     ? irisGenerator
                     : null;
-            boolean generatorUnbound = false;
+            boolean unloadEventStarted = false;
             try {
                 evacuate(server, level);
+                level.save(null, true, false);
+                unloadEventStarted = true;
+                ModdedEngineBootstrap.loader().fireDynamicLevelUnload(server, level);
                 if (generator != null) {
                     generator.unbindEngine(level);
-                    generatorUnbound = true;
                 }
                 ModdedWorldEngines.evictOrThrow(level);
-                level.save(null, true, false);
                 serverAccess.removeLevel(server, key);
                 // Undo snapshots pin the ServerLevel and could replay into the dead level.
                 art.arcane.iris.modded.command.ModdedObjectUndo.forget(level);
@@ -233,7 +237,7 @@ public final class ModdedDimensionManager {
                 ModdedIrisLog.info("Iris removed runtime dimension '{}'", dimensionId);
                 return true;
             } catch (Throwable e) {
-                rollbackRemoval(server, serverAccess, key, level, generator, generatorUnbound, e);
+                rollbackRemoval(server, serverAccess, key, level, generator, unloadEventStarted, e);
                 ModdedIrisLog.error("Iris failed to remove runtime dimension '{}'", dimensionId, e);
                 throw new IllegalStateException("Iris runtime dimension removal failed for " + dimensionId, e);
             }
@@ -242,13 +246,16 @@ public final class ModdedDimensionManager {
 
     private static void rollbackRemoval(MinecraftServer server, ModdedServerAccess serverAccess,
                                         ResourceKey<Level> key, ServerLevel level,
-                                        IrisModdedChunkGenerator generator, boolean generatorUnbound,
+                                        IrisModdedChunkGenerator generator, boolean unloadEventStarted,
         Throwable failure) {
         try {
-            if (!generatorUnbound || generator == null || !serverAccess.hasLevel(server, key)) {
+            if (!unloadEventStarted || !serverAccess.hasLevel(server, key)) {
                 return;
             }
+            if (generator != null) {
                 generator.bindLevel(level);
+            }
+            ModdedEngineBootstrap.loader().fireDynamicLevelLoad(server, level);
         } catch (Throwable rollbackFailure) {
             if (rollbackFailure != failure) {
                 failure.addSuppressed(rollbackFailure);
@@ -258,44 +265,263 @@ public final class ModdedDimensionManager {
         }
     }
 
-    public static boolean teleport(ServerPlayer player, MinecraftServer server, String dimensionId, double x, double y, double z) {
+    public static CompletableFuture<Boolean> teleportAsync(
-        ServerLevel level = level(server, dimensionId);
+            ServerPlayer player,
-        if (level == null) {
+            MinecraftServer server,
-            return false;
+            String dimensionId,
-        }
+            double x,
-        int blockX = (int) Math.floor(x);
+            double y,
-        int blockZ = (int) Math.floor(z);
+            double z
-        ChunkPos chunkPos = new ChunkPos(blockX >> 4, blockZ >> 4);
+    ) {
-        if (level.getChunkSource().hasChunk(chunkPos.x(), chunkPos.z())) {
+        return teleportAsync(player, server, dimensionId, x, y, z,
-            completeTeleport(player, level, x, y, z, blockX, blockZ);
+                System.nanoTime() + TimeUnit.SECONDS.toNanos(TELEPORT_TIMEOUT_SECONDS));
-            return true;
-        }
-        UUID playerId = player.getUUID();
-        CompletableFuture
-                .supplyAsync(() -> level.getChunkSource().addTicketAndLoadWithRadius(TELEPORT_WARM_TICKET, chunkPos, 1), server)
-                .thenCompose((CompletableFuture<?> inner) -> inner)
-                // The ticket has no timeout of its own: bound the wait so the release below always runs.
-                .orTimeout(TELEPORT_WARM_TIMEOUT_SECONDS, TimeUnit.SECONDS)
-                .whenComplete((Object result, Throwable error) -> server.execute(() -> {
-                    level.getChunkSource().removeTicketWithRadius(TELEPORT_WARM_TICKET, chunkPos, 1);
-                    if (error != null) {
-                        ModdedIrisLog.warn("Iris chunk warm for teleport into '{}' at {},{} failed: {}", dimensionId, chunkPos.x(), chunkPos.z(), error.toString());
-                    }
-                    ServerPlayer target = server.getPlayerList().getPlayer(playerId);
-                    if (target == null) {
-                        return;
-                    }
-                    completeTeleport(target, level, x, y, z, blockX, blockZ);
-                }));
-        return true;
     }
 
-    private static void completeTeleport(ServerPlayer player, ServerLevel level, double x, double y, double z, int blockX, int blockZ) {
+    public static CompletableFuture<Boolean> teleportAsync(
-        double targetY = y;
+            ServerPlayer player,
-        if (y == Double.MIN_VALUE) {
+            MinecraftServer server,
-            targetY = level.getHeight(Heightmap.Types.MOTION_BLOCKING, blockX, blockZ);
+            String dimensionId,
+            double x,
+            double y,
+            double z,
+            long deadlineNanos
+    ) {
+        ServerLevel level = level(server, dimensionId);
+        if (level == null) {
+            return CompletableFuture.completedFuture(false);
         }
-        player.teleportTo(level, x, targetY, z, Set.<Relative>of(), player.getYRot(), player.getXRot(), false);
+        return teleportAsync(player, server, level, x, y, z, deadlineNanos);
+    }
+
+    public static CompletableFuture<Boolean> teleportAsync(
+            ServerPlayer player,
+            MinecraftServer server,
+            ServerLevel level,
+            double x,
+            double y,
+            double z
+    ) {
+        return teleportAsync(player, server, level, x, y, z, 0L);
+    }
+
+    public static CompletableFuture<Boolean> teleportAsync(
+            ServerPlayer player,
+            MinecraftServer server,
+            ServerLevel level,
+            double x,
+            double y,
+            double z,
+            long deadlineNanos
+    ) {
+        CompletableFuture<Boolean> result = new CompletableFuture<>();
+        if (player == null || server == null || level == null || level.getServer() != server) {
+            result.complete(false);
+            return result;
+        }
+        if (!Double.isFinite(x) || !Double.isFinite(z)
+                || (y != Double.MIN_VALUE && !Double.isFinite(y))) {
+            result.completeExceptionally(new IllegalArgumentException("Teleport coordinates must be finite."));
+            return result;
+        }
+        if (deadlineNanos != 0L) {
+            long remainingNanos = deadlineNanos - System.nanoTime();
+            if (remainingNanos <= 0L) {
+                result.completeExceptionally(teleportTimeout(level, x, z));
+                return result;
+            }
+            result.orTimeout(remainingNanos, TimeUnit.NANOSECONDS);
+        }
+        UUID playerId = player.getUUID();
+        runOnServer(server, () -> beginTeleport(
+                result,
+                playerId,
+                server,
+                level,
+                x,
+                y,
+                z,
+                deadlineNanos));
+        return result;
+    }
+
+    private static void beginTeleport(
+            CompletableFuture<Boolean> result,
+            UUID playerId,
+            MinecraftServer server,
+            ServerLevel level,
+            double x,
+            double y,
+            double z,
+            long deadlineNanos
+    ) {
+        if (result.isDone()) {
+            return;
+        }
+        if (deadlineNanos != 0L && System.nanoTime() >= deadlineNanos) {
+            result.completeExceptionally(teleportTimeout(level, x, z));
+            return;
+        }
+        ServerLevel active = level(server, level.dimension().identifier().toString());
+        if (active != level) {
+            result.complete(false);
+            return;
+        }
+        int blockX = ModdedTeleportBounds.blockCoordinate(x);
+        int blockZ = ModdedTeleportBounds.blockCoordinate(z);
+        ChunkPos chunkPos = new ChunkPos(blockX >> 4, blockZ >> 4);
+        if (level.getChunkSource().hasChunk(chunkPos.x(), chunkPos.z())) {
+            completeTeleport(result, playerId, server, level, x, y, z, blockX, blockZ, deadlineNanos);
+            return;
+        }
+        warmAndTeleport(result, playerId, server, level, x, y, z, blockX, blockZ, chunkPos, deadlineNanos);
+    }
+
+    private static void warmAndTeleport(
+            CompletableFuture<Boolean> result,
+            UUID playerId,
+            MinecraftServer server,
+            ServerLevel level,
+            double x,
+            double y,
+            double z,
+            int blockX,
+            int blockZ,
+            ChunkPos chunkPos,
+            long deadlineNanos
+    ) {
+        AtomicBoolean ticketReleased = new AtomicBoolean();
+        CompletableFuture<?> chunkLoad;
+        try {
+            chunkLoad = level.getChunkSource().addTicketAndLoadWithRadius(
+                    TELEPORT_WARM_TICKET,
+                    chunkPos,
+                    TELEPORT_WARM_RADIUS);
+        } catch (Throwable failure) {
+            result.completeExceptionally(failure);
+            return;
+        }
+        if (chunkLoad == null) {
+            releaseTeleportTicket(level, chunkPos, ticketReleased);
+            result.completeExceptionally(new IllegalStateException(
+                    "Chunk warm returned no completion future for " + level.dimension().identifier()
+                            + " at " + chunkPos.x() + "," + chunkPos.z() + "."));
+            return;
+        }
+        result.whenComplete((success, failure) -> runOnServer(server,
+                () -> releaseTeleportTicket(level, chunkPos, ticketReleased)));
+        chunkLoad.whenComplete((ignored, failure) -> runOnServer(server, () -> {
+            releaseTeleportTicket(level, chunkPos, ticketReleased);
+            if (result.isDone()) {
+                return;
+            }
+            if (failure != null) {
+                result.completeExceptionally(failure);
+                return;
+            }
+            completeTeleport(result, playerId, server, level, x, y, z, blockX, blockZ, deadlineNanos);
+        }));
+    }
+
+    private static void releaseTeleportTicket(
+            ServerLevel level,
+            ChunkPos chunkPos,
+            AtomicBoolean ticketReleased
+    ) {
+        if (ticketReleased.compareAndSet(false, true)) {
+            level.getChunkSource().removeTicketWithRadius(
+                    TELEPORT_WARM_TICKET,
+                    chunkPos,
+                    TELEPORT_WARM_RADIUS);
+        }
+    }
+
+    private static void completeTeleport(
+            CompletableFuture<Boolean> result,
+            UUID playerId,
+            MinecraftServer server,
+            ServerLevel level,
+            double x,
+            double y,
+            double z,
+            int blockX,
+            int blockZ,
+            long deadlineNanos
+    ) {
+        if (result.isDone()) {
+            return;
+        }
+        if (deadlineNanos != 0L && System.nanoTime() >= deadlineNanos) {
+            result.completeExceptionally(teleportTimeout(level, x, z));
+            return;
+        }
+        ServerLevel active = level(server, level.dimension().identifier().toString());
+        ServerPlayer player = server.getPlayerList().getPlayer(playerId);
+        if (active != level || player == null) {
+            result.complete(false);
+            return;
+        }
+        try {
+            int targetY = resolveSafeTeleportY(level, blockX, blockZ, y);
+            boolean teleported = player.teleportTo(
+                    level,
+                    x,
+                    targetY,
+                    z,
+                    Set.<Relative>of(),
+                    player.getYRot(),
+                    player.getXRot(),
+                    false);
+            result.complete(teleported);
+        } catch (Throwable failure) {
+            result.completeExceptionally(failure);
+        }
+    }
+
+    private static int resolveSafeTeleportY(ServerLevel level, int blockX, int blockZ, double requestedY) {
+        int initialY = requestedY == Double.MIN_VALUE
+                ? level.getHeight(Heightmap.Types.MOTION_BLOCKING, blockX, blockZ)
+                : (int) Math.floor(requestedY);
+        int startY = ModdedTeleportBounds.clampY(level.getMinY(), level.getMaxY(), initialY);
+        int maximumY = ModdedTeleportBounds.maximumY(level.getMinY(), level.getMaxY());
+        int minimumY = ModdedTeleportBounds.minimumY(level.getMinY(), level.getMaxY());
+        for (int candidateY = startY; candidateY <= maximumY; candidateY++) {
+            if (isSafeStandingPosition(level, blockX, candidateY, blockZ)) {
+                return candidateY;
+            }
+        }
+        for (int candidateY = startY - 1; candidateY >= minimumY; candidateY--) {
+            if (isSafeStandingPosition(level, blockX, candidateY, blockZ)) {
+                return candidateY;
+            }
+        }
+        throw new IllegalStateException("No safe teleport position exists in "
+                + level.dimension().identifier() + " at " + blockX + "," + blockZ + ".");
+    }
+
+    private static boolean isSafeStandingPosition(ServerLevel level, int blockX, int blockY, int blockZ) {
+        BlockPos feet = new BlockPos(blockX, blockY, blockZ);
+        BlockPos head = feet.above();
+        BlockPos support = feet.below();
+        return level.getBlockState(feet).getCollisionShape(level, feet).isEmpty()
+                && level.getBlockState(feet).getFluidState().isEmpty()
+                && level.getBlockState(head).getCollisionShape(level, head).isEmpty()
+                && level.getBlockState(head).getFluidState().isEmpty()
+                && !level.getBlockState(support).getCollisionShape(level, support).isEmpty();
+    }
+
+    private static TimeoutException teleportTimeout(ServerLevel level, double x, double z) {
+        return new TimeoutException("Teleport into " + level.dimension().identifier()
+                + " at " + ModdedTeleportBounds.blockCoordinate(x) + ","
+                + ModdedTeleportBounds.blockCoordinate(z)
+                + " exceeded " + TELEPORT_TIMEOUT_SECONDS + " seconds.");
+    }
+
+    private static void runOnServer(MinecraftServer server, Runnable task) {
+        if (server.isSameThread()) {
+            task.run();
+            return;
+        }
+        server.execute(task);
     }
 
     private static Holder<DimensionType> resolveDimensionType(RegistryAccess registryAccess, String pack, String packDimensionKey) {
@@ -362,6 +588,7 @@ public final class ModdedDimensionManager {
                 List.of(),
                 false);
 
+        boolean loadEventStarted = false;
         try {
             generator.bindLevel(level);
             Handle handle = new Handle(dimensionId, pack, packDimensionKey, seed, level, generator);
@@ -371,9 +598,11 @@ public final class ModdedDimensionManager {
                         + "': the level was registered concurrently");
             }
             server.getPlayerList().addWorldborderListener(level);
+            loadEventStarted = true;
+            ModdedEngineBootstrap.loader().fireDynamicLevelLoad(server, level);
             return handle;
         } catch (Throwable error) {
-            rollbackInjection(server, serverAccess, key, level, generator, error);
+            rollbackInjection(server, serverAccess, key, level, generator, loadEventStarted, error);
             if (error instanceof RuntimeException runtimeException) {
                 throw runtimeException;
             }
@@ -386,7 +615,17 @@ public final class ModdedDimensionManager {
 
     private static void rollbackInjection(MinecraftServer server, ModdedServerAccess serverAccess,
                                           ResourceKey<Level> key, ServerLevel level,
-                                          IrisModdedChunkGenerator generator, Throwable failure) {
+                                          IrisModdedChunkGenerator generator, boolean loadEventStarted,
+                                          Throwable failure) {
+        if (loadEventStarted) {
+            try {
+                ModdedEngineBootstrap.loader().fireDynamicLevelUnload(server, level);
+            } catch (Throwable cleanupError) {
+                failure.addSuppressed(cleanupError);
+                ModdedIrisLog.error("Iris failed to publish rollback unload for {}",
+                        key.identifier(), cleanupError);
+            }
+        }
         try {
             if (serverAccess.hasLevel(server, key)) {
                 ServerLevel removed = serverAccess.removeLevel(server, key);

adapters/modded-common/src/main/java/art/arcane/iris/modded/ModdedLoader.java

@@ -38,6 +38,10 @@ public interface ModdedLoader {
 
     void invalidateLevelCache(MinecraftServer server);
 
+    void fireDynamicLevelLoad(MinecraftServer server, ServerLevel level);
+
+    void fireDynamicLevelUnload(MinecraftServer server, ServerLevel level);
+
     boolean clientEnvironment();
 
     Path configDir();

adapters/modded-common/src/main/java/art/arcane/iris/modded/ModdedPrimaryWorldRouter.java

@@ -26,12 +26,14 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
 
 public final class ModdedPrimaryWorldRouter {
     private static final int TICK_INTERVAL = 20;
 
     private static final Set<UUID> routed = ConcurrentHashMap.newKeySet();
+    private static final Set<UUID> inFlight = ConcurrentHashMap.newKeySet();
     private static int tickCounter = 0;
 
     private ModdedPrimaryWorldRouter() {
@@ -39,6 +41,7 @@ public final class ModdedPrimaryWorldRouter {
 
     public static void clear() {
         routed.clear();
+        inFlight.clear();
     }
 
     /**
@@ -48,6 +51,7 @@ public final class ModdedPrimaryWorldRouter {
     public static void forget(UUID player) {
         if (player != null) {
             routed.remove(player);
+            inFlight.remove(player);
         }
     }
 
@@ -82,17 +86,35 @@ public final class ModdedPrimaryWorldRouter {
         List<ServerPlayer> players = new ArrayList<>(server.getPlayerList().getPlayers());
         for (ServerPlayer player : players) {
             UUID id = player.getUUID();
-            if (routed.contains(id)) {
+            if (routed.contains(id) || !inFlight.add(id)) {
                 continue;
             }
             if (player.level() != overworld) {
+                inFlight.remove(id);
                 routed.add(id);
                 continue;
             }
             try {
-                ModdedDimensionManager.teleport(player, server, primary, player.getX(), Double.MIN_VALUE, player.getZ());
+                CompletableFuture<Boolean> teleport = ModdedDimensionManager.teleportAsync(
+                        player,
+                        server,
+                        primary,
+                        player.getX(),
+                        Double.MIN_VALUE,
+                        player.getZ());
+                teleport.whenComplete((success, failure) -> {
+                    inFlight.remove(id);
+                    if (Boolean.TRUE.equals(success) && failure == null) {
                         routed.add(id);
+                        return;
+                    }
+                    if (failure != null) {
+                        ModdedIrisLog.error("Iris failed to route player {} to primary world '{}'",
+                                id, primary, failure);
+                    }
+                });
             } catch (Throwable e) {
+                inFlight.remove(id);
                 ModdedIrisLog.error("Iris failed to route player {} to primary world '{}'", id, primary, e);
             }
         }

adapters/modded-common/src/main/java/art/arcane/iris/modded/ModdedTeleportBounds.java

@@ -0,0 +1,50 @@
+/*
+ * Iris is a World Generator for Minecraft Servers
+ * Copyright (c) 2026 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package art.arcane.iris.modded;
+
+final class ModdedTeleportBounds {
+    private ModdedTeleportBounds() {
+    }
+
+    static int blockCoordinate(double coordinate) {
+        return (int) Math.floor(coordinate);
+    }
+
+    static int clampY(int minY, int maxY, int requestedY) {
+        int minimumY = minimumY(minY, maxY);
+        int maximumY = maximumY(minY, maxY);
+        return Math.max(minimumY, Math.min(maximumY, requestedY));
+    }
+
+    static int minimumY(int minY, int maxY) {
+        requireStandingSpace(minY, maxY);
+        return minY + 1;
+    }
+
+    static int maximumY(int minY, int maxY) {
+        requireStandingSpace(minY, maxY);
+        return maxY - 2;
+    }
+
+    private static void requireStandingSpace(int minY, int maxY) {
+        if (maxY - minY < 3) {
+            throw new IllegalArgumentException("Level height must provide support, feet, and head space.");
+        }
+    }
+}

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/IrisModdedCommands.java

@@ -131,10 +131,26 @@ public final class IrisModdedCommands {
             return 0;
         }
         String dimensionId = level.dimension().identifier().toString();
-        if (!ModdedDimensionManager.teleport(player, source.getServer(), dimensionId, 8.5D, Double.MIN_VALUE, 8.5D)) {
+        MinecraftServer server = source.getServer();
-            fail(source, IrisLanguage.plain(ModdedCommandMessages.IRIS_MODDED_COMMANDS_TELEPORT_FAILED_DIMENSION_IS_NOT_LOADED, MessageArgument.untrusted("dimensionId", dimensionId)));
+        CompletableFuture<Boolean> teleport = ModdedDimensionManager.teleportAsync(
-            return 0;
+                player,
+                server,
+                dimensionId,
+                8.5D,
+                Double.MIN_VALUE,
+                8.5D);
+        teleport.whenComplete((success, failure) -> {
+            if (Boolean.TRUE.equals(success) && failure == null) {
+                return;
             }
+            if (failure != null) {
+                ModdedIrisLog.error("Iris teleport into '{}' failed for {}",
+                        dimensionId, player.getUUID(), failure);
+            }
+            server.execute(() -> fail(source, IrisLanguage.plain(
+                    ModdedCommandMessages.IRIS_MODDED_COMMANDS_TELEPORT_FAILED_DIMENSION_IS_NOT_LOADED,
+                    MessageArgument.untrusted("dimensionId", dimensionId))));
+        });
         ok(source, IrisLanguage.plain(ModdedCommandMessages.IRIS_MODDED_COMMANDS_TELEPORTING, MessageArgument.untrusted("value", player.getScoreboardName()), MessageArgument.untrusted("dimensionId", dimensionId)));
         return 1;
     }

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedGuiHost.java

@@ -107,7 +107,7 @@ public final class ModdedGuiHost implements GuiHost.Provider {
     }
 
     @Override
-    public GuiOverlay overlayFor(Engine engine) {
+    public GuiOverlay overlayFor(Engine engine, UUID openerId) {
         if (engine == null) {
             return null;
         }
@@ -115,6 +115,7 @@ public final class ModdedGuiHost implements GuiHost.Provider {
         if (level == null || server == null) {
             return null;
         }
-        return new ModdedVisionOverlay(server, level, engine, openers.get(engine));
+        UUID resolvedOpenerId = openerId == null ? openers.get(engine) : openerId;
+        return new ModdedVisionOverlay(server, level, engine, resolvedOpenerId);
     }
 }

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedStudioCommands.java

@@ -44,6 +44,7 @@ import art.arcane.iris.engine.object.IrisSpawner;
 import art.arcane.iris.engine.object.IrisStructurePlacement;
 import art.arcane.iris.modded.ModdedDimensionManager;
 import art.arcane.iris.modded.ModdedEngineBootstrap;
+import art.arcane.iris.modded.ModdedScheduler;
 import art.arcane.iris.modded.ModdedWorkspaceGenerator;
 import art.arcane.iris.util.common.parallel.BurstExecutor;
 import art.arcane.iris.util.common.parallel.MultiBurst;
@@ -67,7 +68,6 @@ import net.minecraft.commands.SharedSuggestionProvider;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.entity.Relative;
 import org.zeroturnaround.zip.ZipUtil;
 
 import java.awt.Desktop;
@@ -79,6 +79,8 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Predicate;
@@ -96,6 +98,7 @@ public final class ModdedStudioCommands {
     private static final String DEFAULT_TEMPLATE = "example";
     private static final UUID CONSOLE_OWNER = new UUID(0L, 0L);
     private static final Map<UUID, String> STUDIOS = new ConcurrentHashMap<>();
+    private static final ModdedStudioTransitionQueue TRANSITIONS = new ModdedStudioTransitionQueue();
     private static final SuggestionProvider<CommandSourceStack> GENERATOR_KEYS = (CommandContext<CommandSourceStack> context, SuggestionsBuilder builder) -> {
         ModdedCommandFeedback.tab(context.getSource());
         try {
@@ -192,6 +195,7 @@ public final class ModdedStudioCommands {
     }
 
     public static void clear() {
+        TRANSITIONS.clear();
         STUDIOS.clear();
     }
 
@@ -272,7 +276,7 @@ public final class ModdedStudioCommands {
         }
         ServerPlayer player = source.getPlayer();
         ModdedGuiHost.bindContext(source.getServer(), level, engine, player == null ? null : player.getUUID());
-        VisionGUI.launch(engine);
+        VisionGUI.launch(engine, player == null ? null : player.getUUID());
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_OPENING_VISION_MAP_ON_SERVER_DISPLAY, MessageArgument.untrusted("value", level.dimension().identifier())));
         return 1;
     }
@@ -402,124 +406,242 @@ public final class ModdedStudioCommands {
         String dimensionId = player == null ? studioConsoleDimensionId() : studioDimensionId(player);
         MinecraftServer server = source.getServer();
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_OPENING_STUDIO_SEED, MessageArgument.untrusted("pack", pack), MessageArgument.untrusted("seed", seed)));
-        Thread thread = new Thread(() -> openAsync(source, server, owner, dimensionId, pack, seed), "Iris Studio Open");
+        CompletableFuture<Void> transition = TRANSITIONS.submit(
-        thread.setDaemon(true);
+                owner,
-        thread.start();
+                () -> openTransition(source, server, owner, dimensionId, pack, seed));
+        reportOpenFailure(source, server, dimensionId, pack, transition);
         return 1;
     }
 
-    private static void openAsync(CommandSourceStack source, MinecraftServer server, UUID owner, String dimensionId, String pack, long seed) {
+    private static CompletableFuture<Void> openTransition(
+            CommandSourceStack source,
+            MinecraftServer server,
+            UUID owner,
+            String dimensionId,
+            String pack,
+            long seed
+    ) {
+        CompletableFuture<Void> transition = new CompletableFuture<>();
+        ModdedScheduler scheduler = ModdedEngineBootstrap.schedulerOrNull();
+        if (scheduler == null) {
+            transition.completeExceptionally(new IllegalStateException(
+                    "Iris modded scheduler is unavailable for Studio open."));
+            return transition;
+        }
+        scheduler.asyncIfRunning(() -> prepareStudioOpen(
+                        source,
+                        server,
+                        owner,
+                        dimensionId,
+                        pack,
+                        seed,
+                        transition),
+                () -> transition.completeExceptionally(new IllegalStateException(
+                        "Iris modded scheduler rejected Studio open.")));
+        return transition;
+    }
+
+    private static void prepareStudioOpen(
+            CommandSourceStack source,
+            MinecraftServer server,
+            UUID owner,
+            String dimensionId,
+            String pack,
+            long seed,
+            CompletableFuture<Void> transition
+    ) {
         try {
             File packFolder = new File(ModdedPackCommands.packsRoot(), pack);
             if (!new File(packFolder, "dimensions/" + pack + ".json").isFile()) {
-                server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(
+                throw new IllegalStateException("Required Studio pack '" + pack
-                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_REQUIRED_PACK_IS_NOT_INSTALLED_INSTALL_THEN_RESTART,
+                        + "' is not installed with dimensions/" + pack + ".json.");
-                        MessageArgument.untrusted("pack", pack))));
-                return;
             }
             IrisData data = IrisData.get(packFolder);
             IrisDimension dimension = data.getDimensionLoader().load(pack);
             if (dimension == null) {
-                server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_PACK_HAS_NO_DIMENSIONS_JSON, MessageArgument.untrusted("pack", pack), MessageArgument.untrusted("pack2", pack))));
+                throw new IllegalStateException("Studio pack '" + pack
-                return;
+                        + "' has no dimensions/" + pack + ".json definition.");
             }
-            try {
             ModdedWorkspaceGenerator.writeWorkspace(data, packFolder, true);
-            } catch (Throwable workspaceError) {
+            server.execute(() -> executeStudioOpen(
-                ModdedIrisLog.error("Iris workspace write failed for {}", packFolder, workspaceError);
+                    source,
-                server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(
+                    server,
-                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_FAILED_WRITE_WORKSPACE,
+                    owner,
-                        MessageArgument.untrusted("value", packFolder.getAbsolutePath()),
+                    dimensionId,
-                        MessageArgument.untrusted("value2", String.valueOf(workspaceError.getMessage())))));
+                    pack,
-            }
+                    seed,
-            server.execute(() -> {
+                    transition));
-                if (owner.equals(CONSOLE_OWNER)) {
+        } catch (Throwable failure) {
-                    injectConsole(source, server, dimensionId, pack, seed);
+            transition.completeExceptionally(failure);
-                } else {
-                    injectAndTeleport(source, server, owner, dimensionId, pack, seed);
-                }
-            });
-        } catch (Throwable e) {
-            ModdedIrisLog.error("Iris studio open failed for {}", pack, e);
-            server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_OPEN_FAILED, MessageArgument.untrusted("value", e.getClass().getSimpleName()), MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(e)))));
         }
     }
 
-    private static void injectConsole(CommandSourceStack source, MinecraftServer server, String dimensionId, String pack, long seed) {
+    private static void executeStudioOpen(
-        ModdedDimensionManager.Handle handle;
+            CommandSourceStack source,
+            MinecraftServer server,
+            UUID owner,
+            String dimensionId,
+            String pack,
+            long seed,
+            CompletableFuture<Void> transition
+    ) {
+        ModdedDimensionManager.Handle handle = null;
         try {
+            replaceExistingStudio(server, owner, dimensionId);
             handle = ModdedDimensionManager.create(server, dimensionId, pack, pack, seed);
-        } catch (Throwable e) {
+            STUDIOS.put(owner, dimensionId);
-            ModdedIrisLog.error("Iris console studio injection failed for {} ({})", dimensionId, pack, e);
+            if (owner.equals(CONSOLE_OWNER)) {
-            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_INJECTION_FAILED, MessageArgument.untrusted("value", e.getClass().getSimpleName()), MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(e))));
+                completeConsoleOpen(source, dimensionId, pack, seed, handle);
+                transition.complete(null);
                 return;
             }
-        STUDIOS.put(CONSOLE_OWNER, dimensionId);
+            ServerPlayer player = server.getPlayerList().getPlayer(owner);
+            if (player == null) {
+                throw new IllegalStateException("Studio owner disconnected before teleport.");
+            }
             ServerLevel studio = handle.level();
-        int surface = studio.getMaxY();
-        try {
             Engine engine = IrisModdedCommands.engineFor(studio);
-            if (engine != null) {
+            if (engine == null) {
-                surface = engine.getMinHeight() + engine.getHeight(8, 8, false) + 2;
+                throw new IllegalStateException("Studio engine is unavailable for " + dimensionId + ".");
             }
-        } catch (Throwable e) {
+            int surfaceY = engine.getMinHeight() + engine.getHeight(8, 8, false) + 2;
-            ModdedIrisLog.error("Iris console studio surface probe failed for {}", dimensionId, e);
+            CompletableFuture<Boolean> teleport = ModdedDimensionManager.teleportAsync(
+                    player,
+                    server,
+                    studio,
+                    8.5D,
+                    surfaceY,
+                    8.5D);
+            teleport.whenComplete((success, failure) -> server.execute(() -> {
+                if (transition.isDone()) {
+                    return;
                 }
+                if (failure != null) {
+                    transition.completeExceptionally(failure);
+                    return;
+                }
+                if (!Boolean.TRUE.equals(success)) {
+                    transition.completeExceptionally(new IllegalStateException(
+                            "Studio native teleport did not complete successfully."));
+                    return;
+                }
+                IrisModdedCommands.ok(source, IrisLanguage.plain(
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_OPEN_NOW_RUNS_SEED_USE_IRIS_STUDIO_CLOSE_WHEN,
+                        MessageArgument.untrusted("dimensionId", dimensionId),
+                        MessageArgument.untrusted("pack", pack),
+                        MessageArgument.untrusted("seed", seed)));
+                transition.complete(null);
+            }));
+        } catch (Throwable failure) {
+            transition.completeExceptionally(failure);
+            if (handle != null && transition.isCompletedExceptionally()) {
+                cleanupFailedOpen(server, owner, dimensionId, failure);
+            }
+        }
+    }
+
+    private static void replaceExistingStudio(MinecraftServer server, UUID owner, String dimensionId) {
+        if (ModdedDimensionManager.level(server, dimensionId) != null
+                || ModdedDimensionManager.handle(dimensionId) != null) {
+            ModdedDimensionManager.remove(server, dimensionId, true);
+        }
+        STUDIOS.remove(owner, dimensionId);
+    }
+
+    private static void cleanupFailedOpen(
+            MinecraftServer server,
+            UUID owner,
+            String dimensionId,
+            Throwable failure
+    ) {
+        try {
+            ModdedDimensionManager.remove(server, dimensionId, true);
+            STUDIOS.remove(owner, dimensionId);
+        } catch (Throwable cleanupFailure) {
+            failure.addSuppressed(cleanupFailure);
+            ModdedIrisLog.error("Iris failed to clean up Studio '{}' after open failure",
+                    dimensionId, cleanupFailure);
+        }
+    }
+
+    private static void completeConsoleOpen(
+            CommandSourceStack source,
+            String dimensionId,
+            String pack,
+            long seed,
+            ModdedDimensionManager.Handle handle
+    ) {
+        ServerLevel studio = handle.level();
+        Engine engine = IrisModdedCommands.engineFor(studio);
+        int surface = engine == null
+                ? studio.getMinY() + 1
+                : engine.getMinHeight() + engine.getHeight(8, 8, false) + 2;
+        surface = Math.max(studio.getMinY() + 1, Math.min(studio.getMaxY() - 2, surface));
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_CONSOLE_STUDIO_OPEN_NOW_RUNS_SEED_TRANSIENT_NOT_WRITTEN_IRIS, MessageArgument.untrusted("dimensionId", dimensionId), MessageArgument.untrusted("pack", pack), MessageArgument.untrusted("seed", seed)));
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_ENTER_IT_WITH_EXECUTE_RUN_TP_S_8_5_8, MessageArgument.untrusted("dimensionId", dimensionId), MessageArgument.untrusted("surface", surface)));
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_PREGEN_IT_WITH_IRIS_PREGEN_START_RADIUS, MessageArgument.untrusted("dimensionId", dimensionId)));
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_REMOVE_IT_WITH_IRIS_STUDIO_CLOSE));
     }
 
-    private static void injectAndTeleport(CommandSourceStack source, MinecraftServer server, UUID owner, String dimensionId, String pack, long seed) {
+    private static void reportOpenFailure(
-        ServerPlayer player = server.getPlayerList().getPlayer(owner);
+            CommandSourceStack source,
-        if (player == null) {
+            MinecraftServer server,
+            String dimensionId,
+            String pack,
+            CompletableFuture<Void> transition
+    ) {
+        transition.whenComplete((ignored, failure) -> {
+            if (failure == null) {
                 return;
             }
-        ModdedDimensionManager.Handle handle;
+            Throwable cause = unwrapFailure(failure);
-        try {
+            ModdedIrisLog.error("Iris Studio open failed for '{}' ({})", dimensionId, pack, cause);
-            handle = ModdedDimensionManager.create(server, dimensionId, pack, pack, seed);
+            server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(
-        } catch (Throwable e) {
+                    ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_OPEN_FAILED,
-            ModdedIrisLog.error("Iris studio injection failed for {} ({})", dimensionId, pack, e);
+                    MessageArgument.untrusted("value", cause.getClass().getSimpleName()),
-            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_INJECTION_FAILED_2, MessageArgument.untrusted("value", e.getClass().getSimpleName()), MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(e))));
+                    MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(cause)))));
-            return;
+        });
-        }
-        STUDIOS.put(owner, dimensionId);
-        ServerLevel studio = handle.level();
-        int surface = studio.getMaxY();
-        try {
-            Engine engine = IrisModdedCommands.engineFor(studio);
-            if (engine != null) {
-                surface = engine.getMinHeight() + engine.getHeight(8, 8, false) + 2;
-            }
-        } catch (Throwable e) {
-            ModdedIrisLog.error("Iris studio surface probe failed for {}", dimensionId, e);
-        }
-        player.teleportTo(studio, 8.5D, surface, 8.5D, java.util.Set.<Relative>of(), player.getYRot(), player.getXRot(), false);
-        IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_OPEN_NOW_RUNS_SEED_USE_IRIS_STUDIO_CLOSE_WHEN, MessageArgument.untrusted("dimensionId", dimensionId), MessageArgument.untrusted("pack", pack), MessageArgument.untrusted("seed", seed)));
     }
 
     private static int close(CommandSourceStack source) {
         ServerPlayer player = source.getPlayer();
         MinecraftServer server = source.getServer();
         UUID owner = player == null ? CONSOLE_OWNER : player.getUUID();
-        // Commit the ownership drop only after removal succeeds: dropping it first orphaned a
+        TRANSITIONS.submit(owner, () -> closeTransition(source, server, owner));
-        // still-registered studio that no command could ever remove again.
+        return 1;
+    }
+
+    private static CompletableFuture<Void> closeTransition(
+            CommandSourceStack source,
+            MinecraftServer server,
+            UUID owner
+    ) {
+        CompletableFuture<Void> transition = new CompletableFuture<>();
+        server.execute(() -> {
             String dimensionId = STUDIOS.get(owner);
             if (dimensionId == null) {
-            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_YOU_DO_NOT_HAVE_OPEN_STUDIO_USE_IRIS_STUDIO_OPEN));
+                IrisModdedCommands.fail(source, IrisLanguage.plain(
-            return 0;
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_YOU_DO_NOT_HAVE_OPEN_STUDIO_USE_IRIS_STUDIO_OPEN));
+                transition.complete(null);
+                return;
             }
             try {
                 ModdedDimensionManager.remove(server, dimensionId, true);
-        } catch (Throwable e) {
-            ModdedIrisLog.error("Iris studio close failed for {}", dimensionId, e);
-            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_CLOSE_FAILED, MessageArgument.untrusted("value", e.getClass().getSimpleName()), MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(e))));
-            return 0;
-        }
                 STUDIOS.remove(owner, dimensionId);
-        IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_CLOSED_WAS_EVACUATED_UNLOADED_ITS_REGION_DATA_DELETED, MessageArgument.untrusted("dimensionId", dimensionId)));
+                IrisModdedCommands.ok(source, IrisLanguage.plain(
-        return 1;
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_CLOSED_WAS_EVACUATED_UNLOADED_ITS_REGION_DATA_DELETED,
+                        MessageArgument.untrusted("dimensionId", dimensionId)));
+                transition.complete(null);
+            } catch (Throwable failure) {
+                ModdedIrisLog.error("Iris Studio close failed for {}", dimensionId, failure);
+                IrisModdedCommands.fail(source, IrisLanguage.plain(
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_CLOSE_FAILED,
+                        MessageArgument.untrusted("value", failure.getClass().getSimpleName()),
+                        MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(failure))));
+                transition.completeExceptionally(failure);
+            }
+        });
+        return transition;
     }
 
     private static int status(CommandSourceStack source) {
@@ -568,29 +690,100 @@ public final class ModdedStudioCommands {
             return 0;
         }
         MinecraftServer server = source.getServer();
-        String dimensionId = STUDIOS.get(player.getUUID());
+        UUID owner = player.getUUID();
+        CompletableFuture<Void> transition = TRANSITIONS.submit(
+                owner,
+                () -> teleportToStudio(source, server, owner));
+        reportTeleportFailure(source, server, transition);
+        return 1;
+    }
+
+    private static CompletableFuture<Void> teleportToStudio(
+            CommandSourceStack source,
+            MinecraftServer server,
+            UUID owner
+    ) {
+        CompletableFuture<Void> transition = new CompletableFuture<>();
+        server.execute(() -> {
+            if (transition.isDone()) {
+                return;
+            }
+            String dimensionId = STUDIOS.get(owner);
             if (dimensionId == null) {
-            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_YOU_DO_NOT_HAVE_OPEN_STUDIO_USE_IRIS_STUDIO_OPEN_2));
+                IrisModdedCommands.fail(source, IrisLanguage.plain(
-            return 0;
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_YOU_DO_NOT_HAVE_OPEN_STUDIO_USE_IRIS_STUDIO_OPEN_2));
+                transition.complete(null);
+                return;
             }
             ServerLevel studio = ModdedDimensionManager.level(server, dimensionId);
             if (studio == null) {
-            STUDIOS.remove(player.getUUID());
+                STUDIOS.remove(owner, dimensionId);
-            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_YOUR_STUDIO_DIMENSION_IS_NO_LONGER_LOADED_USE_IRIS_STUDIO));
+                IrisModdedCommands.fail(source, IrisLanguage.plain(
-            return 0;
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_YOUR_STUDIO_DIMENSION_IS_NO_LONGER_LOADED_USE_IRIS_STUDIO));
+                transition.complete(null);
+                return;
             }
-        int surface = studio.getMaxY();
+            ServerPlayer activePlayer = server.getPlayerList().getPlayer(owner);
-        try {
             Engine engine = IrisModdedCommands.engineFor(studio);
-            if (engine != null) {
+            if (activePlayer == null || engine == null) {
-                surface = engine.getMinHeight() + engine.getHeight(8, 8, false) + 2;
+                transition.completeExceptionally(new IllegalStateException(
+                        "Studio player or engine is unavailable for teleport."));
+                return;
             }
-        } catch (Throwable e) {
+            int surfaceY = engine.getMinHeight() + engine.getHeight(8, 8, false) + 2;
-            ModdedIrisLog.error("Iris tpstudio surface probe failed", e);
+            CompletableFuture<Boolean> teleport = ModdedDimensionManager.teleportAsync(
+                    activePlayer,
+                    server,
+                    studio,
+                    8.5D,
+                    surfaceY,
+                    8.5D);
+            teleport.whenComplete((success, failure) -> server.execute(() -> {
+                if (transition.isDone()) {
+                    return;
                 }
-        player.teleportTo(studio, 8.5D, surface, 8.5D, java.util.Set.<Relative>of(), player.getYRot(), player.getXRot(), false);
+                if (failure != null) {
-        IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_STUDIO_COMMANDS_TELEPORTED_YOUR_STUDIO, MessageArgument.untrusted("dimensionId", dimensionId)));
+                    transition.completeExceptionally(failure);
-        return 1;
+                    return;
+                }
+                if (!Boolean.TRUE.equals(success)) {
+                    transition.completeExceptionally(new IllegalStateException(
+                            "Studio native teleport did not complete successfully."));
+                    return;
+                }
+                IrisModdedCommands.ok(source, IrisLanguage.plain(
+                        ModdedCommandMessages.MODDED_STUDIO_COMMANDS_TELEPORTED_YOUR_STUDIO,
+                        MessageArgument.untrusted("dimensionId", dimensionId)));
+                transition.complete(null);
+            }));
+        });
+        return transition;
+    }
+
+    private static void reportTeleportFailure(
+            CommandSourceStack source,
+            MinecraftServer server,
+            CompletableFuture<Void> transition
+    ) {
+        transition.whenComplete((ignored, failure) -> {
+            if (failure == null) {
+                return;
+            }
+            Throwable cause = unwrapFailure(failure);
+            ModdedIrisLog.error("Iris Studio teleport failed", cause);
+            server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(
+                    ModdedCommandMessages.MODDED_STUDIO_COMMANDS_STUDIO_OPEN_FAILED,
+                    MessageArgument.untrusted("value", cause.getClass().getSimpleName()),
+                    MessageArgument.trusted("errorMessage", IrisLanguage.errorDetail(cause)))));
+        });
+    }
+
+    private static Throwable unwrapFailure(Throwable failure) {
+        Throwable cause = failure;
+        while (cause instanceof CompletionException && cause.getCause() != null) {
+            cause = cause.getCause();
+        }
+        return cause;
     }
 
     private static int version(CommandSourceStack source, String pack) {

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedStudioTransitionQueue.java

@@ -0,0 +1,58 @@
+/*
+ * Iris is a World Generator for Minecraft Servers
+ * Copyright (c) 2026 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package art.arcane.iris.modded.command;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Supplier;
+
+final class ModdedStudioTransitionQueue {
+    private final Object lock = new Object();
+    private final Map<UUID, CompletableFuture<Void>> tails = new HashMap<>();
+
+    CompletableFuture<Void> submit(UUID owner, Supplier<CompletableFuture<Void>> transition) {
+        Objects.requireNonNull(owner, "Studio transition owner");
+        Objects.requireNonNull(transition, "Studio transition");
+        synchronized (lock) {
+            CompletableFuture<Void> previous = tails.get(owner);
+            CompletableFuture<Void> admission = previous == null
+                    ? CompletableFuture.completedFuture(null)
+                    : previous.handle((ignored, failure) -> null);
+            CompletableFuture<Void> current = admission.thenCompose((ignored) -> transition.get());
+            tails.put(owner, current);
+            current.whenComplete((ignored, failure) -> remove(owner, current));
+            return current;
+        }
+    }
+
+    void clear() {
+        synchronized (lock) {
+            tails.clear();
+        }
+    }
+
+    private void remove(UUID owner, CompletableFuture<Void> transition) {
+        synchronized (lock) {
+            tails.remove(owner, transition);
+        }
+    }
+}

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedVisionOverlay.java

@@ -24,12 +24,13 @@ import art.arcane.iris.core.gui.GuiOverlay;
 import art.arcane.iris.engine.IrisComplex;
 import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.framework.render.RenderType;
+import art.arcane.iris.modded.ModdedDimensionManager;
+import art.arcane.iris.modded.ModdedIrisLog;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.entity.Entity;
 import net.minecraft.world.entity.LivingEntity;
-import net.minecraft.world.level.levelgen.Heightmap;
 import net.minecraft.world.phys.Vec3;
 
 import java.awt.Desktop;
@@ -37,6 +38,8 @@ import java.io.File;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
 
 public final class ModdedVisionOverlay implements GuiOverlay {
@@ -80,11 +83,14 @@ public final class ModdedVisionOverlay implements GuiOverlay {
 
     @Override
     public void teleport(double worldX, double worldZ) {
-        int blockX = (int) worldX;
+        int blockX = (int) Math.floor(worldX);
-        int blockZ = (int) worldZ;
+        int blockZ = (int) Math.floor(worldZ);
         server.execute(() -> {
             ServerPlayer player = opener == null ? null : server.getPlayerList().getPlayer(opener);
             if (player == null) {
+                if (opener != null) {
+                    return;
+                }
                 List<ServerPlayer> players = level.players();
                 if (players.isEmpty()) {
                     return;
@@ -92,8 +98,24 @@ public final class ModdedVisionOverlay implements GuiOverlay {
                 player = players.get(0);
             }
             int surfaceY = engine.getMinHeight() + engine.getHeight(blockX, blockZ, false) + 2;
-            int safeY = Math.max(surfaceY, level.getHeight(Heightmap.Types.MOTION_BLOCKING, blockX, blockZ) + 1);
+            CompletableFuture<Boolean> teleport = ModdedDimensionManager.teleportAsync(
-            player.teleportTo(level, blockX + 0.5D, safeY, blockZ + 0.5D, java.util.Set.of(), player.getYRot(), player.getXRot(), false);
+                    player,
+                    server,
+                    level,
+                    blockX + 0.5D,
+                    surfaceY,
+                    blockZ + 0.5D,
+                    System.nanoTime() + TimeUnit.SECONDS.toNanos(10L));
+            UUID playerId = player.getUUID();
+            teleport.whenComplete((success, failure) -> {
+                if (failure != null) {
+                    ModdedIrisLog.error("Iris Vision teleport failed for {} at {},{}",
+                            playerId, blockX, blockZ, failure);
+                } else if (!Boolean.TRUE.equals(success)) {
+                    ModdedIrisLog.warn("Iris Vision teleport did not complete for {} at {},{}",
+                            playerId, blockX, blockZ);
+                }
+            });
         });
     }
 

adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedDimensionManagerTeleportTest.java

@@ -0,0 +1,27 @@
+package art.arcane.iris.modded;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class ModdedDimensionManagerTeleportTest {
+    @Test
+    public void blockCoordinatesUseFloorAcrossZeroAndChunkBoundaries() {
+        assertEquals(0, ModdedTeleportBounds.blockCoordinate(0.99D));
+        assertEquals(-1, ModdedTeleportBounds.blockCoordinate(-0.01D));
+        assertEquals(-17, ModdedTeleportBounds.blockCoordinate(-16.01D));
+        assertEquals(16, ModdedTeleportBounds.blockCoordinate(16D));
+    }
+
+    @Test
+    public void teleportYReservesSupportFeetAndHeadSpace() {
+        assertEquals(-63, ModdedTeleportBounds.clampY(-64, 320, -100));
+        assertEquals(318, ModdedTeleportBounds.clampY(-64, 320, 400));
+        assertEquals(72, ModdedTeleportBounds.clampY(-64, 320, 72));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void teleportYRejectsWorldsWithoutThreeVerticalBlocks() {
+        ModdedTeleportBounds.clampY(0, 2, 1);
+    }
+}

adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedDynamicLevelLifecycleContractTest.java

@@ -0,0 +1,91 @@
+package art.arcane.iris.modded;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertTrue;
+
+public class ModdedDynamicLevelLifecycleContractTest {
+    private static final String SOURCE_ROOT_PROPERTY = "iris.moddedCommonSources";
+
+    @Test
+    public void sharedManagerPublishesDynamicLoadAndUnloadAroundRegistration() throws IOException {
+        String manager = commonSource("ModdedDimensionManager.java");
+        String loader = commonSource("ModdedLoader.java");
+        String injection = method(manager, "private static Handle inject(");
+        String removal = method(manager, "public static boolean remove(");
+        String injectionRollback = method(manager, "private static void rollbackInjection(");
+        String removalRollback = method(manager, "private static void rollbackRemoval(");
+
+        assertTrue(loader.contains("void fireDynamicLevelLoad(MinecraftServer server, ServerLevel level);"));
+        assertTrue(loader.contains("void fireDynamicLevelUnload(MinecraftServer server, ServerLevel level);"));
+        assertBefore(injection, "serverAccess.putLevelIfAbsent(server, key, level);",
+                "fireDynamicLevelLoad(server, level);");
+        assertBefore(removal, "fireDynamicLevelUnload(server, level);",
+                "serverAccess.removeLevel(server, key);");
+        assertTrue(injectionRollback.contains("fireDynamicLevelUnload(server, level);"));
+        assertTrue(removalRollback.contains("fireDynamicLevelLoad(server, level);"));
+    }
+
+    @Test
+    public void everyLoaderUsesItsNativeLifecycleBus() throws IOException {
+        String fabric = loaderSource("fabric", "art/arcane/iris/fabric/FabricModdedLoader.java");
+        String forge = loaderSource("forge", "art/arcane/iris/forge/ForgeModdedLoader.java");
+        String neoForge = loaderSource("neoforge", "art/arcane/iris/neoforge/NeoForgeModdedLoader.java");
+
+        assertTrue(fabric.contains("ServerLevelEvents.LOAD.invoker().onLevelLoad(server, level);"));
+        assertTrue(fabric.contains("ServerLevelEvents.UNLOAD.invoker().onLevelUnload(server, level);"));
+        assertTrue(forge.contains("LevelEvent.Load.BUS.post(new LevelEvent.Load(level));"));
+        assertTrue(forge.contains("LevelEvent.Unload.BUS.post(new LevelEvent.Unload(level));"));
+        assertTrue(neoForge.contains("NeoForge.EVENT_BUS.post(new LevelEvent.Load(level));"));
+        assertTrue(neoForge.contains("NeoForge.EVENT_BUS.post(new LevelEvent.Unload(level));"));
+    }
+
+    private static String commonSource(String file) throws IOException {
+        return Files.readString(commonRoot().resolve("art/arcane/iris/modded").resolve(file))
+                .replace("\r\n", "\n");
+    }
+
+    private static String loaderSource(String loader, String relative) throws IOException {
+        Path adaptersRoot = commonRoot().getParent().getParent().getParent().getParent();
+        return Files.readString(adaptersRoot.resolve(loader).resolve("src/main/java").resolve(relative))
+                .replace("\r\n", "\n");
+    }
+
+    private static Path commonRoot() {
+        String root = System.getProperty(SOURCE_ROOT_PROPERTY);
+        if (root == null || root.isBlank()) {
+            throw new IllegalStateException("Missing test property " + SOURCE_ROOT_PROPERTY);
+        }
+        return Path.of(root);
+    }
+
+    private static String method(String source, String signature) {
+        int start = source.indexOf(signature);
+        if (start < 0) {
+            throw new IllegalArgumentException("Missing source method " + signature);
+        }
+        int open = source.indexOf('{', start);
+        int depth = 0;
+        for (int index = open; index < source.length(); index++) {
+            char current = source.charAt(index);
+            if (current == '{') {
+                depth++;
+            } else if (current == '}' && --depth == 0) {
+                return source.substring(start, index + 1);
+            }
+        }
+        throw new IllegalArgumentException("Unclosed source method " + signature);
+    }
+
+    private static void assertBefore(String source, String first, String second) {
+        int firstIndex = source.indexOf(first);
+        int secondIndex = source.indexOf(second);
+        assertTrue("Missing source token " + first, firstIndex >= 0);
+        assertTrue("Missing source token " + second, secondIndex >= 0);
+        assertTrue(first + " must precede " + second, firstIndex < secondIndex);
+    }
+}

adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedLifecycleFailureContractTest.java

@@ -65,7 +65,7 @@ public class ModdedLifecycleFailureContractTest {
         String reinjection = method(source, "private static void reinjectPersistentDimensions(");
         String failure = catchBlock(reinjection);
 
-        assertTrue(failure.contains("LOGGER.error("));
+        assertTrue(failure.contains("ModdedIrisLog.error("));
         assertFalse(failure.contains("e.toString()"));
         assertFalse(failure.contains("throw new IllegalStateException("));
         assertTrue(reinjection.contains("injected++;"));
@@ -152,7 +152,7 @@ public class ModdedLifecycleFailureContractTest {
         assertBefore(stop, "\"world engines\"", "\"dimension manager\"");
         assertBefore(stop, "\"server state\"", "if (failure != null)");
         assertFalse(stop.contains("throw"));
-        assertTrue(stop.contains("LOGGER.error(\"Iris modded shutdown completed with failures\", failure);"));
+        assertTrue(stop.contains("ModdedIrisLog.error(\"Iris modded shutdown completed with failures\", failure);"));
 
         String runStage = method(source, "private static Throwable runStopStage(");
         assertTrue(runStage.contains("catch (Throwable stageFailure)"));
@@ -207,21 +207,21 @@ public class ModdedLifecycleFailureContractTest {
         String bootstrapSource = source("ModdedEngineBootstrap.java");
         String unload = method(bootstrapSource, "public static void levelUnloaded(ServerLevel level)");
         String failure = catchBlock(unload);
-        assertTrue(failure.contains("LOGGER.error("));
+        assertTrue(failure.contains("ModdedIrisLog.error("));
         assertTrue(failure.contains("throw "));
 
         String managerSource = source("ModdedDimensionManager.java");
         String remove = method(managerSource, "public static boolean remove(MinecraftServer server, String dimensionId, boolean wipeStorage)");
         assertTrue(remove.contains("ModdedWorldEngines.evictOrThrow(level);"));
         assertFalse(remove.contains("ModdedWorldEngines.evict(level);"));
-        assertTrue(remove.contains("generatorUnbound = true;"));
+        assertTrue(remove.contains("unloadEventStarted = true;"));
-        assertTrue(remove.contains("rollbackRemoval(server, serverAccess, key, level, generator, generatorUnbound, e);"));
+        assertTrue(remove.contains("rollbackRemoval(server, serverAccess, key, level, generator, unloadEventStarted, e);"));
 
         String rollback = method(managerSource, "private static void rollbackRemoval(");
         assertTrue(rollback.contains("serverAccess.hasLevel(server, key)"));
         assertTrue(rollback.contains("generator.bindLevel(level);"));
         assertTrue(rollback.contains("failure.addSuppressed(rollbackFailure);"));
-        assertTrue(rollback.contains("LOGGER.error("));
+        assertTrue(rollback.contains("ModdedIrisLog.error("));
     }
 
     @Test

adapters/modded-common/src/test/java/art/arcane/iris/modded/ModdedPlatformPathsTest.java

@@ -45,6 +45,14 @@ public class ModdedPlatformPathsTest {
             public void invalidateLevelCache(MinecraftServer server) {
             }
 
+            @Override
+            public void fireDynamicLevelLoad(MinecraftServer server, ServerLevel level) {
+            }
+
+            @Override
+            public void fireDynamicLevelUnload(MinecraftServer server, ServerLevel level) {
+            }
+
             @Override
             public boolean clientEnvironment() {
                 return false;

adapters/modded-common/src/test/java/art/arcane/iris/modded/command/IrisModdedStructureCommandTest.java

@@ -186,7 +186,7 @@ public class IrisModdedStructureCommandTest {
         assertTrue(command.contains("ModdedLocateCommands.registeredStructureUnavailableMessage("));
         assertTrue(command.contains("engine.getData().getStructureLoader().getPossibleKeys()"));
         assertTrue(command.contains("IrisStructureLocator.hasLocatableEditablePlacement(engine, key)"));
-        assertTrue(command.contains("LOGGER.info(\"[Iris goto unregistered] [{}] {} - {}\""));
+        assertTrue(command.contains("ModdedIrisLog.info(\"[Iris goto unregistered] [{}] {} - {}\""));
         assertTrue(command.contains("UNREGISTERED(\"unregistered\")"));
         assertFalse(command.contains("DatapackIngestService"));
     }

adapters/modded-common/src/test/java/art/arcane/iris/modded/command/ModdedStudioTeleportContractTest.java

@@ -0,0 +1,89 @@
+package art.arcane.iris.modded.command;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ModdedStudioTeleportContractTest {
+    private static final String SOURCE_ROOT_PROPERTY = "iris.moddedCommonSources";
+
+    @Test
+    public void studioOpenSerializesReplacementAndWaitsForTheNativePath() throws IOException {
+        String source = source("command/ModdedStudioCommands.java");
+        String open = method(source, "private static int open(");
+        String execute = method(source, "private static void executeStudioOpen(");
+
+        assertTrue(open.contains("TRANSITIONS.submit("));
+        assertFalse(open.contains("orTimeout("));
+        assertFalse(open.contains("deadlineNanos"));
+        assertBefore(execute, "replaceExistingStudio(", "ModdedDimensionManager.create(");
+        assertBefore(execute, "ModdedDimensionManager.create(", "ModdedDimensionManager.teleportAsync(");
+        assertFalse(execute.contains("deadlineNanos"));
+        assertFalse(source.contains("player.teleportTo(studio"));
+    }
+
+    @Test
+    public void studioTeleportAndVisionShareWarmFutureSemantics() throws IOException {
+        String studio = source("command/ModdedStudioCommands.java");
+        String vision = source("command/ModdedVisionOverlay.java");
+        String dimensions = source("ModdedDimensionManager.java");
+
+        assertTrue(studio.contains("private static CompletableFuture<Void> teleportToStudio("));
+        assertTrue(studio.contains("ModdedDimensionManager.teleportAsync("));
+        assertTrue(dimensions.contains("TELEPORT_WARM_RADIUS = 0"));
+        assertTrue(dimensions.contains("addTicketAndLoadWithRadius(\n"
+                + "                    TELEPORT_WARM_TICKET,\n"
+                + "                    chunkPos,\n"
+                + "                    TELEPORT_WARM_RADIUS)"));
+        assertTrue(dimensions.contains("removeTicketWithRadius(\n"
+                + "                    TELEPORT_WARM_TICKET,\n"
+                + "                    chunkPos,\n"
+                + "                    TELEPORT_WARM_RADIUS)"));
+        assertTrue(vision.contains("Math.floor(worldX)"));
+        assertTrue(vision.contains("Math.floor(worldZ)"));
+        assertTrue(vision.contains("if (opener != null)"));
+        assertTrue(vision.contains("ModdedDimensionManager.teleportAsync("));
+        assertFalse(vision.contains("level.getHeight("));
+        assertFalse(vision.contains("player.teleportTo("));
+    }
+
+    private static String source(String relative) throws IOException {
+        String root = System.getProperty(SOURCE_ROOT_PROPERTY);
+        if (root == null || root.isBlank()) {
+            throw new IllegalStateException("Missing test property " + SOURCE_ROOT_PROPERTY);
+        }
+        return Files.readString(Path.of(root).resolve("art/arcane/iris/modded").resolve(relative))
+                .replace("\r\n", "\n");
+    }
+
+    private static String method(String source, String signature) {
+        int start = source.indexOf(signature);
+        if (start < 0) {
+            throw new IllegalArgumentException("Missing source method " + signature);
+        }
+        int open = source.indexOf('{', start);
+        int depth = 0;
+        for (int index = open; index < source.length(); index++) {
+            char current = source.charAt(index);
+            if (current == '{') {
+                depth++;
+            } else if (current == '}' && --depth == 0) {
+                return source.substring(start, index + 1);
+            }
+        }
+        throw new IllegalArgumentException("Unclosed source method " + signature);
+    }
+
+    private static void assertBefore(String source, String first, String second) {
+        int firstIndex = source.indexOf(first);
+        int secondIndex = source.indexOf(second);
+        assertTrue("Missing source token " + first, firstIndex >= 0);
+        assertTrue("Missing source token " + second, secondIndex >= 0);
+        assertTrue(first + " must precede " + second, firstIndex < secondIndex);
+    }
+}

adapters/modded-common/src/test/java/art/arcane/iris/modded/command/ModdedStudioTransitionQueueTest.java

@@ -0,0 +1,70 @@
+package art.arcane.iris.modded.command;
+
+import org.junit.Test;
+
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ModdedStudioTransitionQueueTest {
+    @Test
+    public void sameOwnerTransitionsRunInSubmissionOrder() {
+        ModdedStudioTransitionQueue queue = new ModdedStudioTransitionQueue();
+        UUID owner = UUID.randomUUID();
+        CompletableFuture<Void> firstGate = new CompletableFuture<>();
+        AtomicInteger starts = new AtomicInteger();
+
+        CompletableFuture<Void> first = queue.submit(owner, () -> {
+            starts.incrementAndGet();
+            return firstGate;
+        });
+        CompletableFuture<Void> second = queue.submit(owner, () -> {
+            starts.incrementAndGet();
+            return CompletableFuture.completedFuture(null);
+        });
+
+        assertEquals(1, starts.get());
+        assertFalse(second.isDone());
+        firstGate.complete(null);
+        assertTrue(first.isDone());
+        assertTrue(second.isDone());
+        assertEquals(2, starts.get());
+    }
+
+    @Test
+    public void differentOwnersDoNotBlockEachOther() {
+        ModdedStudioTransitionQueue queue = new ModdedStudioTransitionQueue();
+        CompletableFuture<Void> firstGate = new CompletableFuture<>();
+
+        CompletableFuture<Void> first = queue.submit(UUID.randomUUID(), () -> firstGate);
+        CompletableFuture<Void> second = queue.submit(
+                UUID.randomUUID(),
+                () -> CompletableFuture.completedFuture(null));
+
+        assertFalse(first.isDone());
+        assertTrue(second.isDone());
+    }
+
+    @Test
+    public void failedTransitionDoesNotPoisonTheOwnerQueue() {
+        ModdedStudioTransitionQueue queue = new ModdedStudioTransitionQueue();
+        UUID owner = UUID.randomUUID();
+        CompletableFuture<Void> failure = CompletableFuture.failedFuture(
+                new IllegalStateException("expected"));
+        AtomicInteger starts = new AtomicInteger();
+
+        CompletableFuture<Void> first = queue.submit(owner, () -> failure);
+        CompletableFuture<Void> second = queue.submit(owner, () -> {
+            starts.incrementAndGet();
+            return CompletableFuture.completedFuture(null);
+        });
+
+        assertTrue(first.isCompletedExceptionally());
+        assertTrue(second.isDone());
+        assertEquals(1, starts.get());
+    }
+}

adapters/neoforge/src/main/java/art/arcane/iris/neoforge/NeoForgeModdedLoader.java

@@ -27,6 +27,7 @@ import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.world.level.block.state.BlockState;
 import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.event.level.LevelEvent;
 import net.neoforged.neoforge.event.level.block.BreakBlockEvent;
 import net.neoforged.fml.ModList;
 import net.neoforged.fml.loading.FMLEnvironment;
@@ -77,6 +78,16 @@ public final class NeoForgeModdedLoader implements ModdedLoader {
         server.markWorldsDirty();
     }
 
+    @Override
+    public void fireDynamicLevelLoad(MinecraftServer server, ServerLevel level) {
+        NeoForge.EVENT_BUS.post(new LevelEvent.Load(level));
+    }
+
+    @Override
+    public void fireDynamicLevelUnload(MinecraftServer server, ServerLevel level) {
+        NeoForge.EVENT_BUS.post(new LevelEvent.Unload(level));
+    }
+
     @Override
     public boolean clientEnvironment() {
         return FMLEnvironment.getDist().isClient();

build.gradle

@@ -4,6 +4,8 @@ import org.gradle.api.tasks.Copy
 import org.gradle.api.tasks.compile.JavaCompile
 import org.gradle.jvm.tasks.Jar
 import org.gradle.jvm.toolchain.JavaLanguageVersion
+import groovy.json.JsonOutput
+import groovy.json.JsonSlurper
 
 /*
  * Iris is a World Generator for Minecraft Bukkit Servers
@@ -73,6 +75,7 @@ String bukkitArtifactName = irisArtifactName('CraftBukkit', bukkitMinecraftRange
 String fabricArtifactName = irisArtifactName('Fabric', "${minecraftVersion}+${loaderDisplayVersion(fabricLoaderVersion)}")
 String forgeArtifactName = irisArtifactName('Forge', "${minecraftVersion}+${loaderDisplayVersion(forgeVersion)}")
 String neoForgeArtifactName = irisArtifactName('NeoForge', "${minecraftVersion}+${loaderDisplayVersion(neoForgeVersion)}")
+long maximumBukkitArtifactBytes = 7_000_000L
 apply plugin: ApiGenerator
 
 // Where `buildAll` drops the per-platform jars for a local test server. Use the approved sibling
@@ -145,6 +148,16 @@ nmsBindings.each { key, value ->
 
 def included = configurations.create('included')
 def jarJar = configurations.create('jarJar')
+def bukkitLanguagesDirectory = layout.buildDirectory.dir('generated/bukkit-languages')
+Set<String> sharedNonEnglishBukkitMessages = [
+    'iris.desktop.vision.fps',
+    'iris.desktop.vision.tiles',
+    'iris.bukkit.runtime.commandpack.message_2',
+    'iris.bukkit.commanddatapack.message_2',
+    'iris.runtime.chunk_job.bossbar.progress',
+    'iris.runtime.studio.action.progress',
+    'iris.runtime.chunk_job.action.progress'
+] as Set
 dependencies {
     nmsBindings.keySet().each { key ->
         add('included', project(path: ":adapters:bukkit:nms:${key}", configuration: 'runtimeElements'))
@@ -154,14 +167,66 @@ dependencies {
     add('jarJar', project(':core:agent'))
 }
 
+def prepareBukkitLanguages = tasks.register('prepareBukkitLanguages') {
+    inputs.files(fileTree(project(':core').file('src/main/resources/languages')) {
+        include('*.json')
+    })
+    outputs.dir(bukkitLanguagesDirectory)
+    doLast {
+        File outputDirectory = bukkitLanguagesDirectory.get().asFile
+        delete(outputDirectory)
+        outputDirectory.mkdirs()
+        List<File> sources = fileTree(project(':core').file('src/main/resources/languages')) {
+            include('*.json')
+        }.files.sort { File left, File right -> left.name <=> right.name }
+        List<Map<String, Object>> catalogs = sources.collect { File source ->
+            (Map<String, Object>) new JsonSlurper().parse(source)
+        }
+        Map<String, Object> referenceMessages = (Map<String, Object>) catalogs.first().get('messages')
+        List<String> messageIds = referenceMessages.keySet()
+                .findAll { String key -> !key.startsWith('iris.modded.') }
+                .sort()
+        Set<String> sharedFallbackIds = new LinkedHashSet<>(messageIds)
+        catalogs.each { Map<String, Object> catalog ->
+            Map<String, Object> messages = (Map<String, Object>) catalog.get('messages')
+            if (!messages.keySet().containsAll(messageIds)) {
+                throw new GradleException("Bundled locale ${catalog.get('locale')} is missing Bukkit messages")
+            }
+            sharedFallbackIds.removeIf { String key -> messages.get(key) != referenceMessages.get(key) }
+        }
+        sharedFallbackIds.removeAll(sharedNonEnglishBukkitMessages)
+
+        sources.eachWithIndex { File source, int index ->
+            Map<String, Object> catalog = catalogs.get(index)
+            Map<String, Object> messages = (Map<String, Object>) catalog.get('messages')
+            List<Object> compactMessages = messageIds.collect { String key ->
+                sharedFallbackIds.contains(key) ? null : messages.get(key)
+            }
+            new File(outputDirectory, source.name).setText(
+                    JsonOutput.toJson([catalog.get('locale'), compactMessages]),
+                    'UTF-8')
+        }
+    }
+}
+
 tasks.named('jar', Jar).configure {
     inputs.files(included)
     duplicatesStrategy = DuplicatesStrategy.EXCLUDE
-    from(jarJar, provider { included.resolve().collect { zipTree(it) } })
+    includeEmptyDirs = false
+    from(jarJar)
+    from(provider { included.resolve().collect { zipTree(it) } }) {
+        exclude('languages/**')
+    }
+    from(prepareBukkitLanguages) {
+        into('languages')
+    }
     doFirst {
         delete(layout.buildDirectory.file("libs/Iris-${project.version}.jar"))
     }
     archiveFileName.set(bukkitArtifactName)
+    doLast {
+        JarCompactor.compact(archiveFile.get().asFile)
+    }
 }
 
 tasks.register('iris', Copy) {
@@ -537,10 +602,8 @@ List<String> requiredBukkitArtifactEntries = [
     'art/arcane/iris/core/lifecycle/WorldLifecycleStaging.class',
     'art/arcane/iris/util/simd/VectorSimdKernels.class',
     'art/arcane/iris/util/simd/VectorNoiseKernels2D.class',
-    'art/arcane/iris/util/paralithic/functions/Function.class',
     'art/arcane/iris/util/project/agent/Agent.class',
     'art/arcane/iris/util/common/misc/getHardware.class',
-    'art/arcane/iris/util/caffeine/cache/Caffeine.class',
     'art/arcane/volmlib/util/io/JarScanner.class',
     'art/arcane/volmlib/util/director/runtime/DirectorRuntimeEngine.class',
     'art/arcane/volmlib/util/mantle/io/Lz4IOWorkerCodecSupport.class',
@@ -553,7 +616,12 @@ tasks.register('verifyBukkitArtifact') {
     File artifact = layout.buildDirectory.file("libs/${bukkitArtifactName}").get().asFile
     inputs.file(artifact)
     doLast {
-        BukkitArtifactVerifier.verify(artifact, requiredBukkitArtifactEntries, 17, 400, 16)
+        BukkitArtifactVerifier.verify(
+                artifact,
+                requiredBukkitArtifactEntries,
+                17,
+                16,
+                maximumBukkitArtifactBytes)
         logger.lifecycle("Verified ${artifact.name} packaging and class reference graph")
     }
 }

buildSrc/src/main/java/BukkitArtifactVerifier.java

@@ -21,9 +21,7 @@ public final class BukkitArtifactVerifier {
     // class under one of these is a NoClassDefFoundError waiting for the right code path.
     private static final List<String> SHIPPED_PREFIXES = List.of(
             "art/arcane/iris/",
-            "art/arcane/volmlib/",
+            "art/arcane/volmlib/"
-            "com/google/gson/",
-            "com/googlecode/concurrentlinkedhashmap/"
     );
     // Relocation targets for the libraries slimjar downloads and relocates at runtime. Compiled
     // references to them are correct and the classes are correctly absent from the jar.
@@ -38,9 +36,12 @@ public final class BukkitArtifactVerifier {
             "art/arcane/iris/util/aether/",
             "art/arcane/iris/util/guice/",
             "art/arcane/iris/util/dom4j/",
-            "art/arcane/iris/util/jaxen/"
+            "art/arcane/iris/util/jaxen/",
+            "art/arcane/iris/util/gson/",
+            "art/arcane/iris/util/lru/",
+            "art/arcane/iris/util/caffeine/",
+            "art/arcane/iris/util/paralithic/"
     );
-    private static final String CAFFEINE_CACHE_PACKAGE = "art/arcane/iris/util/caffeine/cache/";
     private static final String MATTER_SLICE_PACKAGE = "art/arcane/volmlib/util/matter/slices/";
     private static final String LANGUAGE_DIRECTORY = "languages/";
 
@@ -48,10 +49,14 @@ public final class BukkitArtifactVerifier {
     }
 
     public static void verify(File artifact, List<String> requiredEntries, int minimumLocales,
-                              int minimumCaffeineFactories, int minimumMatterSlices) {
+                              int minimumMatterSlices, long maximumArtifactBytes) {
         if (!artifact.isFile()) {
             throw new GradleException("Missing Bukkit Iris artifact: " + artifact.getAbsolutePath());
         }
+        if (artifact.length() > maximumArtifactBytes) {
+            throw new GradleException(artifact.getName() + " is " + artifact.length()
+                    + " bytes; Bukkit artifacts must not exceed " + maximumArtifactBytes + " bytes");
+        }
 
         try (JarFile jar = new JarFile(artifact)) {
             for (String requiredEntry : requiredEntries) {
@@ -65,7 +70,6 @@ public final class BukkitArtifactVerifier {
 
             Set<String> shippedClasses = new LinkedHashSet<>();
             int locales = 0;
-            int caffeineFactories = 0;
             int matterSlices = 0;
             Enumeration<JarEntry> entries = jar.entries();
             while (entries.hasMoreElements()) {
@@ -84,9 +88,6 @@ public final class BukkitArtifactVerifier {
 
                 String internalName = name.substring(0, name.length() - ".class".length());
                 shippedClasses.add(internalName);
-                if (isGeneratedCaffeineFactory(internalName)) {
-                    caffeineFactories++;
-                }
                 if (internalName.startsWith(MATTER_SLICE_PACKAGE)) {
                     matterSlices++;
                 }
@@ -96,14 +97,6 @@ public final class BukkitArtifactVerifier {
                 throw new GradleException(artifact.getName() + " ships " + locales + " locale files; expected at least "
                         + minimumLocales);
             }
-            // Caffeine picks its cache and node implementation with MethodHandles.Lookup.findClass on a
-            // name built from the builder's feature flags. Nothing references these statically, so only a
-            // population check can tell that an exclude or minimize() ate them.
-            if (caffeineFactories < minimumCaffeineFactories) {
-                throw new GradleException(artifact.getName() + " ships " + caffeineFactories
-                        + " generated Caffeine cache classes; expected at least " + minimumCaffeineFactories
-                        + ". Caffeine resolves these by name and cannot survive static pruning");
-            }
             // Matter.read() resolves slice types from the canonical name stored in the payload.
             if (matterSlices < minimumMatterSlices) {
                 throw new GradleException(artifact.getName() + " ships " + matterSlices
@@ -148,23 +141,6 @@ public final class BukkitArtifactVerifier {
         }
     }
 
-    private static boolean isGeneratedCaffeineFactory(String internalName) {
-        if (!internalName.startsWith(CAFFEINE_CACHE_PACKAGE)) {
-            return false;
-        }
-
-        String simpleName = internalName.substring(CAFFEINE_CACHE_PACKAGE.length());
-        if (simpleName.isEmpty() || simpleName.indexOf('/') >= 0) {
-            return false;
-        }
-        for (int i = 0; i < simpleName.length(); i++) {
-            if (simpleName.charAt(i) < 'A' || simpleName.charAt(i) > 'Z') {
-                return false;
-            }
-        }
-        return true;
-    }
-
     private static byte[] readEntryBytes(JarFile jar, JarEntry entry) throws IOException {
         try (InputStream input = jar.getInputStream(entry)) {
             return input.readAllBytes();

buildSrc/src/main/java/JarCompactor.java

@@ -0,0 +1,97 @@
+import org.gradle.api.GradleException;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.file.AtomicMoveNotSupportedException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+import java.util.zip.ZipOutputStream;
+
+public final class JarCompactor {
+    private static final int BUFFER_BYTES = 64 * 1024;
+
+    private JarCompactor() {
+    }
+
+    public static void compact(File artifact) {
+        if (artifact == null || !artifact.isFile()) {
+            throw new GradleException("Cannot compact missing jar artifact: " + artifact);
+        }
+
+        Path source = artifact.toPath();
+        Path temporary = null;
+        try {
+            temporary = Files.createTempFile(source.getParent(), artifact.getName(), ".compact");
+            rewrite(source, temporary);
+            replace(temporary, source);
+        } catch (IOException exception) {
+            if (temporary != null) {
+                try {
+                    Files.deleteIfExists(temporary);
+                } catch (IOException cleanupFailure) {
+                    exception.addSuppressed(cleanupFailure);
+                }
+            }
+            throw new GradleException("Unable to compact jar artifact " + artifact.getAbsolutePath(), exception);
+        }
+    }
+
+    private static void rewrite(Path source, Path destination) throws IOException {
+        byte[] buffer = new byte[BUFFER_BYTES];
+        try (InputStream rawInput = new BufferedInputStream(Files.newInputStream(source));
+             ZipInputStream input = new ZipInputStream(rawInput);
+             OutputStream rawOutput = new BufferedOutputStream(Files.newOutputStream(destination));
+             ZipOutputStream output = new ZipOutputStream(rawOutput)) {
+            output.setLevel(9);
+            ZipEntry entry;
+            while ((entry = input.getNextEntry()) != null) {
+                if (entry.isDirectory()) {
+                    continue;
+                }
+                ZipEntry compacted = copyMetadata(entry);
+                output.putNextEntry(compacted);
+                int read;
+                while ((read = input.read(buffer)) >= 0) {
+                    if (read > 0) {
+                        output.write(buffer, 0, read);
+                    }
+                }
+                output.closeEntry();
+            }
+        }
+    }
+
+    private static ZipEntry copyMetadata(ZipEntry source) {
+        ZipEntry target = new ZipEntry(source.getName());
+        target.setMethod(ZipEntry.DEFLATED);
+        if (source.getTime() >= 0L) {
+            target.setTime(source.getTime());
+        }
+        if (source.getComment() != null) {
+            target.setComment(source.getComment());
+        }
+        if (source.getExtra() != null) {
+            target.setExtra(source.getExtra());
+        }
+        return target;
+    }
+
+    private static void replace(Path temporary, Path source) throws IOException {
+        try {
+            Files.move(
+                    temporary,
+                    source,
+                    StandardCopyOption.ATOMIC_MOVE,
+                    StandardCopyOption.REPLACE_EXISTING);
+        } catch (AtomicMoveNotSupportedException exception) {
+            Files.move(temporary, source, StandardCopyOption.REPLACE_EXISTING);
+        }
+    }
+}

buildSrc/src/test/java/BukkitArtifactVerifierTest.java

@@ -30,7 +30,6 @@ public class BukkitArtifactVerifierTest {
             NMS_BINDING + ".class"
     );
     private static final int LOCALES = 2;
-    private static final int CAFFEINE_FACTORIES = 2;
     private static final int MATTER_SLICES = 1;
 
     @Rule
@@ -40,7 +39,7 @@ public class BukkitArtifactVerifierTest {
     public void acceptsCompleteArtifact() throws Exception {
         File artifact = createArtifact(validEntries());
 
-        BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES, MATTER_SLICES);
+        BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE);
     }
 
     @Test
@@ -50,8 +49,7 @@ public class BukkitArtifactVerifierTest {
         File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE));
-                        MATTER_SLICES));
         assertTrue(failure.getMessage().contains(PLUGIN_DESCRIPTOR));
     }
 
@@ -62,8 +60,7 @@ public class BukkitArtifactVerifierTest {
         File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE));
-                        MATTER_SLICES));
         assertTrue(failure.getMessage().contains(SLIMJAR_DEPENDENCIES));
     }
 
@@ -74,8 +71,7 @@ public class BukkitArtifactVerifierTest {
         File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE));
-                        MATTER_SLICES));
         assertTrue(failure.getMessage().contains(SLIMJAR_RESOLUTIONS));
     }
 
@@ -86,8 +82,7 @@ public class BukkitArtifactVerifierTest {
         File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE));
-                        MATTER_SLICES));
         assertTrue(failure.getMessage().contains("art/arcane/volmlib/util/noise/CNG"));
     }
 
@@ -96,21 +91,31 @@ public class BukkitArtifactVerifierTest {
         Map<String, byte[]> entries = validEntries();
         entries.put("art/arcane/iris/Consumer.class",
                 classReferencing("art/arcane/iris/Consumer", "art/arcane/iris/util/kyori/adventure/text/Component"));
+        entries.put("art/arcane/iris/GsonConsumer.class",
+                classReferencing("art/arcane/iris/GsonConsumer", "art/arcane/iris/util/gson/Gson"));
+        entries.put("art/arcane/iris/LruConsumer.class",
+                classReferencing("art/arcane/iris/LruConsumer", "art/arcane/iris/util/lru/ConcurrentLinkedHashMap"));
+        entries.put("art/arcane/iris/CaffeineConsumer.class",
+                classReferencing("art/arcane/iris/CaffeineConsumer", "art/arcane/iris/util/caffeine/cache/Caffeine"));
+        entries.put("art/arcane/iris/ParalithicConsumer.class",
+                classReferencing("art/arcane/iris/ParalithicConsumer", "art/arcane/iris/util/paralithic/functions/Function"));
         File artifact = createArtifact(entries);
 
-        BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES, MATTER_SLICES);
+        BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE);
     }
 
     @Test
-    public void rejectsStrippedCaffeineFactories() throws Exception {
+    public void rejectsArtifactAboveConfiguredSize() throws Exception {
-        Map<String, byte[]> entries = validEntries();
+        File artifact = createArtifact(validEntries());
-        entries.remove("art/arcane/iris/util/caffeine/cache/SSMS.class");
-        File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(
-                        MATTER_SLICES));
+                        artifact,
-        assertTrue(failure.getMessage().contains("generated Caffeine cache classes"));
+                        REQUIRED_ENTRIES,
+                        LOCALES,
+                        MATTER_SLICES,
+                        artifact.length() - 1L));
+        assertTrue(failure.getMessage().contains("must not exceed"));
     }
 
     @Test
@@ -120,8 +125,7 @@ public class BukkitArtifactVerifierTest {
         File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE));
-                        MATTER_SLICES));
         assertTrue(failure.getMessage().contains("locale files"));
     }
 
@@ -132,8 +136,7 @@ public class BukkitArtifactVerifierTest {
         File artifact = createArtifact(entries);
 
         GradleException failure = assertThrows(GradleException.class,
-                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES,
+                () -> BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE));
-                        MATTER_SLICES));
         assertTrue(failure.getMessage().contains("Matter slice types"));
     }
 
@@ -144,7 +147,7 @@ public class BukkitArtifactVerifierTest {
                 classAnnotatedWith("art/arcane/iris/Annotated", "com/google/errorprone/annotations/CanIgnoreReturnValue"));
         File artifact = createArtifact(entries);
 
-        BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, CAFFEINE_FACTORIES, MATTER_SLICES);
+        BukkitArtifactVerifier.verify(artifact, REQUIRED_ENTRIES, LOCALES, MATTER_SLICES, Long.MAX_VALUE);
     }
 
     private Map<String, byte[]> validEntries() {
@@ -159,10 +162,6 @@ public class BukkitArtifactVerifierTest {
         entries.put("art/arcane/volmlib/util/noise/CNG.class", emptyClass("art/arcane/volmlib/util/noise/CNG"));
         entries.put("art/arcane/volmlib/util/matter/slices/BlockMatter.class",
                 emptyClass("art/arcane/volmlib/util/matter/slices/BlockMatter"));
-        entries.put("art/arcane/iris/util/caffeine/cache/SSMS.class",
-                emptyClass("art/arcane/iris/util/caffeine/cache/SSMS"));
-        entries.put("art/arcane/iris/util/caffeine/cache/SSLMS.class",
-                emptyClass("art/arcane/iris/util/caffeine/cache/SSLMS"));
         return entries;
     }
 

buildSrc/src/test/java/JarCompactorTest.java

@@ -0,0 +1,39 @@
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.jar.JarOutputStream;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertNull;
+
+public class JarCompactorTest {
+    @Rule
+    public final TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+    @Test
+    public void preservesFilesAndOmitsDirectoryEntries() throws Exception {
+        File artifact = temporaryFolder.newFile("artifact.jar");
+        byte[] content = "Iris artifact content".getBytes(StandardCharsets.UTF_8);
+        try (JarOutputStream output = new JarOutputStream(new FileOutputStream(artifact))) {
+            output.putNextEntry(new JarEntry("example/"));
+            output.closeEntry();
+            output.putNextEntry(new JarEntry("example/value.txt"));
+            output.write(content);
+            output.closeEntry();
+        }
+
+        JarCompactor.compact(artifact);
+
+        try (JarFile jar = new JarFile(artifact)) {
+            assertNull(jar.getJarEntry("example/"));
+            assertArrayEquals(content, jar.getInputStream(
+                    jar.getJarEntry("example/value.txt")).readAllBytes());
+        }
+    }
+}

core/build.gradle

@@ -86,12 +86,11 @@ dependencies {
     implementation(volmLibCoordinate) {
         transitive = false
     }
-    implementation(libs.gson)
-    implementation(libs.lru)
-    implementation(libs.caffeine)
-    implementation(libs.paralithic)
-
     // Dynamically Loaded
+    slim(libs.gson)
+    slim(libs.lru)
+    slim(libs.caffeine)
+    slim(libs.paralithic)
     slim(libs.paperlib)
     slim(libs.adventure.api)
     slim(libs.adventure.minimessage)
@@ -154,6 +153,8 @@ slimJar {
     ]
 
     relocate('com.dfsek.paralithic', "${lib}.paralithic")
+    relocate('com.google.gson', "${lib}.gson")
+    relocate('com.googlecode.concurrentlinkedhashmap', "${lib}.lru")
     relocate('io.papermc.lib', "${lib}.paper")
     relocate('net.kyori', "${lib}.kyori")
     relocate('org.bstats', "${lib}.metrics")
@@ -285,9 +286,149 @@ List<String> supersededVolmLibPackages = [
     'art/arcane/volmlib/util/director/visual/**',
     'art/arcane/volmlib/util/value/**',
     'art/arcane/volmlib/util/api/**',
-    'art/arcane/volmlib/util/entity/**'
+    'art/arcane/volmlib/util/entity/**',
+    'art/arcane/volmlib/util/config/**',
+    'art/arcane/volmlib/util/reflect/**',
+    'art/arcane/volmlib/util/documentation/**',
+    'art/arcane/iris/core/report/**',
+    'art/arcane/iris/util/common/inventorygui/**',
+    'art/arcane/iris/util/common/board/**',
+    'art/arcane/volmlib/integration/VaultEconomy*.class'
 ]
 
+List<String> unusedVolmLibClasses = [
+    'art/arcane/volmlib/util/nbt/io/ParseException',
+    'art/arcane/volmlib/util/nbt/io/SNBTDeserializer',
+    'art/arcane/volmlib/util/nbt/io/SNBTParser',
+    'art/arcane/volmlib/util/nbt/io/SNBTSerializer',
+    'art/arcane/volmlib/util/nbt/io/SNBTUtil',
+    'art/arcane/volmlib/util/nbt/io/SNBTWriter',
+    'art/arcane/volmlib/util/nbt/io/StringPointer',
+    'art/arcane/volmlib/util/io/StringDeserializer',
+    'art/arcane/volmlib/util/io/StringSerializer',
+    'art/arcane/volmlib/util/json/EnumType',
+    'art/arcane/volmlib/util/json/HTTP',
+    'art/arcane/volmlib/util/json/HTTPTokener',
+    'art/arcane/volmlib/util/json/JSONML',
+    'art/arcane/volmlib/util/json/JSONStringer',
+    'art/arcane/volmlib/util/json/JSONWriter',
+    'art/arcane/volmlib/util/json/XML',
+    'art/arcane/volmlib/util/json/XMLTokener',
+    'art/arcane/volmlib/util/hud/HudBid',
+    'art/arcane/volmlib/util/hud/HudBidder',
+    'art/arcane/volmlib/util/hud/HudLocalLedger',
+    'art/arcane/volmlib/util/hud/HudTitleClaim',
+    'art/arcane/volmlib/util/hud/HudTitleService',
+    'art/arcane/volmlib/util/scheduling/GroupedExecutor',
+    'art/arcane/volmlib/util/scheduling/SchedulerRuntime',
+    'art/arcane/volmlib/util/scheduling/SchedulerUtils',
+    'art/arcane/volmlib/util/scheduling/TaskExecutor',
+    'art/arcane/volmlib/util/parallel/StreamUtilsSupport',
+    'art/arcane/volmlib/util/parallel/SyncExecutorSupport',
+    'art/arcane/volmlib/util/cache/ByteBitCache',
+    'art/arcane/volmlib/util/cache/DataBitCache',
+    'art/arcane/volmlib/util/cache/FloatBitCache',
+    'art/arcane/volmlib/util/cache/IntBitCache',
+    'art/arcane/volmlib/util/cache/ShortBitCache',
+    'art/arcane/volmlib/util/cache/UByteBitCache',
+    'art/arcane/volmlib/util/data/ChunkCache',
+    'art/arcane/volmlib/util/data/ComplexCache',
+    'art/arcane/volmlib/util/data/IrisBiomeStorage',
+    'art/arcane/volmlib/util/data/NibbleArray',
+    'art/arcane/volmlib/util/data/NibbleDataPalette',
+    'art/arcane/volmlib/util/data/Recycler',
+    'art/arcane/volmlib/util/data/VanillaBiomeMap',
+    'art/arcane/volmlib/util/data/Writable',
+    'art/arcane/volmlib/util/data/base/ComplexCacheBase',
+    'art/arcane/volmlib/util/director/DirectorNodeBase',
+    'art/arcane/volmlib/util/director/DirectorParameterBase',
+    'art/arcane/volmlib/util/director/theme/DirectorThemes',
+    'art/arcane/volmlib/util/interpolation/InterpolationMethod',
+    'art/arcane/volmlib/util/interpolation/IrisInterpolation',
+    'art/arcane/volmlib/util/math/INode',
+    'art/arcane/volmlib/util/math/IrisMathHelper',
+    'art/arcane/volmlib/util/math/KochanekBartelsInterpolation',
+    'art/arcane/volmlib/util/math/PathInterpolation',
+    'art/arcane/volmlib/util/math/Spiral',
+    'art/arcane/volmlib/util/board/BoardManager',
+    'art/arcane/volmlib/util/board/BoardUpdateTask',
+    'art/arcane/volmlib/util/bukkit/Placeholders',
+    'art/arcane/volmlib/util/hunk/HunkFactory',
+    'art/arcane/volmlib/util/hunk/storage/ArrayHunk',
+    'art/arcane/volmlib/util/hunk/storage/AtomicDoubleHunk',
+    'art/arcane/volmlib/util/hunk/storage/AtomicIntegerHunk',
+    'art/arcane/volmlib/util/hunk/storage/AtomicLongHunk',
+    'art/arcane/volmlib/util/hunk/storage/SynchronizedArrayHunk',
+    'art/arcane/volmlib/util/hunk/view/BiomeForceBridge',
+    'art/arcane/volmlib/util/hunk/view/BiomeGridForceSupport',
+    'art/arcane/volmlib/util/hunk/view/BiomeGridHunkHolder',
+    'art/arcane/volmlib/util/hunk/view/BiomeGridHunkView',
+    'art/arcane/volmlib/util/hunk/view/ChunkDataHunkHolder',
+    'art/arcane/volmlib/util/hunk/view/RotatedXHunkView',
+    'art/arcane/volmlib/util/hunk/view/RotatedYHunkView',
+    'art/arcane/volmlib/util/hunk/view/RotatedZHunkView',
+    'art/arcane/volmlib/util/exceptions/MissingDimensionException',
+    'art/arcane/volmlib/util/function/Supplier2',
+    'art/arcane/volmlib/util/function/Supplier3',
+    'art/arcane/volmlib/util/hud/HudPriority',
+    'art/arcane/volmlib/util/interpolation/InterpolationMethod3D',
+    'art/arcane/volmlib/util/interpolation/InterpolationType',
+    'art/arcane/volmlib/util/inventorygui/UIRainbowDecorator',
+    'art/arcane/volmlib/util/io/Converter',
+    'art/arcane/volmlib/util/matter/MatterPlacer',
+    'art/arcane/volmlib/util/plugin/SplashScreenSupport',
+    'art/arcane/volmlib/util/scheduling/Contained',
+    'art/arcane/volmlib/util/scheduling/IrisLock',
+    'art/arcane/volmlib/util/scheduling/QueueExecutor',
+    'art/arcane/volmlib/util/scheduling/S',
+    'art/arcane/volmlib/util/scheduling/SBase',
+    'art/arcane/volmlib/util/scheduling/SlidingWindowRateLimiter',
+    'art/arcane/volmlib/util/scheduling/Switch',
+    'art/arcane/volmlib/util/scheduling/ThreadMonitor',
+    'art/arcane/volmlib/util/cache/ByteCache',
+    'art/arcane/volmlib/util/cache/ChunkCache2DSimple',
+    'art/arcane/volmlib/util/cache/IntCache',
+    'art/arcane/volmlib/util/cache/ShortCache',
+    'art/arcane/volmlib/util/cache/UByteCache',
+    'art/arcane/volmlib/util/cache/WorldCache2DSimple',
+    'art/arcane/volmlib/util/data/CuboidException',
+    'art/arcane/volmlib/util/data/DUTF',
+    'art/arcane/volmlib/util/data/Heafty',
+    'art/arcane/volmlib/util/data/InvertedBiomeGrid',
+    'art/arcane/volmlib/util/data/Shrinkwrap',
+    'art/arcane/volmlib/util/data/WeightMap',
+    'art/arcane/volmlib/util/data/WeightedRandom',
+    'art/arcane/volmlib/util/director/compat/BukkitDirectorContext',
+    'art/arcane/volmlib/util/director/handlers/base/DummyHandlerBase',
+    'art/arcane/volmlib/util/director/handlers/base/OptionalWorldHandlerBase',
+    'art/arcane/volmlib/util/parallel/BurstedHunk',
+    'art/arcane/volmlib/util/parallel/GridLockSupport',
+    'art/arcane/volmlib/util/parallel/NoopGridLockSupport',
+    'art/arcane/volmlib/util/bukkit/ChunkPositionSet',
+    'art/arcane/volmlib/util/bukkit/Events',
+    'art/arcane/volmlib/util/json/SingleCollectionTypeFactory',
+    'art/arcane/volmlib/util/collection/StateList',
+    'art/arcane/iris/core/pack/IrisPack',
+    'art/arcane/iris/core/pack/IrisPackRepository',
+    'art/arcane/iris/core/jobs/DownloadJob',
+    'art/arcane/iris/core/jobs/JobCollection',
+    'art/arcane/iris/core/jobs/ParallelQueueJob',
+    'art/arcane/iris/core/jobs/QueueJob',
+    'art/arcane/iris/engine/framework/placer/WorldObjectPlacer',
+    'art/arcane/iris/engine/object/IPostBlockAccess',
+    'art/arcane/iris/engine/object/IrisPotionEffect',
+    'art/arcane/iris/engine/platform/DummyChunkGenerator',
+    'art/arcane/iris/util/common/math/VectorMath',
+    'art/arcane/iris/util/common/parallel/GridLock',
+    'art/arcane/iris/util/common/reflect/W',
+    'art/arcane/iris/util/slimjar/BuildConstants',
+    'art/arcane/iris/util/slimjar/relocation/meta/AttributeMetaMediator',
+    'art/arcane/iris/util/slimjar/relocation/meta/AttributeMetaMediatorFactory'
+]
+List<String> unusedVolmLibClassEntries = unusedVolmLibClasses.collectMany { String classPath ->
+    [classPath + '.class', classPath + '$*.class']
+}
+
 // Annotation-only artifacts pulled in transitively by Gson and Caffeine. Their types appear solely
 // in annotation attributes, which the JVM skips silently when the type is absent, so nothing loads
 // or links against them at runtime.
@@ -315,6 +456,7 @@ tasks.named('shadowJar', com.github.jengelman.gradle.plugins.shadow.tasks.Shadow
     relocate('io.github.slimjar', "${lib}.slimjar")
     exclude('modules/loader-agent.isolated-jar')
     exclude(supersededVolmLibPackages)
+    exclude(unusedVolmLibClassEntries)
     exclude(annotationOnlyArtifacts)
     exclude(dependencyBuildMetadata)
     from(embeddedAgentJar.map { it.archiveFile }) {

core/src/main/java/art/arcane/iris/core/ServerConfigurator.java

@@ -39,7 +39,6 @@ import art.arcane.iris.engine.object.IrisBiomeCustom;
 import art.arcane.iris.engine.object.IrisDimension;
 import art.arcane.volmlib.util.collection.KList;
 import art.arcane.volmlib.util.collection.KSet;
-import art.arcane.iris.util.common.format.C;
 import art.arcane.iris.util.common.misc.ServerProperties;
 import art.arcane.iris.util.common.plugin.VolmitSender;
 import art.arcane.iris.util.common.scheduling.J;
@@ -90,6 +89,8 @@ public class ServerConfigurator {
     private static final Object DATAPACK_INSTALL_LOCK = new Object();
     private static final String CODE_WORKSPACE_SUFFIX = ".code-workspace";
     private static final String COMPILER_INPUT_FINGERPRINT_CACHE = "datapack-compiler-input-fingerprint";
+    static final String POST_COMPILE_RESTART_WARNING = "Iris installed updated datapack registry entries; "
+            + "restart the server before creating worlds or opening Studios.";
     private static final int FINGERPRINT_BUFFER_BYTES = 64 * 1024;
     private static volatile boolean loadedDatapackRuntimeReady;
     private static volatile String loadedDatapackCompilerInputFingerprint = "";
@@ -419,13 +420,18 @@ public class ServerConfigurator {
                     && !reusableRuntimeFingerprint(
                             loadedDatapackCompilerInputFingerprint,
                             current);
+            boolean loadedRegistryRestartRequired = fullInstall
+                    && loadedCompilerInputsChanged
+                    && currentRegistryRequiresRestart();
             if (!current.isEmpty() && current.equals(cached)) {
                 IrisLogging.debug("Data packs unchanged, skipping install.");
-                DatapackInstallResult result = fullInstall && loadedCompilerInputsChanged
+                DatapackInstallResult result = loadedRegistryRestartRequired
                         ? DatapackInstallResult.restartRequiredResult()
                         : resultForUnchangedFingerprint(fullInstall, reapply);
                 if (result.restartRequired()) {
                     requireDatapackRestart();
+                } else if (result.succeeded()) {
+                    loadedDatapackCompilerInputFingerprint = current;
                 }
                 reportTiming(timingConsumer, "datapack_install_if_changed_total", totalStart);
                 return result;
@@ -435,7 +441,7 @@ public class ServerConfigurator {
                     resolveDataFixer(),
                     fullInstall,
                     reapply);
-            if (fullInstall && loadedCompilerInputsChanged && result.succeeded()) {
+            if (loadedRegistryRestartRequired && result.succeeded()) {
                 result = DatapackInstallResult.restartRequiredResult();
             }
             if (result.restartRequired()) {
@@ -444,6 +450,7 @@ public class ServerConfigurator {
             reportTiming(timingConsumer, "datapack_compile_publish", compileStart);
             if (result.succeeded() && !result.restartRequired()) {
                 writeCompilerInputFingerprintCache(cacheFile.toPath(), current);
+                loadedDatapackCompilerInputFingerprint = current;
             }
             reportTiming(timingConsumer, "datapack_install_if_changed_total", totalStart);
             return result;
@@ -456,6 +463,22 @@ public class ServerConfigurator {
                 IrisWorldStorage.levelRoot().toPath());
     }
 
+    private static boolean currentRegistryRequiresRestart() {
+        try {
+            Map<String, String> currentRequirements = IrisDatapackCompiler.computeRegistryRequirements(
+                    collectCompilerPackRoots(),
+                    resolveDataFixer());
+            return runtimeRequiresRegistryRestart(
+                    loadedDatapackRegistryRequirements,
+                    currentRequirements);
+        } catch (IOException | RuntimeException exception) {
+            IrisLogging.reportError(
+                    "Unable to compare loaded Iris datapack registry requirements.",
+                    exception);
+            return true;
+        }
+    }
+
     private static List<IrisGeneratorBinding> collectConfiguredLevelStemBindings() throws IOException {
         File levelRoot = IrisWorldStorage.levelRoot();
         String levelId = levelRoot.getName();
@@ -545,6 +568,19 @@ public class ServerConfigurator {
         return true;
     }
 
+    static boolean runtimeRequiresRegistryRestart(
+            Map<String, String> loadedRequirements,
+            Map<String, String> currentRequirements
+    ) {
+        if (currentRequirements == null) {
+            return true;
+        }
+        if (currentRequirements.isEmpty()) {
+            return false;
+        }
+        return !loadedRegistrySatisfies(loadedRequirements, currentRequirements);
+    }
+
     static boolean reusableRuntimeFingerprint(String loadedFingerprint, String currentFingerprint) {
         return loadedFingerprint != null
                 && !loadedFingerprint.isBlank()
@@ -961,14 +997,19 @@ public class ServerConfigurator {
 
     private static boolean verifyDataPacksPost() {
         try (Stream<IrisData> stream = allPacks()) {
-            boolean bad = stream
+            return verifyDataPacksPost(stream);
+        }
+    }
+
+    static boolean verifyDataPacksPost(Stream<IrisData> packs) {
+        boolean bad = Objects.requireNonNull(packs, "Iris packs")
                 .map(data -> {
                     IrisLogging.debug("Checking Pack: " + data.getDataFolder().getPath());
                     ResourceLoader<IrisDimension> loader = data.getDimensionLoader();
                     return loader.loadAll(loader.getPossibleKeys())
                             .stream()
                             .filter(Objects::nonNull)
-                                .map(ServerConfigurator::verifyDataPackInstalled)
+                            .map(dimension -> verifyDataPackInstalled(dimension, false))
                             .toList()
                             .contains(false);
                 })
@@ -977,15 +1018,8 @@ public class ServerConfigurator {
         if (!bad) {
             return false;
         }
-        }
-
-
         if (INMS.get().supportsDataPacks()) {
-            // Three sentences, no rules: a separator carries the record's severity too, so a box drawn
+            IrisLogging.warn(POST_COMPILE_RESTART_WARNING);
-            // out of equals signs became three more [SEVERE] lines saying nothing.
-            IrisLogging.error(C.ITALIC + "You need to restart your server to properly generate custom biomes.");
-            IrisLogging.error(C.ITALIC + "By continuing, Iris will use backup biomes in place of the custom biomes.");
-            IrisLogging.error(C.UNDERLINE + "Restart the server before generating.");
 
             for (Player i : Bukkit.getOnlinePlayers()) {
                 if (i.isOp() || i.hasPermission("iris.all")) {
@@ -1054,6 +1088,10 @@ public class ServerConfigurator {
     }
 
     public static boolean verifyDataPackInstalled(IrisDimension dimension) {
+        return verifyDataPackInstalled(dimension, true);
+    }
+
+    private static boolean verifyDataPackInstalled(IrisDimension dimension, boolean reportRuntimeFailure) {
         KSet<String> keys = new KSet<>();
         boolean warn = false;
 
@@ -1082,17 +1120,21 @@ public class ServerConfigurator {
             Object o = INMS.get().getCustomBiomeBaseFor(i);
 
             if (o == null) {
+                if (reportRuntimeFailure) {
                     IrisLogging.warn("The Biome " + i + " is not registered on the server.");
+                }
                 warn = true;
             }
         }
 
         if (INMS.get().missingDimensionTypes(dimension.getDimensionTypeKey())) {
+            if (reportRuntimeFailure) {
                 IrisLogging.warn("The Dimension Type for " + dimension.getLoadFile() + " is not registered on the server.");
+            }
             warn = true;
         }
 
-        if (warn) {
+        if (warn && reportRuntimeFailure) {
             IrisLogging.error("The Pack " + key + " is INCAPABLE of generating custom biomes");
             IrisLogging.error("If not done automatically, restart your server before generating with this pack!");
         }

core/src/main/java/art/arcane/iris/core/gui/GuiHost.java

@@ -31,6 +31,7 @@ import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
 import java.util.Locale;
 import java.util.Set;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -63,7 +64,7 @@ public final class GuiHost {
         default void unregisterHotloadHook(Runnable onHotload) {
         }
 
-        default GuiOverlay overlayFor(Engine engine) {
+        default GuiOverlay overlayFor(Engine engine, UUID openerId) {
             return null;
         }
     }

core/src/main/java/art/arcane/iris/core/gui/VisionGUI.java

@@ -73,6 +73,7 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
+import java.util.UUID;
 
 public final class VisionGUI extends JPanel implements MouseWheelListener, KeyListener, MouseMotionListener, MouseInputListener {
     private static final long serialVersionUID = 2094606939770332040L;
@@ -107,6 +108,7 @@ public final class VisionGUI extends JPanel implements MouseWheelListener, KeyLi
     private static final double KEYBOARD_ZOOM_FACTOR = 1.189207115002721D;
 
     private final JFrame hostFrame;
+    private final UUID openerId;
     private final VisionRenderController controller;
     private final Runnable hotloadHook;
     private final Timer resizeTimer;
@@ -147,11 +149,12 @@ public final class VisionGUI extends JPanel implements MouseWheelListener, KeyLi
     private boolean controlsUpdating;
     private boolean closed;
 
-    private VisionGUI(JFrame hostFrame, Engine engine) {
+    private VisionGUI(JFrame hostFrame, Engine engine, UUID openerId) {
         this.hostFrame = Objects.requireNonNull(hostFrame, "hostFrame");
         this.engine = Objects.requireNonNull(engine, "engine");
+        this.openerId = openerId;
         this.renderer = new IrisRenderer(engine);
-        this.overlay = GuiHost.get().overlayFor(engine);
+        this.overlay = GuiHost.get().overlayFor(engine, openerId);
         this.controller = new VisionRenderController(this::repaint);
         this.hotloadHook = () -> EventQueue.invokeLater(this::refreshContent);
         this.notifications = new LinkedHashMap<>();
@@ -201,14 +204,14 @@ public final class VisionGUI extends JPanel implements MouseWheelListener, KeyLi
         notificationTimer.start();
     }
 
-    public static void launch(Engine engine) {
+    public static void launch(Engine engine, UUID openerId) {
-        EventQueue.invokeLater(() -> createAndShowGUI(engine));
+        EventQueue.invokeLater(() -> createAndShowGUI(engine, openerId));
     }
 
-    private static void createAndShowGUI(Engine engine) {
+    private static void createAndShowGUI(Engine engine, UUID openerId) {
         JFrame frame = new JFrame(IrisLanguage.plain(DesktopUiMessages.VISION_TITLE));
         GuiHost.prepareFrame(frame);
-        VisionGUI vision = new VisionGUI(frame, engine);
+        VisionGUI vision = new VisionGUI(frame, engine, openerId);
         frame.getContentPane().setBackground(BACKGROUND);
         frame.setLayout(new BorderLayout());
         frame.add(buildToolbar(vision), BorderLayout.NORTH);
@@ -739,7 +742,7 @@ public final class VisionGUI extends JPanel implements MouseWheelListener, KeyLi
             }
             engine = reacquired;
             renderer = new IrisRenderer(reacquired);
-            overlay = GuiHost.get().overlayFor(reacquired);
+            overlay = GuiHost.get().overlayFor(reacquired, openerId);
             contentRevision++;
             captureHeightRange();
             return true;
@@ -758,7 +761,7 @@ public final class VisionGUI extends JPanel implements MouseWheelListener, KeyLi
             return;
         }
         renderer = new IrisRenderer(engine);
-        overlay = GuiHost.get().overlayFor(engine);
+        overlay = GuiHost.get().overlayFor(engine, openerId);
         contentRevision++;
         captureHeightRange();
         requestRender();

core/src/main/java/art/arcane/iris/core/localization/IrisLanguage.java

@@ -56,6 +56,10 @@ public final class IrisLanguage {
     private static final Pattern LOCALE_NAME = Pattern.compile("[A-Za-z0-9_-]+");
     private static final Pattern LEGACY_COLOR = Pattern.compile("(?i)\\u00a7[0-9A-FK-ORX]");
     private static final MessageCatalog CATALOG = IrisMessages.catalog();
+    private static final List<String> BUKKIT_MESSAGE_IDS = CATALOG.ids().stream()
+            .filter(id -> !id.startsWith("iris.modded."))
+            .sorted()
+            .toList();
     private static final LocalizationManager MANAGER = new LocalizationManager(
             LocalizationCandidate.english(CATALOG, PluralSelector.oneOther())
     );
@@ -369,8 +373,11 @@ public final class IrisLanguage {
         }
     }
 
-    private static LocaleOverlay parseOverlay(String source, String locale, String raw) {
+    static LocaleOverlay parseOverlay(String source, String locale, String raw) {
         JsonElement parsed = JsonParser.parseString(raw == null || raw.isBlank() ? "{}" : raw);
+        if (parsed.isJsonArray()) {
+            return parseCompactBukkitOverlay(source, locale, parsed.getAsJsonArray());
+        }
         if (!parsed.isJsonObject()) {
             throw new IllegalArgumentException("Locale source is not a JSON object: " + source);
         }
@@ -398,6 +405,49 @@ public final class IrisLanguage {
         return builder.build();
     }
 
+    private static LocaleOverlay parseCompactBukkitOverlay(
+            String source,
+            String locale,
+            JsonArray root
+    ) {
+        if (root.size() != 2 || !root.get(0).isJsonPrimitive() || !root.get(1).isJsonArray()) {
+            throw new IllegalArgumentException("Compact locale source is invalid: " + source);
+        }
+        if (!locale.equals(normalizeLocale(root.get(0).getAsString()))) {
+            throw new IllegalArgumentException("Locale source declares a different locale than its file: " + source);
+        }
+        JsonArray messages = root.get(1).getAsJsonArray();
+        if (messages.size() != BUKKIT_MESSAGE_IDS.size()) {
+            throw new IllegalArgumentException("Compact locale message count is invalid: " + source);
+        }
+        LocaleOverlay.Builder builder = LocaleOverlay.builder(source, locale);
+        for (int i = 0; i < messages.size(); i++) {
+            JsonElement value = messages.get(i);
+            if (value == null || value.isJsonNull()) {
+                continue;
+            }
+            appendCompactMessage(builder, BUKKIT_MESSAGE_IDS.get(i), value);
+        }
+        return builder.build();
+    }
+
+    private static void appendCompactMessage(
+            LocaleOverlay.Builder builder,
+            String key,
+            JsonElement value
+    ) {
+        MessageKey definition = CATALOG.key(key);
+        if (value.isJsonObject() && definition instanceof PluralKey) {
+            builder.plural(key, readPlural(key, value.getAsJsonObject()));
+        } else if (value.isJsonArray()) {
+            builder.lines(key, readLines(key, value.getAsJsonArray()));
+        } else if (value.isJsonPrimitive() && value.getAsJsonPrimitive().isString()) {
+            builder.text(key, value.getAsString());
+        } else {
+            throw new IllegalArgumentException("Compact locale value has an invalid shape: " + key);
+        }
+    }
+
     private static void appendMessages(LocaleOverlay.Builder builder, JsonObject object, String prefix) {
         for (Map.Entry<String, JsonElement> entry : object.entrySet()) {
             String key = prefix.isEmpty() ? entry.getKey() : prefix + "." + entry.getKey();

core/src/main/java/art/arcane/iris/core/pack/PackRiverValidator.java

@@ -13,7 +13,7 @@ import java.util.List;
 import java.util.Set;
 
 final class PackRiverValidator {
-    private static final Set<String> WATER_MODES = Set.of("SEA_LEVEL", "TERRACED");
+    private static final Set<String> WATER_MODES = Set.of("FIXED", "TERRACED");
     private static final Set<String> TERMINAL_MODES = Set.of("SUPPRESS", "DRY_CHANNEL", "SINKHOLE_GROTTO");
     private static final Set<String> ROUTING_POLICIES = Set.of("ALLOW", "AVOID", "BLOCK");
     private static final Set<String> CAVE_MODES = Set.of(
@@ -91,7 +91,7 @@ final class PackRiverValidator {
             validateTerrain(packFolder, path + ".terrain", terrain, errors, warnings);
         }
         if (water != null) {
-            validateWater(path + ".water", water, errors);
+            validateWater(path + ".water", water, context.dimension(), errors);
         }
         if (biomes != null) {
             validateBiomePools(
@@ -107,7 +107,15 @@ final class PackRiverValidator {
         boolean sinkholeTerminal = terrain != null
                 && "SINKHOLE_GROTTO".equals(stringValue(terrain, "terminalMode", "DRY_CHANNEL"));
         if (caves != null) {
-            validateCaves(packFolder, path + ".caves", caves, sinkholeTerminal, errors, warnings);
+            validateCaves(
+                    packFolder,
+                    path + ".caves",
+                    caves,
+                    context.dimension(),
+                    sinkholeTerminal,
+                    errors,
+                    warnings
+            );
         }
 
         if (topology != null && terrain != null) {
@@ -168,6 +176,7 @@ final class PackRiverValidator {
         validateStyledRange(packFolder, terrain, "bankWidth", path, 0D, 2048D, errors, warnings);
         validateStyledRange(packFolder, terrain, "depth", path, 1D, 512D, errors, warnings);
         validateStyledRange(packFolder, terrain, "tunnelWidthMultiplier", path, 1D, 8D, errors, warnings);
+        PackJsonFieldChecks.validateOptionalDoubleRange(path, terrain, "channelRadiusBonus", 0D, 64D, errors);
         PackJsonFieldChecks.validateOptionalDoubleRange(path, terrain, "maxChannelWidth", 1D, 2048D, errors);
         PackJsonFieldChecks.validateOptionalDoubleRange(path, terrain, "maxBankWidth", 0D, 2048D, errors);
         PackJsonFieldChecks.validateOptionalDoubleRange(path, terrain, "maxDepth", 1D, 512D, errors);
@@ -211,18 +220,50 @@ final class PackRiverValidator {
         }
     }
 
-    private static void validateWater(String path, JSONObject water, List<String> errors) {
+    private static void validateWater(
+            String path,
+            JSONObject water,
+            JSONObject dimension,
+            List<String> errors
+    ) {
         PackJsonFieldChecks.validateOptionalEnum(path, water, "mode", WATER_MODES, errors);
         PackJsonFieldChecks.validateOptionalIntegerRange(path, water, "poolLength", 8, 4096, errors);
         PackJsonFieldChecks.validateOptionalIntegerRange(path, water, "maximumPoolRise", 0, 64, errors);
         PackJsonFieldChecks.validateOptionalIntegerRange(path, water, "dropHeight", 1, 32, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(path, water, "fluidHeight", -2048, 2048, errors);
+        validateFluidPalette(path, water, errors);
 
-        String mode = stringValue(water, "mode", "SEA_LEVEL");
+        String mode = stringValue(water, "mode", "FIXED");
+        int fluidHeight = integerValue(water, "fluidHeight", 63);
         int maximumPoolRise = integerValue(water, "maximumPoolRise", 4);
         int dropHeight = integerValue(water, "dropHeight", 1);
         if ("TERRACED".equals(mode) && dropHeight > maximumPoolRise) {
             errors.add(path + ".dropHeight must not exceed maximumPoolRise in TERRACED mode.");
         }
+        JSONObject dimensionHeight = dimension.optJSONObject("dimensionHeight");
+        int minimumHeight = dimensionHeight == null ? -64 : integerValue(dimensionHeight, "min", -64);
+        int maximumHeight = dimensionHeight == null ? 320 : integerValue(dimensionHeight, "max", 320);
+        if (fluidHeight < minimumHeight || fluidHeight > maximumHeight) {
+            errors.add(path + ".fluidHeight must remain inside dimensionHeight.");
+        }
+        if ("TERRACED".equals(mode) && fluidHeight + maximumPoolRise > maximumHeight) {
+            errors.add(path + ".fluidHeight plus maximumPoolRise must remain inside dimensionHeight.");
+        }
+    }
+
+    private static void validateFluidPalette(String path, JSONObject water, List<String> errors) {
+        if (!water.has("fluidPalette")) {
+            return;
+        }
+        Object rawPalette = water.opt("fluidPalette");
+        if (!(rawPalette instanceof JSONObject palette)) {
+            errors.add(path + ".fluidPalette must be an object.");
+            return;
+        }
+        Object rawBlocks = palette.opt("palette");
+        if (!(rawBlocks instanceof JSONArray blocks) || blocks.length() < 1) {
+            errors.add(path + ".fluidPalette.palette must contain at least one fluid block.");
+        }
     }
 
     private static void validateTopologyComplexity(
@@ -345,9 +386,11 @@ final class PackRiverValidator {
             PackJsonFieldChecks.validateOptionalDoubleRange(
                     wormPath, worm, "depthMultiplier", 0.125D, 8D, errors);
             PackJsonFieldChecks.validateOptionalDoubleRange(
-                    wormPath, worm, "bodyWavelength", 32D, 16384D, errors);
+                    wormPath, worm, "bodyWavelength", 8D, 16384D, errors);
             PackJsonFieldChecks.validateOptionalDoubleRange(
-                    wormPath, worm, "bodyDetailWavelength", 32D, 16384D, errors);
+                    wormPath, worm, "bodyDetailWavelength", 8D, 16384D, errors);
+            PackJsonFieldChecks.validateOptionalDoubleRange(
+                    wormPath, worm, "bodyDetailInfluence", 0D, 1D, errors);
             PackJsonFieldChecks.validateOptionalDoubleRange(
                     wormPath, worm, "widthVariation", 0D, 0.875D, errors);
             PackJsonFieldChecks.validateOptionalDoubleRange(
@@ -452,6 +495,7 @@ final class PackRiverValidator {
     }
 
     private static void validateCaves(File packFolder, String path, JSONObject caves,
+                                      JSONObject dimension,
                                       boolean forceGeneratedGrotto,
                                       List<String> errors, List<String> warnings) {
         PackJsonFieldChecks.validateOptionalEnum(path, caves, "mode", CAVE_MODES, errors);
@@ -473,6 +517,19 @@ final class PackRiverValidator {
         validateNoiseChance(packFolder, caves, "entry", path, errors);
         validateStyle(packFolder, caves, "grottoShapeStyle", path, errors);
         validateStyle(packFolder, caves, "grottoWarpStyle", path, errors);
+        JSONObject deepPools = caves.has("deepPools")
+                ? requireObject(caves, "deepPools", path + ".deepPools", errors)
+                : null;
+        if (deepPools != null) {
+            validateDeepPools(
+                    packFolder,
+                    path + ".deepPools",
+                    deepPools,
+                    dimension,
+                    errors,
+                    warnings
+            );
+        }
 
         String mode = stringValue(caves, "mode", "SEALED");
         if ("SEALED".equals(mode) && !forceGeneratedGrotto) {
@@ -505,6 +562,86 @@ final class PackRiverValidator {
         }
     }
 
+    private static void validateDeepPools(
+            File packFolder,
+            String path,
+            JSONObject deepPools,
+            JSONObject dimension,
+            List<String> errors,
+            List<String> warnings
+    ) {
+        PackJsonFieldChecks.validateOptionalBoolean(path, deepPools, "enabled", errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "minimumSpacing", 16, 4096, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "maximumPerReach", 0, 16, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "minimumFluidY", -2048, 2048, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "maximumFluidY", -2048, 2048, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "searchRadius", 0, 256, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "searchAttempts", 1, 64, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "horizontalRadius", 2, 128, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "verticalRadius", 2, 64, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "dryHeadroom", 1, 63, errors);
+        PackJsonFieldChecks.validateOptionalDoubleRange(
+                path, deepPools, "shapeVariation", 0D, 0.75D, errors);
+        PackJsonFieldChecks.validateOptionalDoubleRange(
+                path, deepPools, "warpStrength", 0D, 64D, errors);
+        PackJsonFieldChecks.validateOptionalIntegerRange(
+                path, deepPools, "maximumVolume", 64, 1048576, errors);
+        validateNoiseChance(packFolder, deepPools, "reach", path, errors);
+        validateStyle(packFolder, deepPools, "shapeStyle", path, errors);
+        validateStyle(packFolder, deepPools, "warpStyle", path, errors);
+        validateFluidPalette(path, deepPools, errors);
+
+        int minimumFluidY = integerValue(deepPools, "minimumFluidY", -224);
+        int maximumFluidY = integerValue(deepPools, "maximumFluidY", -104);
+        int searchRadius = integerValue(deepPools, "searchRadius", 16);
+        int horizontalRadius = integerValue(deepPools, "horizontalRadius", 18);
+        int verticalRadius = integerValue(deepPools, "verticalRadius", 8);
+        int dryHeadroom = integerValue(deepPools, "dryHeadroom", 4);
+        int maximumVolume = integerValue(deepPools, "maximumVolume", 32768);
+        if (minimumFluidY > maximumFluidY) {
+            errors.add(path + ".minimumFluidY must not exceed maximumFluidY.");
+        }
+        if (dryHeadroom >= verticalRadius) {
+            errors.add(path + ".dryHeadroom must be smaller than verticalRadius.");
+        }
+        if (searchRadius + horizontalRadius > 128) {
+            errors.add(path + ".searchRadius plus horizontalRadius must not exceed 128 blocks.");
+        }
+        long minimumVolume = grottoVolume(horizontalRadius, verticalRadius);
+        if (minimumVolume > maximumVolume) {
+            errors.add(path + ".maximumVolume must be at least " + minimumVolume
+                    + " to contain the base deep-pool chamber.");
+        }
+
+        if (!booleanValue(deepPools, "enabled", false)) {
+            return;
+        }
+
+        JSONObject dimensionHeight = dimension.optJSONObject("dimensionHeight");
+        int minimumHeight = dimensionHeight == null ? -64 : integerValue(dimensionHeight, "min", -64);
+        int maximumHeight = dimensionHeight == null ? 320 : integerValue(dimensionHeight, "max", 320);
+        int lowestBoundaryY = minimumFluidY - (verticalRadius * 2 - dryHeadroom) - 1;
+        int highestBoundaryY = maximumFluidY + dryHeadroom + 1;
+        if (lowestBoundaryY <= minimumHeight || highestBoundaryY >= maximumHeight) {
+            errors.add(path + " fluid range and chamber envelope must remain inside dimensionHeight.");
+        }
+
+        int maximumPerReach = integerValue(deepPools, "maximumPerReach", 1);
+        double reachChance = noiseChanceValue(deepPools, "reach", 1D / 3D);
+        if (maximumPerReach == 0 || reachChance == 0D) {
+            warnings.add(path + " is enabled but its reach gate cannot accept any pools.");
+        }
+    }
+
     private static void validateGrotto(String path, JSONObject caves, List<String> errors) {
         int throatRadius = integerValue(caves, "throatRadius", 2);
         int dryHeadroom = integerValue(caves, "dryHeadroom", 4);

core/src/main/java/art/arcane/iris/core/pregenerator/methods/AsyncPregenMethod.java

@@ -65,7 +65,7 @@ public class AsyncPregenMethod implements PregeneratorMethod {
     private static final AtomicInteger BOOST_HOLDERS = new AtomicInteger();
     private static final int ADAPTIVE_SLOW_REQUEST_STEP = 3;
     private static final int ADAPTIVE_RECOVERY_INTERVAL = 8;
-    private static final long CLOSE_DRAIN_TIMEOUT_SECONDS = 60L;
+    private static final long CLOSE_DRAIN_WARNING_SECONDS = 60L;
     private static final long FLUSH_TIMEOUT_SECONDS = 120L;
     private final World world;
     private final IrisRuntimeSchedulerMode runtimeSchedulerMode;
@@ -773,17 +773,13 @@ public class AsyncPregenMethod implements PregeneratorMethod {
         // A stop request interrupts the pregen worker; shield the drain and flush so chunks still hit disk.
         boolean interrupted = Thread.interrupted();
         try {
-            boolean drained = false;
+            interrupted |= awaitDrain(
-            try {
+                    semaphore,
-                drained = semaphore.tryAcquire(threads, CLOSE_DRAIN_TIMEOUT_SECONDS, TimeUnit.SECONDS);
+                    threads,
-            } catch (InterruptedException e) {
+                    CLOSE_DRAIN_WARNING_SECONDS,
-                interrupted = true;
+                    TimeUnit.SECONDS,
-            }
+                    () -> IrisLogging.warn("Async pregen is still draining outstanding chunks. " + metricsSnapshot())
-
+            );
-            if (!drained) {
-                IrisLogging.warn("Async pregen close did not drain in " + CLOSE_DRAIN_TIMEOUT_SECONDS
-                        + "s, continuing degraded. " + metricsSnapshot());
-            }
 
             flushAllRemainingChunks();
             executor.shutdown();
@@ -797,6 +793,26 @@ public class AsyncPregenMethod implements PregeneratorMethod {
         }
     }
 
+    static boolean awaitDrain(
+            Semaphore semaphore,
+            int permits,
+            long warningInterval,
+            TimeUnit timeUnit,
+            Runnable onWait
+    ) {
+        boolean interrupted = false;
+        while (true) {
+            try {
+                if (semaphore.tryAcquire(permits, warningInterval, timeUnit)) {
+                    return interrupted;
+                }
+                onWait.run();
+            } catch (InterruptedException e) {
+                interrupted = true;
+            }
+        }
+    }
+
     private boolean isCancelled() {
         return closing.get() || Thread.currentThread().isInterrupted();
     }

core/src/main/java/art/arcane/iris/core/project/IrisProject.java

@@ -85,18 +85,34 @@ public class IrisProject {
             StudioOpenCoordinator.StudioOpenKind openKind,
             Consumer<World> onDone
     ) throws IrisException {
-        if (isOpen()) {
+        return open(sender, seed, openKind, onDone, System.nanoTime());
-            return close().thenCompose(ignored -> openInternal(sender, seed, openKind, onDone));
     }
 
-        return openInternal(sender, seed, openKind, onDone);
+    public CompletableFuture<StudioOpenCoordinator.StudioOpenResult> open(
+            VolmitSender sender,
+            long seed,
+            StudioOpenCoordinator.StudioOpenKind openKind,
+            Consumer<World> onDone,
+            long requestedAtNanos
+    ) throws IrisException {
+        if (isOpen()) {
+            return close().thenCompose(ignored -> openInternal(
+                    sender,
+                    seed,
+                    openKind,
+                    onDone,
+                    requestedAtNanos));
+        }
+
+        return openInternal(sender, seed, openKind, onDone, requestedAtNanos);
     }
 
     private CompletableFuture<StudioOpenCoordinator.StudioOpenResult> openInternal(
             VolmitSender sender,
             long seed,
             StudioOpenCoordinator.StudioOpenKind openKind,
-            Consumer<World> onDone
+            Consumer<World> onDone,
+            long requestedAtNanos
     ) {
         AtomicReference<String> stage = new AtomicReference<>("Queued");
         AtomicReference<Double> progress = new AtomicReference<>(0.01D);
@@ -114,7 +130,8 @@ public class IrisProject {
                             }
                             progress.set(Math.max(0D, Math.min(0.99D, update.progress())));
                         },
-                        onDone
+                        onDone,
+                        requestedAtNanos
                 )
         );
         StudioOpenProgressReporter.startStudioOpenReporter(sender, stage, progress, complete, failed);

core/src/main/java/art/arcane/iris/core/runtime/StudioOpenCoordinator.java

@@ -14,6 +14,7 @@ import art.arcane.iris.core.project.IrisProject;
 import art.arcane.iris.core.project.IrisCodeWorkspace;
 import art.arcane.iris.core.tools.IrisCreator;
 import art.arcane.iris.core.tools.IrisToolbelt;
+import art.arcane.iris.engine.IrisEngine;
 import art.arcane.iris.engine.platform.BukkitChunkGenerator;
 import art.arcane.iris.engine.platform.PlatformChunkGenerator;
 import art.arcane.iris.util.common.plugin.VolmitSender;
@@ -98,16 +99,11 @@ public final class StudioOpenCoordinator {
 
     public CompletableFuture<Boolean> teleportPlayerToProject(
             IrisProject project,
-            Player player,
+            Player player
-            AtomicBoolean admission,
-            long deadlineNanos
     ) {
         if (project == null || player == null) {
             return CompletableFuture.completedFuture(false);
         }
-        AtomicBoolean activeAdmission = Objects.requireNonNull(
-                admission,
-                "Studio teleport admission");
         PlatformChunkGenerator provider = project.getActiveProvider();
         if (provider == null) {
             return CompletableFuture.failedFuture(new IllegalStateException(
@@ -123,10 +119,6 @@ public final class StudioOpenCoordinator {
             return CompletableFuture.failedFuture(new IllegalStateException(
                     "Studio entry point could not be resolved."));
         }
-        if (System.nanoTime() >= deadlineNanos
-                || !activeAdmission.compareAndSet(true, false)) {
-            return studioTeleportDeadlineFailure("native teleport delegation");
-        }
         CompletableFuture<Boolean> teleport = project.getActiveOpenKind() == StudioOpenKind.STANDARD
                 ? WorldRuntimeControlService.get().teleportInMode(player, entry, GameMode.SPECTATOR)
                 : WorldRuntimeControlService.get().teleport(player, entry);
@@ -134,25 +126,12 @@ public final class StudioOpenCoordinator {
             return CompletableFuture.failedFuture(new IllegalStateException(
                     "Studio native teleport returned no completion future."));
         }
-        long remainingNanos = deadlineNanos - System.nanoTime();
-        if (remainingNanos <= 0L) {
-            teleport.completeExceptionally(new TimeoutException(
-                    "Studio teleport deadline expired before native teleport completion."));
         return teleport;
     }
-        teleport.orTimeout(remainingNanos, TimeUnit.NANOSECONDS);
-        return teleport;
-    }
-
-    private <T> CompletableFuture<T> studioTeleportDeadlineFailure(String stageName) {
-        return CompletableFuture.failedFuture(new TimeoutException(
-                "Studio teleport deadline expired before " + stageName + "."));
-    }
 
     private void executeOpen(StudioOpenRequest request, CompletableFuture<StudioOpenResult> future) {
         World world = null;
         PlatformChunkGenerator provider = null;
-        CompletableFuture<Boolean> nativeTeleportFuture = null;
         try {
             long openStart = System.nanoTime();
             long t = openStart;
@@ -181,6 +160,10 @@ public final class StudioOpenCoordinator {
             if (provider == null) {
                 throw new IllegalStateException("Studio runtime provider is unavailable for world \"" + request.worldName() + "\".");
             }
+            World entryWorld = world;
+            PlatformChunkGenerator entryProvider = provider;
+            CompletableFuture<Void> entryBootstrap = J.afut(
+                    () -> endStudioEntryBootstrap(entryWorld, entryProvider));
 
             updateStage(request, "apply_world_rules", 0.72D);
             final World rulesWorld = world;
@@ -204,9 +187,15 @@ public final class StudioOpenCoordinator {
             t = logStudioPhase(request, "resolve_entry_anchor", t, openStart);
 
             updateStage(request, "prepare_structure_rings", 0.79D);
-            endStudioEntryBootstrap(world, provider);
+            entryBootstrap.get(STUDIO_STRUCTURE_ACTIVATION_TIMEOUT_SECONDS, TimeUnit.SECONDS);
             t = logStudioPhase(request, "prepare_structure_rings", t, openStart);
 
+            updateStage(request, "prepare_generation_caches", 0.88D);
+            if (entryProvider.getEngine() instanceof IrisEngine irisEngine) {
+                irisEngine.awaitGenerationCacheWarm();
+            }
+            t = logStudioPhase(request, "prepare_generation_caches", t, openStart);
+
             Location entryLocation = entryAnchor;
 
             if (request.openKind().teleportThroughStandardEntry()
@@ -219,7 +208,7 @@ public final class StudioOpenCoordinator {
                 }
                 Boolean teleported;
                 try {
-                    nativeTeleportFuture = WorldRuntimeControlService.get().teleportInMode(
+                    CompletableFuture<Boolean> nativeTeleportFuture = WorldRuntimeControlService.get().teleportInMode(
                             player,
                             entryLocation,
                             GameMode.SPECTATOR);
@@ -227,15 +216,20 @@ public final class StudioOpenCoordinator {
                         throw new IllegalStateException(
                                 "Studio native teleport returned no completion future.");
                     }
-                    teleported = nativeTeleportFuture.get(60L, TimeUnit.SECONDS);
+                    teleported = nativeTeleportFuture.get();
-                } catch (TimeoutException e) {
+                } catch (ExecutionException e) {
-                    nativeTeleportFuture.completeExceptionally(e);
+                    Throwable failure = unwrapFailure(e);
-                    throw new IllegalStateException("Studio teleport timed out — destination region may still be generating.");
+                    throw new IllegalStateException("Studio teleport failed.", failure);
                 }
                 if (!Boolean.TRUE.equals(teleported)) {
                     throw new IllegalStateException("Studio teleport did not complete successfully.");
                 }
                 t = logStudioPhase(request, "teleport_standard_entry", t, openStart);
+                IrisLogging.info("Studio player %s arrived in %dms: dimension=%s world=%s",
+                        player.getName(),
+                        elapsedMillis(request.requestedAtNanos()),
+                        request.dimensionKey(),
+                        world.getName());
             }
 
             updateStage(request, "finalize_open", 1.00D);
@@ -861,10 +855,14 @@ public final class StudioOpenCoordinator {
             StudioOpenKind openKind,
             boolean retainOnFailure,
             Consumer<StudioOpenProgress> progressConsumer,
-            Consumer<World> onDone
+            Consumer<World> onDone,
+            long requestedAtNanos
     ) {
         public StudioOpenRequest {
             openKind = Objects.requireNonNull(openKind, "Studio open kind");
+            if (requestedAtNanos <= 0L) {
+                throw new IllegalArgumentException("Studio request time must be positive.");
+            }
         }
 
         public static StudioOpenRequest studioProject(
@@ -874,6 +872,25 @@ public final class StudioOpenCoordinator {
                 StudioOpenKind openKind,
                 Consumer<StudioOpenProgress> progressConsumer,
                 Consumer<World> onDone
+        ) {
+            return studioProject(
+                    project,
+                    sender,
+                    seed,
+                    openKind,
+                    progressConsumer,
+                    onDone,
+                    System.nanoTime());
+        }
+
+        public static StudioOpenRequest studioProject(
+                IrisProject project,
+                VolmitSender sender,
+                long seed,
+                StudioOpenKind openKind,
+                Consumer<StudioOpenProgress> progressConsumer,
+                Consumer<World> onDone,
+                long requestedAtNanos
         ) {
             String playerName = sender != null && sender.isPlayer() && sender.player() != null ? sender.player().getName() : null;
             return new StudioOpenRequest(
@@ -886,7 +903,8 @@ public final class StudioOpenCoordinator {
                     openKind,
                     false,
                     progressConsumer,
-                    onDone
+                    onDone,
+                    requestedAtNanos
             );
         }
     }

core/src/main/java/art/arcane/iris/core/runtime/WorldRuntimeControlService.java

@@ -10,6 +10,7 @@ import art.arcane.iris.core.service.BoardSVC;
 import art.arcane.iris.core.tools.IrisToolbelt;
 import art.arcane.iris.engine.platform.BukkitChunkGenerator;
 import art.arcane.iris.engine.platform.PlatformChunkGenerator;
+import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.util.common.scheduling.J;
 import io.papermc.lib.PaperLib;
 import org.bukkit.Bukkit;
@@ -41,10 +42,13 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
 public final class WorldRuntimeControlService {
+    private static final int STUDIO_ENTRY_VIEW_DISTANCE = 2;
     private static final int MAX_SAFE_ENTRY_HORIZONTAL_RADIUS = 15;
-    private static final int MAX_SAFE_ENTRY_VERTICAL_SEARCH = 64;
+    private static final int SAFE_ENTRY_UPWARD_ALLOWANCE = 32;
     private static final double BLOCK_CENTER = 0.5D;
     private static final double COLLISION_EPSILON = 0.000001D;
+    private static final Method PLAYER_GET_VIEW_DISTANCE_METHOD = findPlayerMethod("getViewDistance");
+    private static final Method PLAYER_SET_VIEW_DISTANCE_METHOD = findPlayerMethod("setViewDistance", int.class);
     private static final Set<Material> UNSAFE_ENTRY_MATERIALS = Set.of(
             Material.CACTUS,
             Material.CAMPFIRE,
@@ -302,7 +306,7 @@ public final class WorldRuntimeControlService {
         CompletableFuture<Location> future = new CompletableFuture<>();
         boolean scheduled = J.runRegion(world, chunkX, chunkZ, () -> {
             try {
-                future.complete(findTopSafeLocation(world, source));
+                future.complete(findTopSafeLocationWithTicket(world, source, chunkX, chunkZ));
             } catch (Throwable t) {
                 future.completeExceptionally(t);
             }
@@ -314,6 +318,22 @@ public final class WorldRuntimeControlService {
         return future;
     }
 
+    private static Location findTopSafeLocationWithTicket(
+            World world,
+            Location source,
+            int chunkX,
+            int chunkZ
+    ) {
+        boolean ticketAdded = world.addPluginChunkTicket(chunkX, chunkZ, BukkitPlatform.plugin());
+        try {
+            return findTopSafeLocation(world, source);
+        } finally {
+            if (ticketAdded) {
+                world.removePluginChunkTicket(chunkX, chunkZ, BukkitPlatform.plugin());
+            }
+        }
+    }
+
     public CompletableFuture<Boolean> teleport(Player player, Location location) {
         return scheduleTeleport(player, location, null);
     }
@@ -350,6 +370,7 @@ public final class WorldRuntimeControlService {
 
         CompletableFuture<Boolean> future = new CompletableFuture<>();
         GameModeRestore modeRestore = new GameModeRestore(player);
+        PlayerViewDistanceRestore viewDistanceRestore = new PlayerViewDistanceRestore(player);
         AtomicReference<CompletableFuture<Boolean>> activeTeleport = new AtomicReference<>();
         future.whenComplete((success, failure) -> {
             if (Boolean.TRUE.equals(success)) {
@@ -359,6 +380,7 @@ public final class WorldRuntimeControlService {
             if (teleport != null && !teleport.isDone()) {
                 teleport.cancel(false);
             }
+            viewDistanceRestore.restore();
             modeRestore.restore();
         });
         boolean scheduled = J.runEntity(player, () -> {
@@ -368,7 +390,9 @@ public final class WorldRuntimeControlService {
                 }
                 if (gameMode != null) {
                     modeRestore.apply(gameMode);
+                    viewDistanceRestore.apply();
                     if (future.isDone()) {
+                        viewDistanceRestore.restore();
                         modeRestore.restore();
                         return;
                     }
@@ -393,6 +417,7 @@ public final class WorldRuntimeControlService {
 
                     if (Boolean.TRUE.equals(success)) {
                         if (future.complete(true)) {
+                            viewDistanceRestore.restore();
                             J.runEntity(player, () -> IrisServices.get(BoardSVC.class).updatePlayer(player));
                         }
                         return;
@@ -479,6 +504,7 @@ public final class WorldRuntimeControlService {
                             z,
                             minimumFloorY,
                             maximumFloorY,
+                            source.getBlockY() - 1,
                             yaw,
                             pitch
                     );
@@ -498,13 +524,14 @@ public final class WorldRuntimeControlService {
             int z,
             int minimumFloorY,
             int maximumFloorY,
+            int preferredFloorY,
             float yaw,
             float pitch
     ) {
         int highestY = world.getHighestBlockYAt(x, z, HeightMap.MOTION_BLOCKING_NO_LEAVES);
-        int startingFloorY = Math.max(minimumFloorY, Math.min(maximumFloorY, highestY));
+        int preferredMaximumY = Math.min(maximumFloorY, preferredFloorY + SAFE_ENTRY_UPWARD_ALLOWANCE);
-        int lowestFloorY = Math.max(minimumFloorY, startingFloorY - MAX_SAFE_ENTRY_VERTICAL_SEARCH + 1);
+        int startingFloorY = Math.max(minimumFloorY, Math.min(preferredMaximumY, highestY));
-        for (int floorY = startingFloorY; floorY >= lowestFloorY; floorY--) {
+        for (int floorY = startingFloorY; floorY >= minimumFloorY; floorY--) {
             Block floor = world.getBlockAt(x, floorY, z);
             if (!isSafeFloor(floor)) {
                 continue;
@@ -777,6 +804,14 @@ public final class WorldRuntimeControlService {
         return method.invoke(instance);
     }
 
+    private static Method findPlayerMethod(String methodName, Class<?>... parameterTypes) {
+        try {
+            return Player.class.getMethod(methodName, parameterTypes);
+        } catch (NoSuchMethodException ignored) {
+            return null;
+        }
+    }
+
     @FunctionalInterface
     interface TeleportExecutor {
         CompletableFuture<Boolean> teleport(Player player, Location location);
@@ -822,4 +857,56 @@ public final class WorldRuntimeControlService {
             }
         }
     }
+
+    private static final class PlayerViewDistanceRestore {
+        private final Player player;
+        private final AtomicBoolean changed;
+        private final AtomicBoolean restored;
+        private int previousViewDistance;
+
+        private PlayerViewDistanceRestore(Player player) {
+            this.player = player;
+            changed = new AtomicBoolean(false);
+            restored = new AtomicBoolean(false);
+        }
+
+        private void apply() {
+            if (PLAYER_GET_VIEW_DISTANCE_METHOD == null || PLAYER_SET_VIEW_DISTANCE_METHOD == null) {
+                return;
+            }
+            try {
+                Object currentValue = PLAYER_GET_VIEW_DISTANCE_METHOD.invoke(player);
+                if (!(currentValue instanceof Number)) {
+                    return;
+                }
+                int currentViewDistance = ((Number) currentValue).intValue();
+                if (currentViewDistance <= STUDIO_ENTRY_VIEW_DISTANCE) {
+                    return;
+                }
+                PLAYER_SET_VIEW_DISTANCE_METHOD.invoke(player, STUDIO_ENTRY_VIEW_DISTANCE);
+                previousViewDistance = currentViewDistance;
+                changed.set(true);
+            } catch (ReflectiveOperationException failure) {
+                IrisLogging.reportError("Failed to apply a temporary player view distance for a studio teleport.", failure);
+            }
+        }
+
+        private void restore() {
+            if (!changed.get() || !restored.compareAndSet(false, true)) {
+                return;
+            }
+            Runnable restoration = () -> {
+                try {
+                    PLAYER_SET_VIEW_DISTANCE_METHOD.invoke(player, previousViewDistance);
+                } catch (ReflectiveOperationException failure) {
+                    IrisLogging.reportError("Failed to restore a player's view distance after a studio teleport.", failure);
+                }
+            };
+            if (!J.runEntity(player, restoration)) {
+                IrisLogging.reportError(
+                        "Failed to restore a player's view distance after a studio teleport.",
+                        new IllegalStateException("The player entity scheduler rejected the view-distance restoration."));
+            }
+        }
+    }
 }

core/src/main/java/art/arcane/iris/core/service/StudioSVC.java

@@ -83,7 +83,6 @@ import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
@@ -95,7 +94,6 @@ import art.arcane.volmlib.util.localization.MessageArgument;
 public class StudioSVC implements IrisService {
     public static final String WORKSPACE_NAME = "packs";
     private static final long DOWNLOAD_SHUTDOWN_POLL_SECONDS = 15L;
-    private static final long STUDIO_PLAYER_TELEPORT_TIMEOUT_SECONDS = 10L;
     private static final Pattern PROJECT_NAME = Pattern.compile("[a-z0-9_-]+");
     private static final AtomicCache<Integer> counter = new AtomicCache<>();
     private final StudioTransitionQueue studioTransitions = new StudioTransitionQueue();
@@ -478,24 +476,14 @@ public class StudioSVC implements IrisService {
 
     public CompletableFuture<Boolean> teleportToActiveProject(Player player) {
         Player target = Objects.requireNonNull(player, "Studio teleport player");
-        AtomicBoolean admission = new AtomicBoolean(true);
+        return studioTransitions.submit(() -> {
-        long deadlineNanos = System.nanoTime()
-                + TimeUnit.SECONDS.toNanos(STUDIO_PLAYER_TELEPORT_TIMEOUT_SECONDS);
-        CompletableFuture<Boolean> transition = studioTransitions.submit(() -> {
             IrisProject project = activeProject;
             if (project == null || !project.isOpen()) {
                 return CompletableFuture.failedFuture(new IllegalStateException(
                         "No active Studio project is available for teleport."));
             }
-            return StudioOpenCoordinator.get().teleportPlayerToProject(
+            return StudioOpenCoordinator.get().teleportPlayerToProject(project, target);
-                    project,
-                    target,
-                    admission,
-                    deadlineNanos);
         });
-        transition.orTimeout(STUDIO_PLAYER_TELEPORT_TIMEOUT_SECONDS, TimeUnit.SECONDS);
-        transition.whenComplete((ignored, failure) -> admission.set(false));
-        return transition;
     }
 
     public void open(VolmitSender sender, String dimm) {
@@ -565,13 +553,20 @@ public class StudioSVC implements IrisService {
             StudioOpenCoordinator.StudioOpenKind openKind,
             Consumer<World> onDone
     ) throws IrisException {
+        long requestedAtNanos = System.nanoTime();
         if (reportPackAdmissionFailure(sender, dimm) != null) {
             return;
         }
         StudioOpenCoordinator.StudioOpenKind requiredOpenKind = Objects.requireNonNull(
                 openKind,
                 "Studio open kind");
-        studioTransitions.submit(() -> replaceActiveProject(sender, seed, dimm, requiredOpenKind, onDone))
+        studioTransitions.submit(() -> replaceActiveProject(
+                        sender,
+                        seed,
+                        dimm,
+                        requiredOpenKind,
+                        onDone,
+                        requestedAtNanos))
                 .whenComplete((ignored, throwable) -> {
                     if (throwable == null) {
                         return;
@@ -591,6 +586,7 @@ public class StudioSVC implements IrisService {
             Runnable beforeOpen,
             Consumer<World> onDone
     ) {
+        long requestedAtNanos = System.nanoTime();
         BrokenPackException failure = reportPackAdmissionFailure(sender, dimension);
         if (failure != null) {
             return CompletableFuture.failedFuture(failure);
@@ -601,7 +597,8 @@ public class StudioSVC implements IrisService {
                 dimension,
                 Objects.requireNonNull(openKind, "Studio open kind"),
                 Objects.requireNonNull(beforeOpen, "Studio before-open callback"),
-                Objects.requireNonNull(onDone, "Studio open completion callback")));
+                Objects.requireNonNull(onDone, "Studio open completion callback"),
+                requestedAtNanos));
     }
 
     private CompletableFuture<StudioOpenCoordinator.StudioOpenResult> replaceActiveProjectTracked(
@@ -610,7 +607,8 @@ public class StudioSVC implements IrisService {
             String dimension,
             StudioOpenCoordinator.StudioOpenKind openKind,
             Runnable beforeOpen,
-            Consumer<World> onDone
+            Consumer<World> onDone,
+            long requestedAtNanos
     ) {
         return closeActiveProject().thenCompose(closeResult -> {
             if (closeResult == null) {
@@ -621,7 +619,13 @@ public class StudioSVC implements IrisService {
                 return CompletableFuture.failedFuture(closeResult.failureCause());
             }
             beforeOpen.run();
-            return beginStudioOpenTracked(sender, seed, dimension, openKind, onDone);
+            return beginStudioOpenTracked(
+                    sender,
+                    seed,
+                    dimension,
+                    openKind,
+                    onDone,
+                    requestedAtNanos);
         });
     }
 
@@ -630,13 +634,14 @@ public class StudioSVC implements IrisService {
             long seed,
             String dimension,
             StudioOpenCoordinator.StudioOpenKind openKind,
-            Consumer<World> onDone
+            Consumer<World> onDone,
+            long requestedAtNanos
     ) {
         IrisProject project = new IrisProject(new File(getWorkspaceFolder(), dimension));
         activeProject = project;
         CompletableFuture<StudioOpenCoordinator.StudioOpenResult> opening;
         try {
-            opening = project.open(sender, seed, openKind, onDone);
+            opening = project.open(sender, seed, openKind, onDone, requestedAtNanos);
         } catch (IrisException exception) {
             if (activeProject == project) {
                 activeProject = null;
@@ -663,7 +668,8 @@ public class StudioSVC implements IrisService {
             long seed,
             String dimension,
             StudioOpenCoordinator.StudioOpenKind openKind,
-            Consumer<World> onDone
+            Consumer<World> onDone,
+            long requestedAtNanos
     ) {
         return closeActiveProjectForReplacement(sender).handle((closeResult, closeThrowable) -> {
             if (closeThrowable != null) {
@@ -691,7 +697,13 @@ public class StudioSVC implements IrisService {
             }
             return true;
         }).thenCompose(closed -> closed
-                ? beginStudioOpen(sender, seed, dimension, openKind, onDone)
+                ? beginStudioOpen(
+                        sender,
+                        seed,
+                        dimension,
+                        openKind,
+                        onDone,
+                        requestedAtNanos)
                 : CompletableFuture.completedFuture(null));
     }
 
@@ -700,7 +712,8 @@ public class StudioSVC implements IrisService {
             long seed,
             String dimension,
             StudioOpenCoordinator.StudioOpenKind openKind,
-            Consumer<World> onDone
+            Consumer<World> onDone,
+            long requestedAtNanos
     ) {
         IrisProject project = new IrisProject(new File(getWorkspaceFolder(), dimension));
         activeProject = project;
@@ -710,7 +723,8 @@ public class StudioSVC implements IrisService {
                     sender,
                     seed,
                     openKind,
-                    onDone);
+                    onDone,
+                    requestedAtNanos);
         } catch (IrisException e) {
             if (activeProject == project) {
                 activeProject = null;

core/src/main/java/art/arcane/iris/core/tools/IrisCreator.java

@@ -306,6 +306,9 @@ public class IrisCreator {
                 world = J.sfut(() -> INMS.get().createWorldAsync(wc, request))
                         .thenCompose(Function.identity())
                         .get(WORLD_CREATE_TIMEOUT_SECONDS, TimeUnit.SECONDS);
+                if (!studio && !benchmark) {
+                    awaitInitialSpawnPreparation(access, name);
+                }
             } catch (Throwable e) {
                 done.set(true);
                 cancelRepeatingTask(createProgressTask);
@@ -603,6 +606,21 @@ public class IrisCreator {
         return taskId;
     }
 
+    static void awaitInitialSpawnPreparation(
+            PlatformChunkGenerator generator,
+            String worldName
+    ) throws InterruptedException, ExecutionException, TimeoutException {
+        CompletableFuture<Void> initialSpawnReady = Objects.requireNonNull(
+                generator.getInitialSpawnReady(),
+                "Initial spawn preparation future");
+        try {
+            initialSpawnReady.get(WORLD_CREATE_TIMEOUT_SECONDS, TimeUnit.SECONDS);
+        } catch (TimeoutException failure) {
+            throw new TimeoutException("Initial spawn preparation timed out for world \""
+                    + worldName + "\".");
+        }
+    }
+
     private AtomicInteger startPregenProgressReporter(
             AtomicDouble progress,
             AtomicBoolean done,

core/src/main/java/art/arcane/iris/engine/IrisComplex.java

@@ -29,10 +29,14 @@ import art.arcane.iris.engine.object.IrisDecorationPart;
 import art.arcane.iris.engine.object.IrisDecorator;
 import art.arcane.iris.engine.object.IrisGenerator;
 import art.arcane.iris.engine.object.IrisInterpolator;
+import art.arcane.iris.engine.object.IrisMaterialPalette;
 import art.arcane.iris.engine.object.IrisRegion;
+import art.arcane.iris.engine.object.IrisRiverCaves;
+import art.arcane.iris.engine.object.IrisRiverDeepPools;
+import art.arcane.iris.engine.object.IrisRiverNetwork;
 import art.arcane.iris.engine.object.IrisRiverOverride;
 import art.arcane.iris.engine.object.IrisRiverRoutingPolicy;
-import art.arcane.iris.engine.object.IrisRiverWaterMode;
+import art.arcane.iris.engine.object.IrisRiverWater;
 import art.arcane.iris.engine.object.IrisShapedGeneratorStyle;
 import art.arcane.iris.engine.river.runtime.IrisRiverRuntime;
 import art.arcane.iris.engine.river.runtime.IrisRiverRuntimeContext;
@@ -40,6 +44,7 @@ import art.arcane.iris.engine.river.runtime.IrisRiverSurfaceSample;
 import art.arcane.iris.engine.river.RiverRouteState;
 import art.arcane.iris.engine.river.RiverSample;
 import art.arcane.iris.engine.river.RiverSection;
+import art.arcane.iris.engine.river.cave.RiverCaveFluidKind;
 import art.arcane.iris.spi.IrisPlatforms;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.iris.spi.PlatformBiome;
@@ -66,6 +71,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.IdentityHashMap;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.UUID;
 import java.util.concurrent.atomic.AtomicLong;
@@ -132,6 +138,8 @@ public class IrisComplex implements DataProvider {
     private ProceduralStream<IrisDecorator> shoreSurfaceDecoration;
     private ProceduralStream<PlatformBlockState> rockStream;
     private ProceduralStream<PlatformBlockState> fluidStream;
+    private ProceduralStream<PlatformBlockState> riverFluidStream;
+    private ProceduralStream<PlatformBlockState> riverDeepPoolFluidStream;
     private IrisBiome focusBiome;
     private IrisRegion focusRegion;
     private Map<IrisInterpolator, IdentityHashMap<IrisBiome, GeneratorBounds>> generatorBounds;
@@ -213,6 +221,29 @@ public class IrisComplex implements DataProvider {
                 .select(engine.getDimension().getRockPalette().getBlockData(data));
         fluidStream = engine.getDimension().getFluidPalette().getLayerGenerator(rng.nextParallelRNG(78), data).stream()
                 .select(engine.getDimension().getFluidPalette().getBlockData(data));
+        IrisRiverNetwork configuredRivers = engine.getDimension().getRivers();
+        IrisRiverWater configuredRiverWater = configuredRivers == null ? null : configuredRivers.getWater();
+        riverFluidStream = configuredRivers != null && configuredRivers.isEnabled()
+                ? configuredFluidStream(
+                        Objects.requireNonNull(configuredRiverWater).getFluidPalette(),
+                        rng.nextParallelRNG(79),
+                        "River water"
+                )
+                : fluidStream;
+        IrisRiverCaves configuredRiverCaves = configuredRivers == null ? null : configuredRivers.getCaves();
+        IrisRiverDeepPools configuredDeepPools = configuredRiverCaves == null
+                ? null
+                : configuredRiverCaves.getDeepPools();
+        riverDeepPoolFluidStream = configuredRivers != null
+                && configuredRivers.isEnabled()
+                && configuredDeepPools != null
+                && configuredDeepPools.isEnabled()
+                ? configuredFluidStream(
+                        configuredDeepPools.getFluidPalette(),
+                        rng.nextParallelRNG(80),
+                        "River deep-pool"
+                )
+                : riverFluidStream;
         regionStyleStream = engine.getDimension().getRegionStyle().create(rng.nextParallelRNG(883), getData()).stream()
                 .zoom(engine.getDimension().getRegionZoom());
         regionIdentityStream = regionStyleStream.fit(Integer.MIN_VALUE, Integer.MAX_VALUE);
@@ -303,16 +334,16 @@ public class IrisComplex implements DataProvider {
                 .cache2D("naturalTrueBiomeStream", engine, cacheSize);
         if (engine.getDimension().getRivers() != null && engine.getDimension().getRivers().isEnabled()) {
             ProceduralStream<Boolean> naturalOceanStream = createNaturalOceanStream(
-                    naturalHeightStream,
                     bridgeStream,
-                    focusBiome,
+                    focusBiome
-                    fluidHeight,
-                    engine.getDimension().getRivers().getWater().getMode()
             ).cache2D("naturalOceanStream", engine, cacheSize);
+            int riverFluidHeight = engine.getDimension().getRivers().getWater().getFluidHeight()
+                    - engine.getDimension().getMinHeight();
             riverRuntime = new IrisRiverRuntime(new IrisRiverRuntimeContext(
                     engine.getSeedManager().getBodies(),
                     engine.getDimension().getRivers(),
                     data,
+                    riverFluidHeight,
                     (int) Math.round(fluidHeight),
                     IrisEngineMantle.isRiverHydrologyEnabled(engine.getDimension()),
                     IrisEngineMantle.isRiverCaveHydrologyEnabled(engine.getDimension()),
@@ -458,23 +489,49 @@ public class IrisComplex implements DataProvider {
     }
 
     static ProceduralStream<Boolean> createNaturalOceanStream(
-            ProceduralStream<Double> naturalHeightStream,
             ProceduralStream<InferredType> bridgeStream,
-            IrisBiome focusBiome,
+            IrisBiome focusBiome
-            double fluidHeight,
-            IrisRiverWaterMode waterMode
     ) {
         if (focusBiome != null) {
             boolean ocean = focusBiome.getInferredType() == InferredType.SEA;
             return ProceduralStream.of((x, z) -> ocean, Interpolated.BOOLEAN);
         }
-        if (waterMode == IrisRiverWaterMode.SEA_LEVEL) {
         return bridgeStream.convert(type -> type == InferredType.SEA);
     }
-        return ProceduralStream.of(
+
-                (x, z) -> naturalHeightStream.getDouble(x, z) < fluidHeight - 1D,
+    private ProceduralStream<PlatformBlockState> configuredFluidStream(
-                Interpolated.BOOLEAN
+            IrisMaterialPalette palette,
-        );
+            RNG fluidRng,
+            String configurationName
+    ) {
+        Objects.requireNonNull(palette, configurationName + " fluidPalette must be configured");
+        KList<PlatformBlockState> blocks = palette.getBlockData(data);
+        if (blocks.isEmpty()) {
+            throw new IllegalArgumentException(
+                    configurationName + " fluidPalette must resolve at least one fluid block");
+        }
+        for (PlatformBlockState block : blocks) {
+            if (block == null || !block.isFluid()) {
+                throw new IllegalArgumentException(
+                        configurationName + " fluidPalette may contain only fluid blocks");
+            }
+        }
+        return palette.getLayerGenerator(fluidRng, data).stream().select(blocks);
+    }
+
+    public PlatformBlockState resolveRiverCaveFluid(RiverCaveFluidKind fluidKind, double x, double z) {
+        return switch (Objects.requireNonNull(fluidKind)) {
+            case RIVER -> riverFluidStream.get(x, z);
+            case DEEP_POOL -> riverDeepPoolFluidStream.get(x, z);
+        };
+    }
+
+    public PlatformBlockState resolveSurfaceFluid(double x, double z) {
+        IrisRiverSurfaceSample sample = riverSurfaceStream.get(x, z);
+        if (sample.river().present() && sample.surfaceFluid()) {
+            return riverFluidStream.get(x, z);
+        }
+        return fluidStream.get(x, z);
     }
 
     public ProceduralStream<IrisBiome> getBiomeStream(InferredType type) {

core/src/main/java/art/arcane/iris/engine/IrisEngine.java

@@ -71,6 +71,7 @@ import java.util.Locale;
 import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -93,6 +94,7 @@ public class IrisEngine implements Engine {
     private final ChronoLatch perSecondLatch;
     private final ChronoLatch perSecondBudLatch;
     private final EngineMetrics metrics;
+    private final CompletableFuture<Void> generationCacheWarm;
     private final boolean studio;
     private final AtomicRollingSequence wallClock;
     @Getter(AccessLevel.NONE)
@@ -186,6 +188,7 @@ public class IrisEngine implements Engine {
         bud = new AtomicInteger(0);
         buds = new AtomicInteger(0);
         metrics = new EngineMetrics(32);
+        generationCacheWarm = new CompletableFuture<>();
         cleanLatch = new ChronoLatch(10000);
         generatedLast = new AtomicInteger(0);
         perSecond = new AtomicDouble(0);
@@ -232,16 +235,17 @@ public class IrisEngine implements Engine {
             runtimeBuilder.publishRuntime(initialRuntime, null);
             IrisLogging.debug("[IrisEngine timing] setupEngine total=" + (M.ms() - _t0) + "ms");
             logStudioInitializationPhase("build_runtime", phaseStartedAt, false);
-            _t0 = M.ms();
             phaseStartedAt = System.nanoTime();
             if (requiredMode.warmGenerationCaches()) {
-                GenerationCacheWarmer.warm(this);
+                if (requiredMode.studio()) {
+                    startGenerationCacheWarm(phaseStartedAt);
+                } else {
+                    warmGenerationCaches(phaseStartedAt);
+                }
+            } else {
+                generationCacheWarm.complete(null);
+                logStudioInitializationPhase("generation_cache_warm", phaseStartedAt, true);
             }
-            IrisLogging.debug("[IrisEngine timing] cache warm total=" + (M.ms() - _t0) + "ms");
-            logStudioInitializationPhase(
-                    "generation_cache_warm",
-                    phaseStartedAt,
-                    !requiredMode.warmGenerationCaches());
             EngineTickRegistry.registerTicking(this);
         } catch (Throwable e) {
             shutdownSequence.cleanupFailedConstruction(e);
@@ -250,6 +254,21 @@ public class IrisEngine implements Engine {
         IrisLogging.debug("Engine Initialized " + getCacheID());
     }
 
+    public void awaitGenerationCacheWarm() {
+        if (generationCacheWarm.isDone() && !generationCacheWarm.isCompletedExceptionally()) {
+            return;
+        }
+        try {
+            generationCacheWarm.join();
+        } catch (CompletionException failure) {
+            throw new IllegalStateException("Iris generation caches did not become ready.", failure.getCause());
+        }
+    }
+
+    public boolean isGenerationCacheWarmPending() {
+        return !generationCacheWarm.isDone();
+    }
+
     private void logStudioInitializationPhase(String phase, long startedAtNanos, boolean skipped) {
         if (!studio) {
             return;
@@ -262,6 +281,32 @@ public class IrisEngine implements Engine {
                 Boolean.toString(skipped));
     }
 
+    private void startGenerationCacheWarm(long phaseStartedAtNanos) {
+        if (!backgroundTasks.scheduleTrackedTask(() -> warmGenerationCaches(phaseStartedAtNanos))) {
+            throw new IllegalStateException("Iris background task admission closed before generation cache warming.");
+        }
+    }
+
+    private void warmGenerationCaches(long phaseStartedAtNanos) {
+        long startedAtMillis = M.ms();
+        try {
+            GenerationCacheWarmer.warm(this);
+            generationCacheWarm.complete(null);
+        } catch (Throwable failure) {
+            generationCacheWarm.completeExceptionally(failure);
+            if (failure instanceof Error error) {
+                throw error;
+            }
+            if (failure instanceof RuntimeException runtimeException) {
+                throw runtimeException;
+            }
+            throw new IllegalStateException("Generation cache warming failed.", failure);
+        } finally {
+            IrisLogging.debug("[IrisEngine timing] cache warm total=" + (M.ms() - startedAtMillis) + "ms");
+            logStudioInitializationPhase("generation_cache_warm", phaseStartedAtNanos, false);
+        }
+    }
+
     private void verifySeed() {
         if (getEngineData().getSeed() != null && getEngineData().getSeed() != target.getWorld().getRawWorldSeed()) {
             target.getWorld().setRawWorldSeed(getEngineData().getSeed());
@@ -323,6 +368,7 @@ public class IrisEngine implements Engine {
 
     @Override
     public void generateMatter(int x, int z, boolean multicore, ChunkContext context) {
+        awaitGenerationCacheWarm();
         try (GenerationSessionLease lease = acquireGenerationLease("matter_generate");
              IrisContext.Scope ignored = IrisContext.open(this, lease.sessionId(), context)) {
             IrisComplex activeComplex = getComplex();
@@ -574,6 +620,7 @@ public class IrisEngine implements Engine {
     @BlockCoordinates
     @Override
     public void generate(int x, int z, Hunk<PlatformBlockState> vblocks, Hunk<PlatformBiome> vbiomes, boolean multicore) throws WrongEngineBroException {
+        awaitGenerationCacheWarm();
         try (GenerationSessionLease lease = acquireGenerationLease("chunk_generate");
              IrisContext.Scope generationScope = IrisContext.open(this, lease.sessionId(), null)) {
             getEngineData().getStatistics().generatedChunk();

core/src/main/java/art/arcane/iris/engine/IrisWorldManager.java

@@ -48,7 +48,6 @@ import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
 
 @EqualsAndHashCode(callSuper = true)
 @Data
@@ -78,7 +77,7 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
     final WorldBlockDropRouter blockDropRouter = new WorldBlockDropRouter(this);
     @Getter(AccessLevel.NONE)
     @Setter(AccessLevel.NONE)
-    final WorldTeleportWarmup teleportWarmup = new WorldTeleportWarmup(this);
+    final WorldTeleportWarmup teleportWarmup = new WorldTeleportWarmup();
     private boolean looperStopped;
     private volatile boolean cleanupServiceStopped;
     volatile int entityCount = 0;
@@ -193,10 +192,6 @@ public class IrisWorldManager extends EngineAssignedWorldManager {
         };
     }
 
-    AtomicBoolean ignoreTeleport() {
-        return ignoreTP;
-    }
-
     @Override
     public void onTick() {
 

core/src/main/java/art/arcane/iris/engine/WorldTeleportWarmup.java

@@ -18,87 +18,53 @@
 
 package art.arcane.iris.engine;
 
-import art.arcane.iris.core.localization.IrisLanguage;
+import art.arcane.iris.platform.bukkit.BukkitPlatform;
-import art.arcane.iris.core.localization.RuntimeUiMessages;
 import art.arcane.iris.spi.IrisLogging;
-import art.arcane.iris.util.common.parallel.MultiBurst;
-import art.arcane.iris.util.common.plugin.VolmitSender;
-import art.arcane.iris.util.common.scheduling.J;
-import art.arcane.iris.util.common.scheduling.jobs.QueueJob;
-import art.arcane.volmlib.util.collection.KList;
-import io.papermc.lib.PaperLib;
-import org.bukkit.Chunk;
 import org.bukkit.Location;
 import org.bukkit.entity.Player;
 import org.bukkit.event.player.PlayerTeleportEvent;
 
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Future;
 
-/**
- * Cancels a teleport, loads the destination chunks off the main thread and then replays the teleport
- * on the thread that owns the player. The replay sets the manager's ignore flag so the reissued
- * teleport is not intercepted again.
- */
 final class WorldTeleportWarmup {
-    private final IrisWorldManager manager;
-
-    WorldTeleportWarmup(IrisWorldManager manager) {
-        this.manager = manager;
-    }
-
     void teleportAsync(PlayerTeleportEvent e) {
+        Location destination = e.getTo();
+        if (destination == null) {
+            return;
+        }
+
+        Player player = e.getPlayer();
+        PlayerTeleportEvent.TeleportCause cause = e.getCause();
         e.setCancelled(true);
-        warmupAreaAsync(e.getPlayer(), e.getTo(), () -> J.runEntity(e.getPlayer(), manager.managedTask(
+        CompletableFuture<Boolean> teleport;
-                "bukkit_world_manager_teleport",
-                () -> {
-            manager.ignoreTeleport().set(true);
-            e.getPlayer().teleport(e.getTo(), e.getCause());
-            manager.ignoreTeleport().set(false);
-        })));
-    }
-
-    private void warmupAreaAsync(Player player, Location to, Runnable r) {
-        J.a(manager.managedTask("bukkit_world_manager_teleport_warmup", () -> {
-            int viewDistance = 2;
-            KList<Future<Chunk>> futures = new KList<>();
-            for (int i = -viewDistance; i <= viewDistance; i++) {
-                for (int j = -viewDistance; j <= viewDistance; j++) {
-                    int finalJ = j;
-                    int finalI = i;
-
-                    if (to.getWorld().isChunkLoaded((to.getBlockX() >> 4) + i, (to.getBlockZ() >> 4) + j)) {
-                        futures.add(CompletableFuture.completedFuture(null));
-                        continue;
-                    }
-
-                    futures.add(MultiBurst.burst.completeValue(()
-                            -> PaperLib.getChunkAtAsync(to.getWorld(),
-                            (to.getBlockX() >> 4) + finalI,
-                            (to.getBlockZ() >> 4) + finalJ,
-                            true, false).get()));
-                }
-            }
-
-            new QueueJob<Future<Chunk>>() {
-                @Override
-                public void execute(Future<Chunk> chunkFuture) {
         try {
-                        chunkFuture.get();
+            teleport = BukkitPlatform.teleportAsync(
-                    } catch (InterruptedException ex) {
+                    player,
-                        Thread.currentThread().interrupt();
+                    destination.clone(),
-                        IrisLogging.debug("Chunk warmup interrupted while loading async teleport chunk.");
+                    cause);
-                    } catch (ExecutionException ex) {
+        } catch (Throwable failure) {
-                        IrisLogging.reportError(ex);
+            reportFailure(player, destination, failure);
+            return;
         }
+        if (teleport == null) {
+            reportFailure(player, destination, new IllegalStateException(
+                    "Async teleport returned no completion future."));
+            return;
+        }
+        teleport.whenComplete((success, failure) -> {
+            if (failure != null) {
+                reportFailure(player, destination, failure);
+            } else if (!Boolean.TRUE.equals(success)) {
+                reportFailure(player, destination, new IllegalStateException(
+                        "Async teleport did not complete successfully."));
+            }
+        });
     }
 
-                @Override
+    private void reportFailure(Player player, Location destination, Throwable failure) {
-                public String getName() {
+        IrisLogging.error("Async teleport into Iris world failed for " + player.getName()
-                    return IrisLanguage.text(RuntimeUiMessages.JOB_LOADING_CHUNKS);
+                + " at " + destination.getBlockX() + ", " + destination.getBlockY() + ", "
-                }
+                + destination.getBlockZ() + ".");
-            }.queue(futures).execute(new VolmitSender(player), true, r);
+        IrisLogging.reportError(failure);
-        }));
     }
 }

core/src/main/java/art/arcane/iris/engine/actuator/IrisDecorantActuator.java

@@ -102,7 +102,7 @@ public class IrisDecorantActuator extends EngineAssignedActuator<PlatformBlockSt
                 }
 
                 if (height < surfaceFluidHeight && PREDICATE_SOLID.test(output.get(i, height, j))
-                        && height + 1 < output.getHeight() && B.isWater(output.get(i, height + 1, j))) {
+                        && height + 1 < output.getHeight() && B.isFluid(output.get(i, height + 1, j))) {
                     getSeaSurfaceDecorator().decorate(i, j,
                             realX, Math.round(i + 1), Math.round(x + i - 1),
                             realZ, Math.round(z + j + 1), Math.round(z + j - 1),

core/src/main/java/art/arcane/iris/engine/actuator/IrisTerrainNormalActuator.java

@@ -92,7 +92,6 @@ public class IrisTerrainNormalActuator extends EngineAssignedActuator<PlatformBl
         boolean hideOres = dimension.isHideOresForHiddenOre();
         ChunkedDataCache<IrisBiome> biomeCache = context.getBiome();
         ChunkedDataCache<IrisRegion> regionCache = context.getRegion();
-        ChunkedDataCache<PlatformBlockState> fluidCache = context.getFluid();
         ChunkedDataCache<PlatformBlockState> rockCache = context.getRock();
         int realX = xf + x;
         UpperDimensionContext upperContext = getEngine().getUpperContext();
@@ -118,7 +117,7 @@ public class IrisTerrainNormalActuator extends EngineAssignedActuator<PlatformBl
             }
 
             int topY = Math.min(hf, chunkHeight - 1);
-            PlatformBlockState fluid = fluidCache.get(xf, zf);
+            PlatformBlockState fluid = complex.resolveSurfaceFluid(realX, realZ);
             PlatformBlockState rock = rockCache.get(xf, zf);
             PlatformBlockState mappedSurfaceBlock = complex.getImageMapRuntime().sampleSurfaceBlock(realX, realZ);
             KList<IrisOreGenerator> biomeSurfaceOres = hideOres ? null : biome.getSurfaceOreGenerators();

core/src/main/java/art/arcane/iris/engine/framework/EngineAssignedWorldManager.java

@@ -26,12 +26,16 @@ import art.arcane.iris.core.events.IrisEngineHotloadEvent;
 import art.arcane.iris.util.common.format.C;
 import art.arcane.iris.util.common.plugin.VolmitSender;
 import art.arcane.iris.util.common.scheduling.J;
+import org.bukkit.Location;
 import org.bukkit.Sound;
+import org.bukkit.World;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.block.BlockBreakEvent;
 import org.bukkit.event.block.BlockPlaceEvent;
+import org.bukkit.event.player.PlayerTeleportEvent;
 import org.bukkit.event.world.ChunkLoadEvent;
 import org.bukkit.event.world.ChunkUnloadEvent;
 import org.bukkit.event.world.WorldSaveEvent;
@@ -45,7 +49,6 @@ public abstract class EngineAssignedWorldManager extends EngineAssignedComponent
     private boolean listenerRegistered;
     private boolean closeRequested;
     private int taskId;
-    protected AtomicBoolean ignoreTP = new AtomicBoolean(false);
 
     public EngineAssignedWorldManager() {
         super(null, null);
@@ -126,6 +129,29 @@ public abstract class EngineAssignedWorldManager extends EngineAssignedComponent
         });
     }
 
+    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
+    public void on(PlayerTeleportEvent e) {
+        if (!BukkitPlatform.isPaperServer()
+                || !getEngine().isStudio()
+                || e.getCause() != PlayerTeleportEvent.TeleportCause.COMMAND) {
+            return;
+        }
+
+        Location destination = e.getTo();
+        World targetWorld = BukkitWorldBinding.world(getTarget().getWorld());
+        if (destination == null || targetWorld == null || !targetWorld.equals(destination.getWorld())) {
+            return;
+        }
+
+        int chunkX = destination.getBlockX() >> 4;
+        int chunkZ = destination.getBlockZ() >> 4;
+        if (targetWorld.isChunkLoaded(chunkX, chunkZ)) {
+            return;
+        }
+
+        runManagerTask("bukkit_world_manager_teleport_event", () -> teleportAsync(e));
+    }
+
     @EventHandler
     public void on(ChunkLoadEvent e) {
         runManagerTask("bukkit_world_manager_chunk_load", () -> {

core/src/main/java/art/arcane/iris/engine/mantle/MantleComponent.java

@@ -38,6 +38,19 @@ public interface MantleComponent extends Comparable<MantleComponent> {
         return 0;
     }
 
+    default int getInputRadius(
+            int targetChunkX,
+            int targetChunkZ,
+            int invocationChunkRadius,
+            ChunkContext context
+    ) {
+        return getInputRadius();
+    }
+
+    default boolean isInputGenerationLazy() {
+        return false;
+    }
+
     default IrisData getData() {
         return getEngineMantle().getData();
     }

core/src/main/java/art/arcane/iris/engine/mantle/MantleWriter.java

@@ -66,9 +66,21 @@ public class MantleWriter implements IObjectPlacer, AutoCloseable {
     private final AtomicReferenceArray<MantleChunk<Matter>> window;
 
     public MantleWriter(EngineMantle engineMantle, Mantle<Matter> mantle, int x, int z, int radius, boolean multicore) {
+        this(engineMantle, mantle, x, z, radius, radius * 2, multicore);
+    }
+
+    public MantleWriter(
+            EngineMantle engineMantle,
+            Mantle<Matter> mantle,
+            int x,
+            int z,
+            int prefetchRadius,
+            int accessRadius,
+            boolean multicore
+    ) {
         this.engineMantle = engineMantle;
         this.mantle = mantle;
-        this.radius = radius * 2;
+        this.radius = accessRadius;
         this.x = x;
         this.z = z;
         // Every coordinate acquireChunk accepts lives in this window, so a flat array replaces the
@@ -78,7 +90,10 @@ public class MantleWriter implements IObjectPlacer, AutoCloseable {
 
         final boolean foliaMaintenance = J.isFolia()
                 && WorldMaintenance.isWorldMaintenanceActive(engineMantle.getEngine().getWorld().identity());
-        final int parallelism = foliaMaintenance ? 1 : (multicore ? Runtime.getRuntime().availableProcessors() / 2 : 4);
+        final int parallelism = resolvePrefetchParallelism(
+                foliaMaintenance,
+                multicore,
+                Runtime.getRuntime().availableProcessors());
         if (foliaMaintenance && IrisSettings.get().getGeneral().isDebug()) {
             IrisLogging.info("MantleWriter using sequential chunk prefetch for maintenance regen at " + x + "," + z + ".");
         }
@@ -86,10 +101,10 @@ public class MantleWriter implements IObjectPlacer, AutoCloseable {
         // prefetch must release the permits already pinned into the window here.
         try {
             mantle.getChunks(
-                    x - radius,
+                    x - prefetchRadius,
-                    x + radius,
+                    x + prefetchRadius,
-                    z - radius,
+                    z - prefetchRadius,
-                    z + radius,
+                    z + prefetchRadius,
                     parallelism,
                     this::storePrefetchedChunk
             );
@@ -99,6 +114,16 @@ public class MantleWriter implements IObjectPlacer, AutoCloseable {
         }
     }
 
+    static int resolvePrefetchParallelism(boolean foliaMaintenance, boolean multicore, int availableProcessors) {
+        if (foliaMaintenance) {
+            return 1;
+        }
+        if (!multicore) {
+            return 4;
+        }
+        return Math.max(1, availableProcessors / 2);
+    }
+
     private static Set<IrisPosition> getBallooned(Set<IrisPosition> vset, double radius) {
         Set<IrisPosition> returnset = new HashSet<>();
         int ceilrad = (int) Math.ceil(radius);

core/src/main/java/art/arcane/iris/engine/mantle/MatterGenerator.java

@@ -4,6 +4,7 @@ import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.iris.util.common.parallel.MultiBurst;
 import art.arcane.iris.util.project.context.ChunkContext;
+import art.arcane.iris.util.project.context.IrisContext;
 import art.arcane.volmlib.util.documentation.ChunkCoordinates;
 import art.arcane.volmlib.util.mantle.flag.MantleFlag;
 import art.arcane.volmlib.util.mantle.runtime.Mantle;
@@ -43,18 +44,31 @@ public interface MatterGenerator {
             return;
         }
 
-        int writeRadius = getRadius();
+        MatterGenerationPlan generationPlan = resolveGenerationPlan(x, z, context);
+        MatterPassPlan[] passPlans = generationPlan.passPlans();
+        if (passPlans.length == 0) {
+            return;
+        }
+        int prefetchRadius = passPlans[0].passChunkRadius();
         LongOpenHashSet partialChunks = new LongOpenHashSet();
 
-        try (MantleWriter writer = new MantleWriter(getEngine().getMantle(), getMantle(), x, z, writeRadius, multicore)) {
+        try (MantleWriter writer = new MantleWriter(
+                getEngine().getMantle(),
+                getMantle(),
+                x,
+                z,
+                prefetchRadius,
+                generationPlan.writerAccessRadius(),
+                multicore)) {
             // Every task launched below writes through this writer. They must all be finished before
             // close() releases the cached chunks, even when a pass throws, or detached pool threads
             // write into released chunks.
             List<MatterComponentTask> outstandingTasks = null;
 
             try {
-                for (MantlePass pass : getComponents()) {
+                for (MatterPassPlan passPlan : passPlans) {
-                    int passRadius = pass.passChunkRadius();
+                    MantlePass pass = passPlan.pass();
+                    int passRadius = passPlan.passChunkRadius();
                     List<MantleComponent> passComponents = pass.components();
                     MantleComponent[] enabledComponents = new MantleComponent[passComponents.size()];
                     int[] componentPassRadii = new int[passComponents.size()];
@@ -63,7 +77,7 @@ public interface MatterGenerator {
                         if (component.isEnabled()) {
                             // A component must cover its own reach plus every later pass' reach, or a
                             // later pass reads this component's data from chunks it never wrote.
-                            int componentReach = component.getRadius() + pass.downstreamBlockRadius();
+                            int componentReach = component.getRadius() + passPlan.downstreamBlockRadius();
                             componentPassRadii[enabledComponentCount] = componentReach > 0 ? Math.ceilDiv(componentReach, 16) : 0;
                             enabledComponents[enabledComponentCount++] = component;
                         }
@@ -112,7 +126,8 @@ public interface MatterGenerator {
                             MantleChunk<Matter> chunk = writer.acquireChunk(passX, passZ);
                             if (chunk == null) {
                                 throw new IllegalStateException("Mantle pass chunk " + passX + "," + passZ
-                                        + " is outside the writer prepared at " + x + "," + z + " with radius " + writeRadius);
+                                        + " is outside the writer prepared at " + x + "," + z
+                                        + " with radius " + generationPlan.writerAccessRadius());
                             }
 
                             if (chunk.isFlagged(MantleFlag.PLANNED)) {
@@ -174,8 +189,9 @@ public interface MatterGenerator {
                     }
                 }
 
-                for (int i = -getRealRadius(); i <= getRealRadius(); i++) {
+                int realRadius = passPlans[passPlans.length - 1].passChunkRadius();
-                    for (int j = -getRealRadius(); j <= getRealRadius(); j++) {
+                for (int i = -realRadius; i <= realRadius; i++) {
+                    for (int j = -realRadius; j <= realRadius; j++) {
                         int realX = x + i;
                         int realZ = z + j;
                         long realKey = chunkKey(realX, realZ);
@@ -195,6 +211,45 @@ public interface MatterGenerator {
         return (((long) x) << 32) ^ (z & 0xffffffffL);
     }
 
+    private MatterGenerationPlan resolveGenerationPlan(int x, int z, ChunkContext context) {
+        List<MantlePass> passes = getComponents();
+        MatterPassPlan[] plans = new MatterPassPlan[passes.size()];
+        int accessDownstreamBlockRadius = 0;
+        int generationDownstreamBlockRadius = 0;
+        for (int passIndex = passes.size() - 1; passIndex >= 0; passIndex--) {
+            MantlePass pass = passes.get(passIndex);
+            int passBlockRadius = 0;
+            int passAccessInputRadius = 0;
+            int passGenerationInputRadius = 0;
+            for (MantleComponent component : pass.components()) {
+                if (!component.isEnabled()) {
+                    continue;
+                }
+                int componentRadius = component.getRadius();
+                passBlockRadius = Math.max(passBlockRadius, componentRadius);
+                int componentReach = componentRadius + generationDownstreamBlockRadius;
+                int invocationChunkRadius = componentReach > 0
+                        ? Math.ceilDiv(componentReach, 16)
+                        : 0;
+                int componentInputRadius = component.getInputRadius(x, z, invocationChunkRadius, context);
+                passAccessInputRadius = Math.max(passAccessInputRadius, componentInputRadius);
+                if (!component.isInputGenerationLazy()) {
+                    passGenerationInputRadius = Math.max(passGenerationInputRadius, componentInputRadius);
+                }
+            }
+            int accessInvocationRadius = accessDownstreamBlockRadius + passBlockRadius;
+            int generationInvocationRadius = generationDownstreamBlockRadius + passBlockRadius;
+            int passChunkRadius = generationInvocationRadius > 0 ? Math.ceilDiv(generationInvocationRadius, 16) : 0;
+            plans[passIndex] = new MatterPassPlan(pass, passChunkRadius, generationDownstreamBlockRadius);
+            accessDownstreamBlockRadius = accessInvocationRadius + passAccessInputRadius;
+            generationDownstreamBlockRadius = generationInvocationRadius + passGenerationInputRadius;
+        }
+        int writerChunkRadius = accessDownstreamBlockRadius > 0
+                ? Math.ceilDiv(accessDownstreamBlockRadius, 16)
+                : 0;
+        return new MatterGenerationPlan(plans, writerChunkRadius * 2);
+    }
+
     private MatterComponentTask runComponentAsync(
             MantleChunk<Matter> chunk,
             MantleComponent component,
@@ -217,11 +272,21 @@ public interface MatterGenerator {
 
         try {
             if (DISPATCHER.ownsCurrentThread()) {
-                completeComponentTask(future, key, chunk, component, writer, chunkX, chunkZ, context);
+                completeComponentTask(future, key, chunk, component, writer, chunkX, chunkZ, context, IrisContext.get());
                 return new MatterComponentTask(key, future, null);
             }
 
-            Future<?> submission = DISPATCHER.submit(() -> completeComponentTask(future, key, chunk, component, writer, chunkX, chunkZ, context));
+            IrisContext callerContext = IrisContext.get();
+            Future<?> submission = DISPATCHER.submit(() -> completeComponentTask(
+                    future,
+                    key,
+                    chunk,
+                    component,
+                    writer,
+                    chunkX,
+                    chunkZ,
+                    context,
+                    callerContext));
             return new MatterComponentTask(key, future, submission);
         } catch (Throwable throwable) {
             IN_FLIGHT_COMPONENTS.remove(key, future);
@@ -329,10 +394,11 @@ public interface MatterGenerator {
             MantleWriter writer,
             int chunkX,
             int chunkZ,
-            ChunkContext context
+            ChunkContext context,
+            IrisContext callerContext
     ) {
         try {
-            runComponentInline(chunk, component, writer, chunkX, chunkZ, context);
+            runComponentWithContext(chunk, component, writer, chunkX, chunkZ, context, callerContext);
             future.complete(null);
         } catch (Throwable throwable) {
             future.completeExceptionally(throwable);
@@ -342,6 +408,28 @@ public interface MatterGenerator {
         }
     }
 
+    private void runComponentWithContext(
+            MantleChunk<Matter> chunk,
+            MantleComponent component,
+            MantleWriter writer,
+            int chunkX,
+            int chunkZ,
+            ChunkContext context,
+            IrisContext callerContext
+    ) {
+        if (callerContext == null) {
+            runComponentInline(chunk, component, writer, chunkX, chunkZ, context);
+            return;
+        }
+
+        try (IrisContext.Scope ignored = IrisContext.open(
+                callerContext.getEngine(),
+                callerContext.getGenerationSessionId(),
+                callerContext.getChunkContext())) {
+            runComponentInline(chunk, component, writer, chunkX, chunkZ, context);
+        }
+    }
+
     private void runComponentInline(
             MantleChunk<Matter> chunk,
             MantleComponent component,
@@ -360,6 +448,12 @@ public interface MatterGenerator {
     record MatterComponentTask(MatterTaskKey key, CompletableFuture<Void> future, Future<?> submission) {
     }
 
+    record MatterPassPlan(MantlePass pass, int passChunkRadius, int downstreamBlockRadius) {
+    }
+
+    record MatterGenerationPlan(MatterPassPlan[] passPlans, int writerAccessRadius) {
+    }
+
     final class MatterTaskKey {
         private final Mantle<Matter> mantle;
         private final int chunkX;

core/src/main/java/art/arcane/iris/engine/mantle/components/CaveCarveScratch.java

@@ -27,6 +27,7 @@ final class CaveCarveScratch {
     final int[] fluidMaxY = new int[256];
     final int[] surfaceBreakFloorY = new int[256];
     final boolean[] surfaceBreakColumn = new boolean[256];
+    final boolean[] surfaceCeilingColumn = new boolean[256];
     final double[] columnThreshold = new double[256];
     final double[] passThreshold = new double[256];
     final double[] fullWeights = new double[256];
@@ -62,6 +63,7 @@ final class CaveCarveScratch {
     int activeModulesY = Integer.MIN_VALUE;
     int activeModuleCount;
     double[] verticalEdgeFade = new double[0];
+    double[] surfaceClosureThreshold = new double[0];
     MatterCavern[] matterByY = new MatterCavern[0];
     Matter[] sectionMatter = new Matter[0];
     MatterSlice<?>[] sectionSlices = new MatterSlice<?>[0];

core/src/main/java/art/arcane/iris/engine/mantle/components/ConfiguredRiverGrottoShape.java

@@ -20,13 +20,15 @@ final class ConfiguredRiverGrottoShape implements RiverCaveGrottoShape {
     private final CNG warpY;
     private final CNG warpZ;
     private final double warpStrength;
+    private final double boundaryVariation;
 
     ConfiguredRiverGrottoShape(
             long seed,
             IrisData data,
             IrisGeneratorStyle shapeStyle,
             IrisGeneratorStyle warpStyle,
-            double warpStrength
+            double warpStrength,
+            double boundaryVariation
     ) {
         IrisGeneratorStyle resolvedShape = shapeStyle == null
                 ? new IrisGeneratorStyle(NoiseStyle.FLAT)
@@ -39,6 +41,7 @@ final class ConfiguredRiverGrottoShape implements RiverCaveGrottoShape {
         warpY = resolvedWarp.createNoCache(new RNG(seed ^ WARP_Y_SALT), data);
         warpZ = resolvedWarp.createNoCache(new RNG(seed ^ WARP_Z_SALT), data);
         this.warpStrength = Math.max(0D, warpStrength);
+        this.boundaryVariation = Math.max(0D, Math.min(0.75D, boundaryVariation));
     }
 
     @Override
@@ -60,7 +63,7 @@ final class ConfiguredRiverGrottoShape implements RiverCaveGrottoShape {
         double normalized = (warpedX * warpedX / (horizontalRadius * horizontalRadius))
                 + (warpedY * warpedY / (verticalRadius * verticalRadius))
                 + (warpedZ * warpedZ / (horizontalRadius * horizontalRadius));
-        double boundary = shape.fitDouble(-0.2D, 0.2D, worldX, worldY, worldZ);
+        double boundary = shape.fitDouble(-boundaryVariation, boundaryVariation, worldX, worldY, worldZ);
         return normalized <= 1D + boundary;
     }
 }

core/src/main/java/art/arcane/iris/engine/mantle/components/IrisCaveCarver3D.java

@@ -48,6 +48,8 @@ public class IrisCaveCarver3D {
     private static final int ADAPTIVE_DEEP_SAMPLE_STEP = 8;
     private static final double ADAPTIVE_LOCAL_RANGE_SCALE = 0.125D;
     private static final double ADAPTIVE_DEEP_MARGIN_BOOST = 0.015D;
+    private static final int SURFACE_CEILING_FADE_DEPTH = 12;
+    private static final double SURFACE_CEILING_SOLID_EPSILON = 0.000001D;
 
     private final Engine engine;
     private final IrisData data;
@@ -250,9 +252,11 @@ public class IrisCaveCarver3D {
             int[] fluidMaxY = scratch.fluidMaxY;
             int[] surfaceBreakFloorY = scratch.surfaceBreakFloorY;
             boolean[] surfaceBreakColumn = scratch.surfaceBreakColumn;
+            boolean[] surfaceCeilingColumn = scratch.surfaceCeilingColumn;
             double[] columnThreshold = scratch.columnThreshold;
             double[] clampedWeights = scratch.clampedColumnWeights;
             double[] verticalEdgeFade = prepareVerticalEdgeFadeTable(scratch, minY, maxY);
+            prepareSurfaceClosureThresholdTable(scratch, minY, maxY);
             MatterCavern[] matterByY = prepareMatterByYTable(scratch, minY, maxY);
             prepareSectionCaches(scratch, minY, maxY);
 
@@ -284,7 +288,8 @@ public class IrisCaveCarver3D {
                     } else {
                         columnSurfaceY = engine.getHeight(x, z);
                     }
-                    int clearanceTopY = Math.min(maxY, Math.max(minY, columnSurfaceY - surfaceClearance));
+                    int unclampedClearanceTopY = columnSurfaceY - surfaceClearance;
+                    int clearanceTopY = Math.min(maxY, Math.max(minY, unclampedClearanceTopY));
                     boolean breakColumn = allowSurfaceBreak
                             && surfaceBreakDensity.noiseFastSigned2D(x, z) >= surfaceBreakNoiseThreshold;
                     int columnTopY = breakColumn
@@ -297,6 +302,7 @@ public class IrisCaveCarver3D {
                             : Integer.MIN_VALUE;
                     surfaceBreakFloorY[index] = Math.max(minY, columnSurfaceY - surfaceBreakDepth);
                     surfaceBreakColumn[index] = breakColumn;
+                    surfaceCeilingColumn[index] = !breakColumn && unclampedClearanceTopY <= maxY;
                     columnThreshold[index] = (thresholdDensity == null
                             ? constantThreshold
                             : thresholdDensity.fitDouble(thresholdMin, thresholdMax, x, z)) - thresholdBias;
@@ -487,6 +493,7 @@ public class IrisCaveCarver3D {
                         localThreshold += surfaceBreakThresholdBoost;
                     }
                     localThreshold -= verticalEdgeFade[y - minY];
+                    localThreshold = applySurfaceCeilingFade(scratch, localThreshold, columnIndex, y, minY);
                     planeThresholdLimit[planeCount] = localThreshold * normalizationFactor;
                     planeCount++;
                 }
@@ -514,7 +521,7 @@ public class IrisCaveCarver3D {
                         }
 
                         double localThreshold = planeThresholdLimit[planeIndex] * inverseNormalization;
-                        MatterCavern matter = resolveMatter(verticalMatter, x0 + localX, y, z0 + localZ,
+                        MatterCavern matter = resolveMatter(scratch, verticalMatter, x0 + localX, y, z0 + localZ,
                                 columnIndex, fluidMaxY, localThreshold);
                         writeCavern(cavernSlice, localX, y, localZ, matter, fluidSupportPlan);
                         carved++;
@@ -531,7 +538,7 @@ public class IrisCaveCarver3D {
                     int localX = PowerOfTwoCoordinates.unpackLocal16X(columnIndex);
                     int localZ = columnIndex & 15;
                     double localThreshold = planeThresholdLimit[planeIndex] * inverseNormalization;
-                    MatterCavern matter = resolveMatter(verticalMatter, x0 + localX, y, z0 + localZ,
+                    MatterCavern matter = resolveMatter(scratch, verticalMatter, x0 + localX, y, z0 + localZ,
                             columnIndex, fluidMaxY, localThreshold);
                     writeCavern(cavernSlice, localX, y, localZ, matter, fluidSupportPlan);
                     carved++;
@@ -624,6 +631,7 @@ public class IrisCaveCarver3D {
                         localThreshold += surfaceBreakThresholdBoost;
                     }
                     localThreshold -= verticalEdgeFade[y - minY];
+                    localThreshold = applySurfaceCeilingFade(scratch, localThreshold, columnIndex, y, minY);
                     planeThresholdLimit[planeCount] = localThreshold * normalizationFactor;
                     planeCount++;
                 }
@@ -662,7 +670,7 @@ public class IrisCaveCarver3D {
                         }
 
                         double localThreshold = planeThresholdLimit[planeIndex] * inverseNormalization;
-                        MatterCavern matter = resolveMatter(verticalMatter, x0 + localX, y, z0 + localZ,
+                        MatterCavern matter = resolveMatter(scratch, verticalMatter, x0 + localX, y, z0 + localZ,
                                 columnIndex, fluidMaxY, localThreshold);
                         writeCavern(cavernSlice, localX, y, localZ, matter, fluidSupportPlan);
                         carved++;
@@ -679,7 +687,7 @@ public class IrisCaveCarver3D {
                     int localX = PowerOfTwoCoordinates.unpackLocal16X(columnIndex);
                     int localZ = columnIndex & 15;
                     double localThreshold = planeThresholdLimit[planeIndex] * inverseNormalization;
-                    MatterCavern matter = resolveMatter(verticalMatter, x0 + localX, y, z0 + localZ,
+                    MatterCavern matter = resolveMatter(scratch, verticalMatter, x0 + localX, y, z0 + localZ,
                             columnIndex, fluidMaxY, localThreshold);
                     writeCavern(cavernSlice, localX, y, localZ, matter, fluidSupportPlan);
                     carved++;
@@ -822,6 +830,7 @@ public class IrisCaveCarver3D {
                                 localThreshold += surfaceBreakThresholdBoost;
                             }
                             localThreshold -= verticalEdgeFade[fadeIndex];
+                            localThreshold = applySurfaceCeilingFade(scratch, localThreshold, index, yy, minY);
                             if (density > localThreshold) {
                                 continue;
                             }
@@ -830,7 +839,7 @@ public class IrisCaveCarver3D {
                             int localZ = tileLocalZ[columnIndex];
                             int worldX = x0 + localX;
                             int worldZ = z0 + localZ;
-                            MatterCavern matter = resolveMatter(verticalMatter, worldX, yy, worldZ,
+                            MatterCavern matter = resolveMatter(scratch, verticalMatter, worldX, yy, worldZ,
                                     index, fluidMaxY, localThreshold);
                             if (skipExistingCarved) {
                                 if (cavernSlice.get(localX, localY, localZ) == null) {
@@ -897,23 +906,23 @@ public class IrisCaveCarver3D {
                 double threshold = columnThreshold[index] + thresholdBoost - ((1D - columnWeight) * thresholdPenalty);
 
                 for (int y = minY; y <= columnTopY; y += sampleStep) {
-                    double localThreshold = threshold;
+                    double density = sampleDensityOptimized(scratch, x, y, z);
-                    if (breakColumn && y >= breakFloorY) {
-                        localThreshold += surfaceBreakThresholdBoost;
-                    }
-
-                    localThreshold -= verticalEdgeFade[y - minY];
-                    if (sampleDensityOptimized(scratch, x, y, z) > localThreshold) {
-                        continue;
-                    }
-
                     int carveMaxY = Math.min(columnTopY, y + sampleStep - 1);
                     for (int yy = y; yy <= carveMaxY; yy++) {
                         if (SurfaceFluidBoundaryPlan.protects(surfaceFluidBoundaries, index, yy)) {
                             continue;
                         }
+                        double localThreshold = threshold;
+                        if (breakColumn && yy >= breakFloorY) {
+                            localThreshold += surfaceBreakThresholdBoost;
+                        }
+                        localThreshold -= verticalEdgeFade[yy - minY];
+                        localThreshold = applySurfaceCeilingFade(scratch, localThreshold, index, yy, minY);
+                        if (density > localThreshold) {
+                            continue;
+                        }
                         MatterCavern verticalMatter = matterByY[yy - minY];
-                        MatterCavern matter = resolveMatter(verticalMatter, x, yy, z,
+                        MatterCavern matter = resolveMatter(scratch, verticalMatter, x, yy, z,
                                 index, fluidMaxY, localThreshold);
                         MatterSlice<MatterCavern> cavernSlice = resolveCavernSlice(scratch, chunk, PowerOfTwoCoordinates.floorDivPow2(yy, 4));
                         int localY = yy & 15;
@@ -2191,57 +2200,61 @@ public class IrisCaveCarver3D {
         return matterByY;
     }
 
-    private MatterCavern resolveMatter(MatterCavern verticalMatter, int x, int y, int z,
+    private MatterCavern resolveMatter(CaveCarveScratch scratch, MatterCavern verticalMatter, int x, int y, int z,
                                        int columnIndex, int[] fluidMaxY, double localThreshold) {
         if (verticalMatter != carveLava
                 && y <= fluidMaxY[columnIndex]
-                && isAquiferCandidate(x, y, z, localThreshold)) {
+                && isAquiferCandidate(scratch, x, y, z, localThreshold)) {
             return carveFluid;
         }
         return verticalMatter;
     }
 
-    private boolean isAquiferCandidate(int x, int y, int z, double localThreshold) {
+    private boolean isAquiferCandidate(CaveCarveScratch scratch, int x, int y, int z, double localThreshold) {
         double depthFactor = Math.max(0D, Math.min(1.5D, (fluidHeight - y) / 48D));
         double cutoff = 0.35D + (depthFactor * 0.2D);
         if (detailDensity.noiseFastSigned3D(x, y * 0.5D, z) <= cutoff) {
             return false;
         }
-        return !fluidRequiresFloor || hasAquiferCupSupport(x, y, z, localThreshold);
+        return !fluidRequiresFloor || hasAquiferCupSupport(scratch, x, y, z, localThreshold);
     }
 
-    private boolean hasAquiferCupSupport(int x, int y, int z, double threshold) {
+    private boolean isAquiferCandidate(int x, int y, int z, double localThreshold) {
+        return isAquiferCandidate(scratchCache.get(), x, y, z, localThreshold);
+    }
+
+    private boolean hasAquiferCupSupport(CaveCarveScratch scratch, int x, int y, int z, double threshold) {
         int floorY = Math.max(0, y - 1);
         int deepFloorY = Math.max(0, y - 2);
         int aboveY = Math.min(aquiferCeilingY, y + 1);
-        if (!isDensitySolid(x, floorY, z, threshold)) {
+        if (!isDensitySolid(scratch, x, floorY, z, threshold)) {
             return false;
         }
-        if (!isDensitySolid(x, deepFloorY, z, threshold - 0.05D)) {
+        if (!isDensitySolid(scratch, x, deepFloorY, z, threshold - 0.05D)) {
             return false;
         }
 
         int support = 0;
-        if (isDensitySolid(x + 1, y, z, threshold)) {
+        if (isDensitySolid(scratch, x + 1, y, z, threshold)) {
             support++;
         }
-        if (isDensitySolid(x - 1, y, z, threshold)) {
+        if (isDensitySolid(scratch, x - 1, y, z, threshold)) {
             support++;
         }
-        if (isDensitySolid(x, y, z + 1, threshold)) {
+        if (isDensitySolid(scratch, x, y, z + 1, threshold)) {
             support++;
         }
-        if (isDensitySolid(x, y, z - 1, threshold)) {
+        if (isDensitySolid(scratch, x, y, z - 1, threshold)) {
             support++;
         }
-        if (isDensitySolid(x, aboveY, z, threshold)) {
+        if (isDensitySolid(scratch, x, aboveY, z, threshold)) {
             support++;
         }
         return support >= 4;
     }
 
-    private boolean isDensitySolid(int x, int y, int z, double threshold) {
+    private boolean isDensitySolid(CaveCarveScratch scratch, int x, int y, int z, double threshold) {
-        return sampleDensityOptimized(x, y, z) > threshold;
+        return sampleDensityOptimized(scratch, x, y, z) > threshold;
     }
 
     private void writeCavern(MatterSlice<MatterCavern> cavernSlice, int localX, int y, int localZ,
@@ -2288,6 +2301,52 @@ public class IrisCaveCarver3D {
         return (value * 2D) - 1D;
     }
 
+    private double applySurfaceCeilingFade(
+            CaveCarveScratch scratch,
+            double threshold,
+            int columnIndex,
+            int y,
+            int minY
+    ) {
+        if (!scratch.surfaceCeilingColumn[columnIndex]) {
+            return threshold;
+        }
+
+        int ceilingDistance = scratch.columnMaxY[columnIndex] - y;
+        if (ceilingDistance < 0 || ceilingDistance >= SURFACE_CEILING_FADE_DEPTH) {
+            return threshold;
+        }
+
+        double closureThreshold = scratch.surfaceClosureThreshold[y - minY];
+        if (threshold <= closureThreshold) {
+            return threshold;
+        }
+
+        double progress = ceilingDistance / (double) SURFACE_CEILING_FADE_DEPTH;
+        double smooth = progress * progress * (3D - (2D * progress));
+        return closureThreshold + ((threshold - closureThreshold) * smooth);
+    }
+
+    private void prepareSurfaceClosureThresholdTable(CaveCarveScratch scratch, int minY, int maxY) {
+        int size = Math.max(0, maxY - minY + 1);
+        if (scratch.surfaceClosureThreshold.length < size) {
+            scratch.surfaceClosureThreshold = new double[size];
+        }
+
+        double baseMinimum = -Math.abs(baseWeight) - Math.abs(detailWeight);
+        for (int y = minY; y <= maxY; y++) {
+            double minimumDensity = baseMinimum;
+            for (CaveFieldModuleState module : modules) {
+                if (y < module.minY || y > module.maxY) {
+                    continue;
+                }
+                minimumDensity += Math.min(module.minContribution, module.maxContribution);
+            }
+            scratch.surfaceClosureThreshold[y - minY] =
+                    (minimumDensity * inverseNormalization) - SURFACE_CEILING_SOLID_EPSILON;
+        }
+    }
+
     private double[] prepareVerticalEdgeFadeTable(CaveCarveScratch scratch, int minY, int maxY) {
         int size = Math.max(0, maxY - minY + 1);
         if (scratch.verticalEdgeFade.length < size) {

core/src/main/java/art/arcane/iris/engine/mantle/components/MantleCarvingComponent.java

@@ -474,7 +474,7 @@ public class MantleCarvingComponent extends IrisMantleComponent {
     private void prefillProfileFieldSamples(int startX, int startZ, IrisComplex complex, BlendScratch blendScratch) {
         fillFieldHeights(complex.getHeightStream(), startX, startZ, blendScratch.fieldSurfaceHeights);
         fillFieldHeights(complex.getRiverWaterSurfaceStream(), startX, startZ, blendScratch.fieldFluidHeights);
-        fillFieldFluidPresence(complex.getFluidStream(), startX, startZ, blendScratch.fieldSurfaceHeights,
+        fillFieldFluidPresence(complex, startX, startZ, blendScratch.fieldSurfaceHeights,
                 blendScratch.fieldFluidHeights, blendScratch.fieldHasFluid);
         fillFieldObjects(complex.getRegionStream(), startX, startZ, blendScratch.fieldRegions);
         fillFieldObjects(complex.getTrueBiomeStream(), startX, startZ, blendScratch.fieldSurfaceBiomes);
@@ -500,7 +500,7 @@ public class MantleCarvingComponent extends IrisMantleComponent {
     }
 
     private void fillFieldFluidPresence(
-            ProceduralStream<PlatformBlockState> stream,
+            IrisComplex complex,
             int startX,
             int startZ,
             double[] surfaceHeights,
@@ -511,7 +511,7 @@ public class MantleCarvingComponent extends IrisMantleComponent {
             int worldX = startX + fieldX;
             for (int fieldZ = 0; fieldZ < FIELD_SIZE; fieldZ++) {
                 int fieldIndex = (fieldX * FIELD_SIZE) + fieldZ;
-                target[fieldIndex] = B.isFluid(stream.get(worldX, startZ + fieldZ))
+                target[fieldIndex] = B.isFluid(complex.resolveSurfaceFluid(worldX, startZ + fieldZ))
                         && Math.round(surfaceHeights[fieldIndex]) < Math.round(fluidHeights[fieldIndex]);
             }
         }

core/src/main/java/art/arcane/iris/engine/mantle/components/MantleRiverCaveVoxelView.java

@@ -3,7 +3,7 @@ package art.arcane.iris.engine.mantle.components;
 import art.arcane.iris.engine.river.cave.CavePosition;
 import art.arcane.iris.engine.river.cave.CaveVoxel;
 import art.arcane.iris.engine.river.cave.CaveVoxelView;
-import art.arcane.iris.engine.river.cave.RiverCaveAction;
+import art.arcane.iris.engine.river.cave.RiverCaveFluidKind;
 import art.arcane.iris.engine.river.cave.RiverCaveHydrology;
 import art.arcane.iris.engine.data.cache.Cache;
 import art.arcane.iris.engine.object.IrisProceduralBlocks;
@@ -15,8 +15,10 @@ import art.arcane.volmlib.util.mantle.runtime.TectonicPlate;
 import art.arcane.volmlib.util.matter.Matter;
 import art.arcane.volmlib.util.matter.MatterCavern;
 import it.unimi.dsi.fastutil.longs.Long2IntOpenHashMap;
+import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
 
 import java.util.Objects;
+import java.util.function.BiConsumer;
 
 final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.TunnelVoxelView {
     private static final int CLOSED_COLUMN = Integer.MAX_VALUE;
@@ -26,6 +28,9 @@ final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.Tu
     private final int worldHeight;
     private final Function2<Integer, Integer, Integer> surfaceHeight;
     private final Function2<Integer, Integer, PlatformBlockState> compatibleFluid;
+    private final RiverCaveFluidKind planningFluidKind;
+    private final BiConsumer<Integer, Integer> chunkLoader;
+    private final LongOpenHashSet loadedChunks;
     private final Long2IntOpenHashMap openFloorCache;
     private final Long2IntOpenHashMap surfaceHeightCache;
 
@@ -33,12 +38,17 @@ final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.Tu
             Mantle<Matter> mantle,
             int worldHeight,
             Function2<Integer, Integer, Integer> surfaceHeight,
-            Function2<Integer, Integer, PlatformBlockState> compatibleFluid
+            Function2<Integer, Integer, PlatformBlockState> compatibleFluid,
+            RiverCaveFluidKind planningFluidKind,
+            BiConsumer<Integer, Integer> chunkLoader
     ) {
         this.mantle = Objects.requireNonNull(mantle);
         this.worldHeight = worldHeight;
         this.surfaceHeight = Objects.requireNonNull(surfaceHeight);
         this.compatibleFluid = Objects.requireNonNull(compatibleFluid);
+        this.planningFluidKind = Objects.requireNonNull(planningFluidKind);
+        this.chunkLoader = Objects.requireNonNull(chunkLoader);
+        loadedChunks = new LongOpenHashSet();
         openFloorCache = new Long2IntOpenHashMap();
         openFloorCache.defaultReturnValue(CACHE_MISS);
         surfaceHeightCache = new Long2IntOpenHashMap();
@@ -52,10 +62,18 @@ final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.Tu
 
     @Override
     public CaveVoxel voxelAt(CavePosition position) {
+        RiverCaveHydrology hydrology = dataIfPresent(position, RiverCaveHydrology.class);
+        if (hydrology != null && hydrology.fluidKind() != planningFluidKind) {
+            return CaveVoxel.INCOMPATIBLE_FLUID;
+        }
         MatterCavern cavern = dataIfPresent(position, MatterCavern.class);
         if (cavern != null) {
             if (cavern.isLava()) {
-                return CaveVoxel.LAVA;
+                PlatformBlockState expected = compatibleFluid.apply(position.x(), position.z());
+                return expected != null
+                        && IrisProceduralBlocks.materialKey(expected).endsWith(":lava")
+                        ? CaveVoxel.COMPATIBLE_FLUID
+                        : CaveVoxel.LAVA;
             }
             if (cavern.getLiquid() == 1) {
                 return CaveVoxel.COMPATIBLE_FLUID;
@@ -71,13 +89,13 @@ final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.Tu
         if (!block.isFluid()) {
             return CaveVoxel.SOLID;
         }
-        if (IrisProceduralBlocks.materialKey(block).endsWith(":lava")) {
-            return CaveVoxel.LAVA;
-        }
         PlatformBlockState expected = compatibleFluid.apply(position.x(), position.z());
-        return expected != null
+        if (expected != null
-                && IrisProceduralBlocks.materialKey(expected).equals(IrisProceduralBlocks.materialKey(block))
+                && IrisProceduralBlocks.materialKey(expected).equals(IrisProceduralBlocks.materialKey(block))) {
-                ? CaveVoxel.COMPATIBLE_FLUID
+            return CaveVoxel.COMPATIBLE_FLUID;
+        }
+        return IrisProceduralBlocks.materialKey(block).endsWith(":lava")
+                ? CaveVoxel.LAVA
                 : CaveVoxel.INCOMPATIBLE_FLUID;
     }
 
@@ -99,9 +117,8 @@ final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.Tu
     }
 
     @Override
-    public RiverCaveAction riverActionAt(CavePosition position) {
+    public RiverCaveHydrology riverHydrologyAt(CavePosition position) {
-        RiverCaveHydrology hydrology = dataIfPresent(position, RiverCaveHydrology.class);
+        return dataIfPresent(position, RiverCaveHydrology.class);
-        return hydrology == null ? null : hydrology.action();
     }
 
     private int resolveOpenFloor(int x, int z) {
@@ -131,6 +148,10 @@ final class MantleRiverCaveVoxelView implements MantleRiverHydrologyComponent.Tu
     private <T> T dataIfPresent(CavePosition position, Class<T> type) {
         int chunkX = position.x() >> 4;
         int chunkZ = position.z() >> 4;
+        long chunkKey = Mantle.key(chunkX, chunkZ);
+        if (loadedChunks.add(chunkKey)) {
+            chunkLoader.accept(chunkX, chunkZ);
+        }
         TectonicPlate<Matter> plate = mantle.getLoadedRegions().get(Mantle.key(chunkX >> 5, chunkZ >> 5));
         if (plate == null || plate.isClosed()) {
             return null;

core/src/main/java/art/arcane/iris/engine/mantle/components/MantleRiverHydrologyComponent.java

@@ -1,17 +1,21 @@
 package art.arcane.iris.engine.mantle.components;
 
 import art.arcane.iris.core.loader.IrisData;
+import art.arcane.iris.engine.data.cache.Cache;
 import art.arcane.iris.engine.mantle.ComponentFlag;
 import art.arcane.iris.engine.mantle.EngineMantle;
 import art.arcane.iris.engine.mantle.IrisMantleComponent;
+import art.arcane.iris.engine.mantle.MantleComponent;
 import art.arcane.iris.engine.mantle.MantleWriter;
 import art.arcane.iris.engine.object.IrisRiverCaveFallback;
 import art.arcane.iris.engine.object.IrisRiverCaveMode;
 import art.arcane.iris.engine.object.IrisRiverCaves;
+import art.arcane.iris.engine.object.IrisRiverDeepPools;
 import art.arcane.iris.engine.object.IrisRiverExistingFluidPolicy;
 import art.arcane.iris.engine.object.IrisDimension;
 import art.arcane.iris.engine.object.IrisRiverNetwork;
 import art.arcane.iris.engine.river.RiverAnchor;
+import art.arcane.iris.engine.river.RiverNetwork;
 import art.arcane.iris.engine.river.RiverRouteState;
 import art.arcane.iris.engine.river.RiverSample;
 import art.arcane.iris.engine.river.RiverSection;
@@ -22,6 +26,7 @@ import art.arcane.iris.engine.river.cave.CaveVoxelPrecondition;
 import art.arcane.iris.engine.river.cave.CaveVoxelView;
 import art.arcane.iris.engine.river.cave.RiverCaveAction;
 import art.arcane.iris.engine.river.cave.RiverCaveContainmentPlanner;
+import art.arcane.iris.engine.river.cave.RiverCaveFluidKind;
 import art.arcane.iris.engine.river.cave.RiverCaveFluidPolicy;
 import art.arcane.iris.engine.river.cave.RiverCaveHydrology;
 import art.arcane.iris.engine.river.cave.RiverCaveMode;
@@ -35,8 +40,13 @@ import art.arcane.iris.engine.river.runtime.IrisRiverTunnelSample;
 import art.arcane.iris.util.project.context.ChunkContext;
 import art.arcane.volmlib.util.mantle.flag.MantleFlag;
 import art.arcane.volmlib.util.mantle.flag.ReservedFlag;
+import art.arcane.volmlib.util.mantle.runtime.MantleChunk;
+import art.arcane.volmlib.util.math.BlockPosition;
+import art.arcane.volmlib.util.matter.Matter;
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
@@ -47,6 +57,8 @@ import java.util.Set;
 @ComponentFlag(ReservedFlag.RIVER_HYDROLOGY)
 public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
     private static final long CANDIDATE_SALT = 0x6A09E667F3BCC909L;
+    private static final long DEEP_POOL_CANDIDATE_SALT = 0xBB67AE8584CAA73BL;
+    private static final long DEEP_POOL_POSITION_SALT = 0x3C6EF372FE94F82BL;
     static final int PRIORITY = 1;
     private static final int[] FALLBACK_X = {0, 1, -1, 0, 0};
     private static final int[] FALLBACK_Z = {0, 0, 0, 1, -1};
@@ -73,6 +85,11 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         return PREREQUISITES;
     }
 
+    @Override
+    public boolean isInputGenerationLazy() {
+        return true;
+    }
+
     @Override
     public int getInputRadius() {
         if (!getDimension().isCarvingEnabled()
@@ -87,6 +104,122 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         return inputRadius(runtime.caveSettings(), tunnelHalo(runtime));
     }
 
+    @Override
+    public int getInputRadius(
+            int targetChunkX,
+            int targetChunkZ,
+            int invocationChunkRadius,
+            ChunkContext context
+    ) {
+        if (!getDimension().isCarvingEnabled()
+                || getDimension().getRivers() == null
+                || !getDimension().getRivers().isEnabled()) {
+            return 0;
+        }
+        if (context == null || context.getComplex() == null) {
+            return getInputRadius();
+        }
+        IrisRiverRuntime runtime = context.getComplex().getRiverRuntime();
+        if (runtime == null) {
+            return getInputRadius();
+        }
+        IrisRiverCaves caves = runtime.caveSettings();
+        int tunnelRadius = tunnelHalo(runtime);
+        int radius = hasRiverFootprint(
+                runtime,
+                targetChunkX,
+                targetChunkZ,
+                invocationChunkRadius,
+                tunnelRadius
+        ) ? tunnelRadius : 0;
+        if (caves.getMode() != IrisRiverCaveMode.SEALED
+                && caves.getMaximumPerReach() > 0) {
+            radius = Math.max(radius, hasAcceptedCaveAnchor(
+                    runtime,
+                    caves,
+                    targetChunkX,
+                    targetChunkZ,
+                    invocationChunkRadius
+            ) ? planningHalo(caves) : 0);
+        }
+        IrisRiverDeepPools deepPools = caves.getDeepPools();
+        if (deepPools != null
+                && deepPools.isEnabled()
+                && deepPools.getMaximumPerReach() > 0) {
+            radius = Math.max(radius, hasAcceptedDeepPoolAnchor(
+                    runtime,
+                    deepPools,
+                    targetChunkX,
+                    targetChunkZ,
+                    invocationChunkRadius
+            ) ? deepPoolPlanningHalo(deepPools) : 0);
+        }
+        return radius;
+    }
+
+    private static boolean hasRiverFootprint(
+            IrisRiverRuntime runtime,
+            int targetChunkX,
+            int targetChunkZ,
+            int invocationChunkRadius,
+            int tunnelRadius
+    ) {
+        return runtime.hasRiverFootprint(
+                ((targetChunkX - invocationChunkRadius) << 4) - tunnelRadius,
+                ((targetChunkZ - invocationChunkRadius) << 4) - tunnelRadius,
+                ((targetChunkX + invocationChunkRadius + 1) << 4) + tunnelRadius,
+                ((targetChunkZ + invocationChunkRadius + 1) << 4) + tunnelRadius
+        );
+    }
+
+    private static boolean hasAcceptedCaveAnchor(
+            IrisRiverRuntime runtime,
+            IrisRiverCaves caves,
+            int targetChunkX,
+            int targetChunkZ,
+            int invocationChunkRadius
+    ) {
+        int candidateHalo = candidateHalo(caves);
+        List<RiverAnchor> anchors = runtime.candidateAnchors(
+                ((targetChunkX - invocationChunkRadius) << 4) - candidateHalo,
+                ((targetChunkZ - invocationChunkRadius) << 4) - candidateHalo,
+                ((targetChunkX + invocationChunkRadius + 1) << 4) + candidateHalo,
+                ((targetChunkZ + invocationChunkRadius + 1) << 4) + candidateHalo,
+                caves.getMinimumSpacing(),
+                CANDIDATE_SALT
+        );
+        for (RiverAnchor anchor : anchors) {
+            if (runtime.acceptsCaveAnchor(anchor)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private static boolean hasAcceptedDeepPoolAnchor(
+            IrisRiverRuntime runtime,
+            IrisRiverDeepPools deepPools,
+            int targetChunkX,
+            int targetChunkZ,
+            int invocationChunkRadius
+    ) {
+        int candidateHalo = deepPoolCandidateHalo(deepPools);
+        List<RiverAnchor> anchors = runtime.candidateAnchors(
+                ((targetChunkX - invocationChunkRadius) << 4) - candidateHalo,
+                ((targetChunkZ - invocationChunkRadius) << 4) - candidateHalo,
+                ((targetChunkX + invocationChunkRadius + 1) << 4) + candidateHalo,
+                ((targetChunkZ + invocationChunkRadius + 1) << 4) + candidateHalo,
+                deepPools.getMinimumSpacing(),
+                DEEP_POOL_CANDIDATE_SALT
+        );
+        for (RiverAnchor anchor : anchors) {
+            if (runtime.acceptsDeepPoolAnchor(anchor)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     @Override
     public void generateLayer(MantleWriter writer, int chunkX, int chunkZ, ChunkContext context) {
         IrisRiverRuntime runtime = context.getComplex().getRiverRuntime();
@@ -96,11 +229,21 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         publishTunnels(writer, context, runtime, chunkX, chunkZ);
 
         IrisRiverCaves caves = runtime.caveSettings();
-        if (caves.getMode() == IrisRiverCaveMode.SEALED || caves.getMaximumPerReach() <= 0) {
+        if (caves.getMode() != IrisRiverCaveMode.SEALED && caves.getMaximumPerReach() > 0) {
-            return;
+            publishCaveConnections(writer, context, runtime, caves, chunkX, chunkZ);
+        }
+        publishDeepPools(writer, context, runtime, caves.getDeepPools(), chunkX, chunkZ);
     }
 
-        MantleRiverCaveVoxelView view = createView(writer, context);
+    private void publishCaveConnections(
+            MantleWriter writer,
+            ChunkContext context,
+            IrisRiverRuntime runtime,
+            IrisRiverCaves caves,
+            int chunkX,
+            int chunkZ
+    ) {
+        MantleRiverCaveVoxelView view = createView(writer, context, RiverCaveFluidKind.RIVER);
         int candidateHalo = candidateHalo(caves);
         int minimumX = (chunkX << 4) - candidateHalo;
         int minimumZ = (chunkZ << 4) - candidateHalo;
@@ -146,11 +289,202 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         }
 
         RiverCavePlanningResult result = planner.planAll(view, sources, settings);
-        MantleRiverCaveVoxelView revalidationView = createView(writer, context);
+        MantleRiverCaveVoxelView revalidationView = createView(
+                writer,
+                context,
+                RiverCaveFluidKind.RIVER
+        );
         if (!preconditionsHold(revalidationView, result.baselinePreconditions())) {
             return;
         }
-        publishLocal(writer, chunkX, chunkZ, result, floodedBiomes);
+        publishLocal(
+                writer,
+                chunkX,
+                chunkZ,
+                result,
+                floodedBiomes,
+                RiverCaveFluidKind.RIVER
+        );
+    }
+
+    private void publishDeepPools(
+            MantleWriter writer,
+            ChunkContext context,
+            IrisRiverRuntime runtime,
+            IrisRiverDeepPools deepPools,
+            int chunkX,
+            int chunkZ
+    ) {
+        if (deepPools == null || !deepPools.isEnabled() || deepPools.getMaximumPerReach() <= 0) {
+            return;
+        }
+        MantleRiverCaveVoxelView view = createView(
+                writer,
+                context,
+                RiverCaveFluidKind.DEEP_POOL
+        );
+        int candidateHalo = deepPoolCandidateHalo(deepPools);
+        int minimumX = (chunkX << 4) - candidateHalo;
+        int minimumZ = (chunkZ << 4) - candidateHalo;
+        int maximumX = ((chunkX + 1) << 4) + candidateHalo;
+        int maximumZ = ((chunkZ + 1) << 4) + candidateHalo;
+        List<RiverAnchor> anchors = runtime.candidateAnchors(
+                minimumX,
+                minimumZ,
+                maximumX,
+                maximumZ,
+                deepPools.getMinimumSpacing(),
+                DEEP_POOL_CANDIDATE_SALT
+        );
+        if (anchors.isEmpty()) {
+            return;
+        }
+
+        RiverCavePlannerSettings settings = deepPoolPlannerSettings(deepPools, seed(), getData());
+        List<RiverCaveSource> sources = new ArrayList<>();
+        Map<Long, String> floodedBiomes = new HashMap<>();
+        for (RiverAnchor anchor : anchors) {
+            if (!runtime.acceptsDeepPoolAnchor(anchor)) {
+                continue;
+            }
+            RiverCaveSource source = deepPoolSourceFor(
+                    view,
+                    deepPools,
+                    anchor,
+                    getDimension().getMinHeight(),
+                    seed()
+            );
+            if (source == null) {
+                continue;
+            }
+            sources.add(source);
+            floodedBiomes.put(source.sourceId(), runtime.selectFloodedCaveBiome(anchor));
+        }
+        if (sources.isEmpty()) {
+            return;
+        }
+
+        RiverCavePlanningResult result = planner.planAll(view, sources, settings);
+        MantleRiverCaveVoxelView revalidationView = createView(
+                writer,
+                context,
+                RiverCaveFluidKind.DEEP_POOL
+        );
+        if (!preconditionsHold(revalidationView, result.baselinePreconditions())) {
+            return;
+        }
+        publishLocal(
+                writer,
+                chunkX,
+                chunkZ,
+                result,
+                floodedBiomes,
+                RiverCaveFluidKind.DEEP_POOL
+        );
+    }
+
+    static RiverCavePlannerSettings deepPoolPlannerSettings(
+            IrisRiverDeepPools deepPools,
+            long seed,
+            IrisData data
+    ) {
+        int verticalDepth = deepPools.getVerticalRadius() * 2 - deepPools.getDryHeadroom() + 1;
+        int proofRadius = (int) StrictMath.ceil(
+                StrictMath.sqrt(2D) * deepPools.getHorizontalRadius()
+        ) + 1;
+        return new RiverCavePlannerSettings(
+                proofRadius,
+                verticalDepth,
+                deepPools.getMaximumVolume(),
+                deepPools.getVerticalRadius(),
+                1,
+                deepPools.getHorizontalRadius(),
+                deepPools.getVerticalRadius(),
+                deepPools.getDryHeadroom(),
+                RiverCaveFluidPolicy.REJECT_EXISTING,
+                new ConfiguredRiverGrottoShape(
+                        seed ^ DEEP_POOL_POSITION_SALT,
+                        data,
+                        deepPools.getShapeStyle(),
+                        deepPools.getWarpStyle(),
+                        deepPools.getWarpStrength(),
+                        deepPools.getShapeVariation()
+                ),
+                proofRadius,
+                verticalDepth
+        );
+    }
+
+    static RiverCaveSource deepPoolSourceFor(
+            CaveVoxelView view,
+            IrisRiverDeepPools deepPools,
+            RiverAnchor anchor,
+            int worldMinimumY,
+            long seed
+    ) {
+        int minimumHead = deepPools.getMinimumFluidY() - worldMinimumY;
+        int maximumHead = deepPools.getMaximumFluidY() - worldMinimumY;
+        int headRange = maximumHead - minimumHead + 1;
+        if (headRange <= 0) {
+            return null;
+        }
+        int searchRadius = deepPools.getSearchRadius();
+        int searchWidth = searchRadius * 2 + 1;
+        int targetDepth = Math.max(
+                1,
+                deepPools.getVerticalRadius() - deepPools.getDryHeadroom()
+        );
+        for (int attempt = 0; attempt < deepPools.getSearchAttempts(); attempt++) {
+            long hash = RiverNetwork.mix(
+                    seed
+                            ^ anchor.stableId()
+                            ^ DEEP_POOL_POSITION_SALT
+                            ^ (long) attempt * 0x9E3779B97F4A7C15L
+            );
+            int offsetX = searchRadius == 0
+                    ? 0
+                    : Math.floorMod((int) hash, searchWidth) - searchRadius;
+            int offsetZ = searchRadius == 0
+                    ? 0
+                    : Math.floorMod((int) (hash >>> 32), searchWidth) - searchRadius;
+            if ((long) offsetX * offsetX + (long) offsetZ * offsetZ
+                    > (long) searchRadius * searchRadius) {
+                continue;
+            }
+            int x = (int) StrictMath.floor(anchor.x()) + offsetX;
+            int z = (int) StrictMath.floor(anchor.z()) + offsetZ;
+            int startOffset = (int) StrictMath.floor(unit(hash) * headRange);
+            for (int scanned = 0; scanned < headRange; scanned++) {
+                int headY = maximumHead - Math.floorMod(startOffset + scanned, headRange);
+                CavePosition floor = new CavePosition(x, headY, z);
+                CavePosition above = new CavePosition(x, headY + 1, z);
+                CavePosition target = new CavePosition(x, headY - targetDepth, z);
+                if (!view.isInWorld(target)
+                        || !view.isInWorld(above)
+                        || view.voxelAt(floor) != CaveVoxel.SOLID
+                        || view.voxelAt(above) != CaveVoxel.CAVE_AIR
+                        || view.isOpenToSurface(above)) {
+                    continue;
+                }
+                long sourceId = RiverNetwork.mix(
+                        anchor.stableId()
+                                ^ BlockPosition.toLong(x, headY, z)
+                                ^ DEEP_POOL_POSITION_SALT
+                );
+                return new RiverCaveSource(
+                        sourceId,
+                        floor,
+                        target,
+                        headY,
+                        RiverCaveMode.DEEP_POOL
+                );
+            }
+        }
+        return null;
+    }
+
+    private static double unit(long hash) {
+        return (hash >>> 11) * 0x1.0p-53;
     }
 
     @Override
@@ -176,9 +510,15 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
             return false;
         }
         IrisRiverCaves caves = dimension.getRivers().getCaves();
-        return caves != null
+        if (caves == null) {
-                && caves.getMode() != IrisRiverCaveMode.SEALED
+            return false;
+        }
+        boolean caveConnections = caves.getMode() != IrisRiverCaveMode.SEALED
                 && caves.getMaximumPerReach() > 0;
+        IrisRiverDeepPools deepPools = caves.getDeepPools();
+        return caveConnections || deepPools != null
+                && deepPools.isEnabled()
+                && deepPools.getMaximumPerReach() > 0;
     }
 
     static int planningHalo(IrisRiverCaves caves) {
@@ -186,16 +526,33 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
     }
 
     static int inputRadius(IrisRiverCaves caves, int tunnelRadius) {
-        if (caves.getMode() == IrisRiverCaveMode.SEALED || caves.getMaximumPerReach() <= 0) {
+        int radius = tunnelRadius;
-            return tunnelRadius;
+        if (caves.getMode() != IrisRiverCaveMode.SEALED && caves.getMaximumPerReach() > 0) {
+            radius = Math.max(radius, planningHalo(caves));
         }
-        return Math.max(tunnelRadius, planningHalo(caves));
+        IrisRiverDeepPools deepPools = caves.getDeepPools();
+        if (deepPools != null && deepPools.isEnabled() && deepPools.getMaximumPerReach() > 0) {
+            radius = Math.max(radius, deepPoolPlanningHalo(deepPools));
+        }
+        return radius;
     }
 
     static int candidateHalo(IrisRiverCaves caves) {
         return cavePublicationRadius(caves) * 3;
     }
 
+    static int deepPoolPlanningHalo(IrisRiverDeepPools deepPools) {
+        return deepPoolPublicationRadius(deepPools) * 4;
+    }
+
+    static int deepPoolCandidateHalo(IrisRiverDeepPools deepPools) {
+        return deepPoolPublicationRadius(deepPools) * 3;
+    }
+
+    static int deepPoolPublicationRadius(IrisRiverDeepPools deepPools) {
+        return deepPools.getSearchRadius() + deepPools.getHorizontalRadius() + 1;
+    }
+
     static int cavePublicationRadius(IrisRiverCaves caves) {
         int generatedRadius = generatedGrottoPublicationRadius(caves);
         return switch (caves.getMode()) {
@@ -296,13 +653,13 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         boolean changed;
         do {
             changed = false;
-            Set<CavePosition> candidateActions = mergeActions(containedColumns).keySet();
+            Long2ObjectOpenHashMap<TunnelColumn> candidateColumns = indexColumns(containedColumns);
             for (int index = containedColumns.size() - 1; index >= 0; index--) {
                 TunnelColumn column = containedColumns.get(index);
                 if (!isTunnelColumnContained(
                         view,
                         column,
-                        candidateActions,
+                        candidateColumns,
                         dryHeadroom,
                         surfaceSampler
                 )) {
@@ -348,7 +705,10 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
                 ));
             }
         }
-        return new TunnelPlan(Map.copyOf(actions), Map.copyOf(preconditions));
+        return new TunnelPlan(
+                Collections.unmodifiableMap(actions),
+                Collections.unmodifiableMap(preconditions)
+        );
     }
 
     private static TunnelColumn createTunnelColumn(
@@ -360,8 +720,9 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         if (sample == null) {
             return null;
         }
-        LinkedHashMap<CavePosition, RiverCaveAction> actions = new LinkedHashMap<>();
+        int minimumY = sample.bedY() + 1;
-        for (int y = sample.bedY() + 1; y <= sample.ceilingY(); y++) {
+        int maximumY = sample.ceilingY();
+        for (int y = minimumY; y <= maximumY; y++) {
             CavePosition position = new CavePosition(x, y, z);
             RiverCaveAction action = y <= sample.waterHeadY()
                     ? RiverCaveAction.WET_SOURCE
@@ -371,22 +732,24 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
                     && !matchesPublishedAction(view, position, action))) {
                 return null;
             }
-            actions.put(position, action);
         }
-        return actions.isEmpty() ? null : new TunnelColumn(actions);
+        return minimumY > maximumY
+                ? null
+                : new TunnelColumn(x, z, minimumY, sample.waterHeadY(), maximumY);
     }
 
     private static boolean isTunnelColumnContained(
             CaveVoxelView view,
             TunnelColumn column,
-            Set<CavePosition> candidateActions,
+            Long2ObjectOpenHashMap<TunnelColumn> candidateColumns,
             int dryHeadroom,
             SurfaceSampler surfaceSampler
     ) {
-        for (CavePosition position : column.actions().keySet()) {
+        for (int y = column.minimumY(); y <= column.maximumY(); y++) {
+            CavePosition position = new CavePosition(column.x(), y, column.z());
             for (int[] offset : NEIGHBORS) {
                 CavePosition neighbor = offset(position, offset);
-                if (candidateActions.contains(neighbor)) {
+                if (containsAction(candidateColumns, neighbor)) {
                     continue;
                 }
                 if (!view.isInWorld(neighbor)) {
@@ -417,7 +780,9 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
             SurfaceSampler surfaceSampler
     ) {
         IrisRiverSurfaceSample sample = surfaceSampler.sample(position.x(), position.z());
-        if (!isWetChannelBed(sample) || sample.subterranean()) {
+        if (!sample.river().present()
+                || sample.river().state() != RiverRouteState.WET
+                || sample.subterranean()) {
             return false;
         }
         int bedY = (int) Math.round(sample.terrainHeight());
@@ -428,18 +793,48 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
     private static Map<CavePosition, RiverCaveAction> mergeActions(List<TunnelColumn> columns) {
         LinkedHashMap<CavePosition, RiverCaveAction> actions = new LinkedHashMap<>();
         for (TunnelColumn column : columns) {
-            actions.putAll(column.actions());
+            for (int y = column.minimumY(); y <= column.maximumY(); y++) {
+                actions.put(
+                        new CavePosition(column.x(), y, column.z()),
+                        y <= column.waterHeadY()
+                                ? RiverCaveAction.WET_SOURCE
+                                : RiverCaveAction.DRY_AIR
+                );
+            }
         }
         return actions;
     }
 
+    private static Long2ObjectOpenHashMap<TunnelColumn> indexColumns(List<TunnelColumn> columns) {
+        Long2ObjectOpenHashMap<TunnelColumn> indexed = new Long2ObjectOpenHashMap<>(columns.size());
+        for (TunnelColumn column : columns) {
+            indexed.put(Cache.key(column.x(), column.z()), column);
+        }
+        return indexed;
+    }
+
+    private static boolean containsAction(
+            Long2ObjectOpenHashMap<TunnelColumn> columns,
+            CavePosition position
+    ) {
+        TunnelColumn column = columns.get(Cache.key(position.x(), position.z()));
+        return column != null
+                && position.y() >= column.minimumY()
+                && position.y() <= column.maximumY();
+    }
+
     private static boolean matchesPublishedAction(
             CaveVoxelView view,
             CavePosition position,
             RiverCaveAction action
     ) {
-        return view instanceof TunnelVoxelView tunnelView
+        if (!(view instanceof TunnelVoxelView tunnelView)) {
-                && tunnelView.riverActionAt(position) == action;
+            return false;
+        }
+        RiverCaveHydrology hydrology = tunnelView.riverHydrologyAt(position);
+        return hydrology != null
+                && hydrology.action() == action
+                && hydrology.fluidKind() == RiverCaveFluidKind.RIVER;
     }
 
     private static CavePosition offset(CavePosition position, int[] offset) {
@@ -450,15 +845,39 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         );
     }
 
-    private MantleRiverCaveVoxelView createView(MantleWriter writer, ChunkContext context) {
+    private MantleRiverCaveVoxelView createView(
+            MantleWriter writer,
+            ChunkContext context,
+            RiverCaveFluidKind fluidKind
+    ) {
         return new MantleRiverCaveVoxelView(
                 writer.getMantle(),
                 writer.getMantle().getWorldHeight(),
                 (x, z) -> context.getComplex().getRoundedHeighteightStream().get(x, z),
-                (x, z) -> context.getComplex().getFluidStream().get(x, z)
+                (x, z) -> context.getComplex().resolveRiverCaveFluid(fluidKind, x, z),
+                fluidKind,
+                (chunkX, chunkZ) -> generateCarvingInput(writer, context, chunkX, chunkZ)
         );
     }
 
+    private void generateCarvingInput(
+            MantleWriter writer,
+            ChunkContext context,
+            int chunkX,
+            int chunkZ
+    ) {
+        MantleComponent carving = getEngineMantle().getRegisteredComponents().get(ReservedFlag.CARVED);
+        if (carving == null || !carving.isEnabled()) {
+            throw new IllegalStateException("River hydrology requires the carving component");
+        }
+        MantleChunk<Matter> chunk = writer.acquireChunk(chunkX, chunkZ);
+        if (chunk == null) {
+            throw new IllegalStateException("River hydrology read exceeded the prepared mantle radius at "
+                    + chunkX + "," + chunkZ);
+        }
+        chunk.raiseFlagSuspend(ReservedFlag.CARVED, () -> carving.generateLayer(writer, chunkX, chunkZ, context));
+    }
+
     private void publishTunnels(
             MantleWriter writer,
             ChunkContext context,
@@ -467,7 +886,11 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
             int chunkZ
     ) {
         for (int attempt = 0; attempt < 2; attempt++) {
-            MantleRiverCaveVoxelView view = createView(writer, context);
+            MantleRiverCaveVoxelView view = createView(
+                    writer,
+                    context,
+                    RiverCaveFluidKind.RIVER
+            );
             TunnelPlan plan = planTunnels(
                     view,
                     chunkX,
@@ -478,7 +901,11 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
                     runtime::sampleTunnel,
                     runtime::sample
             );
-            MantleRiverCaveVoxelView revalidationView = createView(writer, context);
+            MantleRiverCaveVoxelView revalidationView = createView(
+                    writer,
+                    context,
+                    RiverCaveFluidKind.RIVER
+            );
             if (preconditionsHold(revalidationView, plan.preconditions())) {
                 publishTunnelLocal(writer, chunkX, chunkZ, plan);
                 return;
@@ -505,7 +932,8 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
                         data,
                         caves.getGrottoShapeStyle(),
                         caves.getGrottoWarpStyle(),
-                        caves.getGrottoWarpStrength()
+                        caves.getGrottoWarpStrength(),
+                        0.2D
                 ),
                 caves.getMaxFloodRadius(),
                 caves.getMaxFloodDepth()
@@ -673,7 +1101,8 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
             int chunkX,
             int chunkZ,
             RiverCavePlanningResult result,
-            Map<Long, String> floodedBiomes
+            Map<Long, String> floodedBiomes,
+            RiverCaveFluidKind fluidKind
     ) {
         Map<CavePosition, RiverCaveSource> owners = actionOwners(result);
         ArrayList<Map.Entry<CavePosition, RiverCaveAction>> actions = new ArrayList<>(result.actions().entrySet());
@@ -692,7 +1121,7 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
                     position.x(),
                     position.y(),
                     position.z(),
-                    new RiverCaveHydrology(entry.getValue(), biome)
+                    new RiverCaveHydrology(entry.getValue(), biome, fluidKind)
             );
         }
     }
@@ -708,7 +1137,12 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         for (Map.Entry<CavePosition, RiverCaveAction> entry : actions) {
             CavePosition position = entry.getKey();
             if (owns(chunkX, chunkZ, position)) {
-                writer.setData(position.x(), position.y(), position.z(), RiverCaveHydrology.of(entry.getValue()));
+                writer.setData(
+                        position.x(),
+                        position.y(),
+                        position.z(),
+                        RiverCaveHydrology.of(entry.getValue(), RiverCaveFluidKind.RIVER)
+                );
             }
         }
     }
@@ -749,7 +1183,7 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
     }
 
     interface TunnelVoxelView extends CaveVoxelView {
-        RiverCaveAction riverActionAt(CavePosition position);
+        RiverCaveHydrology riverHydrologyAt(CavePosition position);
     }
 
     record TunnelPlan(
@@ -761,6 +1195,12 @@ public final class MantleRiverHydrologyComponent extends IrisMantleComponent {
         }
     }
 
-    private record TunnelColumn(Map<CavePosition, RiverCaveAction> actions) {
+    private record TunnelColumn(
+            int x,
+            int z,
+            int minimumY,
+            int waterHeadY,
+            int maximumY
+    ) {
     }
 }

core/src/main/java/art/arcane/iris/engine/mode/ModeOverworld.java

@@ -57,7 +57,11 @@ public class ModeOverworld extends IrisEngineMode implements EngineMode {
             if (shouldBypassMantleStages()) {
                 return;
             }
-            generateMatter(x >> 4, z >> 4, m, c);
+            generateMatter(
+                    x >> 4,
+                    z >> 4,
+                    m || getEngine().isStudio(),
+                    c);
         };
         EngineStage sTerrain = (x, z, k, p, m, c) -> terrain.actuate(x, z, k, m, c);
         EngineStage sDecorant = (x, z, k, p, m, c) -> decorant.actuate(x, z, k, m, c);

core/src/main/java/art/arcane/iris/engine/modifier/IrisCarveModifier.java

@@ -117,7 +117,9 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
                     columnMasks,
                     upperSurfaceHeights,
                     worldHeightSpan,
-                    caveLavaHeight
+                    caveLavaHeight,
+                    chunkBlockX,
+                    chunkBlockZ
             );
             CarveResolver carveResolver = new CarveResolver(resolutionContext);
             mantleChunk.iterate(MatterCavern.class, (xx, yy, zz, cavern) -> carveResolver.apply(
@@ -166,8 +168,6 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
                 });
 
                 for (int columnIndex = 0; columnIndex < 256; columnIndex++) {
-                    int localX = PowerOfTwoCoordinates.unpackLocal16X(columnIndex);
-                    int localZ = columnIndex & 15;
                     processColumnFromMask(
                             output,
                             mantleChunk,
@@ -178,8 +178,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
                             z,
                             resolverState,
                             caveBiomeCache,
-                            customBiomeCache,
+                            customBiomeCache
-                            context.getFluid().get(localX, localZ)
                     );
                 }
 
@@ -279,7 +278,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
         }
         return switch (hydrology.action()) {
             case WET_SOURCE -> fluid;
-            case FALLING_WATER -> fallingFluidState(fluid);
+            case FALLING_FLUID -> fallingFluidState(fluid);
             case DRY_AIR -> air;
             case SEAL_GUARD -> normalizeWaterlogging(current, null);
         };
@@ -369,9 +368,16 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
                 return;
             }
 
-            PlatformBlockState fluid = isFluidIntent(cavern)
+            PlatformBlockState fluid = null;
+            if (isFluidIntent(cavern)) {
+                fluid = hydrology == null
                         ? context.chunkContext().getFluid().get(localX, localZ)
-                    : null;
+                        : getComplex().resolveRiverCaveFluid(
+                                hydrology.fluidKind(),
+                                context.chunkBlockX() + localX,
+                                context.chunkBlockZ() + localZ
+                        );
+            }
             if (hydrology != null) {
                 context.output().setRaw(localX, y, localZ,
                         resolveHydrologyState(hydrology, current, fluid, AIR));
@@ -395,7 +401,9 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
             CarveColumnMask[] columnMasks,
             int[] upperSurfaceHeights,
             int worldHeightSpan,
-            int caveLavaHeight
+            int caveLavaHeight,
+            int chunkBlockX,
+            int chunkBlockZ
     ) {
     }
 
@@ -572,8 +580,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
             int chunkZ,
             IrisDimensionCarvingResolver.State resolverState,
             Long2ObjectOpenHashMap<IrisBiome> caveBiomeCache,
-            Map<String, IrisBiome> customBiomeCache,
+            Map<String, IrisBiome> customBiomeCache
-            PlatformBlockState columnFluid
     ) {
         if (columnMask == null || columnMask.isEmpty()) {
             return;
@@ -601,7 +608,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
                 } else {
                     if (zone.isValid(getEngine())) {
                         processZone(output, mc, mantle, zone, rx, rz, worldX, worldZ, resolverState,
-                                caveBiomeCache, customBiomeCache, columnFluid);
+                                caveBiomeCache, customBiomeCache);
                     }
                     zone = new CaveZone();
                     zone.setFloor(y);
@@ -614,7 +621,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
 
         if (zone.isValid(getEngine())) {
             processZone(output, mc, mantle, zone, rx, rz, worldX, worldZ, resolverState,
-                    caveBiomeCache, customBiomeCache, columnFluid);
+                    caveBiomeCache, customBiomeCache);
         }
     }
 
@@ -767,8 +774,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
                              CaveZone zone, int rx, int rz, int xx, int zz,
                              IrisDimensionCarvingResolver.State resolverState,
                              Long2ObjectOpenHashMap<IrisBiome> caveBiomeCache,
-                             Map<String, IrisBiome> customBiomeCache,
+                             Map<String, IrisBiome> customBiomeCache) {
-                             PlatformBlockState columnFluid) {
         int maxY = output.getHeight();
 
         if (zone.ceiling + 1 < maxY && B.isDecorant(output.getRaw(rx, zone.ceiling + 1, rz))) {
@@ -793,7 +799,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
         IrisBiome floorBiome = resolveCaveBoundaryBiome(mc, rx, zone.floor, rz, xx, zz, resolverState, caveBiomeCache, customBiomeCache);
         IrisBiome ceilingBiome = resolveCaveBoundaryBiome(mc, rx, zone.ceiling, rz, xx, zz, resolverState, caveBiomeCache, customBiomeCache);
         if (floorBiome == null && ceilingBiome == null) {
-            normalizeCaveZoneWaterlogging(output, mc, zone, rx, rz, columnFluid);
+            normalizeCaveZoneWaterlogging(output, mc, zone, rx, rz, xx, zz);
             return;
         }
 
@@ -865,7 +871,7 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
             decorant.getCeilingDecorator().decorate(rx, rz, xx, xx, xx, zz, zz, zz, output, ceilingBiome, InferredType.CAVE, zone.getCeiling(), zone.airThickness());
         }
 
-        normalizeCaveZoneWaterlogging(output, mc, zone, rx, rz, columnFluid);
+        normalizeCaveZoneWaterlogging(output, mc, zone, rx, rz, xx, zz);
     }
 
     private void normalizeCaveZoneWaterlogging(
@@ -874,7 +880,8 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
             CaveZone zone,
             int localX,
             int localZ,
-            PlatformBlockState columnFluid
+            int worldX,
+            int worldZ
     ) {
         int minimumY = Math.max(0, zone.floor - 1);
         int maximumY = Math.min(output.getHeight() - 1, zone.ceiling + 1);
@@ -887,6 +894,11 @@ public class IrisCarveModifier extends EngineAssignedModifier<PlatformBlockState
             MatterCavern baseline = dataIfPresent(
                     mantleChunk, localX, y, localZ, MatterCavern.class);
             PlatformBlockState current = output.getRaw(localX, y, localZ);
+            PlatformBlockState columnFluid = getComplex().resolveRiverCaveFluid(
+                    hydrology.fluidKind(),
+                    worldX,
+                    worldZ
+            );
             PlatformBlockState normalized = normalizeHydrologyWaterlogging(
                     current,
                     baseline,

core/src/main/java/art/arcane/iris/engine/object/IrisImageMapOrigin.java

@@ -10,7 +10,10 @@ import lombok.experimental.Accessors;
 @Desc("A two-dimensional image-map coordinate")
 @Data
 public class IrisImageMapOrigin {
+    @Desc("X coordinate in world blocks for origin, or source pixels for sourceOrigin")
     private double x = 0D;
+
+    @Desc("Z coordinate in world blocks for origin, or source image Y pixels for sourceOrigin")
     private double z = 0D;
 
     public IrisImageMapOrigin(double x, double z) {

core/src/main/java/art/arcane/iris/engine/object/IrisObjectTransforms.java

@@ -25,6 +25,11 @@ import art.arcane.iris.util.common.math.IrisBlockVector;
 import art.arcane.iris.util.common.math.IrisVector;
 import art.arcane.iris.util.project.interpolation.Interpolation3D;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+
 /**
  * Geometric transforms for {@link IrisObject}: rotation, scaling and the interpolated upscalers.
  */
@@ -133,6 +138,7 @@ final class IrisObjectTransforms {
             VectorMap<PlatformBlockState> b = new VectorMap<>();
             IrisPosition min = self.getAABB().min();
             IrisPosition max = self.getAABB().max();
+            NearestBlockIndex nearestBlocks = NearestBlockIndex.create(v);
 
             for (int x = min.getX(); x <= max.getX(); x++) {
                 for (int y = min.getY(); y <= max.getY(); y++) {
@@ -146,7 +152,7 @@ final class IrisObjectTransforms {
 
                             return 1;
                         }) >= 0.5) {
-                            b.put(new IrisBlockVector(x, y, z), nearestBlockData(self, x, y, z));
+                            b.put(new IrisBlockVector(x, y, z), nearestBlockData(v, nearestBlocks, x, y, z));
                         } else {
                             b.put(new IrisBlockVector(x, y, z), IrisObject.States.AIR);
                         }
@@ -169,6 +175,7 @@ final class IrisObjectTransforms {
             VectorMap<PlatformBlockState> b = new VectorMap<>();
             IrisPosition min = self.getAABB().min();
             IrisPosition max = self.getAABB().max();
+            NearestBlockIndex nearestBlocks = NearestBlockIndex.create(v);
 
             for (int x = min.getX(); x <= max.getX(); x++) {
                 for (int y = min.getY(); y <= max.getY(); y++) {
@@ -182,7 +189,7 @@ final class IrisObjectTransforms {
 
                             return 1;
                         }) >= 0.5) {
-                            b.put(new IrisBlockVector(x, y, z), nearestBlockData(self, x, y, z));
+                            b.put(new IrisBlockVector(x, y, z), nearestBlockData(v, nearestBlocks, x, y, z));
                         } else {
                             b.put(new IrisBlockVector(x, y, z), IrisObject.States.AIR);
                         }
@@ -209,6 +216,7 @@ final class IrisObjectTransforms {
             VectorMap<PlatformBlockState> b = new VectorMap<>();
             IrisPosition min = self.getAABB().min();
             IrisPosition max = self.getAABB().max();
+            NearestBlockIndex nearestBlocks = NearestBlockIndex.create(v);
 
             for (int x = min.getX(); x <= max.getX(); x++) {
                 for (int y = min.getY(); y <= max.getY(); y++) {
@@ -222,7 +230,7 @@ final class IrisObjectTransforms {
 
                             return 1;
                         }, tension, bias) >= 0.5) {
-                            b.put(new IrisBlockVector(x, y, z), nearestBlockData(self, x, y, z));
+                            b.put(new IrisBlockVector(x, y, z), nearestBlockData(v, nearestBlocks, x, y, z));
                         } else {
                             b.put(new IrisBlockVector(x, y, z), IrisObject.States.AIR);
                         }
@@ -238,36 +246,124 @@ final class IrisObjectTransforms {
         }
     }
 
-    private static PlatformBlockState nearestBlockData(IrisObject self, int x, int y, int z) {
+    private static PlatformBlockState nearestBlockData(VectorMap<PlatformBlockState> blocks,
+                                                       NearestBlockIndex nearestBlocks,
+                                                       int x, int y, int z) {
         IrisBlockVector vv = new IrisBlockVector(x, y, z);
-        self.readLock.lock();
+        PlatformBlockState direct = blocks.get(vv);
-        try {
+        if (!B.isAir(direct)) {
-            PlatformBlockState r = self.blocks.get(vv);
+            return direct;
-
+        }
-            if (!B.isAir(r)) {
+        return nearestBlocks.nearest(x, y, z, direct);
-                return r;
     }
 
-            double d = Double.MAX_VALUE;
+    static final class NearestBlockIndex {
+        private static final Comparator<NearestBlock> X_ORDER = Comparator
+                .comparingInt(NearestBlock::x)
+                .thenComparingInt(NearestBlock::rank);
+        private static final Comparator<NearestBlock> Y_ORDER = Comparator
+                .comparingInt(NearestBlock::y)
+                .thenComparingInt(NearestBlock::rank);
+        private static final Comparator<NearestBlock> Z_ORDER = Comparator
+                .comparingInt(NearestBlock::z)
+                .thenComparingInt(NearestBlock::rank);
 
-            for (var entry : self.blocks) {
+        private final NearestNode root;
-                PlatformBlockState dat = entry.getValue();
+        private PlatformBlockState bestState;
+        private double bestDistance;
+        private int bestRank;
 
-                if (B.isAir(dat)) {
+        private NearestBlockIndex(NearestNode root) {
-                    continue;
+            this.root = root;
         }
 
-                double dx = entry.getKey().distanceSquared(vv);
+        static NearestBlockIndex create(VectorMap<PlatformBlockState> blocks) {
-
+            List<NearestBlock> points = new ArrayList<>(blocks.size());
-                if (dx < d) {
+            VectorMap<PlatformBlockState>.Cursor cursor = blocks.cursor();
-                    d = dx;
+            int rank = 0;
-                    r = dat;
+            while (cursor.next()) {
+                PlatformBlockState state = cursor.value();
+                if (!B.isAir(state)) {
+                    IrisBlockVector position = cursor.key();
+                    points.add(new NearestBlock(position.getBlockX(), position.getBlockY(), position.getBlockZ(),
+                            rank, state));
                 }
+                rank++;
             }
 
-            return r;
+            NearestBlock[] pointArray = points.toArray(new NearestBlock[0]);
-        } finally {
+            return new NearestBlockIndex(build(pointArray, 0, pointArray.length, 0));
-            self.readLock.unlock();
+        }
+
+        PlatformBlockState nearest(int x, int y, int z, PlatformBlockState fallback) {
+            if (root == null) {
+                return fallback;
+            }
+
+            bestState = fallback;
+            bestDistance = Double.MAX_VALUE;
+            bestRank = Integer.MAX_VALUE;
+            search(root, x, y, z);
+            return bestState;
+        }
+
+        private static NearestNode build(NearestBlock[] points, int from, int to, int depth) {
+            if (from >= to) {
+                return null;
+            }
+
+            int axis = depth % 3;
+            Arrays.sort(points, from, to, comparator(axis));
+            int middle = (from + to) >>> 1;
+            return new NearestNode(
+                    points[middle],
+                    axis,
+                    build(points, from, middle, depth + 1),
+                    build(points, middle + 1, to, depth + 1)
+            );
+        }
+
+        private static Comparator<NearestBlock> comparator(int axis) {
+            return switch (axis) {
+                case 0 -> X_ORDER;
+                case 1 -> Y_ORDER;
+                default -> Z_ORDER;
+            };
+        }
+
+        private void search(NearestNode node, int x, int y, int z) {
+            if (node == null) {
+                return;
+            }
+
+            NearestBlock point = node.point();
+            double xDistance = point.x() - x;
+            double yDistance = point.y() - y;
+            double zDistance = point.z() - z;
+            double distance = (xDistance * xDistance) + (yDistance * yDistance) + (zDistance * zDistance);
+            if (distance < bestDistance || (distance == bestDistance && point.rank() < bestRank)) {
+                bestState = point.state();
+                bestDistance = distance;
+                bestRank = point.rank();
+            }
+
+            double axisDistance = switch (node.axis()) {
+                case 0 -> x - point.x();
+                case 1 -> y - point.y();
+                default -> z - point.z();
+            };
+            NearestNode near = axisDistance <= 0D ? node.lower() : node.upper();
+            NearestNode far = axisDistance <= 0D ? node.upper() : node.lower();
+            search(near, x, y, z);
+            if ((axisDistance * axisDistance) <= bestDistance) {
+                search(far, x, y, z);
             }
         }
     }
+
+    private record NearestNode(NearestBlock point, int axis, NearestNode lower, NearestNode upper) {
+    }
+
+    private record NearestBlock(int x, int y, int z, int rank, PlatformBlockState state) {
+    }
+}

core/src/main/java/art/arcane/iris/engine/object/IrisRiverCaves.java

@@ -97,4 +97,7 @@ public class IrisRiverCaves {
 
     @Desc("The policy for fluid already present in a candidate contained cave body.")
     private IrisRiverExistingFluidPolicy existingFluidPolicy = IrisRiverExistingFluidPolicy.REJECT;
+
+    @Desc("Sparse, independently filled cave-floor pools generated at deep river-network anchors.")
+    private IrisRiverDeepPools deepPools = new IrisRiverDeepPools();
 }

core/src/main/java/art/arcane/iris/engine/object/IrisRiverDeepPools.java

@@ -0,0 +1,92 @@
+package art.arcane.iris.engine.object;
+
+import art.arcane.iris.engine.object.annotations.Desc;
+import art.arcane.iris.engine.object.annotations.MaxNumber;
+import art.arcane.iris.engine.object.annotations.MinNumber;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+import lombok.experimental.Accessors;
+
+@Accessors(chain = true)
+@NoArgsConstructor
+@Desc("Controls sparse, river-anchored fluid pools attached to deep cave floors.")
+@Data
+public class IrisRiverDeepPools {
+    @Desc("Enables independently configured deep cave pools along eligible wet river reaches.")
+    private boolean enabled = false;
+
+    @Desc("Selects complete wet river reaches that may host deep pools.")
+    private IrisRiverNoiseChance reach = new IrisRiverNoiseChance()
+            .setChance(1D / 3D)
+            .setStyle(new IrisGeneratorStyle(NoiseStyle.IRIS).zoomed(4096D))
+            .setInfluence(0.08D);
+
+    @MinNumber(16)
+    @MaxNumber(4096)
+    @Desc("The minimum distance in blocks between deep-pool candidates.")
+    private int minimumSpacing = 768;
+
+    @MinNumber(0)
+    @MaxNumber(16)
+    @Desc("The maximum accepted deep pools on one river reach.")
+    private int maximumPerReach = 1;
+
+    @MinNumber(-2048)
+    @MaxNumber(2048)
+    @Desc("The lowest absolute world Y considered for the pool fluid surface.")
+    private int minimumFluidY = -224;
+
+    @MinNumber(-2048)
+    @MaxNumber(2048)
+    @Desc("The highest absolute world Y considered for the pool fluid surface.")
+    private int maximumFluidY = -104;
+
+    @MinNumber(0)
+    @MaxNumber(256)
+    @Desc("The horizontal distance searched from a river anchor for a contained cave floor.")
+    private int searchRadius = 16;
+
+    @MinNumber(1)
+    @MaxNumber(64)
+    @Desc("The number of deterministic nearby columns tested for a contained cave floor.")
+    private int searchAttempts = 12;
+
+    @MinNumber(2)
+    @MaxNumber(128)
+    @Desc("The horizontal radius of the generated deep-pool chamber.")
+    private int horizontalRadius = 18;
+
+    @MinNumber(2)
+    @MaxNumber(64)
+    @Desc("The vertical radius of the generated deep-pool chamber.")
+    private int verticalRadius = 8;
+
+    @MinNumber(1)
+    @MaxNumber(63)
+    @Desc("The dry chamber height retained above the deep-pool fluid surface.")
+    private int dryHeadroom = 4;
+
+    @Desc("Noise shaping the deep-pool chamber boundary.")
+    private IrisGeneratorStyle shapeStyle = new IrisGeneratorStyle(NoiseStyle.IRIS).zoomed(12D);
+
+    @MinNumber(0)
+    @MaxNumber(0.75)
+    @Desc("The proportional noise displacement applied to the deep-pool chamber boundary.")
+    private double shapeVariation = 0.5D;
+
+    @Desc("Noise warping the deep-pool chamber coordinate field.")
+    private IrisGeneratorStyle warpStyle = new IrisGeneratorStyle(NoiseStyle.IRIS).zoomed(24D);
+
+    @MinNumber(0)
+    @MaxNumber(64)
+    @Desc("The maximum coordinate warp applied to the deep-pool chamber in blocks.")
+    private double warpStrength = 6D;
+
+    @MinNumber(64)
+    @MaxNumber(1048576)
+    @Desc("The greatest generated deep-pool chamber volume that may be transactionally published.")
+    private int maximumVolume = 32768;
+
+    @Desc("The fluid palette used only by accepted deep pools.")
+    private IrisMaterialPalette fluidPalette = new IrisMaterialPalette().qclear().qadd("lava");
+}

core/src/main/java/art/arcane/iris/engine/object/IrisRiverTerrain.java

@@ -24,6 +24,11 @@ public class IrisRiverTerrain {
     @Desc("The wet-bed depth below the local water surface, or dry-channel depth below natural terrain, in blocks.")
     private IrisStyledRange depth = range(2D, 7D, NoiseStyle.IRIS, 768D);
 
+    @MinNumber(0)
+    @MaxNumber(64)
+    @Desc("The radius added to every channel after worm, regional, local, and stream-order shaping.")
+    private double channelRadiusBonus = 0D;
+
     @MinNumber(1)
     @MaxNumber(2048)
     @Desc("The final wet-channel width cap after region, biome, and stream-order scaling.")
@@ -64,7 +69,7 @@ public class IrisRiverTerrain {
 
     @MinNumber(0)
     @MaxNumber(16)
-    @Desc("The extra lateral tunnel-mouth blend carved on each side where a surface river enters or exits solid terrain.")
+    @Desc("The longitudinal transition length and maximum lateral and roof flare where a surface river enters or exits solid terrain.")
     private double tunnelMouthBlend = 2D;
 
     @Desc("Noise modulating the submerged floor of river tunnels.")

core/src/main/java/art/arcane/iris/engine/object/IrisRiverWater.java

@@ -13,7 +13,15 @@ import lombok.experimental.Accessors;
 @Data
 public class IrisRiverWater {
     @Desc("The strategy used to determine river water-surface height.")
-    private IrisRiverWaterMode mode = IrisRiverWaterMode.SEA_LEVEL;
+    private IrisRiverWaterMode mode = IrisRiverWaterMode.FIXED;
+
+    @MinNumber(-2048)
+    @MaxNumber(2048)
+    @Desc("The base river fluid surface in absolute world Y, independent of the dimension ocean height.")
+    private int fluidHeight = 63;
+
+    @Desc("The river fluid palette used by surface channels, contained tunnels, grottos, and waterfall throats.")
+    private IrisMaterialPalette fluidPalette = new IrisMaterialPalette().qclear().qadd("water");
 
     @MinNumber(8)
     @MaxNumber(4096)
@@ -22,7 +30,7 @@ public class IrisRiverWater {
 
     @MinNumber(0)
     @MaxNumber(64)
-    @Desc("The greatest river water height permitted above the dimension fluid height.")
+    @Desc("The greatest terraced river height permitted above fluidHeight.")
     private int maximumPoolRise = 4;
 
     @MinNumber(1)

core/src/main/java/art/arcane/iris/engine/object/IrisRiverWaterMode.java

@@ -4,8 +4,8 @@ import art.arcane.iris.engine.object.annotations.Desc;
 
 @Desc("Selects how a river determines its surface fluid height.")
 public enum IrisRiverWaterMode {
-    @Desc("Use the dimension fluid height for every wet river reach.")
+    @Desc("Use the river water configuration's fixed fluid height for every wet reach.")
-    SEA_LEVEL,
+    FIXED,
 
     @Desc("Use flat pools connected by controlled vertical drops.")
     TERRACED

core/src/main/java/art/arcane/iris/engine/object/IrisRiverWorm.java

@@ -72,16 +72,21 @@ public class IrisRiverWorm {
     @Desc("Depth multiplier for reaches selecting this worm.")
     private double depthMultiplier = 1D;
 
-    @MinNumber(32)
+    @MinNumber(8)
     @MaxNumber(16384)
     @Desc("Primary world-space wavelength controlling longitudinal body swelling and pinching.")
     private double bodyWavelength = 512D;
 
-    @MinNumber(32)
+    @MinNumber(8)
     @MaxNumber(16384)
     @Desc("Detail wavelength adding smaller changes to the longitudinal body profile.")
     private double bodyDetailWavelength = 128D;
 
+    @MinNumber(0)
+    @MaxNumber(1)
+    @Desc("Share of the longitudinal body field supplied by bodyDetailWavelength; the remainder uses bodyWavelength.")
+    private double bodyDetailInfluence = 0.3D;
+
     @MinNumber(0)
     @MaxNumber(0.875)
     @Desc("Maximum proportional channel-width variation along this style's body.")

core/src/main/java/art/arcane/iris/engine/platform/BukkitChunkGenerator.java

@@ -121,6 +121,7 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
     private final AtomicInteger a = new AtomicInteger(0);
     private volatile long lastChunkGenTime = 0L;
     private final CompletableFuture<Integer> spawnChunks = new CompletableFuture<>();
+    private final CompletableFuture<Void> initialSpawnReady = new CompletableFuture<>();
     private final AtomicCache<EngineTarget> targetCache = new AtomicCache<>();
     private final AtomicReference<CompletableFuture<Void>> closeFuture = new AtomicReference<>();
     private volatile Engine engine;
@@ -194,11 +195,19 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
             engine.getPlatformHooks().applyWorldBoundary(engine);
             IrisLogging.debug("Injected Iris Biome Source into " + world.getName());
             if (!studio) {
-                J.s(() -> updateSpawnLocation(world), 1);
+                J.sfut(() -> updateSpawnLocation(world), 1)
+                        .whenComplete((ignored, failure) -> {
+                            if (failure != null) {
+                                initialSpawnReady.completeExceptionally(failure);
+                            }
+                        });
+            } else {
+                initialSpawnReady.complete(null);
             }
         } catch (Throwable e) {
             initializationFailure = e;
             spawnChunks.completeExceptionally(e);
+            initialSpawnReady.completeExceptionally(e);
             IrisLogging.reportError(e);
             IrisLogging.error("Failed to initialize Iris generator for " + world.getName());
             if (e instanceof RuntimeException runtimeException) {
@@ -231,16 +240,58 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
     }
 
     private void updateSpawnLocation(World world) {
+        try {
             Location initialSpawn = getInitialSpawnLocation(world);
             int chunkX = initialSpawn.getBlockX() >> 4;
             int chunkZ = initialSpawn.getBlockZ() >> 4;
             CompletableFuture<Chunk> chunkFuture = requestChunkAsync(world, chunkX, chunkZ, true);
             if (chunkFuture == null) {
+                initialSpawnReady.completeExceptionally(new IllegalStateException(
+                        "Initial spawn chunk request returned no completion future for world \""
+                                + world.getName() + "\"."));
                 return;
             }
 
-        chunkFuture.thenAccept(chunk ->
+            chunkFuture.whenComplete((chunk, failure) -> {
-                J.runRegion(chunk.getWorld(), chunk.getX(), chunk.getZ(), () -> applySpawnLocation(chunk.getWorld(), initialSpawn)));
+                try {
+                    if (failure != null) {
+                        initialSpawnReady.completeExceptionally(failure);
+                        return;
+                    }
+                    if (chunk == null) {
+                        throw new IllegalStateException(
+                                "Initial spawn chunk request completed without a chunk for world \""
+                                        + world.getName() + "\".");
+                    }
+                    J.runRegionFuture(
+                            chunk.getWorld(),
+                            chunk.getX(),
+                            chunk.getZ(),
+                            () -> completeSpawnLocation(chunk.getWorld(), initialSpawn))
+                            .whenComplete((ignored, scheduleFailure) -> {
+                                if (scheduleFailure != null) {
+                                    initialSpawnReady.completeExceptionally(scheduleFailure);
+                                }
+                            });
+                } catch (Throwable callbackFailure) {
+                    initialSpawnReady.completeExceptionally(new IllegalStateException(
+                            "Initial spawn preparation failed for world \""
+                                    + world.getName() + "\".",
+                            callbackFailure));
+                }
+            });
+        } catch (Throwable failure) {
+            initialSpawnReady.completeExceptionally(failure);
+        }
+    }
+
+    private void completeSpawnLocation(World world, Location initialSpawn) {
+        try {
+            applySpawnLocation(world, initialSpawn);
+            initialSpawnReady.complete(null);
+        } catch (Throwable failure) {
+            initialSpawnReady.completeExceptionally(failure);
+        }
     }
 
     private void applySpawnLocation(World world, Location initialSpawn) {
@@ -255,10 +306,27 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
 
         int minY = world.getMinHeight() + 1;
         int maxY = world.getMaxHeight() - 2;
-        int y = Math.max(minY, Math.min(maxY, world.getHighestBlockYAt(initialSpawn) + 1));
+        int y = resolveInitialSpawnY(world, initialSpawn, minY, maxY);
         world.setSpawnLocation(new Location(world, initialSpawn.getX(), y, initialSpawn.getZ(), initialSpawn.getYaw(), initialSpawn.getPitch()));
     }
 
+    private int resolveInitialSpawnY(World world, Location initialSpawn, int minY, int maxY) {
+        Engine activeEngine = engine;
+        if (activeEngine != null && activeEngine.getComplex() != null && activeEngine.getComplex().getHeightStream() != null) {
+            int generatedY = activeEngine.getMinHeight()
+                    + activeEngine.getComplex().getHeightStream().get(initialSpawn.getX(), initialSpawn.getZ()).intValue()
+                    + 1;
+            return Math.max(minY, Math.min(maxY, generatedY));
+        }
+
+        return Math.max(minY, Math.min(maxY, world.getHighestBlockYAt(initialSpawn) + 1));
+    }
+
+    @Override
+    public CompletableFuture<Void> getInitialSpawnReady() {
+        return initialSpawnReady;
+    }
+
     @SuppressWarnings("unchecked")
     private CompletableFuture<Chunk> requestChunkAsync(World world, int chunkX, int chunkZ, boolean generate) {
         try {
@@ -377,6 +445,11 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
             this.hotloader = shouldRunStudioHotload(studio, closing, jigsawStudioActive) ? new Looper() {
                 @Override
                 protected long loop() {
+                    Engine activeEngine = engine;
+                    if (activeEngine instanceof IrisEngine irisEngine
+                            && irisEngine.isGenerationCacheWarmPending()) {
+                        return HOTLOAD_LOOP_DELAY_MS;
+                    }
                     if (shouldThrottleHotload()) {
                         return HOTLOAD_MAINTENANCE_DELAY_MS;
                     }

core/src/main/java/art/arcane/iris/engine/platform/PlatformChunkGenerator.java

@@ -76,4 +76,8 @@ public interface PlatformChunkGenerator extends Hotloadable, DataProvider {
     }
 
     CompletableFuture<Integer> getSpawnChunks();
+
+    default CompletableFuture<Void> getInitialSpawnReady() {
+        return CompletableFuture.completedFuture(null);
+    }
 }

core/src/main/java/art/arcane/iris/engine/river/RiverBodyProfile.java

@@ -119,6 +119,15 @@ public final class RiverBodyProfile {
         return roofScales[index];
     }
 
+    public int intervalIndex(double alongReach) {
+        double position = StrictMath.max(0D, StrictMath.min(1D, alongReach));
+        int index = Arrays.binarySearch(positions, position);
+        if (index >= 0) {
+            return StrictMath.min(index, positions.length - 2);
+        }
+        return StrictMath.max(0, StrictMath.min(-index - 2, positions.length - 2));
+    }
+
     @Override
     public boolean equals(Object object) {
         if (this == object) {

core/src/main/java/art/arcane/iris/engine/river/RiverNetwork.java

@@ -38,7 +38,7 @@ public final class RiverNetwork {
     private static final long BRANCH_SLOT_SALT = 0x94D049BB133111EBL;
     private static final long BRANCH_GATE_SALT = 0x2545F4914F6CDD1DL;
     private static final int MINIMUM_BODY_PROFILE_SAMPLES = 12;
-    private static final int MAXIMUM_BODY_PROFILE_SAMPLES = 32;
+    private static final int MAXIMUM_BODY_PROFILE_SAMPLES = 512;
     private static final double PERLIN_NORMALIZATION = 1.4142135623730951D;
 
     private final RiverNetworkOptions options;
@@ -670,7 +670,8 @@ public final class RiverNetwork {
                 worm.bodyDetailWavelength(),
                 worm.seed() ^ detailSalt
         );
-        return primary * 0.7D + detail * 0.3D;
+        double detailInfluence = worm.bodyDetailInfluence();
+        return primary * (1D - detailInfluence) + detail * detailInfluence;
     }
 
     private FlowTangent resolveFlowTangent(RiverNode node, RiverTerrainSampler terrain) {
@@ -1263,6 +1264,7 @@ public final class RiverNetwork {
                                                 BODY_WIDTH_DETAIL_SALT,
                                                 worm.widthVariation()
                                         )
+                                        + options.channelRadiusBonus() * 2D
                         )
                 );
                 double baseBankWidth = nonNegativeOrFallback(

core/src/main/java/art/arcane/iris/engine/river/RiverNetworkOptions.java

@@ -29,6 +29,7 @@ public record RiverNetworkOptions(
         double channelWidth,
         double bankWidth,
         double depth,
+        double channelRadiusBonus,
         double maxChannelWidth,
         double maxBankWidth,
         double maxDepth,
@@ -60,6 +61,7 @@ public record RiverNetworkOptions(
         requirePositive(channelWidth, "channelWidth");
         requireFiniteNonNegative(bankWidth, "bankWidth");
         requirePositive(depth, "depth");
+        requireFiniteNonNegative(channelRadiusBonus, "channelRadiusBonus");
         requirePositive(maxChannelWidth, "maxChannelWidth");
         requireFiniteNonNegative(maxBankWidth, "maxBankWidth");
         requirePositive(maxDepth, "maxDepth");
@@ -215,6 +217,7 @@ public record RiverNetworkOptions(
         private double channelWidth;
         private double bankWidth;
         private double depth;
+        private double channelRadiusBonus;
         private double maxChannelWidth;
         private double maxBankWidth;
         private double maxDepth;
@@ -269,6 +272,7 @@ public record RiverNetworkOptions(
                     1D,
                     512D,
                     128D,
+                    0.3D,
                     0D,
                     0D,
                     0D,
@@ -397,6 +401,11 @@ public record RiverNetworkOptions(
             return this;
         }
 
+        public Builder channelRadiusBonus(double value) {
+            channelRadiusBonus = value;
+            return this;
+        }
+
         public Builder maxChannelWidth(double value) {
             maxChannelWidth = value;
             return this;
@@ -461,6 +470,7 @@ public record RiverNetworkOptions(
                     channelWidth,
                     bankWidth,
                     depth,
+                    channelRadiusBonus,
                     maxChannelWidth,
                     maxBankWidth,
                     maxDepth,

core/src/main/java/art/arcane/iris/engine/river/RiverTile.java

@@ -325,25 +325,35 @@ public final class RiverTile {
             double additionalRadius
     ) {
         RiverPolyline polyline = reach.polyline();
-        if (polyline.length() == 0D) {
+        RiverBodyProfile bodyProfile = reach.bodyProfile();
+        double polylineLength = polyline.length();
+        if (polylineLength == 0D) {
             double distanceSquared = squared(x - polyline.x(0)) + squared(z - polyline.z(0));
             double radius = reach.widthAt(0D) * 0.5D + reach.bankWidthAt(0D) + additionalRadius;
             return distanceSquared <= radius * radius ? new ClosestPoint(distanceSquared, 0D) : null;
         }
         double nearest = Double.POSITIVE_INFINITY;
         double nearestAlong = 0.0;
-        for (int point = 0; point < polyline.size() - 1; point++) {
+        int pointLimit = polyline.size() - 1;
-            double segmentStartAlong = polyline.cumulativeLength(point) / polyline.length();
+        int profileLimit = bodyProfile.size() - 1;
-            double segmentEndAlong = polyline.cumulativeLength(point + 1) / polyline.length();
+        for (int point = 0; point < pointLimit; point++) {
+            double segmentStartAlong = polyline.cumulativeLength(point) / polylineLength;
+            double segmentEndAlong = polyline.cumulativeLength(point + 1) / polylineLength;
             double segmentAlongSpan = segmentEndAlong - segmentStartAlong;
             if (segmentAlongSpan == 0D) {
                 continue;
             }
-            double deltaX = polyline.x(point + 1) - polyline.x(point);
+            double startX = polyline.x(point);
-            double deltaZ = polyline.z(point + 1) - polyline.z(point);
+            double startZ = polyline.z(point);
-            for (int profileIndex = 0; profileIndex < reach.bodyProfile().size() - 1; profileIndex++) {
+            double deltaX = polyline.x(point + 1) - startX;
-                double profileStart = reach.bodyProfile().position(profileIndex);
+            double deltaZ = polyline.z(point + 1) - startZ;
-                double profileEnd = reach.bodyProfile().position(profileIndex + 1);
+            int firstProfileIndex = bodyProfile.intervalIndex(segmentStartAlong);
+            for (int profileIndex = firstProfileIndex;
+                 profileIndex < profileLimit
+                         && bodyProfile.position(profileIndex) <= segmentEndAlong;
+                 profileIndex++) {
+                double profileStart = bodyProfile.position(profileIndex);
+                double profileEnd = bodyProfile.position(profileIndex + 1);
                 double overlapStart = StrictMath.max(segmentStartAlong, profileStart);
                 double overlapEnd = StrictMath.min(segmentEndAlong, profileEnd);
                 if (overlapStart > overlapEnd) {
@@ -351,13 +361,16 @@ public final class RiverTile {
                 }
                 double intervalStart = (overlapStart - segmentStartAlong) / segmentAlongSpan;
                 double intervalEnd = (overlapEnd - segmentStartAlong) / segmentAlongSpan;
-                double widthSlope = (reach.bodyProfile().widthAtIndex(profileIndex + 1)
+                double profileSpan = profileEnd - profileStart;
-                        - reach.bodyProfile().widthAtIndex(profileIndex)) / (profileEnd - profileStart);
+                double profileWidth = bodyProfile.widthAtIndex(profileIndex);
-                double bankSlope = (reach.bodyProfile().bankWidthAtIndex(profileIndex + 1)
+                double profileBankWidth = bodyProfile.bankWidthAtIndex(profileIndex);
-                        - reach.bodyProfile().bankWidthAtIndex(profileIndex)) / (profileEnd - profileStart);
+                double widthSlope = (bodyProfile.widthAtIndex(profileIndex + 1)
-                double radiusBase = (reach.bodyProfile().widthAtIndex(profileIndex)
+                        - profileWidth) / profileSpan;
+                double bankSlope = (bodyProfile.bankWidthAtIndex(profileIndex + 1)
+                        - profileBankWidth) / profileSpan;
+                double radiusBase = (profileWidth
                         + widthSlope * (segmentStartAlong - profileStart)) * 0.5D
-                        + reach.bodyProfile().bankWidthAtIndex(profileIndex)
+                        + profileBankWidth
                         + bankSlope * (segmentStartAlong - profileStart)
                         + additionalRadius;
                 double radiusSlope = (widthSlope * 0.5D + bankSlope) * segmentAlongSpan;
@@ -365,9 +378,9 @@ public final class RiverTile {
                         intervalStart,
                         intervalEnd,
                         deltaX,
-                        polyline.x(point) - x,
+                        startX - x,
                         deltaZ,
-                        polyline.z(point) - z,
+                        startZ - z,
                         radiusSlope,
                         radiusBase,
                         segmentStartAlong,
@@ -390,7 +403,9 @@ public final class RiverTile {
             double maximumZ
     ) {
         RiverPolyline polyline = reach.polyline();
-        if (polyline.length() == 0D) {
+        RiverBodyProfile bodyProfile = reach.bodyProfile();
+        double polylineLength = polyline.length();
+        if (polylineLength == 0D) {
             double distanceSquared = pointRectangleDistanceSquared(
                     polyline.x(0),
                     polyline.z(0),
@@ -404,9 +419,11 @@ public final class RiverTile {
         }
         double nearest = Double.POSITIVE_INFINITY;
         double nearestAlong = 0.0;
-        for (int point = 0; point < polyline.size() - 1; point++) {
+        int pointLimit = polyline.size() - 1;
-            double segmentStartAlong = polyline.cumulativeLength(point) / polyline.length();
+        int profileLimit = bodyProfile.size() - 1;
-            double segmentEndAlong = polyline.cumulativeLength(point + 1) / polyline.length();
+        for (int point = 0; point < pointLimit; point++) {
+            double segmentStartAlong = polyline.cumulativeLength(point) / polylineLength;
+            double segmentEndAlong = polyline.cumulativeLength(point + 1) / polylineLength;
             double segmentAlongSpan = segmentEndAlong - segmentStartAlong;
             if (segmentAlongSpan == 0D) {
                 continue;
@@ -415,9 +432,13 @@ public final class RiverTile {
             double startZ = polyline.z(point);
             double deltaX = polyline.x(point + 1) - startX;
             double deltaZ = polyline.z(point + 1) - startZ;
-            for (int profileIndex = 0; profileIndex < reach.bodyProfile().size() - 1; profileIndex++) {
+            int firstProfileIndex = bodyProfile.intervalIndex(segmentStartAlong);
-                double profileStart = reach.bodyProfile().position(profileIndex);
+            for (int profileIndex = firstProfileIndex;
-                double profileEnd = reach.bodyProfile().position(profileIndex + 1);
+                 profileIndex < profileLimit
+                         && bodyProfile.position(profileIndex) <= segmentEndAlong;
+                 profileIndex++) {
+                double profileStart = bodyProfile.position(profileIndex);
+                double profileEnd = bodyProfile.position(profileIndex + 1);
                 double overlapStart = StrictMath.max(segmentStartAlong, profileStart);
                 double overlapEnd = StrictMath.min(segmentEndAlong, profileEnd);
                 if (overlapStart > overlapEnd) {
@@ -425,13 +446,16 @@ public final class RiverTile {
                 }
                 double intervalStart = (overlapStart - segmentStartAlong) / segmentAlongSpan;
                 double intervalEnd = (overlapEnd - segmentStartAlong) / segmentAlongSpan;
-                double widthSlope = (reach.bodyProfile().widthAtIndex(profileIndex + 1)
+                double profileSpan = profileEnd - profileStart;
-                        - reach.bodyProfile().widthAtIndex(profileIndex)) / (profileEnd - profileStart);
+                double profileWidth = bodyProfile.widthAtIndex(profileIndex);
-                double bankSlope = (reach.bodyProfile().bankWidthAtIndex(profileIndex + 1)
+                double profileBankWidth = bodyProfile.bankWidthAtIndex(profileIndex);
-                        - reach.bodyProfile().bankWidthAtIndex(profileIndex)) / (profileEnd - profileStart);
+                double widthSlope = (bodyProfile.widthAtIndex(profileIndex + 1)
-                double radiusBase = (reach.bodyProfile().widthAtIndex(profileIndex)
+                        - profileWidth) / profileSpan;
+                double bankSlope = (bodyProfile.bankWidthAtIndex(profileIndex + 1)
+                        - profileBankWidth) / profileSpan;
+                double radiusBase = (profileWidth
                         + widthSlope * (segmentStartAlong - profileStart)) * 0.5D
-                        + reach.bodyProfile().bankWidthAtIndex(profileIndex)
+                        + profileBankWidth
                         + bankSlope * (segmentStartAlong - profileStart);
                 double radiusSlope = (widthSlope * 0.5D + bankSlope) * segmentAlongSpan;
                 double cursor = intervalStart;
@@ -626,8 +650,7 @@ public final class RiverTile {
     }
 
     private List<RiverReach> indexedReaches(double x, double z) {
-        List<RiverReach> indexed = spatialIndex.get(bucketKey(bucket(x), bucket(z)));
+        return spatialIndex.getOrDefault(bucketKey(bucket(x), bucket(z)), List.of());
-        return indexed == null ? List.of() : indexed;
     }
 
     private List<RiverReach> indexedReaches(
@@ -641,12 +664,15 @@ public final class RiverTile {
         int maximumBucketX = bucket(StrictMath.nextDown(queryMaximumX));
         int minimumBucketZ = bucket(queryMinimumZ);
         int maximumBucketZ = bucket(StrictMath.nextDown(queryMaximumZ));
+        if (minimumBucketX == maximumBucketX && minimumBucketZ == maximumBucketZ) {
+            return spatialIndex.getOrDefault(
+                    bucketKey(minimumBucketX, minimumBucketZ),
+                    List.of()
+            );
+        }
         for (int bucketX = minimumBucketX; bucketX <= maximumBucketX; bucketX++) {
             for (int bucketZ = minimumBucketZ; bucketZ <= maximumBucketZ; bucketZ++) {
-                List<RiverReach> bucketReaches = spatialIndex.get(bucketKey(bucketX, bucketZ));
+                indexed.addAll(spatialIndex.getOrDefault(bucketKey(bucketX, bucketZ), List.of()));
-                if (bucketReaches != null) {
-                    indexed.addAll(bucketReaches);
-                }
             }
         }
         return List.copyOf(indexed);
@@ -662,26 +688,13 @@ public final class RiverTile {
         int maximumBucketX = bucket(queryMaximumX);
         int minimumBucketZ = bucket(queryMinimumZ);
         int maximumBucketZ = bucket(queryMaximumZ);
-        if (spatialIndex.isEmpty()) {
-            return List.of();
-        }
         if (minimumBucketX == maximumBucketX && minimumBucketZ == maximumBucketZ) {
-            List<RiverReach> bucketReaches = spatialIndex.get(bucketKey(minimumBucketX, minimumBucketZ));
+            return indexedReaches(queryMinimumX, queryMinimumZ);
-            return bucketReaches == null ? List.of() : bucketReaches;
-        }
-        long bucketWidth = (long) maximumBucketX - minimumBucketX + 1L;
-        long bucketDepth = (long) maximumBucketZ - minimumBucketZ + 1L;
-        if (bucketWidth > spatialIndex.size() / bucketDepth
-                || bucketWidth * bucketDepth >= spatialIndex.size()) {
-            return reaches;
         }
         LinkedHashSet<RiverReach> indexed = new LinkedHashSet<>();
         for (int bucketX = minimumBucketX; bucketX <= maximumBucketX; bucketX++) {
             for (int bucketZ = minimumBucketZ; bucketZ <= maximumBucketZ; bucketZ++) {
-                List<RiverReach> bucketReaches = spatialIndex.get(bucketKey(bucketX, bucketZ));
+                indexed.addAll(spatialIndex.getOrDefault(bucketKey(bucketX, bucketZ), List.of()));
-                if (bucketReaches != null) {
-                    indexed.addAll(bucketReaches);
-                }
             }
         }
         return List.copyOf(indexed);

core/src/main/java/art/arcane/iris/engine/river/RiverWorm.java

@@ -17,6 +17,7 @@ public record RiverWorm(
         double depthMultiplier,
         double bodyWavelength,
         double bodyDetailWavelength,
+        double bodyDetailInfluence,
         double widthVariation,
         double bankVariation,
         double depthVariation,
@@ -44,8 +45,9 @@ public record RiverWorm(
         requireRange(widthMultiplier, 0.125D, 8D, "widthMultiplier");
         requireRange(bankMultiplier, 0.125D, 8D, "bankMultiplier");
         requireRange(depthMultiplier, 0.125D, 8D, "depthMultiplier");
-        requireRange(bodyWavelength, 32D, 16384D, "bodyWavelength");
+        requireRange(bodyWavelength, 8D, 16384D, "bodyWavelength");
-        requireRange(bodyDetailWavelength, 32D, 16384D, "bodyDetailWavelength");
+        requireRange(bodyDetailWavelength, 8D, 16384D, "bodyDetailWavelength");
+        requireRange(bodyDetailInfluence, 0D, 1D, "bodyDetailInfluence");
         requireRange(widthVariation, 0D, 0.875D, "widthVariation");
         requireRange(bankVariation, 0D, 0.875D, "bankVariation");
         requireRange(depthVariation, 0D, 0.875D, "depthVariation");

core/src/main/java/art/arcane/iris/engine/river/cave/RiverCaveAction.java

@@ -2,7 +2,7 @@ package art.arcane.iris.engine.river.cave;
 
 public enum RiverCaveAction {
     WET_SOURCE,
-    FALLING_WATER,
+    FALLING_FLUID,
     DRY_AIR,
     SEAL_GUARD
 }

core/src/main/java/art/arcane/iris/engine/river/cave/RiverCaveContainmentPlanner.java

@@ -70,6 +70,7 @@ public final class RiverCaveContainmentPlanner {
                     settings,
                     throat.positions()
             );
+            case DEEP_POOL -> planDeepPool(view, source, settings, throat.positions());
         };
     }
 
@@ -302,6 +303,111 @@ public final class RiverCaveContainmentPlanner {
         return accepted(view, source, actions);
     }
 
+    private RiverCavePlan planDeepPool(
+            CaveVoxelView view,
+            RiverCaveSource source,
+            RiverCavePlannerSettings settings,
+            List<CavePosition> throat
+    ) {
+        GrottoResult grotto = buildGrotto(source, settings);
+        if (grotto.rejection() != RiverCaveRejection.NONE) {
+            return rejected(source, grotto.rejection());
+        }
+        Set<CavePosition> chamber = grotto.positions();
+        Set<CavePosition> carve = new HashSet<>(chamber.size() + throat.size());
+        carve.addAll(chamber);
+        carve.addAll(throat);
+
+        RiverCaveRejection carveRejection = validateDeepPoolCarve(view, source, settings, carve);
+        if (carveRejection != RiverCaveRejection.NONE) {
+            return rejected(source, carveRejection);
+        }
+        BoundaryResult boundary = validateDeepPoolBoundary(view, source, settings, carve);
+        if (boundary.rejection() != RiverCaveRejection.NONE) {
+            return rejected(source, boundary.rejection());
+        }
+
+        Map<CavePosition, RiverCaveAction> actions = new HashMap<>();
+        addChamberActions(actions, chamber, source.waterHeadY());
+        addThroatActions(actions, throat, source);
+        for (CavePosition position : boundary.sealGuards()) {
+            actions.put(position, RiverCaveAction.SEAL_GUARD);
+        }
+        return accepted(view, source, actions);
+    }
+
+    private RiverCaveRejection validateDeepPoolCarve(
+            CaveVoxelView view,
+            RiverCaveSource source,
+            RiverCavePlannerSettings settings,
+            Set<CavePosition> carve
+    ) {
+        for (CavePosition position : carve) {
+            if (!view.isInWorld(position)) {
+                return RiverCaveRejection.WORLD_BOUNDARY;
+            }
+            RiverCaveRejection boundsRejection = validateBounds(source, settings, position);
+            if (boundsRejection != RiverCaveRejection.NONE) {
+                return boundsRejection;
+            }
+            CaveVoxel voxel = voxelAt(view, position);
+            RiverCaveRejection hazard = rejectionForHazard(voxel, settings);
+            if (hazard != RiverCaveRejection.NONE) {
+                return hazard;
+            }
+            if (voxel == CaveVoxel.SOLID) {
+                continue;
+            }
+            if (position.y() > source.waterHeadY()
+                    && voxel == CaveVoxel.CAVE_AIR
+                    && !view.isOpenToSurface(position)) {
+                continue;
+            }
+            return RiverCaveRejection.GROTTO_INTERSECTION;
+        }
+        return RiverCaveRejection.NONE;
+    }
+
+    private BoundaryResult validateDeepPoolBoundary(
+            CaveVoxelView view,
+            RiverCaveSource source,
+            RiverCavePlannerSettings settings,
+            Set<CavePosition> carve
+    ) {
+        Set<CavePosition> guards = new HashSet<>();
+        for (CavePosition position : carve) {
+            for (CavePosition direction : DIRECTIONS) {
+                CavePosition neighbor = position.offset(direction.x(), direction.y(), direction.z());
+                if (carve.contains(neighbor)) {
+                    continue;
+                }
+                if (!view.isInWorld(neighbor)) {
+                    return BoundaryResult.rejected(RiverCaveRejection.WORLD_BOUNDARY);
+                }
+                RiverCaveRejection boundsRejection = validateBounds(source, settings, neighbor);
+                if (boundsRejection != RiverCaveRejection.NONE) {
+                    return BoundaryResult.rejected(boundsRejection);
+                }
+                CaveVoxel voxel = voxelAt(view, neighbor);
+                RiverCaveRejection hazard = rejectionForHazard(voxel, settings);
+                if (hazard != RiverCaveRejection.NONE) {
+                    return BoundaryResult.rejected(hazard);
+                }
+                if (voxel == CaveVoxel.SOLID) {
+                    guards.add(neighbor);
+                    continue;
+                }
+                if (neighbor.y() > source.waterHeadY()
+                        && voxel == CaveVoxel.CAVE_AIR
+                        && !view.isOpenToSurface(neighbor)) {
+                    continue;
+                }
+                return BoundaryResult.rejected(RiverCaveRejection.GROTTO_SHELL_OPEN);
+            }
+        }
+        return BoundaryResult.accepted(guards);
+    }
+
     private ComponentResult resolveClosedComponent(
             CaveVoxelView view,
             RiverCaveSource source,
@@ -732,7 +838,7 @@ public final class RiverCaveContainmentPlanner {
                 action = RiverCaveAction.WET_SOURCE;
             } else if (source.mode() == RiverCaveMode.WATERFALL_POOL
                     || source.mode() == RiverCaveMode.GENERATED_GROTTO) {
-                action = RiverCaveAction.FALLING_WATER;
+                action = RiverCaveAction.FALLING_FLUID;
             } else {
                 action = RiverCaveAction.DRY_AIR;
             }

core/src/main/java/art/arcane/iris/engine/river/cave/RiverCaveFluidKind.java

@@ -0,0 +1,6 @@
+package art.arcane.iris.engine.river.cave;
+
+public enum RiverCaveFluidKind {
+    RIVER,
+    DEEP_POOL
+}

core/src/main/java/art/arcane/iris/engine/river/cave/RiverCaveHydrology.java

@@ -11,20 +11,30 @@ public final class RiverCaveHydrology {
 
     private final RiverCaveAction action;
     private final String floodedBiomeKey;
+    private final RiverCaveFluidKind fluidKind;
     private final MatterCavern cavern;
 
-    public RiverCaveHydrology(RiverCaveAction action, String floodedBiomeKey) {
+    public RiverCaveHydrology(
+            RiverCaveAction action,
+            String floodedBiomeKey,
+            RiverCaveFluidKind fluidKind
+    ) {
         this.action = Objects.requireNonNull(action);
         this.floodedBiomeKey = floodedBiomeKey == null ? "" : floodedBiomeKey.trim();
+        this.fluidKind = Objects.requireNonNull(fluidKind);
         this.cavern = switch (action) {
-            case WET_SOURCE, FALLING_WATER -> new MatterCavern(true, this.floodedBiomeKey, LIQUID_FLUID);
+            case WET_SOURCE, FALLING_FLUID -> new MatterCavern(true, this.floodedBiomeKey, LIQUID_FLUID);
             case DRY_AIR -> new MatterCavern(true, this.floodedBiomeKey, LIQUID_FORCED_AIR);
             case SEAL_GUARD -> null;
         };
     }
 
     public static RiverCaveHydrology of(RiverCaveAction action) {
-        return new RiverCaveHydrology(action, "");
+        return new RiverCaveHydrology(action, "", RiverCaveFluidKind.RIVER);
+    }
+
+    public static RiverCaveHydrology of(RiverCaveAction action, RiverCaveFluidKind fluidKind) {
+        return new RiverCaveHydrology(action, "", fluidKind);
     }
 
     public Optional<String> floodedBiome() {
@@ -36,11 +46,11 @@ public final class RiverCaveHydrology {
     }
 
     public boolean isWet() {
-        return action == RiverCaveAction.WET_SOURCE || action == RiverCaveAction.FALLING_WATER;
+        return action == RiverCaveAction.WET_SOURCE || action == RiverCaveAction.FALLING_FLUID;
     }
 
     public boolean isFalling() {
-        return action == RiverCaveAction.FALLING_WATER;
+        return action == RiverCaveAction.FALLING_FLUID;
     }
 
     public boolean protectsPlacement() {
@@ -59,6 +69,10 @@ public final class RiverCaveHydrology {
         return floodedBiomeKey;
     }
 
+    public RiverCaveFluidKind fluidKind() {
+        return fluidKind;
+    }
+
     @Override
     public boolean equals(Object object) {
         if (this == object) {
@@ -67,16 +81,19 @@ public final class RiverCaveHydrology {
         if (!(object instanceof RiverCaveHydrology hydrology)) {
             return false;
         }
-        return action == hydrology.action && floodedBiomeKey.equals(hydrology.floodedBiomeKey);
+        return action == hydrology.action
+                && floodedBiomeKey.equals(hydrology.floodedBiomeKey)
+                && fluidKind == hydrology.fluidKind;
     }
 
     @Override
     public int hashCode() {
-        return (31 * action.hashCode()) + floodedBiomeKey.hashCode();
+        return (31 * ((31 * action.hashCode()) + floodedBiomeKey.hashCode())) + fluidKind.hashCode();
     }
 
     @Override
     public String toString() {
-        return "RiverCaveHydrology[action=" + action + ", floodedBiomeKey=" + floodedBiomeKey + "]";
+        return "RiverCaveHydrology[action=" + action + ", floodedBiomeKey=" + floodedBiomeKey
+                + ", fluidKind=" + fluidKind + "]";
     }
 }

core/src/main/java/art/arcane/iris/engine/river/cave/RiverCaveMode.java

@@ -4,5 +4,6 @@ public enum RiverCaveMode {
     CLOSED_COMPONENT,
     GENERATED_GROTTO,
     GROTTO_OR_CLOSED_COMPONENT,
-    WATERFALL_POOL
+    WATERFALL_POOL,
+    DEEP_POOL
 }

core/src/main/java/art/arcane/iris/engine/river/runtime/IrisRiverRuntime.java

@@ -9,6 +9,7 @@ import art.arcane.iris.engine.object.IrisRegion;
 import art.arcane.iris.engine.object.IrisRiverNetwork;
 import art.arcane.iris.engine.object.IrisRiverCaveMode;
 import art.arcane.iris.engine.object.IrisRiverCaves;
+import art.arcane.iris.engine.object.IrisRiverDeepPools;
 import art.arcane.iris.engine.object.IrisRiverNoiseChance;
 import art.arcane.iris.engine.object.IrisRiverRoutingPolicy;
 import art.arcane.iris.engine.object.IrisRiverTerminalMode;
@@ -41,6 +42,8 @@ import art.arcane.iris.util.project.noise.CNG;
 import art.arcane.iris.util.project.stream.ProceduralStream;
 import art.arcane.volmlib.util.collection.KList;
 import art.arcane.volmlib.util.math.RNG;
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -48,6 +51,7 @@ import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicReferenceArray;
 
 public final class IrisRiverRuntime implements AutoCloseable {
     static final int MAXIMUM_REACH_FEASIBILITY_SAMPLES = 65;
@@ -66,17 +70,22 @@ public final class IrisRiverRuntime implements AutoCloseable {
     private static final long BIOME_NOISE_SALT = 0x2FFD72DBD01ADFB7L;
     private static final long CAVE_ENTRY_NOISE_SALT = 0xB8E1AFED6A267E96L;
     private static final long CAVE_ENTRY_GATE_SALT = 0xBA7C9045F12C7F99L;
+    private static final long DEEP_POOL_REACH_NOISE_SALT = 0x7137449123EF65CDL;
+    private static final long DEEP_POOL_REACH_GATE_SALT = 0xE9B5DBA58189DBBCL;
     private static final long TUNNEL_FLOOR_NOISE_SALT = 0x8CB92BA72F3D8DD7L;
     private static final long TUNNEL_ROOF_NOISE_SALT = 0xDB4F0B9175AE2165L;
     private static final long TUNNEL_WIDTH_NOISE_SALT = 0xC6EF372FE94F82BEL;
     private static final long FLOODED_CAVE_BIOME_SALT = 0x24A19947B3916CF7L;
     private static final long TERMINAL_CAVE_ANCHOR_SALT = 0x9E3779B97F4A7C15L;
     private static final int TILE_CACHE_SIZE = 32;
+    private static final int TUNNEL_SAMPLE_CHUNK_CACHE_SIZE = 4_096;
+    private static final Object ABSENT_TUNNEL_SAMPLE = new Object();
 
     private final long seed;
     private final IrisRiverNetwork configuration;
     private final IrisData data;
-    private final int fluidHeight;
+    private final int riverFluidHeight;
+    private final int dimensionFluidHeight;
     private final boolean boreMantleActive;
     private final boolean caveHydrologyActive;
     private final boolean blockingRoutingPossible;
@@ -101,12 +110,14 @@ public final class IrisRiverRuntime implements AutoCloseable {
     private final CNG bedNoise;
     private final CNG biomeNoise;
     private final CNG caveEntryNoise;
+    private final CNG deepPoolReachNoise;
     private final CNG tunnelFloorNoise;
     private final CNG tunnelRoofNoise;
     private final CNG tunnelWidthNoise;
     private final art.arcane.iris.engine.river.RiverNetwork network;
     private final RuntimeTerrainSampler terrainSampler;
     private final RiverTileCache tileCache;
+    private final Cache<Long, TunnelSampleChunk> tunnelSampleCache;
     private final ConcurrentHashMap<IdentitySettingsKey, EffectiveRiverSettings> settingsCache;
     private final ConcurrentHashMap<BiomePoolKey, List<IrisBiome>> biomePoolCache;
 
@@ -115,7 +126,8 @@ public final class IrisRiverRuntime implements AutoCloseable {
         seed = context.seed();
         configuration = context.configuration();
         data = context.data();
-        fluidHeight = context.fluidHeight();
+        riverFluidHeight = context.riverFluidHeight();
+        dimensionFluidHeight = context.dimensionFluidHeight();
         boreMantleActive = context.boreMantleActive();
         caveHydrologyActive = context.caveHydrologyActive();
         blockingRoutingPossible = context.blockingRoutingPossible();
@@ -146,6 +158,11 @@ public final class IrisRiverRuntime implements AutoCloseable {
         bedNoise = noise(terrain.getBedRoughnessStyle(), BED_NOISE_SALT);
         biomeNoise = noise(configuration.getBiomes().getSelectionStyle(), BIOME_NOISE_SALT);
         caveEntryNoise = noise(caves.getEntry(), CAVE_ENTRY_NOISE_SALT);
+        IrisRiverDeepPools deepPools = caves.getDeepPools();
+        deepPoolReachNoise = noise(
+                deepPools == null ? null : deepPools.getReach(),
+                DEEP_POOL_REACH_NOISE_SALT
+        );
         tunnelFloorNoise = noise(terrain.getTunnelFloorStyle(), TUNNEL_FLOOR_NOISE_SALT);
         tunnelRoofNoise = noise(terrain.getTunnelRoofStyle(), TUNNEL_ROOF_NOISE_SALT);
         tunnelWidthNoise = noise(terrain.getTunnelWidthMultiplier(), TUNNEL_WIDTH_NOISE_SALT);
@@ -158,12 +175,15 @@ public final class IrisRiverRuntime implements AutoCloseable {
                 TILE_CACHE_SIZE,
                 (tileX, tileZ) -> network.buildTile(tileX, tileZ, terrainSampler)
         );
+        tunnelSampleCache = Caffeine.newBuilder()
+                .maximumSize(TUNNEL_SAMPLE_CHUNK_CACHE_SIZE)
+                .build();
     }
 
     public IrisRiverSurfaceSample sample(double x, double z) {
         ResolvedRiverColumn column = resolveColumn(x, z);
         if (column == null) {
-            return IrisRiverSurfaceSample.none(naturalHeight.get(x, z), fluidHeight);
+            return IrisRiverSurfaceSample.none(naturalHeight.get(x, z), dimensionFluidHeight);
         }
         if (column.subterranean()) {
             return new IrisRiverSurfaceSample(
@@ -229,9 +249,8 @@ public final class IrisRiverRuntime implements AutoCloseable {
         if (!column.subterranean()) {
             return null;
         }
-        if (isTunnelMouth(column, mouthBlend)) {
+        double mouthFactor = tunnelMouthFactor(column, mouthBlend);
-            channelRadius += mouthBlend;
+        channelRadius += mouthBlend * mouthFactor;
-        }
         if (column.river().distance() > channelRadius) {
             return null;
         }
@@ -255,13 +274,20 @@ public final class IrisRiverRuntime implements AutoCloseable {
         );
         int ceilingY = shapedTunnelCeilingY(
                 waterHeadY,
-                caves.getDryHeadroom() * column.reach().roofScaleAt(column.river().alongReach()),
+                caves.getDryHeadroom() * column.reach().roofScaleAt(column.river().alongReach())
+                        + mouthBlend * mouthFactor,
                 profile,
                 roofOffset
         );
         return new IrisRiverTunnelSample(column.river(), bedY, waterHeadY, ceilingY);
     }
 
+    public IrisRiverTunnelSample sampleTunnel(int x, int z) {
+        long chunkKey = ((long) (x >> 4) << 32) ^ ((z >> 4) & 0xFFFFFFFFL);
+        TunnelSampleChunk chunk = tunnelSampleCache.get(chunkKey, ignored -> new TunnelSampleChunk());
+        return chunk.sample(this, x, z);
+    }
+
     static int shapedTunnelBedY(
             int waterHeadY,
             double baseBedY,
@@ -331,18 +357,44 @@ public final class IrisRiverRuntime implements AutoCloseable {
         );
     }
 
-    private boolean isTunnelMouth(ResolvedRiverColumn column, double mouthBlend) {
+    private double tunnelMouthFactor(ResolvedRiverColumn column, double mouthBlend) {
         if (mouthBlend <= 0D) {
-            return false;
+            return 0D;
         }
         double length = column.reach().polyline().length();
         if (length <= 0D) {
-            return false;
+            return 0D;
         }
         double offset = mouthBlend / length;
         double alongReach = column.river().alongReach();
-        return !isCenterlineSubterranean(column.reach(), clamp01(alongReach - offset))
+        return Math.max(
-                || !isCenterlineSubterranean(column.reach(), clamp01(alongReach + offset));
+                tunnelMouthFactor(column.reach(), alongReach, clamp01(alongReach - offset), mouthBlend),
+                tunnelMouthFactor(column.reach(), alongReach, clamp01(alongReach + offset), mouthBlend)
+        );
+    }
+
+    private double tunnelMouthFactor(
+            RiverReach reach,
+            double subterraneanAlong,
+            double candidateOpenAlong,
+            double mouthBlend
+    ) {
+        if (candidateOpenAlong == subterraneanAlong
+                || isCenterlineSubterranean(reach, candidateOpenAlong)) {
+            return 0D;
+        }
+        double openAlong = candidateOpenAlong;
+        double solidAlong = subterraneanAlong;
+        for (int iteration = 0; iteration < 5; iteration++) {
+            double midpoint = (openAlong + solidAlong) * 0.5D;
+            if (isCenterlineSubterranean(reach, midpoint)) {
+                solidAlong = midpoint;
+            } else {
+                openAlong = midpoint;
+            }
+        }
+        double distance = StrictMath.abs(solidAlong - subterraneanAlong) * reach.polyline().length();
+        return clamp01(1D - distance / mouthBlend);
     }
 
     private boolean isCenterlineSubterranean(RiverReach reach, double alongReach) {
@@ -401,6 +453,35 @@ public final class IrisRiverRuntime implements AutoCloseable {
         return tileAt(centerX, centerZ).sampleFootprint(minimumX, minimumZ, maximumX, maximumZ);
     }
 
+    public boolean hasRiverFootprint(
+            int minimumX,
+            int minimumZ,
+            int maximumX,
+            int maximumZ
+    ) {
+        if (minimumX >= maximumX || minimumZ >= maximumZ) {
+            return false;
+        }
+        int minimumTileX = network.tileXForBlock(minimumX);
+        int minimumTileZ = network.tileZForBlock(minimumZ);
+        int maximumTileX = network.tileXForBlock(maximumX - 1);
+        int maximumTileZ = network.tileZForBlock(maximumZ - 1);
+        for (int tileX = minimumTileX; tileX <= maximumTileX; tileX++) {
+            for (int tileZ = minimumTileZ; tileZ <= maximumTileZ; tileZ++) {
+                RiverSample sample = tileCache.get(tileX, tileZ).sampleFootprint(
+                        minimumX,
+                        minimumZ,
+                        maximumX,
+                        maximumZ
+                );
+                if (sample.present()) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
     public List<RiverAnchor> candidateAnchors(
             int minimumX,
             int minimumZ,
@@ -481,7 +562,9 @@ public final class IrisRiverRuntime implements AutoCloseable {
     }
 
     public int maximumTunnelHeadroom() {
-        return caves.getDryHeadroom() + (int) StrictMath.ceil(terrain.getTunnelRoofVariation());
+        return caves.getDryHeadroom()
+                + (int) StrictMath.ceil(terrain.getTunnelRoofVariation())
+                + (int) StrictMath.ceil(terrain.getTunnelMouthBlend());
     }
 
     public boolean acceptsCaveAnchor(RiverAnchor anchor) {
@@ -535,6 +618,52 @@ public final class IrisRiverRuntime implements AutoCloseable {
         return false;
     }
 
+    public boolean acceptsDeepPoolAnchor(RiverAnchor anchor) {
+        Objects.requireNonNull(anchor);
+        IrisRiverDeepPools deepPools = caves.getDeepPools();
+        if (deepPools == null
+                || !deepPools.isEnabled()
+                || deepPools.getMaximumPerReach() <= 0
+                || anchor.state() != RiverRouteState.WET
+                || !caveHydrologyActive) {
+            return false;
+        }
+        RiverReach reach = tileAt(anchor.x(), anchor.z()).reach(anchor.reachId());
+        if (reach == null || reach.state() != RiverRouteState.WET) {
+            return false;
+        }
+        if (!deepPoolReachEligible(deepPools, reach)) {
+            return false;
+        }
+        TerminalCaveAnchor terminal = terminalCaveAnchor(reach);
+        if (terminal != null && anchor.stableId() == terminal.stableId()) {
+            return false;
+        }
+        double firstDistance = unit(art.arcane.iris.engine.river.RiverNetwork.mix(
+                reach.id().stableId() ^ anchor.samplingSalt()
+        )) * anchor.samplingSpacing();
+        double anchorDistance = firstDistance + anchor.index() * anchor.samplingSpacing();
+        if (anchorDistance >= reach.polyline().length()) {
+            return false;
+        }
+        int accepted = 0;
+        for (int index = 0; index <= anchor.index(); index++) {
+            long stableId = art.arcane.iris.engine.river.RiverNetwork.mix(
+                    reach.id().stableId()
+                            ^ anchor.samplingSalt()
+                            ^ (long) index * 0x9E3779B97F4A7C15L
+            );
+            if (index == anchor.index()) {
+                return stableId == anchor.stableId() && accepted < deepPools.getMaximumPerReach();
+            }
+            accepted++;
+            if (accepted >= deepPools.getMaximumPerReach()) {
+                return false;
+            }
+        }
+        return false;
+    }
+
     private boolean isCaveAnchorSourceable(double x, double z) {
         IrisRiverSurfaceSample surface = sample(x, z);
         if (surface.river().present()
@@ -603,6 +732,7 @@ public final class IrisRiverRuntime implements AutoCloseable {
     @Override
     public void close() {
         tileCache.close();
+        tunnelSampleCache.invalidateAll();
         settingsCache.clear();
         biomePoolCache.clear();
     }
@@ -620,7 +750,7 @@ public final class IrisRiverRuntime implements AutoCloseable {
                 .routingDeviationScaleCells(topology.getRoutingDeviationScaleCells())
                 .routingDeviationStrengthCells(topology.getRoutingDeviationStrengthCells())
                 .routingPlateauHeight(topology.getRoutingPlateauHeight())
-                .hydraulicBaseHeight(fluidHeight)
+                .hydraulicBaseHeight(riverFluidHeight)
                 .requireOcean(topology.isRequireOcean())
                 .sourceChance(chance(topology.getSource()))
                 .reachChance(chance(topology.getContinuation()))
@@ -633,6 +763,7 @@ public final class IrisRiverRuntime implements AutoCloseable {
                 .channelWidth(mid(riverTerrain.getChannelWidth(), 12D))
                 .bankWidth(mid(riverTerrain.getBankWidth(), 8D))
                 .depth(mid(riverTerrain.getDepth(), 4D))
+                .channelRadiusBonus(riverTerrain.getChannelRadiusBonus())
                 .maxChannelWidth(riverTerrain.getMaxChannelWidth())
                 .maxBankWidth(riverTerrain.getMaxBankWidth())
                 .maxDepth(riverTerrain.getMaxDepth())
@@ -683,6 +814,7 @@ public final class IrisRiverRuntime implements AutoCloseable {
                 configured.getDepthMultiplier(),
                 configured.getBodyWavelength(),
                 configured.getBodyDetailWavelength(),
+                configured.getBodyDetailInfluence(),
                 configured.getWidthVariation(),
                 configured.getBankVariation(),
                 configured.getDepthVariation(),
@@ -757,6 +889,24 @@ public final class IrisRiverRuntime implements AutoCloseable {
         return unit(hash) < chance;
     }
 
+    private boolean deepPoolReachEligible(
+            IrisRiverDeepPools deepPools,
+            RiverReach reach
+    ) {
+        CenterlinePosition center = centerlinePosition(reach, 0.5D);
+        EffectiveRiverSettings settings = settingsAt(center.x(), center.z());
+        double chance = clamp01(effectiveChance(
+                deepPools.getReach(),
+                deepPoolReachNoise,
+                (int) StrictMath.floor(center.x()),
+                (int) StrictMath.floor(center.z())
+        ) * settings.caveEntryMultiplier());
+        long hash = art.arcane.iris.engine.river.RiverNetwork.mix(
+                seed ^ reach.id().stableId() ^ DEEP_POOL_REACH_GATE_SALT
+        );
+        return unit(hash) < chance;
+    }
+
     private TerminalCaveAnchor terminalCaveAnchor(RiverReach reach) {
         if (!caveHydrologyActive || !reach.terminal() || reach.state() != RiverRouteState.WET) {
             return null;
@@ -809,8 +959,11 @@ public final class IrisRiverRuntime implements AutoCloseable {
     }
 
     double waterSurface(RiverReach reach, double alongReach, boolean naturalOcean) {
-        if (reach == null || water.getMode() == IrisRiverWaterMode.SEA_LEVEL || naturalOcean) {
+        if (naturalOcean) {
-            return fluidHeight;
+            return dimensionFluidHeight;
+        }
+        if (reach == null || water.getMode() == IrisRiverWaterMode.FIXED) {
+            return riverFluidHeight;
         }
         return terracedWaterSurface(
                 reach.from().hydraulicHeight(),
@@ -883,10 +1036,10 @@ public final class IrisRiverRuntime implements AutoCloseable {
 
     private int nodeWaterHead(double naturalNodeHeight, int dropHeight) {
         int availableRise = Math.max(0, water.getMaximumPoolRise());
-        int maximumHead = fluidHeight + availableRise;
+        int maximumHead = riverFluidHeight + availableRise;
         int naturalHead = (int) StrictMath.floor(naturalNodeHeight - 1D);
-        int clamped = Math.max(fluidHeight, Math.min(maximumHead, naturalHead));
+        int clamped = Math.max(riverFluidHeight, Math.min(maximumHead, naturalHead));
-        return fluidHeight + Math.floorDiv(clamped - fluidHeight, dropHeight) * dropHeight;
+        return riverFluidHeight + Math.floorDiv(clamped - riverFluidHeight, dropHeight) * dropHeight;
     }
 
     private static boolean isNaturalOcean(IrisBiome biome) {
@@ -1011,6 +1164,25 @@ public final class IrisRiverRuntime implements AutoCloseable {
         return (hash >>> 11) * 0x1.0p-53;
     }
 
+    private static final class TunnelSampleChunk {
+        private final AtomicReferenceArray<Object> samples = new AtomicReferenceArray<>(256);
+
+        private IrisRiverTunnelSample sample(IrisRiverRuntime runtime, int x, int z) {
+            int index = ((x & 15) << 4) | (z & 15);
+            Object cached = samples.get(index);
+            if (cached == null) {
+                IrisRiverTunnelSample computed = runtime.sampleTunnel((double) x, (double) z);
+                Object encoded = computed == null ? ABSENT_TUNNEL_SAMPLE : computed;
+                if (samples.compareAndSet(index, null, encoded)) {
+                    cached = encoded;
+                } else {
+                    cached = samples.get(index);
+                }
+            }
+            return cached == ABSENT_TUNNEL_SAMPLE ? null : (IrisRiverTunnelSample) cached;
+        }
+    }
+
     private final class RuntimeTerrainSampler implements RiverTerrainSampler {
         private final IrisRiverTopology topology;
 
@@ -1022,11 +1194,11 @@ public final class IrisRiverRuntime implements AutoCloseable {
         public RiverTerrainNodeSample sampleNode(int blockX, int blockZ) {
             boolean oceanIntent = Boolean.TRUE.equals(naturalOcean.get(blockX, blockZ));
             boolean naturalHeightRequired = topology.getTerrainHeightWeight() > 0D
-                    || water.getMode() != IrisRiverWaterMode.SEA_LEVEL
+                    || water.getMode() != IrisRiverWaterMode.FIXED
                     || oceanIntent;
             double sampledNaturalHeight = naturalHeightRequired
                     ? naturalHeight.get(blockX, blockZ)
-                    : fluidHeight;
+                    : dimensionFluidHeight;
             boolean sampledOcean = oceanIntent && isSubmergedOutlet(sampledNaturalHeight);
             IrisRegion sampledRegion = region.get(blockX, blockZ);
             IrisBiome sampledBiome = biomeRiverOverridesPossible ? naturalBiome.get(blockX, blockZ) : null;
@@ -1068,7 +1240,7 @@ public final class IrisRiverRuntime implements AutoCloseable {
         }
 
         private boolean isSubmergedOutlet(double sampledNaturalHeight) {
-            return Math.round(sampledNaturalHeight) < Math.round(fluidHeight);
+            return Math.round(sampledNaturalHeight) < Math.round(dimensionFluidHeight);
         }
 
         @Override
@@ -1150,8 +1322,8 @@ public final class IrisRiverRuntime implements AutoCloseable {
                 }
                 maximumIncision *= settings.maxIncisionMultiplier();
             }
-            double head = configuration.getWater().getMode() == IrisRiverWaterMode.SEA_LEVEL
+            double head = configuration.getWater().getMode() == IrisRiverWaterMode.FIXED
-                    ? fluidHeight
+                    ? riverFluidHeight
                     : terracedWaterSurface(
                             context.from().hydraulicHeight(),
                             context.to().hydraulicHeight(),

core/src/main/java/art/arcane/iris/engine/river/runtime/IrisRiverRuntimeContext.java

@@ -12,7 +12,8 @@ public record IrisRiverRuntimeContext(
         long seed,
         IrisRiverNetwork configuration,
         IrisData data,
-        int fluidHeight,
+        int riverFluidHeight,
+        int dimensionFluidHeight,
         boolean boreMantleActive,
         boolean caveHydrologyActive,
         boolean blockingRoutingPossible,

core/src/main/java/art/arcane/iris/platform/bukkit/BukkitPlatform.java

@@ -52,6 +52,7 @@ import org.bukkit.entity.EntityType;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Listener;
 import org.bukkit.event.entity.CreatureSpawnEvent;
+import org.bukkit.event.player.PlayerTeleportEvent;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.plugin.Plugin;
 import org.bukkit.util.Vector;
@@ -236,6 +237,11 @@ public final class BukkitPlatform implements IrisPlatform {
         return io.papermc.lib.PaperLib.teleportAsync(entity, destination);
     }
 
+    public static java.util.concurrent.CompletableFuture<Boolean> teleportAsync(Entity entity, Location destination,
+                                                                                PlayerTeleportEvent.TeleportCause cause) {
+        return io.papermc.lib.PaperLib.teleportAsync(entity, destination, cause);
+    }
+
     public static boolean isPaperServer() {
         return io.papermc.lib.PaperLib.isPaper();
     }

core/src/main/java/art/arcane/iris/util/common/misc/SlimJar.java

@@ -19,12 +19,55 @@ public class SlimJar {
     private static final ReentrantLock lock = new ReentrantLock();
     private static final AtomicBoolean loaded = new AtomicBoolean();
 
+    public static void loadBootstrap(Path downloadPath, BootstrapLogger logger) {
+        if (loaded.get()) {
+            return;
+        }
+        lock.lock();
+        try {
+            if (loaded.get()) {
+                return;
+            }
+            ApplicationBuilder.appending("Iris")
+                    .injectableFactory(InjectableFactory.selecting(
+                            InjectableFactory.ERROR,
+                            InjectableFactory.INJECTABLE,
+                            InjectableFactory.WRAPPED,
+                            InjectableFactory.UNSAFE))
+                    .downloadDirectoryPath(downloadPath)
+                    .logger(new ProcessLogger() {
+                        @Override
+                        public void info(@NotNull String message, @Nullable Object... args) {
+                            logger.info(message.formatted(args));
+                        }
+
+                        @Override
+                        public void error(@NotNull String message, @Nullable Object... args) {
+                            logger.error(message.formatted(args));
+                        }
+
+                        @Override
+                        public void debug(@NotNull String message, @Nullable Object... args) {
+                            logger.debug(message.formatted(args));
+                        }
+                    })
+                    .build();
+            loaded.set(true);
+        } finally {
+            lock.unlock();
+        }
+    }
+
     public static void load() {
-        if (loaded.get()) return;
+        if (loaded.get()) {
+            return;
+        }
         lock.lock();
 
         try {
-            if (loaded.getAndSet(true)) return;
+            if (loaded.get()) {
+                return;
+            }
             VolmitPlugin plugin = BukkitPlatform.volmitPlugin();
             Path downloadPath = plugin.getDataFolder("cache", "libraries").toPath();
             debug(plugin, "Loading libraries...");
@@ -58,6 +101,7 @@ public class SlimJar {
                         })
                         .build();
             }
+            loaded.set(true);
             debug(plugin, "Libraries loaded successfully!");
         } finally {
             lock.unlock();
@@ -69,4 +113,12 @@ public class SlimJar {
             plugin.getLogger().info("[DEBUG] " + message);
         }
     }
+
+    public interface BootstrapLogger {
+        void info(String message);
+
+        void error(String message);
+
+        void debug(String message);
+    }
 }

core/src/main/java/art/arcane/iris/util/common/scheduling/J.java

@@ -303,6 +303,43 @@ public class J {
         return true;
     }
 
+    public static CompletableFuture<Void> runRegionFuture(
+            World world,
+            int chunkX,
+            int chunkZ,
+            Runnable runnable
+    ) {
+        if (world == null || runnable == null) {
+            return CompletableFuture.failedFuture(new IllegalArgumentException(
+                    "Region task world and runnable are required."));
+        }
+
+        if (isFolia()) {
+            CompletableFuture<Void> future = new CompletableFuture<>();
+            if (isOwnedByCurrentRegion(world, chunkX, chunkZ)) {
+                settle(future, runnable);
+                return future;
+            }
+            if (!runRegionImmediate(
+                    world,
+                    chunkX,
+                    chunkZ,
+                    () -> settle(future, runnable))) {
+                future.completeExceptionally(new IllegalStateException(
+                        "Failed to schedule region task for " + world.getName()
+                                + "@" + chunkX + "," + chunkZ + "."));
+            }
+            return future;
+        }
+
+        if (isPrimaryThread()) {
+            CompletableFuture<Void> future = new CompletableFuture<>();
+            settle(future, runnable);
+            return future;
+        }
+        return sfut(runnable);
+    }
+
     public static boolean runGlobal(Runnable runnable) {
         if (runnable == null) {
             return false;

core/src/main/java/art/arcane/iris/util/project/matter/slices/RiverCaveHydrologyMatter.java

@@ -1,6 +1,7 @@
 package art.arcane.iris.util.project.matter.slices;
 
 import art.arcane.iris.engine.river.cave.RiverCaveAction;
+import art.arcane.iris.engine.river.cave.RiverCaveFluidKind;
 import art.arcane.iris.engine.river.cave.RiverCaveHydrology;
 import art.arcane.volmlib.util.data.palette.Palette;
 import art.arcane.volmlib.util.matter.Sliced;
@@ -28,19 +29,21 @@ public final class RiverCaveHydrologyMatter extends RawMatter<RiverCaveHydrology
     @Override
     public void writeNode(RiverCaveHydrology hydrology, DataOutputStream output) throws IOException {
         output.writeByte(actionCode(hydrology.action()));
+        output.writeByte(fluidKindCode(hydrology.fluidKind()));
         output.writeUTF(hydrology.floodedBiomeKey());
     }
 
     @Override
     public RiverCaveHydrology readNode(DataInputStream input) throws IOException {
         RiverCaveAction action = actionFromCode(input.readUnsignedByte());
-        return new RiverCaveHydrology(action, input.readUTF());
+        RiverCaveFluidKind fluidKind = fluidKindFromCode(input.readUnsignedByte());
+        return new RiverCaveHydrology(action, input.readUTF(), fluidKind);
     }
 
     private int actionCode(RiverCaveAction action) {
         return switch (action) {
             case WET_SOURCE -> 1;
-            case FALLING_WATER -> 2;
+            case FALLING_FLUID -> 2;
             case DRY_AIR -> 3;
             case SEAL_GUARD -> 4;
         };
@@ -49,10 +52,25 @@ public final class RiverCaveHydrologyMatter extends RawMatter<RiverCaveHydrology
     private RiverCaveAction actionFromCode(int code) throws IOException {
         return switch (code) {
             case 1 -> RiverCaveAction.WET_SOURCE;
-            case 2 -> RiverCaveAction.FALLING_WATER;
+            case 2 -> RiverCaveAction.FALLING_FLUID;
             case 3 -> RiverCaveAction.DRY_AIR;
             case 4 -> RiverCaveAction.SEAL_GUARD;
             default -> throw new IOException("Unknown river cave hydrology action code " + code);
         };
     }
+
+    private int fluidKindCode(RiverCaveFluidKind fluidKind) {
+        return switch (fluidKind) {
+            case RIVER -> 1;
+            case DEEP_POOL -> 2;
+        };
+    }
+
+    private RiverCaveFluidKind fluidKindFromCode(int code) throws IOException {
+        return switch (code) {
+            case 1 -> RiverCaveFluidKind.RIVER;
+            case 2 -> RiverCaveFluidKind.DEEP_POOL;
+            default -> throw new IOException("Unknown river cave fluid-kind code " + code);
+        };
+    }
 }

core/src/test/java/art/arcane/iris/core/ServerConfiguratorDatapackFingerprintTest.java

@@ -447,6 +447,15 @@ public class ServerConfiguratorDatapackFingerprintTest {
         assertFalse(ServerConfigurator.loadedRegistrySatisfies(
                 loaded,
                 Map.of("worldgen/biome/overworld:new", "biome-new")));
+        assertFalse(ServerConfigurator.runtimeRequiresRegistryRestart(
+                loaded,
+                Map.of(
+                        "dimension_type/iris:overworld", "dimension-a",
+                        "worldgen/biome/overworld:forest", "biome-a")));
+        assertTrue(ServerConfigurator.runtimeRequiresRegistryRestart(
+                loaded,
+                Map.of("dimension_type/iris:overworld", "dimension-b")));
+        assertFalse(ServerConfigurator.runtimeRequiresRegistryRestart(loaded, Map.of()));
     }
 
     @Test

core/src/test/java/art/arcane/iris/core/ServerConfiguratorRegistryVerificationTest.java

@@ -0,0 +1,106 @@
+package art.arcane.iris.core;
+
+import art.arcane.iris.core.loader.IrisData;
+import art.arcane.iris.core.loader.ResourceLoader;
+import art.arcane.iris.core.nms.INMS;
+import art.arcane.iris.core.nms.INMSBinding;
+import art.arcane.iris.engine.object.IrisBiome;
+import art.arcane.iris.engine.object.IrisBiomeCustom;
+import art.arcane.iris.engine.object.IrisDimension;
+import art.arcane.iris.spi.IrisLogging;
+import art.arcane.volmlib.util.collection.KList;
+import org.bukkit.Bukkit;
+import org.junit.Test;
+import org.mockito.MockedStatic;
+
+import java.io.File;
+import java.util.List;
+import java.util.stream.Stream;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.mockStatic;
+import static org.mockito.Mockito.when;
+
+public class ServerConfiguratorRegistryVerificationTest {
+    @Test
+    public void freshlyCompiledRegistryMissReportsOneRestartWarning() {
+        VerificationFixture fixture = missingRegistryFixture();
+
+        try (MockedStatic<IrisLogging> logging = mockStatic(IrisLogging.class);
+             MockedStatic<Bukkit> bukkit = mockStatic(Bukkit.class);
+             MockedStatic<INMS> nms = mockStatic(INMS.class)) {
+            nms.when(INMS::get).thenReturn(fixture.binding());
+            bukkit.when(Bukkit::getOnlinePlayers).thenReturn(List.of());
+
+            assertTrue(ServerConfigurator.verifyDataPacksPost(Stream.of(fixture.data())));
+
+            logging.verify(() -> IrisLogging.debug("Checking Pack: packs/overworld"));
+            logging.verify(() -> IrisLogging.warn(ServerConfigurator.POST_COMPILE_RESTART_WARNING));
+            logging.verifyNoMoreInteractions();
+        }
+    }
+
+    @Test
+    public void worldCreationRegistryMissRetainsFullOperationalError() {
+        VerificationFixture fixture = missingRegistryFixture();
+
+        try (MockedStatic<IrisLogging> logging = mockStatic(IrisLogging.class);
+             MockedStatic<INMS> nms = mockStatic(INMS.class)) {
+            nms.when(INMS::get).thenReturn(fixture.binding());
+
+            assertFalse(ServerConfigurator.verifyDataPackInstalled(fixture.dimension()));
+
+            logging.verify(() -> IrisLogging.warn(
+                    "The Biome overworld:missing is not registered on the server."));
+            logging.verify(() -> IrisLogging.warn(
+                    "The Dimension Type for packs/overworld/dimensions/overworld.json is not registered on the server."));
+            logging.verify(() -> IrisLogging.error(
+                    "The Pack overworld is INCAPABLE of generating custom biomes"));
+            logging.verify(() -> IrisLogging.error(
+                    "If not done automatically, restart your server before generating with this pack!"));
+            logging.verifyNoMoreInteractions();
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    private static VerificationFixture missingRegistryFixture() {
+        IrisBiomeCustom customBiome = mock(IrisBiomeCustom.class);
+        when(customBiome.getId()).thenReturn("missing");
+
+        IrisBiome biome = mock(IrisBiome.class);
+        when(biome.isCustom()).thenReturn(true);
+        when(biome.getCustomDerivitives()).thenReturn(new KList<>(customBiome));
+
+        IrisData data = mock(IrisData.class);
+        when(data.getDataFolder()).thenReturn(new File("packs/overworld"));
+
+        IrisDimension dimension = mock(IrisDimension.class);
+        when(dimension.getAllBiomes(any())).thenReturn(new KList<>(biome));
+        when(dimension.getLoadKey()).thenReturn("overworld");
+        when(dimension.getLoadFile()).thenReturn(
+                new File("packs/overworld/dimensions/overworld.json"));
+        when(dimension.getDimensionTypeKey()).thenReturn("iris:overworld");
+        when(dimension.getLoader()).thenReturn(data);
+
+        ResourceLoader<IrisDimension> loader = mock(ResourceLoader.class);
+        when(loader.getPossibleKeys()).thenReturn(new String[]{"overworld"});
+        when(loader.loadAll(any(String[].class))).thenReturn(new KList<>(dimension));
+        when(data.getDimensionLoader()).thenReturn(loader);
+
+        INMSBinding binding = mock(INMSBinding.class);
+        when(binding.supportsDataPacks()).thenReturn(true);
+        when(binding.getCustomBiomeBaseFor("overworld:missing")).thenReturn(null);
+        when(binding.missingDimensionTypes("iris:overworld")).thenReturn(true);
+        return new VerificationFixture(data, dimension, binding);
+    }
+
+    private record VerificationFixture(
+            IrisData data,
+            IrisDimension dimension,
+            INMSBinding binding
+    ) {
+    }
+}

core/src/test/java/art/arcane/iris/core/localization/IrisLanguageTest.java

@@ -11,6 +11,7 @@ import art.arcane.volmlib.util.localization.MessageValue;
 import art.arcane.volmlib.util.localization.PluralValue;
 import art.arcane.volmlib.util.localization.TextValue;
 import art.arcane.volmlib.util.localization.VolmitLocales;
+import com.google.gson.JsonArray;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
@@ -174,6 +175,29 @@ public class IrisLanguageTest {
         }
     }
 
+    @Test
+    public void compactBukkitLocaleUsesSortedCatalogPositionsAndEnglishFallbacks() {
+        List<String> messageIds = IrisLanguage.catalog().ids().stream()
+                .filter(id -> !id.startsWith("iris.modded."))
+                .sorted()
+                .toList();
+        String translatedId = IrisMessages.COMMAND_UNKNOWN.id();
+        JsonArray values = new JsonArray(messageIds.size());
+        for (int i = 0; i < messageIds.size(); i++) {
+            values.add(messageIds.get(i).equals(translatedId) ? "Unbekannter Iris-Befehl" : null);
+        }
+        JsonArray compact = new JsonArray(2);
+        compact.add("de_DE");
+        compact.add(values);
+
+        LocaleOverlay overlay = IrisLanguage.parseOverlay("test", "de_DE", compact.toString());
+
+        assertEquals(Set.of(translatedId), overlay.values().keySet());
+        assertEquals(
+                "Unbekannter Iris-Befehl",
+                ((TextValue) overlay.value(translatedId)).template());
+    }
+
     @Test
     public void bundledServerResourcesExactlyMatchNonEnglishManifest() throws Exception {
         Set<String> expected = VolmitLocales.nonEnglish().stream()

core/src/test/java/art/arcane/iris/core/pack/PackDownloaderTest.java

@@ -651,6 +651,35 @@ public class PackDownloaderTest {
         assertEquals(0, PackDownloader.downloadLockCount());
     }
 
+    @Test
+    public void invalidBuiltInRiverSchemaPreservesExistingTarget() throws Exception {
+        File packsFolder = temp.newFolder("invalid-river-packs");
+        File target = writePack(packsFolder.toPath().resolve("overworld"), "overworld", "old");
+        File extracted = writePack(temp.newFolder("invalid-river-source").toPath(), "overworld", "new");
+        Files.writeString(
+                extracted.toPath().resolve("dimensions/overworld.json"),
+                "{\"name\":\"Overworld\",\"regions\":[\"local\"],\"logicalHeight\":256,"
+                        + "\"dimensionHeight\":{\"min\":-64,\"max\":320},\"rivers\":{\"enabled\":true,"
+                        + "\"terrain\":{},\"water\":{\"mode\":\"SEA_LEVEL\"}}}",
+                StandardCharsets.UTF_8
+        );
+
+        PackDownloader.PackInstallResult result = PackDownloader.installExtractedPack(
+                packsFolder,
+                extracted,
+                true,
+                "overworld",
+                ignored -> {
+                }
+        );
+
+        assertNull(result);
+        assertEquals("old", Files.readString(target.toPath().resolve("state.txt"), StandardCharsets.UTF_8));
+        assertTrue(Files.isRegularFile(target.toPath().resolve("regions/local.json")));
+        assertTransactionStateClean(packsFolder);
+        assertEquals(0, PackDownloader.downloadLockCount());
+    }
+
     @Test
     public void forceOverwriteReplacesEnginelessLoadedPackData() throws Exception {
         // A registered loader with no engines is a stale catalog registration (startup

core/src/test/java/art/arcane/iris/core/pack/PackRiverValidatorTest.java

@@ -127,8 +127,9 @@ public class PackRiverValidatorTest {
                         {
                           "id": "trunk",
                           "seed": 17,
-                          "bodyWavelength": 31,
+                          "bodyWavelength": 7,
                           "bodyDetailWavelength": 16385,
+                          "bodyDetailInfluence": 1.1,
                           "widthVariation": -0.1,
                           "bankVariation": 0.876,
                           "depthVariation": -0.1,
@@ -150,8 +151,9 @@ public class PackRiverValidatorTest {
 
         PackRiverValidator.Validation result = validate(pack);
 
-        assertContains(result.errors(), "rivers.terrain.worms[0].bodyWavelength must be at least 32");
+        assertContains(result.errors(), "rivers.terrain.worms[0].bodyWavelength must be at least 8");
         assertContains(result.errors(), "rivers.terrain.worms[0].bodyDetailWavelength must be at most 16384");
+        assertContains(result.errors(), "rivers.terrain.worms[0].bodyDetailInfluence must be at most 1");
         assertContains(result.errors(), "rivers.terrain.worms[0].widthVariation must be at least 0");
         assertContains(result.errors(), "rivers.terrain.worms[0].bankVariation must be at most 0.875");
         assertContains(result.errors(), "rivers.terrain.worms[0].depthVariation must be at least 0");
@@ -357,6 +359,140 @@ public class PackRiverValidatorTest {
         assertContains(result.errors(), "rivers.water.dropHeight must not exceed maximumPoolRise");
     }
 
+    @Test
+    public void acceptsIndependentCaveLavaRiverHeightAndPalette() throws Exception {
+        File pack = pack("""
+                {
+                  "regions": ["region"],
+                  "dimensionHeight": {"min": -64, "max": 320},
+                  "fluidHeight": 63,
+                  "rivers": {
+                    "enabled": true,
+                    "terrain": {"worms": [{"id": "river"}]},
+                    "water": {
+                      "mode": "FIXED",
+                      "fluidHeight": -48,
+                      "fluidPalette": {
+                        "palette": [{"block": "minecraft:lava"}]
+                      }
+                    }
+                  }
+                }
+                """);
+
+        PackRiverValidator.Validation result = validate(pack);
+
+        assertTrue(result.errors().toString(), result.errors().isEmpty());
+    }
+
+    @Test
+    public void acceptsSparseBlobbyDeepLavaPoolsWithIndependentHeight() throws Exception {
+        File pack = pack("""
+                {
+                  "regions": ["region"],
+                  "dimensionHeight": {"min": -256, "max": 512},
+                  "rivers": {
+                    "enabled": true,
+                    "terrain": {"worms": [{"id": "river"}]},
+                    "caves": {
+                      "deepPools": {
+                        "enabled": true,
+                        "reach": {
+                          "chance": 0.08,
+                          "influence": 0.04,
+                          "style": {"style": "IRIS", "zoom": 4096}
+                        },
+                        "minimumSpacing": 768,
+                        "maximumPerReach": 1,
+                        "minimumFluidY": -224,
+                        "maximumFluidY": -108,
+                        "searchRadius": 20,
+                        "searchAttempts": 12,
+                        "horizontalRadius": 24,
+                        "verticalRadius": 10,
+                        "dryHeadroom": 5,
+                        "shapeStyle": {"style": "IRIS", "zoom": 12},
+                        "shapeVariation": 0.6,
+                        "warpStyle": {"style": "IRIS", "zoom": 24},
+                        "warpStrength": 8,
+                        "maximumVolume": 65536,
+                        "fluidPalette": {
+                          "palette": [{"block": "minecraft:lava"}]
+                        }
+                      }
+                    }
+                  }
+                }
+                """);
+
+        PackRiverValidator.Validation result = validate(pack);
+
+        assertTrue(result.errors().toString(), result.errors().isEmpty());
+    }
+
+    @Test
+    public void rejectsUnsafeDeepPoolEnvelopeShapeAndPalette() throws Exception {
+        File pack = pack("""
+                {
+                  "regions": ["region"],
+                  "dimensionHeight": {"min": -64, "max": 320},
+                  "rivers": {
+                    "enabled": true,
+                    "terrain": {"worms": [{"id": "river"}]},
+                    "caves": {
+                      "deepPools": {
+                        "enabled": true,
+                        "reach": {"chance": 0},
+                        "minimumFluidY": -90,
+                        "maximumFluidY": -120,
+                        "searchRadius": 120,
+                        "horizontalRadius": 20,
+                        "verticalRadius": 8,
+                        "dryHeadroom": 8,
+                        "maximumVolume": 64,
+                        "fluidPalette": {"palette": []}
+                      }
+                    }
+                  }
+                }
+                """);
+
+        PackRiverValidator.Validation result = validate(pack);
+
+        assertContains(result.errors(), "deepPools.minimumFluidY must not exceed maximumFluidY");
+        assertContains(result.errors(), "deepPools.dryHeadroom must be smaller than verticalRadius");
+        assertContains(result.errors(), "deepPools.searchRadius plus horizontalRadius must not exceed 128");
+        assertContains(result.errors(), "deepPools.maximumVolume must be at least");
+        assertContains(result.errors(), "deepPools.fluidPalette.palette must contain at least one fluid block");
+        assertContains(result.errors(), "deepPools fluid range and chamber envelope must remain inside dimensionHeight");
+        assertContains(result.warnings(), "deepPools is enabled but its reach gate cannot accept any pools");
+    }
+
+    @Test
+    public void rejectsRetiredWaterModeInvalidPaletteAndOutOfBoundsHeight() throws Exception {
+        File pack = pack("""
+                {
+                  "regions": ["region"],
+                  "dimensionHeight": {"min": -64, "max": 320},
+                  "rivers": {
+                    "enabled": true,
+                    "terrain": {"worms": [{"id": "river"}]},
+                    "water": {
+                      "mode": "SEA_LEVEL",
+                      "fluidHeight": -80,
+                      "fluidPalette": {"palette": []}
+                    }
+                  }
+                }
+                """);
+
+        PackRiverValidator.Validation result = validate(pack);
+
+        assertContains(result.errors(), "rivers.water.mode must be one of");
+        assertContains(result.errors(), "rivers.water.fluidHeight must remain inside dimensionHeight");
+        assertContains(result.errors(), "rivers.water.fluidPalette.palette must contain at least one fluid block");
+    }
+
     @Test
     public void rejectsPathologicalCombinedTopologyComplexity() throws Exception {
         File pack = pack("""

core/src/test/java/art/arcane/iris/core/pregenerator/methods/AsyncPregenMethodConcurrencyCapTest.java

@@ -3,11 +3,17 @@ package art.arcane.iris.core.pregenerator.methods;
 import org.junit.Test;
 
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
 
 public class AsyncPregenMethodConcurrencyCapTest {
     @Test
@@ -77,4 +83,31 @@ public class AsyncPregenMethodConcurrencyCapTest {
         assertEquals(0, slowRequests.get());
         assertEquals("generated", request.join());
     }
+
+    @Test
+    public void closeDrainWaitsPastWarningIntervalsUntilEveryPermitReturns() throws Exception {
+        Semaphore semaphore = new Semaphore(0);
+        AtomicInteger warnings = new AtomicInteger();
+        ExecutorService executor = Executors.newSingleThreadExecutor();
+        try {
+            Future<Boolean> drain = executor.submit(() -> AsyncPregenMethod.awaitDrain(
+                    semaphore,
+                    2,
+                    10L,
+                    TimeUnit.MILLISECONDS,
+                    warnings::incrementAndGet
+            ));
+
+            while (warnings.get() == 0) {
+                Thread.onSpinWait();
+            }
+            semaphore.release(2);
+
+            assertFalse(drain.get(1L, TimeUnit.SECONDS));
+            assertTrue(warnings.get() > 0);
+            assertEquals(0, semaphore.availablePermits());
+        } finally {
+            executor.shutdownNow();
+        }
+    }
 }