Merge master

# Conflicts:
#	core/src/main/java/art/arcane/iris/world/pregen/AsyncPregenMethod.java

adapters/fabric/build.gradle

@@ -201,6 +201,7 @@ dependencies {
         libs.asm,
         libs.lru,
         libs.caffeine,
+        'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
         libs.jaxen
     ]

adapters/forge/build.gradle

@@ -200,6 +200,7 @@ dependencies {
         libs.asm,
         libs.lru,
         libs.caffeine,
+        'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
         libs.jaxen
     ]

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

@@ -391,10 +391,7 @@ public final class ModdedEngineBootstrap {
                 BlockDataMergeSupport.StateMerger previousMerger = BlockDataMergeSupport.bindPlatformMerger(new NativeStateMerger(ModdedBlockResolution.BLOCKS)::merge);
                 rollback.add(() -> BlockDataMergeSupport.restorePlatformMerger(previousMerger));
 
-                NativeTileReader nativeTileReader = new NativeTileReader(() -> {
+                NativeTileReader nativeTileReader = NativeTileReader.forServer(boundLoader::currentServer);
-                    NativeModdedServer server = boundLoader.currentServer();
-                    return server == null ? null : server.registryAccess();
-                });
                 TileData.TileReader previousTileReader = TileData.bindPlatformReader(in -> ModdedTileData.wrap(nativeTileReader.read(in)));
                 rollback.add(() -> TileData.restorePlatformReader(previousTileReader));
 

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

@@ -38,8 +38,6 @@ import art.arcane.iris.spi.PlatformScheduler;
 import art.arcane.iris.spi.PlatformStructureHooks;
 import art.arcane.volmlib.nativelib.terrain.NativeWorld;
 
-import net.minecraft.core.HolderLookup;
-
 import java.io.File;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -64,7 +62,7 @@ public final class ModdedPlatform implements IrisPlatform {
         this.loader = loader;
         this.registries = new ModdedRegistries(
                 new NativeRegistryAccess(new NativeRegistryAccess.Configuration(
-                        ModdedPlatform::nativeRegistries, ModdedPlatform::reloadableRegistries,
+                        ModdedEngineBootstrap::currentServer,
                         ModdedRegistries::warnNotReady)),
                 ModdedPlatform::generationRegistry);
         this.scheduler = new ModdedScheduler();
@@ -72,16 +70,6 @@ public final class ModdedPlatform implements IrisPlatform {
         this.biomeWriter = new ModdedBiomeWriter(new NativeBiomeRegistry(ModdedEngineBootstrap::currentServer, "minecraft:plains"));
     }
 
-    private static HolderLookup.Provider nativeRegistries() {
-        NativeModdedServer server = ModdedEngineBootstrap.currentServer();
-        return server == null ? null : server.registryAccess();
-    }
-
-    private static HolderLookup.Provider reloadableRegistries() {
-        NativeModdedServer server = ModdedEngineBootstrap.currentServer();
-        return server == null ? null : server.reloadableRegistries();
-    }
-
     public static void errorSink(Consumer<Throwable> sink) {
         ERROR_SINK = sink;
     }

adapters/modded-common/src/main/resources/pack.mcmeta

@@ -0,0 +1,7 @@
+{
+  "pack": {
+    "description": "Iris client resources and mod data",
+    "min_format": [88, 0],
+    "max_format": [107, 1]
+  }
+}

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

@@ -72,10 +72,10 @@ public class IrisModLanguageAssetsTest {
     }
 
     private Set<String> resourceFiles() throws Exception {
-        URL resource = IrisModLanguageAssetsTest.class.getClassLoader().getResource(ROOT);
+        URL resource = IrisModLanguageAssetsTest.class.getClassLoader().getResource(ROOT + "en_us.json");
-        assertNotNull("Missing mod language resource directory: " + ROOT, resource);
+        assertNotNull("Missing English mod language resource", resource);
         assertEquals("Mod language resources must resolve to a directory on disk", "file", resource.getProtocol());
-        Path directory = Path.of(resource.toURI());
+        Path directory = Path.of(resource.toURI()).getParent();
         try (Stream<Path> paths = Files.list(directory)) {
             return paths
                     .filter(Files::isRegularFile)

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

@@ -0,0 +1,45 @@
+package art.arcane.iris.modded;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.mojang.serialization.JsonOps;
+import net.minecraft.SharedConstants;
+import net.minecraft.server.Bootstrap;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.metadata.pack.PackMetadataSection;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+public class ModdedPackMetadataTest {
+    @BeforeClass
+    public static void bootstrapMinecraftRegistries() {
+        SharedConstants.tryDetectVersion();
+        Bootstrap.bootStrap();
+    }
+
+    @Test
+    public void metadataLoadsClientResourcesAndServerDataForCurrentMinecraft() throws IOException {
+        try (InputStream resource = ModdedPackMetadataTest.class.getResourceAsStream("/pack.mcmeta")) {
+            assertNotNull(resource);
+            try (InputStreamReader reader = new InputStreamReader(resource, StandardCharsets.UTF_8)) {
+                JsonObject metadata = JsonParser.parseReader(reader).getAsJsonObject();
+                for (PackType type : PackType.values()) {
+                    PackMetadataSection section = PackMetadataSection.forPackType(type).codec()
+                            .parse(JsonOps.INSTANCE, metadata.get("pack")).getOrThrow();
+                    assertEquals("Iris client resources and mod data", section.description().getString());
+                    assertTrue(type.toString(), section.supportedFormats().isValueInRange(
+                            SharedConstants.getCurrentVersion().packVersion(type)));
+                }
+            }
+        }
+    }
+}

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

@@ -1,6 +1,7 @@
 package art.arcane.iris.modded;
 
 import org.junit.Test;
+import org.objectweb.asm.ClassReader;
 
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
@@ -62,9 +63,11 @@ public class ModdedStructureTemplateCacheTest {
             config = new String(input.readAllBytes(), StandardCharsets.UTF_8);
         }
         assertTrue(config.contains("\"StructureTemplatePaletteConcurrencyMixin\""));
-        assertNotNull(Class.forName(
+        String mixin = "art/arcane/volmlib/nativelib/minecraft26_2/modded/mixin/StructureTemplatePaletteConcurrencyMixin";
-                "art.arcane.volmlib.nativelib.minecraft26_2.modded.mixin.StructureTemplatePaletteConcurrencyMixin",
+        try (InputStream input = ModdedStructureTemplateCacheTest.class.getClassLoader()
-                false,
+                .getResourceAsStream(mixin + ".class")) {
-                ModdedStructureTemplateCacheTest.class.getClassLoader()));
+            assertNotNull(input);
+            assertEquals(mixin, new ClassReader(input).getClassName());
+        }
     }
 }

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

@@ -41,7 +41,7 @@ public class ModdedTileParityTest {
         SharedConstants.tryDetectVersion();
         Bootstrap.bootStrap();
         registries = RegistryAccess.fromRegistryOfRegistries(BuiltInRegistries.REGISTRY);
-        NativeTileReader nativeTileReader = new NativeTileReader(() -> null);
+        NativeTileReader nativeTileReader = NativeTileReader.forServer(() -> null);
         TileData.bindPlatformReader(in -> ModdedTileData.wrap(nativeTileReader.read(in)));
         TileData.bindPlatformFactory(ModdedTileData::fromProperties);
     }

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

@@ -11,9 +11,12 @@ import art.arcane.iris.generation.decoration.IrisSurface;
 import art.arcane.volmlib.util.math.RNG;
 import net.minecraft.SharedConstants;
 import net.minecraft.core.BlockPos;
+import net.minecraft.core.registries.BuiltInRegistries;
 import net.minecraft.server.Bootstrap;
 import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.block.Block;
 import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.block.state.properties.BlockStateProperties;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -34,6 +37,11 @@ public class ModdedWaterEntitySpawnTest {
     public static void bootstrapMinecraftRegistries() {
         SharedConstants.tryDetectVersion();
         Bootstrap.bootStrap();
+        for (Block block : BuiltInRegistries.BLOCK) {
+            for (BlockState state : block.getStateDefinition().getPossibleStates()) {
+                state.initCache();
+            }
+        }
     }
 
     @Test

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

@@ -1,20 +1,31 @@
 package art.arcane.iris.modded;
 
 import art.arcane.volmlib.nativelib.minecraft26_2.modded.NativeRegistryAccess;
+import art.arcane.volmlib.nativelib.minecraft26_2.modded.NativeModdedServer;
 import art.arcane.volmlib.nativelib.terrain.NativeBlockProperty;
 import net.minecraft.SharedConstants;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.resources.ResourceKey;
 import net.minecraft.server.Bootstrap;
+import net.minecraft.server.MinecraftServer;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.Stream;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.RETURNS_DEEP_STUBS;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 public class NativeRegistryAccessTest {
     @BeforeClass
@@ -25,7 +36,7 @@ public class NativeRegistryAccessTest {
 
     @Test
     public void statePropertiesPreserveTypesDefaultsAndSharedGroups() {
-        NativeRegistryAccess access = new NativeRegistryAccess(new NativeRegistryAccess.Configuration(() -> null, () -> null, message -> {}));
+        NativeRegistryAccess access = new NativeRegistryAccess(new NativeRegistryAccess.Configuration(() -> null, message -> {}));
         Map<String, List<NativeBlockProperty>> properties = access.blockStateProperties();
 
         assertSame(properties.get("minecraft:stone"), properties.get("minecraft:dirt"));
@@ -41,7 +52,7 @@ public class NativeRegistryAccessTest {
     @Test
     public void staticRegistriesResolveWithoutAnActiveServerAndDynamicReadsStayEmpty() {
         List<String> warnings = new ArrayList<>();
-        NativeRegistryAccess access = new NativeRegistryAccess(new NativeRegistryAccess.Configuration(() -> null, () -> null, warnings::add));
+        NativeRegistryAccess access = new NativeRegistryAccess(new NativeRegistryAccess.Configuration(() -> null, warnings::add));
 
         assertEquals("minecraft:diamond_sword", access.item("DIAMOND SWORD").key());
         assertEquals("creature", access.entity("minecraft:cow").spawnCategory());
@@ -49,6 +60,34 @@ public class NativeRegistryAccessTest {
         assertTrue(access.biomeKeys().isEmpty());
         assertTrue(access.structureKeys().isEmpty());
         assertTrue(access.enchantmentKeys().isEmpty());
-        assertEquals(List.of("biome", "structure", "enchantment"), warnings);
+        assertTrue(access.lootTableKeys().isEmpty());
+        assertEquals(List.of("biome", "structure", "enchantment", "loot table"), warnings);
+    }
+
+    @Test
+    public void dynamicRegistriesFollowServerStartupReloadAndShutdown() {
+        AtomicReference<NativeModdedServer> activeServer = new AtomicReference<>();
+        List<String> warnings = new ArrayList<>();
+        NativeRegistryAccess access = new NativeRegistryAccess(new NativeRegistryAccess.Configuration(activeServer::get, warnings::add));
+        assertTrue(access.lootTableKeys().isEmpty());
+
+        MinecraftServer server = mock(MinecraftServer.class, RETURNS_DEEP_STUBS);
+        when(server.registryAccess().lookupOrThrow(Registries.BIOME).listElementIds())
+                .thenAnswer(invocation -> Stream.of(ResourceKey.create(Registries.BIOME, Identifier.parse("example:biome"))));
+        when(server.reloadableRegistries().lookup().lookupOrThrow(Registries.LOOT_TABLE).listElementIds())
+                .thenAnswer(invocation -> Stream.of(ResourceKey.create(Registries.LOOT_TABLE, Identifier.parse("example:initial"))));
+        activeServer.set(NativeModdedServer.fromHandle(server));
+
+        assertEquals(List.of("example:biome"), access.biomeKeys());
+        assertEquals(List.of("example:initial"), access.lootTableKeys());
+        HolderLookup.Provider reloadedRegistries = mock(HolderLookup.Provider.class, RETURNS_DEEP_STUBS);
+        when(reloadedRegistries.lookupOrThrow(Registries.LOOT_TABLE).listElementIds())
+                .thenAnswer(invocation -> Stream.of(ResourceKey.create(Registries.LOOT_TABLE, Identifier.parse("example:reloaded"))));
+        when(server.reloadableRegistries().lookup()).thenReturn(reloadedRegistries);
+        assertEquals(List.of("example:reloaded"), access.lootTableKeys());
+        activeServer.set(null);
+        assertTrue(access.biomeKeys().isEmpty());
+        assertTrue(access.lootTableKeys().isEmpty());
+        assertEquals(List.of("loot table", "biome", "loot table"), warnings);
     }
 }

adapters/neoforge/build.gradle

@@ -173,6 +173,7 @@ dependencies {
         libs.asm,
         libs.lru,
         libs.caffeine,
+        'com.fulcrumgenomics:jlibdeflate:0.2.0',
         libs.dom4j,
         libs.jaxen
     ]

build.gradle

@@ -576,6 +576,14 @@ tasks.named('check').configure {
 }
 
 List<String> commonModdedArtifactEntries = [
+    'pack.mcmeta',
+    'com/fulcrumgenomics/jlibdeflate/LibdeflateDecompressor.class',
+    'com/fulcrumgenomics/jlibdeflate/LibdeflateException.class',
+    'native/linux-aarch64/libjlibdeflate.so',
+    'native/linux-x86_64/libjlibdeflate.so',
+    'native/osx-aarch64/libjlibdeflate.dylib',
+    'native/osx-x86_64/libjlibdeflate.dylib',
+    'native/windows-x86_64/jlibdeflate.dll',
     'META-INF/iris/generation-kernels/catalog.tsv',
     'META-INF/iris/generation-kernels/abi-1.revision',
     'META-INF/services/art.arcane.iris.localization.IrisMessageContributor',

buildSrc/src/main/java/ModdedArtifactVerifier.java

@@ -85,6 +85,11 @@ public final class ModdedArtifactVerifier {
                     throw new GradleException(artifact.getName() + " is missing " + requiredEntry);
                 }
             }
+            if (jar.getJarEntry("assets/irisworldgen/lang/en_us.json") != null
+                    && jar.getJarEntry("pack.mcmeta") == null) {
+                throw new GradleException(artifact.getName()
+                        + " ships Iris client language resources without pack.mcmeta");
+            }
 
             Set<String> bundledRuntimeEntries = new LinkedHashSet<>();
             Set<String> privateReferenceClasses = new LinkedHashSet<>();

buildSrc/src/test/java/ModdedArtifactVerifierTest.java

@@ -44,6 +44,28 @@ public class ModdedArtifactVerifierTest {
         ModdedArtifactVerifier.verify(artifact, REQUIRED_ENTRIES);
     }
 
+    @Test
+    public void rejectsClientLanguagesWithoutPackMetadata() throws Exception {
+        Map<String, byte[]> entries = validEntries();
+        entries.put("assets/irisworldgen/lang/en_us.json", "{}".getBytes(StandardCharsets.UTF_8));
+        File artifact = createArtifact(entries);
+
+        GradleException failure = assertThrows(GradleException.class,
+                () -> ModdedArtifactVerifier.verify(artifact, REQUIRED_ENTRIES));
+        assertTrue(failure.getMessage().contains("client language resources without pack.mcmeta"));
+    }
+
+    @Test
+    public void acceptsClientLanguagesWithPackMetadata() throws Exception {
+        Map<String, byte[]> entries = validEntries();
+        entries.put("assets/irisworldgen/lang/en_us.json", "{}".getBytes(StandardCharsets.UTF_8));
+        entries.put("pack.mcmeta", ("{\"pack\":{\"description\":\"Iris\","
+                + "\"min_format\":[88,0],\"max_format\":[107,1]}}")
+                .getBytes(StandardCharsets.UTF_8));
+
+        ModdedArtifactVerifier.verify(createArtifact(entries), REQUIRED_ENTRIES);
+    }
+
     @Test
     public void rejectsRelocatedRuntimeReference() throws Exception {
         Map<String, byte[]> entries = validEntries();

core/src/main/java/art/arcane/iris/generation/runtime/IrisComplex.java

@@ -1089,16 +1089,18 @@ public class IrisComplex implements DataProvider {
                 continue;
             }
             HydrologyColumnLayer original = sample.layers().get(index);
-            int head = (int) Math.round(transitionDisplacement.fluidHeight(sample.x(), sample.z(), layer.fluidHeadY()));
+            int displacedHead = (int) Math.round(
+                    transitionDisplacement.fluidHeight(sample.x(), sample.z(), original.fluidHeadY()));
+            boolean channel = original.channel() && layer.bedY() <= displacedHead;
+            int head = channel ? displacedHead : layer.bedY();
             if ((tapered.naturalHeight() < seaLevel || tapered.naturalHeight() == seaLevel && head > seaLevel)
                     && (original.terrainOwned() || original.fluidOwned() || original.grading() || original.shore())) {
                 continue;
             }
-            boolean dryChannel = original.channel() && layer.bedY() > head;
             layers.add(new HydrologyColumnLayer(layer.feature(), layer.bedY(),
-                    head, head, original.channel() && !dryChannel, layer.shore(), layer.grading(), original.connectedFluid() && !dryChannel,
+                    head, head, channel, layer.shore(), layer.grading(), original.connectedFluid() && channel,
-                    original.fallingFluid() && !dryChannel, original.receivingPool() && !dryChannel,
+                    original.fallingFluid() && channel, original.receivingPool() && channel,
-                    layer.terrainOwned(), original.fluidOwned() && !dryChannel, layer.oceanApron(),
+                    layer.terrainOwned(), original.fluidOwned() && channel, layer.oceanApron(),
                     layer.profileKey(), layer.surfaceBiomeKey(), layer.mouthBiomeKey(), layer.shoreBiomeKey(),
                     layer.bankBiomeKey(), layer.floodedCaveBiomeKey()));
         }
@@ -1140,20 +1142,21 @@ public class IrisComplex implements DataProvider {
             return layer;
         }
         int bed = GenerationBlend.interpolateHeight(naturalHeight, layer.bedY(), hydrologyWeight);
-        boolean dryChannel = layer.channel() && bed > layer.fluidHeadY();
+        boolean channel = layer.channel() && bed <= layer.fluidHeadY();
+        int head = channel ? layer.fluidHeadY() : bed;
         return new HydrologyColumnLayer(
                 layer.feature(),
                 bed,
-                layer.fluidHeadY(),
+                head,
-                layer.ceilingY(),
+                head,
-                layer.channel() && !dryChannel,
+                channel,
                 layer.shore(),
                 layer.grading(),
-                layer.connectedFluid() && !dryChannel,
+                layer.connectedFluid() && channel,
-                layer.fallingFluid() && !dryChannel,
+                layer.fallingFluid() && channel,
-                layer.receivingPool() && !dryChannel,
+                layer.receivingPool() && channel,
                 layer.terrainOwned(),
-                layer.fluidOwned() && !dryChannel,
+                layer.fluidOwned() && channel,
                 layer.oceanApron(),
                 layer.profileKey(),
                 layer.surfaceBiomeKey(),

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

@@ -30,6 +30,7 @@ import java.util.concurrent.Semaphore;
 import art.arcane.iris.spi.IrisServices;
 import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.configuration.IrisSettings;
+import art.arcane.iris.studio.view.PregeneratorJob;
 import art.arcane.iris.world.IrisWorlds;
 import art.arcane.iris.pack.loading.IrisData;
 import art.arcane.iris.platform.bukkit.nms.INMS;
@@ -1290,6 +1291,15 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
 
     @Override
     public void generateNoise(@NotNull WorldInfo world, @NotNull Random random, int x, int z, @NotNull ChunkGenerator.ChunkData d) {
+        try {
+            generateNoiseChunk(world, random, x, z, d);
+        } catch (Throwable e) {
+            PregeneratorJob.reportChunkGenerationFailure(this.world.identity(), x, z, e);
+            throw e;
+        }
+    }
+
+    private void generateNoiseChunk(WorldInfo world, Random random, int x, int z, ChunkGenerator.ChunkData d) {
         if (closing) {
             throw new IllegalStateException("Iris chunk generation was rejected while the generator is closing.");
         }

core/src/main/java/art/arcane/iris/studio/view/PregeneratorJob.java

@@ -254,6 +254,14 @@ public class PregeneratorJob implements PregenListener, PregenRenderSource {
         return instance.get();
     }
 
+    public static void reportChunkGenerationFailure(String worldIdentity, int chunkX, int chunkZ, Throwable failure) {
+        PregeneratorJob inst = instance.get();
+        if (inst == null || worldIdentity == null || !worldIdentity.equals(inst.worldIdentity())) {
+            return;
+        }
+        inst.pregenerator.onChunkGenerationFailed(chunkX, chunkZ, failure);
+    }
+
     public static boolean pauseResume() {
         PregeneratorJob inst = instance.get();
         return inst != null && inst.togglePause();

core/src/main/java/art/arcane/iris/world/pregen/AsyncOrMedievalPregenMethod.java

@@ -85,6 +85,11 @@ public class AsyncOrMedievalPregenMethod implements PregeneratorMethod {
         method.onRegionBounds(minRegionX, minRegionZ, maxRegionX, maxRegionZ);
     }
 
+    @Override
+    public void onChunkGenerationFailed(int chunkX, int chunkZ, Throwable failure) {
+        method.onChunkGenerationFailed(chunkX, chunkZ, failure);
+    }
+
     @Override
     public void onPregenStart(int centerBlockX, int centerBlockZ) {
         method.onPregenStart(centerBlockX, centerBlockZ);

core/src/main/java/art/arcane/iris/world/pregen/AsyncPregenMethod.java

@@ -21,6 +21,7 @@ package art.arcane.iris.world.pregen;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.iris.world.lifecycle.WorldLifecycleService;
 import art.arcane.volmlib.nativelib.terrain.NativeWorkerPool;
+import java.util.Map;
 import java.util.Objects;
 import art.arcane.iris.world.IrisPaperLikeBackendMode;
 import art.arcane.iris.world.IrisRuntimeSchedulerMode;
@@ -55,6 +56,7 @@ import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
 
 public class AsyncPregenMethod implements PregeneratorMethod {
     // THREAD_COUNT records the pool's original size while boosted; BOOST_HOLDERS counts live
@@ -64,7 +66,8 @@ 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_WARNING_SECONDS = 60L;
+    private static final long CLOSE_DRAIN_WARNING_SECONDS = 20L;
+    private static final long CLOSE_DRAIN_TIMEOUT_SECONDS = 60L;
     private static final long FLUSH_TIMEOUT_SECONDS = 120L;
     private static final long MANTLE_CLEANUP_DRAIN_SECONDS = 60L;
     private static final long CHUNK_FLUSH_DRAIN_SECONDS = 30L;
@@ -113,6 +116,8 @@ public class AsyncPregenMethod implements PregeneratorMethod {
     private final AtomicLong failed = new AtomicLong();
     private final AtomicLong lastProgressAt = new AtomicLong(M.ms());
     private final AtomicBoolean closing = new AtomicBoolean();
+    private final PregenInFlightRequests inFlightRequests = new PregenInFlightRequests();
+    private final AtomicReference<GenerationFailure> generationFailure = new AtomicReference<>();
     private final AtomicBoolean holdsWorkerBoost = new AtomicBoolean();
     private volatile Engine metricsEngine;
     private volatile Mantle cachedMantle;
@@ -515,10 +520,20 @@ public class AsyncPregenMethod implements PregeneratorMethod {
     }
 
     private void completeChunk(int x, int z, PregenListener listener, Chunk chunk, Throwable throwable) {
+        PregenListener owner = inFlightRequests.settle(PregenInFlightRequests.key(x, z));
+        if (owner == null) {
+            return;
+        }
+        settleChunk(x, z, owner, chunk, throwable, true);
+    }
+
+    private void settleChunk(int x, int z, PregenListener listener, Chunk chunk, Throwable throwable, boolean reportFailure) {
         boolean success = false;
         try {
             if (throwable != null) {
+                if (reportFailure) {
                     onChunkFutureFailure(x, z, throwable);
+                }
                 onChunkFailedToLoad(x, z);
                 listener.onChunkFailed(x, z);
             } else if (chunk == null) {
@@ -718,11 +733,57 @@ public class AsyncPregenMethod implements PregeneratorMethod {
                 + " stalledForMs=" + stalledFor;
     }
 
-    private void markSubmitted() {
+    private void markSubmitted(int x, int z, PregenListener listener) {
+        inFlightRequests.add(PregenInFlightRequests.key(x, z), listener);
         submitted.incrementAndGet();
         inFlight.incrementAndGet();
     }
 
+    @Override
+    public void onChunkGenerationFailed(int chunkX, int chunkZ, Throwable failure) {
+        GenerationFailure recorded = new GenerationFailure(chunkX, chunkZ, failure);
+        if (generationFailure.compareAndSet(null, recorded)) {
+            IrisLogging.error("Async pregen aborting: Iris failed to generate chunk " + chunkX + "," + chunkZ
+                    + " and the server's chunk system will not complete the " + inFlightRequests.size()
+                    + " outstanding chunk request(s). " + metricsSnapshot());
+        }
+        failOutstandingRequests(failure);
+    }
+
+    private void failOutstandingRequests(Throwable failure) {
+        Map<Long, PregenListener> outstanding = inFlightRequests.drain();
+        for (Map.Entry<Long, PregenListener> entry : outstanding.entrySet()) {
+            long key = entry.getKey();
+            settleChunk(PregenInFlightRequests.chunkX(key), PregenInFlightRequests.chunkZ(key), entry.getValue(),
+                    null, failure, false);
+        }
+        admission.wake();
+        backpressure.signalProgress();
+    }
+
+    private void throwIfGenerationFailed() {
+        GenerationFailure failure = generationFailure.get();
+        if (failure != null) {
+            throw new IllegalStateException("Pregen aborted: Iris failed to generate chunk " + failure.chunkX() + ","
+                    + failure.chunkZ() + " in world " + world.getName()
+                    + " and the server's chunk system stopped completing requests.", failure.cause());
+        }
+    }
+
+    private void abandonOutstandingRequests(PregenAdmissionGate.Drain drain) {
+        Map<Long, PregenListener> abandoned = inFlightRequests.drain();
+        IrisLogging.error("Async pregen abandoned " + abandoned.size() + " chunk request(s) that did not complete within "
+                + CLOSE_DRAIN_TIMEOUT_SECONDS + "s of closing (" + drain.outstanding()
+                + " permit(s) still held). They are not cached and regenerate on the next run. " + metricsSnapshot());
+        IllegalStateException cause = new IllegalStateException(
+                "Async chunk request never completed before the pregen closed in world " + world.getName() + ".");
+        for (Map.Entry<Long, PregenListener> entry : abandoned.entrySet()) {
+            long key = entry.getKey();
+            settleChunk(PregenInFlightRequests.chunkX(key), PregenInFlightRequests.chunkZ(key), entry.getValue(),
+                    null, cause, false);
+        }
+    }
+
     private void markFinished(boolean success) {
         if (success) {
             completed.incrementAndGet();
@@ -840,11 +901,17 @@ 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 {
-            interrupted |= admission.awaitDrain(
+            PregenAdmissionGate.Drain drain = admission.awaitDrain(
                     CLOSE_DRAIN_WARNING_SECONDS,
                     TimeUnit.SECONDS,
+                    CLOSE_DRAIN_TIMEOUT_SECONDS,
+                    TimeUnit.SECONDS,
                     () -> IrisLogging.warn("Async pregen is still draining outstanding chunks. " + metricsSnapshot())
             );
+            interrupted |= drain.interrupted();
+            if (!drain.drained()) {
+                abandonOutstandingRequests(drain);
+            }
             syncGenerationHistory();
 
             mantleCleanup.close(MANTLE_CLEANUP_DRAIN_SECONDS, TimeUnit.SECONDS);
@@ -889,7 +956,7 @@ public class AsyncPregenMethod implements PregeneratorMethod {
     }
 
     private boolean isCancelled() {
-        return closing.get() || Thread.currentThread().isInterrupted();
+        return closing.get() || generationFailure.get() != null || Thread.currentThread().isInterrupted();
     }
 
     @Override
@@ -917,6 +984,7 @@ public class AsyncPregenMethod implements PregeneratorMethod {
 
     @Override
     public void generateChunk(int x, int z, PregenListener listener) {
+        throwIfGenerationFailed();
         listener.onChunkGenerating(x, z);
         if (MantleHeapPressure.overHighWater()) {
             reclaimMemory();
@@ -947,10 +1015,15 @@ public class AsyncPregenMethod implements PregeneratorMethod {
             recordPermitWait(waited.permitMs());
         }
 
+        throwIfGenerationFailed();
         regionPending.computeIfAbsent(rkey(x >> 5, z >> 5), k -> new AtomicInteger(1)).incrementAndGet();
         retainAround(x, z);
-        markSubmitted();
+        markSubmitted(x, z, listener);
         executor.generate(x, z, listener);
+        GenerationFailure failure = generationFailure.get();
+        if (failure != null) {
+            failOutstandingRequests(failure.cause());
+        }
     }
 
     private void reclaimHeapPressure() {
@@ -1187,6 +1260,9 @@ public class AsyncPregenMethod implements PregeneratorMethod {
         }
     }
 
+    private record GenerationFailure(int chunkX, int chunkZ, Throwable cause) {
+    }
+
     private record ChunkAsyncMethodSelection(Method urgentMethod, Method standardMethod, String mode) {
     }
 }

core/src/main/java/art/arcane/iris/world/pregen/CachedPregenMethod.java

@@ -189,6 +189,11 @@ public class CachedPregenMethod implements PregeneratorMethod {
         method.onRegionBounds(minRegionX, minRegionZ, maxRegionX, maxRegionZ);
     }
 
+    @Override
+    public void onChunkGenerationFailed(int chunkX, int chunkZ, Throwable failure) {
+        method.onChunkGenerationFailed(chunkX, chunkZ, failure);
+    }
+
     @Override
     public void onPregenStart(int centerBlockX, int centerBlockZ) {
         method.onPregenStart(centerBlockX, centerBlockZ);

core/src/main/java/art/arcane/iris/world/pregen/HybridPregenMethod.java

@@ -78,6 +78,11 @@ public class HybridPregenMethod implements PregeneratorMethod {
         inWorld.onRegionBounds(minRegionX, minRegionZ, maxRegionX, maxRegionZ);
     }
 
+    @Override
+    public void onChunkGenerationFailed(int chunkX, int chunkZ, Throwable failure) {
+        inWorld.onChunkGenerationFailed(chunkX, chunkZ, failure);
+    }
+
     @Override
     public void onPregenStart(int centerBlockX, int centerBlockZ) {
         inWorld.onPregenStart(centerBlockX, centerBlockZ);

core/src/main/java/art/arcane/iris/world/pregen/IrisPregenerator.java

@@ -215,6 +215,10 @@ public class IrisPregenerator {
         signalState();
     }
 
+    public void onChunkGenerationFailed(int chunkX, int chunkZ, Throwable failure) {
+        generator.onChunkGenerationFailed(chunkX, chunkZ, failure);
+    }
+
     public void start() {
         PrecisionStopwatch p = PrecisionStopwatch.start();
         boolean completed = false;

core/src/main/java/art/arcane/iris/world/pregen/PregenAdmissionGate.java

@@ -111,14 +111,20 @@ public final class PregenAdmissionGate {
         }
     }
 
-    public boolean awaitDrain(long warningInterval, TimeUnit timeUnit, Runnable onWait) {
+    public Drain awaitDrain(long warningInterval, TimeUnit warningUnit, long deadline, TimeUnit deadlineUnit, Runnable onWait) {
+        long warningNanos = warningUnit.toNanos(warningInterval);
+        long deadlineAt = System.nanoTime() + deadlineUnit.toNanos(deadline);
         boolean interrupted = false;
         lock.lock();
         try {
             while (free < permits) {
+                long remaining = deadlineAt - System.nanoTime();
+                if (remaining <= 0L) {
+                    return new Drain(false, interrupted, permits - free);
+                }
                 boolean signalled = false;
                 try {
-                    signalled = changed.await(warningInterval, timeUnit);
+                    signalled = changed.awaitNanos(Math.min(warningNanos, remaining)) > 0L;
                 } catch (InterruptedException e) {
                     interrupted = true;
                     continue;
@@ -127,10 +133,12 @@ public final class PregenAdmissionGate {
                     onWait.run();
                 }
             }
+            return new Drain(true, interrupted, 0);
         } finally {
             lock.unlock();
         }
+    }
 
-        return interrupted;
+    public record Drain(boolean drained, boolean interrupted, int outstanding) {
     }
 }

core/src/main/java/art/arcane/iris/world/pregen/PregenInFlightRequests.java

@@ -0,0 +1,47 @@
+package art.arcane.iris.world.pregen;
+
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
+
+public final class PregenInFlightRequests {
+    private final ConcurrentHashMap<Long, PregenListener> requests = new ConcurrentHashMap<>();
+
+    public static long key(int chunkX, int chunkZ) {
+        return ((long) chunkX << 32) | (chunkZ & 0xFFFFFFFFL);
+    }
+
+    public static int chunkX(long key) {
+        return (int) (key >> 32);
+    }
+
+    public static int chunkZ(long key) {
+        return (int) key;
+    }
+
+    public boolean add(long key, PregenListener listener) {
+        return requests.putIfAbsent(key, Objects.requireNonNull(listener, "listener")) == null;
+    }
+
+    public PregenListener settle(long key) {
+        return requests.remove(key);
+    }
+
+    public Map<Long, PregenListener> drain() {
+        HashMap<Long, PregenListener> drained = new HashMap<>();
+        Iterator<Map.Entry<Long, PregenListener>> iterator = requests.entrySet().iterator();
+        while (iterator.hasNext()) {
+            Map.Entry<Long, PregenListener> entry = iterator.next();
+            if (requests.remove(entry.getKey(), entry.getValue())) {
+                drained.put(entry.getKey(), entry.getValue());
+            }
+        }
+        return drained;
+    }
+
+    public int size() {
+        return requests.size();
+    }
+}

core/src/main/java/art/arcane/iris/world/pregen/PregeneratorMethod.java

@@ -83,6 +83,9 @@ public interface PregeneratorMethod {
     default void onRegionBounds(int minRegionX, int minRegionZ, int maxRegionX, int maxRegionZ) {
     }
 
+    default void onChunkGenerationFailed(int chunkX, int chunkZ, Throwable failure) {
+    }
+
     default void onPregenStart(int centerBlockX, int centerBlockZ) {
     }
 

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexTransitionTest.java

@@ -31,13 +31,14 @@ public class IrisComplexTransitionTest {
 
     @Test
     public void tapersRiverDepthWithoutRaisingItsFluidHead() {
-        HydrologyColumnSample tapered = IrisComplex.taperHydrologySample(hydrologySample(), 0.5D);
+        HydrologyColumnSample tapered = IrisComplex.taperHydrologySample(hydrologySample(), 0.8D);
         HydrologyColumnLayer layer = tapered.layers().getFirst();
 
-        assertEquals(73, layer.bedY());
+        assertEquals(69, layer.bedY());
         assertEquals(70, layer.fluidHeadY());
         assertEquals(70, layer.ceilingY());
-        assertEquals(73, tapered.terrainHeight());
+        assertTrue(layer.channel());
+        assertEquals(69, tapered.terrainHeight());
         assertEquals("river", layer.profileKey());
     }
 
@@ -61,10 +62,10 @@ public class IrisComplexTransitionTest {
         HydrologyColumnLayer surface = hydrologySample().layers().getFirst();
         HydrologyColumnSample sample = new HydrologyColumnSample(4, 6, 80, 63, false, "parent", List.of(surface, cave));
 
-        HydrologyColumnSample tapered = IrisComplex.taperHydrologySample(sample, 0.5D);
+        HydrologyColumnSample tapered = IrisComplex.taperHydrologySample(sample, 0.8D);
 
         assertSame(cave, tapered.layers().getFirst());
-        assertEquals(73, tapered.layers().getLast().bedY());
+        assertEquals(69, tapered.layers().getLast().bedY());
         assertEquals(70, tapered.layers().getLast().fluidHeadY());
         assertEquals(70, tapered.layers().getLast().ceilingY());
     }
@@ -85,6 +86,62 @@ public class IrisComplexTransitionTest {
         assertSame(sample, IrisComplex.transitionHydrologySample(sample, 1D, null));
     }
 
+    @Test
+    public void taperedDryBankKeepsItsHeadOnItsBed() {
+        HydrologyColumnSample tapered = IrisComplex.taperHydrologySample(bankSample(364, 366), 0.5D);
+        HydrologyColumnLayer bank = tapered.layers().getFirst();
+
+        assertEquals(365, bank.bedY());
+        assertEquals(365, bank.fluidHeadY());
+        assertEquals(365, bank.ceilingY());
+        assertFalse(bank.channel());
+        assertTrue(bank.grading());
+        assertTrue(bank.terrainOwned());
+        assertEquals(365, tapered.terrainHeight());
+    }
+
+    @Test
+    public void transitionedDryBankKeepsItsHeadOnItsBed() {
+        HydrologyColumnSample sample = bankSample(365, 380);
+        TransitionDisplacementField displacement = mock(TransitionDisplacementField.class);
+        when(displacement.sample(4, 6)).thenReturn(
+                new TransitionDisplacementField.Sample(0D, 8D, 0.25D, 0D, 0D, 300D, "minecraft:water"));
+        when(displacement.fluidHeight(4, 6, 63D)).thenReturn(63D);
+        when(displacement.fluidHeight(4, 6, 365D)).thenReturn(364D);
+
+        HydrologyColumnSample transitioned = IrisComplex.transitionHydrologySample(sample, 1D, displacement);
+        HydrologyColumnLayer bank = transitioned.layers().getFirst();
+
+        assertEquals(365, bank.bedY());
+        assertEquals(365, bank.fluidHeadY());
+        assertEquals(365, bank.ceilingY());
+        assertFalse(bank.channel());
+        assertTrue(bank.terrainOwned());
+        assertEquals(365, transitioned.terrainHeight());
+    }
+
+    @Test
+    public void driedChannelHeadFollowsItsTaperedBed() {
+        HydrologyColumnSample sample = hydrologySample();
+        TransitionDisplacementField displacement = mock(TransitionDisplacementField.class);
+        when(displacement.sample(4, 6)).thenReturn(
+                new TransitionDisplacementField.Sample(0D, 8D, 0.25D, 1D, 80D, 80D, "minecraft:water"));
+        when(displacement.fluidHeight(4, 6, 63D)).thenReturn(63D);
+        when(displacement.fluidHeight(4, 6, 70D)).thenReturn(70D);
+
+        HydrologyColumnSample transitioned = IrisComplex.transitionHydrologySample(sample, 0.35D, displacement);
+        HydrologyColumnLayer river = transitioned.layers().getFirst();
+
+        assertEquals(75, river.bedY());
+        assertEquals(75, river.fluidHeadY());
+        assertEquals(75, river.ceilingY());
+        assertFalse(river.channel());
+        assertFalse(river.fluidOwned());
+        assertFalse(river.connectedFluid());
+        assertTrue(river.terrainOwned());
+        assertEquals(75, transitioned.terrainHeight());
+    }
+
     @Test
     public void tinyRiverWeightsExcavateGraduallyUntilReachingUnraisedWater() {
         HydrologyColumnSample sample = hydrologySample();
@@ -93,13 +150,14 @@ public class IrisComplexTransitionTest {
             double weight = step / 100D;
             HydrologyColumnSample tapered = IrisComplex.taperHydrologySample(sample, weight);
             HydrologyColumnLayer layer = tapered.layers().getFirst();
-            assertEquals(70, layer.fluidHeadY());
+            assertEquals(layer.bedY() <= 70, layer.channel());
+            assertEquals(layer.channel() ? 70 : layer.bedY(), layer.fluidHeadY());
+            assertEquals(layer.fluidHeadY(), layer.ceilingY());
             assertTrue(layer.bedY() <= previousBed);
             assertTrue(previousBed - layer.bedY() <= 1);
             assertEquals(layer.bedY(), tapered.terrainHeight());
-            assertEquals(layer.bedY() <= layer.fluidHeadY(), layer.channel());
             assertEquals(layer.channel(), layer.fluidOwned());
-            if (layer.bedY() > layer.fluidHeadY()) {
+            if (!layer.channel()) {
                 assertFalse(layer.connectedFluid());
                 assertFalse(layer.fallingFluid());
                 assertFalse(layer.receivingPool());
@@ -209,6 +267,15 @@ public class IrisComplexTransitionTest {
         return hydrologySample(HydrologyFeatureType.SURFACE_POOL);
     }
 
+    private static HydrologyColumnSample bankSample(int bankHeight, int naturalHeight) {
+        HydrologyFeatureRef feature = new HydrologyFeatureRef(
+                1L, HydrologyFeatureType.SURFACE_POOL, 2L, 3L, 1080, 346, 204, 0, -1, false);
+        HydrologyColumnLayer bank = new HydrologyColumnLayer(feature, bankHeight, bankHeight, bankHeight,
+                false, false, true, false, false, false, true, false, false,
+                "water", "surface", "mouth", "shore", "bank", "cave");
+        return new HydrologyColumnSample(4, 6, naturalHeight, 63, false, "parent", List.of(bank));
+    }
+
     private static HydrologyColumnSample hydrologySample(HydrologyFeatureType type) {
         HydrologyFeatureRef feature = new HydrologyFeatureRef(
                 1L,

core/src/test/java/art/arcane/iris/world/pregen/AsyncPregenGenerationFailureTest.java

@@ -0,0 +1,147 @@
+package art.arcane.iris.world.pregen;
+
+import org.bukkit.Chunk;
+import org.bukkit.World;
+import org.junit.Test;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertThrows;
+import static org.mockito.Mockito.CALLS_REAL_METHODS;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class AsyncPregenGenerationFailureTest {
+    @Test
+    public void aGenerationFailureFailsEveryOutstandingRequestAndReleasesTheirPermits() throws Exception {
+        Harness harness = Harness.withOutstanding(2);
+        IllegalStateException cause = new IllegalStateException("Accepted hydrology layer exceeds the mantle bounds");
+
+        harness.method.onChunkGenerationFailed(48, -4, cause);
+
+        assertEquals(2, harness.admission.availablePermits());
+        assertEquals(2, harness.failed.get());
+        assertEquals(0, harness.inFlight.get());
+        assertEquals(0, harness.requests.size());
+        verify(harness.listener).onChunkFailed(10, 0);
+        verify(harness.listener).onChunkFailed(11, 0);
+
+        IllegalStateException abort = assertThrows(IllegalStateException.class,
+                () -> harness.method.generateChunk(12, 0, harness.listener));
+        assertSame(cause, abort.getCause());
+        verify(harness.listener, never()).onChunkGenerating(12, 0);
+    }
+
+    @Test
+    public void aLateCompletionForASettledRequestIsIgnored() throws Exception {
+        Harness harness = Harness.withOutstanding(2);
+        harness.method.onChunkGenerationFailed(48, -4, new IllegalStateException("boom"));
+
+        harness.completeChunk(10, 0, null, null);
+        harness.completeChunk(11, 0, null, new IllegalStateException("late failure"));
+
+        assertEquals(2, harness.failed.get());
+        assertEquals(0, harness.completed.get());
+        assertEquals(0, harness.inFlight.get());
+        assertEquals(2, harness.admission.availablePermits());
+    }
+
+    @Test
+    public void closingAbandonsRequestsThatNeverCompleteAndReturnsTheirPermits() throws Exception {
+        Harness harness = Harness.withOutstanding(2);
+
+        harness.abandon(new PregenAdmissionGate.Drain(false, false, 2));
+
+        assertEquals(2, harness.admission.availablePermits());
+        assertEquals(2, harness.failed.get());
+        assertEquals(0, harness.requests.size());
+        verify(harness.listener).onChunkFailed(10, 0);
+        verify(harness.listener).onChunkFailed(11, 0);
+    }
+
+    private static final class Harness {
+        private final AsyncPregenMethod method;
+        private final PregenAdmissionGate admission;
+        private final PregenInFlightRequests requests;
+        private final PregenListener listener;
+        private final AtomicInteger inFlight;
+        private final AtomicLong failed;
+        private final AtomicLong completed;
+
+        private Harness(AsyncPregenMethod method, PregenAdmissionGate admission, PregenInFlightRequests requests,
+                        PregenListener listener, AtomicInteger inFlight, AtomicLong failed, AtomicLong completed) {
+            this.method = method;
+            this.admission = admission;
+            this.requests = requests;
+            this.listener = listener;
+            this.inFlight = inFlight;
+            this.failed = failed;
+            this.completed = completed;
+        }
+
+        static Harness withOutstanding(int outstanding) throws Exception {
+            AsyncPregenMethod method = mock(AsyncPregenMethod.class, CALLS_REAL_METHODS);
+            World world = mock(World.class);
+            when(world.getName()).thenReturn("qa");
+            PregenAdmissionGate admission = new PregenAdmissionGate(outstanding, 50L, System::currentTimeMillis);
+            PregenInFlightRequests requests = new PregenInFlightRequests();
+            PregenListener listener = mock(PregenListener.class);
+            AtomicInteger inFlight = new AtomicInteger(outstanding);
+            AtomicLong failed = new AtomicLong();
+            AtomicLong completed = new AtomicLong();
+            for (int index = 0; index < outstanding; index++) {
+                assertNotNull(admission.admit(() -> false, () -> false));
+                requests.add(PregenInFlightRequests.key(10 + index, 0), listener);
+            }
+            set(method, "world", world);
+            set(method, "admission", admission);
+            set(method, "backpressure", mock(PregenMantleBackpressure.class));
+            set(method, "mantleCleanup", mock(PregenSerialWorker.class));
+            set(method, "inFlightRequests", requests);
+            set(method, "generationFailure", new AtomicReference<>());
+            set(method, "regionPending", new ConcurrentHashMap<>());
+            set(method, "lastFailedReleaseLogAt", new AtomicLong());
+            set(method, "slowRequestWarnIntervalMs", 15_000);
+            set(method, "inFlight", inFlight);
+            set(method, "submitted", new AtomicLong(outstanding));
+            set(method, "completed", completed);
+            set(method, "failed", failed);
+            set(method, "lastProgressAt", new AtomicLong());
+            set(method, "adaptiveInFlightLimit", new AtomicInteger(outstanding));
+            set(method, "threads", outstanding);
+            set(method, "closing", new AtomicBoolean());
+            return new Harness(method, admission, requests, listener, inFlight, failed, completed);
+        }
+
+        void completeChunk(int x, int z, Chunk chunk, Throwable throwable) throws Exception {
+            Method complete = AsyncPregenMethod.class.getDeclaredMethod(
+                    "completeChunk", int.class, int.class, PregenListener.class, Chunk.class, Throwable.class);
+            complete.setAccessible(true);
+            complete.invoke(method, x, z, listener, chunk, throwable);
+        }
+
+        void abandon(PregenAdmissionGate.Drain drain) throws Exception {
+            Method abandon = AsyncPregenMethod.class.getDeclaredMethod(
+                    "abandonOutstandingRequests", PregenAdmissionGate.Drain.class);
+            abandon.setAccessible(true);
+            abandon.invoke(method, drain);
+        }
+
+        private static void set(AsyncPregenMethod method, String name, Object value) throws Exception {
+            Field field = AsyncPregenMethod.class.getDeclaredField(name);
+            field.setAccessible(true);
+            field.set(method, value);
+        }
+    }
+}

core/src/test/java/art/arcane/iris/world/pregen/AsyncPregenMethodConcurrencyCapTest.java

@@ -148,9 +148,11 @@ public class AsyncPregenMethodConcurrencyCapTest {
         AtomicInteger warnings = new AtomicInteger();
         ExecutorService executor = Executors.newSingleThreadExecutor();
         try {
-            Future<Boolean> drain = executor.submit(() -> gate.awaitDrain(
+            Future<PregenAdmissionGate.Drain> drain = executor.submit(() -> gate.awaitDrain(
                     10L,
                     TimeUnit.MILLISECONDS,
+                    5L,
+                    TimeUnit.SECONDS,
                     warnings::incrementAndGet
             ));
 
@@ -160,7 +162,9 @@ public class AsyncPregenMethodConcurrencyCapTest {
             gate.release();
             gate.release();
 
-            assertFalse(drain.get(1L, TimeUnit.SECONDS));
+            PregenAdmissionGate.Drain result = drain.get(1L, TimeUnit.SECONDS);
+            assertTrue(result.drained());
+            assertFalse(result.interrupted());
             assertTrue(warnings.get() > 0);
             assertEquals(2, gate.availablePermits());
         } finally {

core/src/test/java/art/arcane/iris/world/pregen/AsyncPregenServerSaveOwnershipTest.java

@@ -514,6 +514,8 @@ public class AsyncPregenServerSaveOwnershipTest {
             set("regionPending", pendingRegions);
             set("pendingEvictions", evictions);
             set("chunkIoExecutor", (Executor) Runnable::run);
+            set("generationFailure", new AtomicReference<>());
+            set("inFlightRequests", new PregenInFlightRequests());
             when(chunk.getX()).thenReturn(2);
             when(chunk.getZ()).thenReturn(3);
             when(binding.saveAndUnloadChunk(world, 2, 3)).thenReturn(true);

core/src/test/java/art/arcane/iris/world/pregen/AsyncPregenWorkerBoostTest.java

@@ -113,7 +113,8 @@ public class AsyncPregenWorkerBoostTest {
             AsyncPregenMethod method = mock(AsyncPregenMethod.class, CALLS_REAL_METHODS);
             PregenAdmissionGate admission = mock(PregenAdmissionGate.class);
             IllegalStateException failure = new IllegalStateException("drain failed");
-            when(admission.awaitDrain(anyLong(), any(TimeUnit.class), any(Runnable.class))).thenThrow(failure);
+            when(admission.awaitDrain(anyLong(), any(TimeUnit.class), anyLong(), any(TimeUnit.class), any(Runnable.class)))
+                    .thenThrow(failure);
             set(method, "closing", new AtomicBoolean());
             set(method, "holdsWorkerBoost", new AtomicBoolean(true));
             set(method, "admission", admission);

core/src/test/java/art/arcane/iris/world/pregen/PregenAdmissionGateTest.java

@@ -12,6 +12,7 @@ import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
@@ -162,7 +163,8 @@ public class PregenAdmissionGateTest {
         AtomicInteger warnings = new AtomicInteger();
         ExecutorService executor = Executors.newSingleThreadExecutor();
         try {
-            Future<Boolean> drain = executor.submit(() -> gate.awaitDrain(5L, TimeUnit.MILLISECONDS, warnings::incrementAndGet));
+            Future<PregenAdmissionGate.Drain> drain = executor.submit(() -> gate.awaitDrain(
+                    5L, TimeUnit.MILLISECONDS, 5L, TimeUnit.SECONDS, warnings::incrementAndGet));
 
             while (warnings.get() < 2) {
                 Thread.onSpinWait();
@@ -170,13 +172,46 @@ public class PregenAdmissionGateTest {
             gate.release();
             gate.release();
 
-            assertEquals(Boolean.FALSE, drain.get(5, TimeUnit.SECONDS));
+            PregenAdmissionGate.Drain result = drain.get(5, TimeUnit.SECONDS);
+            assertTrue(result.drained());
+            assertFalse(result.interrupted());
+            assertEquals(0, result.outstanding());
             assertEquals(2, gate.availablePermits());
         } finally {
             executor.shutdownNow();
         }
     }
 
+    @Test
+    public void drainGivesUpAtItsDeadlineWhilePermitsStayHeld() throws Exception {
+        PregenAdmissionGate gate = new PregenAdmissionGate(2, GENEROUS_BOUND_MS, System::currentTimeMillis);
+        assertNotNull(gate.admit(() -> false, () -> false));
+        assertNotNull(gate.admit(() -> false, () -> false));
+        AtomicInteger warnings = new AtomicInteger();
+
+        PregenAdmissionGate.Drain result = gate.awaitDrain(
+                5L, TimeUnit.MILLISECONDS, 80L, TimeUnit.MILLISECONDS, warnings::incrementAndGet);
+
+        assertFalse(result.drained());
+        assertFalse(result.interrupted());
+        assertEquals(2, result.outstanding());
+        assertTrue(warnings.get() > 0);
+        assertEquals(0, gate.availablePermits());
+    }
+
+    @Test
+    public void drainReturnsAtOnceWhenNothingIsHeld() {
+        PregenAdmissionGate gate = new PregenAdmissionGate(2, GENEROUS_BOUND_MS, System::currentTimeMillis);
+        AtomicInteger warnings = new AtomicInteger();
+
+        PregenAdmissionGate.Drain result = gate.awaitDrain(
+                5L, TimeUnit.MILLISECONDS, 5L, TimeUnit.SECONDS, warnings::incrementAndGet);
+
+        assertTrue(result.drained());
+        assertEquals(0, result.outstanding());
+        assertEquals(0, warnings.get());
+    }
+
     @Test(expected = IllegalArgumentException.class)
     public void aGateWithoutPermitsIsRejected() {
         new PregenAdmissionGate(0, GENEROUS_BOUND_MS, System::currentTimeMillis);

core/src/test/java/art/arcane/iris/world/pregen/PregenInFlightRequestsTest.java

@@ -0,0 +1,62 @@
+package art.arcane.iris.world.pregen;
+
+import org.junit.Test;
+
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+
+public class PregenInFlightRequestsTest {
+    @Test
+    public void settlingARequestReturnsItsListenerOnlyOnce() {
+        PregenInFlightRequests requests = new PregenInFlightRequests();
+        PregenListener listener = mock(PregenListener.class);
+        long key = PregenInFlightRequests.key(48, -4);
+
+        assertTrue(requests.add(key, listener));
+        assertEquals(1, requests.size());
+        assertSame(listener, requests.settle(key));
+        assertNull(requests.settle(key));
+        assertEquals(0, requests.size());
+    }
+
+    @Test
+    public void aDuplicateSubmissionKeepsTheOriginalRequest() {
+        PregenInFlightRequests requests = new PregenInFlightRequests();
+        PregenListener first = mock(PregenListener.class);
+        PregenListener second = mock(PregenListener.class);
+        long key = PregenInFlightRequests.key(1, 2);
+
+        assertTrue(requests.add(key, first));
+        assertFalse(requests.add(key, second));
+        assertSame(first, requests.settle(key));
+    }
+
+    @Test
+    public void drainingHandsBackEveryOutstandingRequestExactlyOnce() {
+        PregenInFlightRequests requests = new PregenInFlightRequests();
+        PregenListener listener = mock(PregenListener.class);
+        requests.add(PregenInFlightRequests.key(0, 0), listener);
+        requests.add(PregenInFlightRequests.key(1, 0), listener);
+        requests.add(PregenInFlightRequests.key(-7, 9), listener);
+
+        Map<Long, PregenListener> drained = requests.drain();
+
+        assertEquals(3, drained.size());
+        assertEquals(0, requests.size());
+        assertTrue(requests.drain().isEmpty());
+        assertNull(requests.settle(PregenInFlightRequests.key(1, 0)));
+    }
+
+    @Test
+    public void keysDistinguishNegativeCoordinates() {
+        assertTrue(PregenInFlightRequests.key(1, -1) != PregenInFlightRequests.key(-1, 1));
+        assertTrue(PregenInFlightRequests.key(0, -1) != PregenInFlightRequests.key(-1, 0));
+        assertEquals(PregenInFlightRequests.key(48, -4), PregenInFlightRequests.key(48, -4));
+    }
+}

gradle/native-minecraft-sources.gradle

@@ -37,6 +37,14 @@ tasks.named('processResources').configure {
     dependsOn(unpackNativeMinecraftSources)
 }
 
+tasks.named('verifyLoggingPolicy').configure {
+    dependsOn(unpackNativeMinecraftSources)
+}
+
+tasks.named('verifyNativeClassBoundary').configure {
+    dependsOn(tasks.named('classes'))
+}
+
 tasks.matching { Task task -> task.name == 'createMinecraftArtifacts' }.configureEach {
     dependsOn(unpackNativeMinecraftSources)
 }