dwa

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

@@ -57,6 +57,7 @@ public class CustomBiomeSource extends BiomeSource {
     private volatile KMap<String, Holder<Biome>> customBiomes;
     private volatile Map<Biome, Holder<Biome>> vanillaSpawnBiomes;
     private volatile IrisDimension cacheDimension;
+    private volatile int cacheRuntimeId;
 
     public CustomBiomeSource(long seed, Engine engine, World world) {
         this.engine = engine;
@@ -67,6 +68,7 @@ public class CustomBiomeSource extends BiomeSource {
         this.customBiomes = fillCustomBiomes(this.biomeCustomRegistry, engine, this.fallbackBiome);
         this.vanillaSpawnBiomes = fillVanillaSpawnBiomes(this.biomeCustomRegistry, this.biomeRegistry, engine);
         this.cacheDimension = engine.getDimension();
+        this.cacheRuntimeId = engine.getCacheID();
     }
 
     private static List<Holder<Biome>> getAllBiomes(Registry<Biome> customRegistry, Registry<Biome> registry, Engine engine) {
@@ -246,11 +248,11 @@ public class CustomBiomeSource extends BiomeSource {
         }
         GenerationSessionLease lease = tryAcquireGenerationLease("bukkit_spawn_biome");
         if (lease == null) {
-            throw new IllegalStateException("Iris spawn biome lookup was rejected during an engine transition");
+            return null;
         }
         try (lease; IrisContext.Scope ignored = IrisContext.open(engine, lease.sessionId(), null)) {
             if (!isRuntimeAvailable()) {
-                throw new IllegalStateException("Iris spawn biome lookup has no active engine runtime");
+                return null;
             }
             ensureCachesCurrent();
             return vanillaSpawnBiomes.get(biome.value());
@@ -434,11 +436,12 @@ public class CustomBiomeSource extends BiomeSource {
 
     private void ensureCachesCurrent() {
         IrisDimension dimension = engine.getDimension();
-        if (cacheDimension == dimension) {
+        int runtimeId = engine.getCacheID();
+        if (cacheDimension == dimension && cacheRuntimeId == runtimeId) {
             return;
         }
         synchronized (this) {
-            if (cacheDimension == dimension) {
+            if (cacheDimension == dimension && cacheRuntimeId == runtimeId) {
                 return;
             }
             KMap<String, Holder<Biome>> refreshedCustomBiomes = fillCustomBiomes(
@@ -451,6 +454,7 @@ public class CustomBiomeSource extends BiomeSource {
             customBiomes = refreshedCustomBiomes;
             vanillaSpawnBiomes = refreshedSpawnBiomes;
             cacheDimension = dimension;
+            cacheRuntimeId = runtimeId;
         }
     }
 

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

@@ -57,6 +57,7 @@ final class ImportedFeatureStage {
     private final Engine engine;
     private volatile FeatureTable featureTable;
     private volatile IrisDimension inertDimension;
+    private volatile int settledRuntimeId;
 
     ImportedFeatureStage(Engine engine) {
         this.engine = engine;
@@ -86,18 +87,23 @@ final class ImportedFeatureStage {
      */
     void prepare(WorldGenLevel level) {
         IrisDimension dimension = engine.getDimension();
-        if (settled(dimension)) {
+        int runtimeId = engine.getCacheID();
+        if (settled(dimension, runtimeId)) {
             return;
         }
         synchronized (this) {
-            if (settled(dimension)) {
+            if (settled(dimension, runtimeId)) {
                 return;
             }
             build(level, dimension);
+            settledRuntimeId = runtimeId;
         }
     }
 
-    private boolean settled(IrisDimension dimension) {
+    private boolean settled(IrisDimension dimension, int runtimeId) {
+        if (settledRuntimeId != runtimeId) {
+            return false;
+        }
         FeatureTable current = featureTable;
         if (current != null && current.dimension() == dimension) {
             return true;

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

@@ -128,6 +128,8 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     private final int runtimeHeight;
     private final int runtimeSeaLevel;
     private final ConcurrentHashMap<SpawnTableKey, WeightedList<MobSpawnSettings.SpawnerData>> mergedSpawnTables = new ConcurrentHashMap<>();
+    private volatile IrisDimension spawnTableDimension;
+    private volatile int spawnTableRuntimeId;
     private final ImportedFeatureStage importedFeatures;
     private final AtomicReference<StudioStructureState> retainedStudioStructureState = new AtomicReference<>();
     private volatile ReachableStructureCache reachableStructureCache;
@@ -310,18 +312,19 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
 
     private Set<String> reachableStructureKeys(ServerLevel level) {
         IrisDimension dimension = engine.getDimension();
+        int runtimeId = engine.getCacheID();
         ReachableStructureCache cached = reachableStructureCache;
-        if (cached != null && cached.dimension() == dimension) {
+        if (cached != null && cached.dimension() == dimension && cached.runtimeId() == runtimeId) {
             return cached.keys();
         }
         synchronized (this) {
             cached = reachableStructureCache;
-            if (cached != null && cached.dimension() == dimension) {
+            if (cached != null && cached.dimension() == dimension && cached.runtimeId() == runtimeId) {
                 return cached.keys();
             }
             Set<String> reachable = Set.copyOf(
                     VanillaStructureBiomes.reachableStructureKeys(level, customBiomeSource));
-            reachableStructureCache = new ReachableStructureCache(dimension, reachable);
+            reachableStructureCache = new ReachableStructureCache(dimension, runtimeId, reachable);
             return reachable;
         }
     }
@@ -738,6 +741,17 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
             return explicitSpawns;
         }
 
+        IrisDimension spawnDimension = engine.getDimension();
+        int spawnRuntimeId = engine.getCacheID();
+        if (spawnTableDimension != spawnDimension || spawnTableRuntimeId != spawnRuntimeId) {
+            synchronized (mergedSpawnTables) {
+                if (spawnTableDimension != spawnDimension || spawnTableRuntimeId != spawnRuntimeId) {
+                    mergedSpawnTables.clear();
+                    spawnTableDimension = spawnDimension;
+                    spawnTableRuntimeId = spawnRuntimeId;
+                }
+            }
+        }
         SpawnTableKey key = new SpawnTableKey(holder.value(), enumcreaturetype);
         return mergedSpawnTables.computeIfAbsent(key, ignored -> mergeSpawnTables(vanillaSpawns, explicitSpawns));
     }
@@ -1160,7 +1174,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
     private record SpawnTableKey(Biome biome, MobCategory category) {
     }
 
-    private record ReachableStructureCache(IrisDimension dimension, Set<String> keys) {
+    private record ReachableStructureCache(IrisDimension dimension, int runtimeId, Set<String> keys) {
     }
 
     private record StructureStepCache(Registry<Structure> registry, List<List<Structure>> structures) {

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

@@ -26,8 +26,9 @@ public class CustomBiomeSourceStructureContractTest {
 
         assertTrue(source.contains("tryAcquireGenerationLease(\"bukkit_possible_biomes\")"));
         assertTrue(source.contains("tryAcquireGenerationLease(\"bukkit_spawn_biome\")"));
-        assertTrue(source.contains("Iris spawn biome lookup was rejected during an engine transition"));
-        assertTrue(source.contains("Iris spawn biome lookup has no active engine runtime"));
+        assertFalse(source.contains("Iris spawn biome lookup was rejected during an engine transition"));
+        assertFalse(source.contains("Iris spawn biome lookup has no active engine runtime"));
+        assertTrue(source.contains("vanillaSpawnBiomes.get(biome.value())"));
         assertTrue(source.contains("tryAcquireGenerationLease(\"bukkit_structure_biome\")"));
         assertTrue(source.contains("tryAcquireGenerationLease(\"bukkit_biomes_within\")"));
         assertTrue(source.contains("tryAcquireGenerationLease(\"bukkit_visible_biome\")"));

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

@@ -613,18 +613,16 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
         // (listeners, shutdown hook, replacement journals) are the safety-critical ones.
         // Only services that actually enabled get listeners and a later onDisable.
         enabledServices.clear();
-        IrisService firstFailedService = null;
         for (IrisService service : orderedServices) {
             try {
                 service.onEnable();
                 enabledServices.add(service);
             } catch (Throwable e) {
-                if (firstFailedService == null) {
-                    firstFailedService = service;
-                }
+                // A service failure is NOT a datapack validation failure: the admission gate
+                // must never lock every login over a broken cosmetic service. Log loudly,
+                // continue degraded, and clean up whatever the partial onEnable started
+                // (a failed service is excluded from the teardown loop).
                 Iris.reportError("Failed to enable " + service.getClass().getSimpleName() + "; continuing with a degraded runtime.", e);
-                // A failed service is excluded from the teardown loop, so clean up whatever
-                // its partial onEnable started right here, best-effort.
                 try {
                     service.onDisable();
                 } catch (Throwable cleanup) {
@@ -632,11 +630,6 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
                 }
             }
         }
-        if (firstFailedService != null) {
-            IrisStartupValidation.markDatapacksInvalid("Iris service "
-                    + firstFailedService.getClass().getSimpleName()
-                    + " failed to enable; world creation and player admission are locked. Check the log above.");
-        }
         for (IrisService service : enabledServices) {
             try {
                 registerListener(service);

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

@@ -468,7 +468,21 @@ public final class PendingWorldReplacementManager implements Listener {
     }
 
     private List<Transaction> loadTransactions() throws IOException {
-        return WorldReplacementJournal.load(dataDirectory(), IrisWorldStorage.levelRoot().toPath());
+        Path levelRoot = IrisWorldStorage.levelRoot().toPath();
+        List<Transaction> transactions = WorldReplacementJournal.load(dataDirectory(), levelRoot);
+        List<Transaction> applicable = new ArrayList<>(transactions.size());
+        for (Transaction transaction : transactions) {
+            // A journal staged against another level root is not this server's transaction;
+            // skip it (the bootstrap already told the operator how to resolve it).
+            if (WorldReplacementJournal.appliesTo(transaction, levelRoot)) {
+                applicable.add(transaction);
+            } else {
+                Iris.warn("Ignoring pending world replacement " + transaction.id() + " for "
+                        + transaction.worldKey() + "; it was staged against level root "
+                        + transaction.levelRoot() + ".");
+            }
+        }
+        return applicable;
     }
 
     private void writeTransaction(Transaction transaction) throws IOException {

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

@@ -263,6 +263,10 @@ public class CommandPack implements DirectorExecutor {
         for (File packDirectory : packDirectories) {
             PackValidationResult result = PackValidationRegistry.get(packDirectory.getName());
             if (result == null) {
+                // The boot cache only loads when it covers every pack, so a partial write is
+                // pointless - but say so instead of silently skipping the persist forever.
+                Iris.warn("Pack validation cache not written: \"" + packDirectory.getName()
+                        + "\" has no registered result. Run /iris pack validate all to repopulate it.");
                 return;
             }
             results.add(result);

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

@@ -329,8 +329,7 @@ public class CommandStudio implements DirectorExecutor {
             return;
         }
         if (radius <= 0 || radius > 2048) {
-            sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_ONLY_WORKS_IRIS_WORLD));
-            sender().sendMessage("Radius must be between 1 and 2048 chunks.");
+            sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_REGIONS_RADIUS_OUT_OF_RANGE));
             return;
         }
         var sender = sender();
@@ -393,7 +392,8 @@ public class CommandStudio implements DirectorExecutor {
                     data.forEach((k, v) -> sender.sendMessage(IrisLanguage.text(BukkitCommandMessages.COMMAND_STUDIO_MESSAGE, MessageArgument.untrusted("k", k), MessageArgument.untrusted("value", loader.load(k).getRarity()), MessageArgument.untrusted("value2", Form.f((double) v.get() / totalTasks * 100, 2)))));
                     } catch (Throwable e) {
                         Iris.reportError(e);
-                        sender.sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_ONLY_WORKS_IRIS_WORLD));
+                        sender.sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_REGIONS_SCAN_FAILED,
+                                MessageArgument.untrusted("value", String.valueOf(e.getMessage()))));
                     } finally {
                         if (c != -1) {
                             J.car(c);
@@ -712,7 +712,7 @@ public class CommandStudio implements DirectorExecutor {
         }
     }
 
-    @Director(aliases = "find-objects", description = "Capture an IGenData chunk report for nearby chunks", descriptionKey = "iris.director.commandstudio.director.capture_igendata_chunk_report_nearby_chunks")
+    @Director(aliases = "find-objects", description = "Capture an IGenData chunk report for nearby chunks", descriptionKey = "iris.director.commandstudio.director.capture_igendata_chunk_report_nearby_chunks", origin = DirectorOrigin.PLAYER)
     public void objects() {
         if (!IrisToolbelt.isIrisWorld(player().getWorld())) {
             sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STUDIO_YOU_MUST_BE_IRIS_WORLD));

adapters/minecraft-common/src/main/java/art/arcane/iris/nativegen/NativeBuildFutures.java

@@ -0,0 +1,31 @@
+package art.arcane.iris.nativegen;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+
+/**
+ * Shared waiter for the racy build caches in this package: the loser of a putIfAbsent race
+ * must surface the same exception the builder threw, not a CompletionException wrapper.
+ */
+final class NativeBuildFutures {
+    private NativeBuildFutures() {
+    }
+
+    static <T> T awaitBuild(CompletableFuture<T> future, String what) {
+        try {
+            return future.join();
+        } catch (CompletionException error) {
+            Throwable cause = error.getCause();
+            if (cause instanceof RuntimeException runtime) {
+                throw runtime;
+            }
+            if (cause instanceof Error fatal) {
+                throw fatal;
+            }
+            if (cause == null) {
+                throw error;
+            }
+            throw new IllegalStateException(what + " failed", cause);
+        }
+    }
+}

adapters/minecraft-common/src/main/java/art/arcane/iris/nativegen/NativeStructureTerrainIntegrator.java

@@ -39,11 +39,13 @@ import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemp
 import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.WeakHashMap;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.ConcurrentHashMap;
@@ -73,8 +75,11 @@ public final class NativeStructureTerrainIntegrator {
             Blocks.SOUL_SOIL, Blocks.END_STONE, Blocks.GRAVEL, Blocks.CLAY,
             Blocks.CALCITE, Blocks.DRIPSTONE_BLOCK, Blocks.SANDSTONE,
             Blocks.RED_SANDSTONE, Blocks.SCULK);
-    private static final Map<CarveFootprintKey, CachedCarveFootprint> CARVE_FOOTPRINTS =
-            new LinkedHashMap<>(16, 0.75F, true);
+    // Weakly keyed on the StructureStart so retired starts (world unload, generation done)
+    // are collectable instead of pinned forever by a process-wide static; values hold only
+    // primitives, so there is no value-to-key cycle defeating the weak keys.
+    private static final Map<StructureStart, Map<Integer, CachedCarveFootprint>> CARVE_FOOTPRINTS =
+            new WeakHashMap<>(16);
     private static final ConcurrentHashMap<CarveFootprintKey, CompletableFuture<StructureCarvingFootprint>>
             CARVE_FOOTPRINT_BUILDS = new ConcurrentHashMap<>();
     private static int cachedCarveCells;
@@ -531,6 +536,15 @@ public final class NativeStructureTerrainIntegrator {
         if (active != null) {
             return awaitCarveFootprint(active);
         }
+        // Close the check-then-claim window: a racer whose cache check missed before the
+        // previous builder cached can claim the build slot after that builder retired it,
+        // and would rebuild a second instance without this re-check.
+        StructureCarvingFootprint published = cachedCarveFootprint(key);
+        if (published != null) {
+            build.complete(published);
+            CARVE_FOOTPRINT_BUILDS.remove(key, build);
+            return published;
+        }
         try {
             StructureCarvingFootprint footprint = StructureCarvingFootprint.fromColumns(
                     sink -> emitCarveColumns(start, templates, sink), horizontalPadding, MAX_CARVE_COLUMNS);
@@ -551,53 +565,64 @@ public final class NativeStructureTerrainIntegrator {
 
     static int cachedCarveFootprintCells() {
         synchronized (CARVE_FOOTPRINTS) {
+            cachedCarveCells = liveCarveCells();
             return cachedCarveCells;
         }
     }
 
+    private static int liveCarveCells() {
+        int total = 0;
+        for (Map<Integer, CachedCarveFootprint> perStart : CARVE_FOOTPRINTS.values()) {
+            for (CachedCarveFootprint cached : perStart.values()) {
+                total += cached.cells();
+            }
+        }
+        return total;
+    }
+
     static int maximumCachedCarveFootprintCells() {
         return MAX_CACHED_CARVE_CELLS;
     }
 
     private static StructureCarvingFootprint cachedCarveFootprint(CarveFootprintKey key) {
         synchronized (CARVE_FOOTPRINTS) {
-            CachedCarveFootprint cached = CARVE_FOOTPRINTS.get(key);
+            Map<Integer, CachedCarveFootprint> perStart = CARVE_FOOTPRINTS.get(key.start());
+            CachedCarveFootprint cached = perStart == null ? null : perStart.get(key.padding());
             return cached == null ? null : cached.footprint();
         }
     }
 
     private static StructureCarvingFootprint awaitCarveFootprint(
             CompletableFuture<StructureCarvingFootprint> future) {
-        try {
-            return future.join();
-        } catch (CompletionException error) {
-            Throwable cause = error.getCause();
-            if (cause instanceof RuntimeException runtime) {
-                throw runtime;
-            }
-            if (cause instanceof Error fatal) {
-                throw fatal;
-            }
-            throw new IllegalStateException("Native structure carve footprint build failed", cause);
-        }
+        return NativeBuildFutures.awaitBuild(future, "Native structure carve footprint build");
     }
 
     private static void cacheCarveFootprint(CarveFootprintKey key,
                                             StructureCarvingFootprint footprint) {
         int cells = Math.multiplyExact(footprint.width(), footprint.depth());
         synchronized (CARVE_FOOTPRINTS) {
-            CachedCarveFootprint previous = CARVE_FOOTPRINTS.remove(key);
+            // Weak keys expunge silently as the GC drops retired starts; re-derive the live
+            // total so the cell budget tracks reality instead of drifting.
+            cachedCarveCells = liveCarveCells();
+            Map<Integer, CachedCarveFootprint> perStart =
+                    CARVE_FOOTPRINTS.computeIfAbsent(key.start(), ignored -> new LinkedHashMap<>(4));
+            CachedCarveFootprint previous = perStart.remove(key.padding());
             if (previous != null) {
                 cachedCarveCells -= previous.cells();
             }
-            while (!CARVE_FOOTPRINTS.isEmpty()
-                    && cachedCarveCells + cells > MAX_CACHED_CARVE_CELLS) {
-                Map.Entry<CarveFootprintKey, CachedCarveFootprint> eldest =
-                        CARVE_FOOTPRINTS.entrySet().iterator().next();
-                cachedCarveCells -= eldest.getValue().cells();
-                CARVE_FOOTPRINTS.remove(eldest.getKey());
+            Iterator<Map.Entry<StructureStart, Map<Integer, CachedCarveFootprint>>> eviction =
+                    CARVE_FOOTPRINTS.entrySet().iterator();
+            while (cachedCarveCells + cells > MAX_CACHED_CARVE_CELLS && eviction.hasNext()) {
+                Map.Entry<StructureStart, Map<Integer, CachedCarveFootprint>> victim = eviction.next();
+                if (victim.getKey() == key.start()) {
+                    continue;
                 }
-            CARVE_FOOTPRINTS.put(key, new CachedCarveFootprint(footprint, cells));
+                for (CachedCarveFootprint evicted : victim.getValue().values()) {
+                    cachedCarveCells -= evicted.cells();
+                }
+                eviction.remove();
+            }
+            perStart.put(key.padding(), new CachedCarveFootprint(footprint, cells));
             cachedCarveCells += cells;
         }
     }

adapters/minecraft-common/src/main/java/art/arcane/iris/nativegen/NativeStructureVolumeIndex.java

@@ -329,7 +329,18 @@ public final class NativeStructureVolumeIndex {
         CompletableFuture<KList<NativeStructureVolume>> future = new CompletableFuture<>();
         CompletableFuture<KList<NativeStructureVolume>> existing = builds.putIfAbsent(key, future);
         if (existing != null) {
-            return existing.join();
+            return NativeBuildFutures.awaitBuild(existing, "Native structure volume build");
+        }
+
+        // Close the check-then-claim window: a racer whose cache check missed before the
+        // previous builder cached could claim the build slot after it retired and rebuild.
+        synchronized (cache) {
+            KList<NativeStructureVolume> published = cache.get(key);
+            if (published != null) {
+                future.complete(published);
+                builds.remove(key, future);
+                return published;
+            }
         }
 
         try {

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

@@ -236,6 +236,19 @@ public final class ModdedPlatform implements IrisPlatform {
      */
     @Override
     public void reportError(Throwable error) {
+        reportThrottled("Iris reported error", error);
+    }
+
+    /**
+     * Contextual reports run the same throttle and emit exactly one trace through the modded
+     * log; the SPI default's raw stderr copy would bypass the per-signature suppression.
+     */
+    @Override
+    public void reportError(String context, Throwable error) {
+        reportThrottled(context == null || context.isBlank() ? "Iris reported error" : context, error);
+    }
+
+    private void reportThrottled(String message, Throwable error) {
         if (error == null) {
             return;
         }
@@ -247,7 +260,7 @@ public final class ModdedPlatform implements IrisPlatform {
             sink.accept(error);
             return;
         }
-        ModdedIrisLog.error("Iris reported error", error);
+        ModdedIrisLog.error(message, error);
         Consumer<Throwable> capture = CAPTURE_SINK;
         if (capture != null) {
             try {

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

@@ -800,6 +800,18 @@ public final class ModdedWorldManager implements EngineWorldManager {
         }
         if (!mantleWarmupExecutorStopped) {
             try {
+                // Drain, don't interrupt: an interrupt inside a FileChannel plate read closes
+                // the channel and the read-failure fallback installs an empty plate that a
+                // later flush persists over real data. Queued tasks no-op on the closed flag,
+                // so the await only covers a single in-flight load; escalate on timeout only.
+                mantleWarmupExecutor.shutdown();
+                if (!mantleWarmupExecutor.awaitTermination(5L, java.util.concurrent.TimeUnit.SECONDS)) {
+                    IrisLogging.warn("Iris mantle warm-up did not stop before world manager close; forcing interrupt");
+                    mantleWarmupExecutor.shutdownNow();
+                }
+                mantleWarmupExecutorStopped = true;
+            } catch (InterruptedException interrupted) {
+                Thread.currentThread().interrupt();
                 mantleWarmupExecutor.shutdownNow();
                 mantleWarmupExecutorStopped = true;
             } catch (Throwable e) {

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

@@ -20,6 +20,7 @@ package art.arcane.iris.modded.api;
 
 import art.arcane.iris.core.tools.WorldMaintenance;
 import art.arcane.iris.engine.framework.Engine;
+import art.arcane.iris.engine.framework.EngineLifecycleTasks;
 import art.arcane.iris.modded.IrisModdedChunkGenerator;
 import art.arcane.iris.modded.command.ModdedPregenJob;
 import net.minecraft.server.level.ServerLevel;
@@ -130,14 +131,17 @@ public final class IrisModdedAPI {
      * never create or load one - or nothing of {@code type} is stored there. A {@code y} outside the engine's
      * height range reads as null rather than throwing.
      *
-     * @throws IllegalStateException if the engine's mantle has already been closed
+     * A closing or closed engine refuses the operation quietly (null / no-op) instead of racing its shutdown.
      */
     public static <T> T getMantleData(ServerLevel level, int x, int y, int z, Class<T> type) {
         Engine engine = getEngine(level);
         if (engine == null) {
             return null;
         }
-        return engine.getMantle().getMantle().get(x, y - engine.getMinHeight(), z, type);
+        // Lease-gated so the engine shutdown drain covers this public accessor; a mantle
+        // mid-close refuses the lease instead of racing the region flush.
+        return EngineLifecycleTasks.call(engine, "modded_api_mantle_get",
+                () -> engine.getMantle().getMantle().get(x, y - engine.getMinHeight(), z, type), null);
     }
 
     /**
@@ -151,28 +155,30 @@ public final class IrisModdedAPI {
      * Values written under a custom type are discarded when Iris trims a mantle region unless the type is
      * declared with {@link #retainMantleDataForSlice(Class)}.
      *
-     * @throws IllegalStateException if the engine's mantle has already been closed
+     * A closing or closed engine refuses the operation quietly (null / no-op) instead of racing its shutdown.
      */
     public static <T> void setMantleData(ServerLevel level, int x, int y, int z, T data) {
         Engine engine = getEngine(level);
         if (engine == null || data == null) {
             return;
         }
-        engine.getMantle().getMantle().set(x, y - engine.getMinHeight(), z, data);
+        EngineLifecycleTasks.run(engine, "modded_api_mantle_set",
+                () -> engine.getMantle().getMantle().set(x, y - engine.getMinHeight(), z, data));
     }
 
     /**
      * Removes any mantle value of {@code type} at world coordinates. A non-Iris level or an out-of-range
      * {@code y} is a silent no-op. Like a write, this creates the mantle region if it is absent.
      *
-     * @throws IllegalStateException if the engine's mantle has already been closed
+     * A closing or closed engine refuses the operation quietly (null / no-op) instead of racing its shutdown.
      */
     public static <T> void deleteMantleData(ServerLevel level, int x, int y, int z, Class<T> type) {
         Engine engine = getEngine(level);
         if (engine == null) {
             return;
         }
-        engine.getMantle().getMantle().remove(x, y - engine.getMinHeight(), z, type);
+        EngineLifecycleTasks.run(engine, "modded_api_mantle_delete",
+                () -> engine.getMantle().getMantle().remove(x, y - engine.getMinHeight(), z, type));
     }
 
     /**

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

@@ -69,6 +69,9 @@ final class ModdedCommandSuggestions {
     private static final Logger LOGGER = LoggerFactory.getLogger("Iris");
     private static final int TAB_FAILURE_KEYS_MAX = 256;
     private static final Set<String> REPORTED_TAB_FAILURES = ConcurrentHashMap.newKeySet();
+    private static final long PACK_NAME_CACHE_TTL_MS = 3_000L;
+    private static volatile Set<String> cachedPackNames;
+    private static volatile long cachedPackNamesAt;
 
     private ModdedCommandSuggestions() {
     }
@@ -228,6 +231,13 @@ final class ModdedCommandSuggestions {
 
     private static CompletableFuture<Suggestions> suggestPackNames(CommandContext<CommandSourceStack> context, SuggestionsBuilder builder) {
         ModdedCommandFeedback.tab(context.getSource());
+        // Suggestion packets arrive per keystroke; a short-lived snapshot keeps the directory
+        // walk off the hot path without ever serving stale names for more than a few seconds.
+        long now = System.currentTimeMillis();
+        Set<String> cached = cachedPackNames;
+        if (cached != null && now - cachedPackNamesAt < PACK_NAME_CACHE_TTL_MS) {
+            return SharedSuggestionProvider.suggest(cached, builder);
+        }
         Set<String> names = new TreeSet<>();
         names.add("overworld");
         try {
@@ -249,6 +259,8 @@ final class ModdedCommandSuggestions {
         } catch (Throwable e) {
             warnTabFailure("pack names", context.getSource(), e);
         }
+        cachedPackNames = names;
+        cachedPackNamesAt = now;
         return SharedSuggestionProvider.suggest(names, builder);
     }
 

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

@@ -70,9 +70,10 @@ final class ModdedCommandTree {
                 .then(Commands.argument("dimension", StringArgumentType.greedyString()).suggests(ModdedCommandSuggestions.DIMENSION_NAMES)
                         .executes((CommandContext<CommandSourceStack> context) -> IrisModdedCommands.info(context.getSource(), StringArgumentType.getString(context, "dimension")))));
 
-        // ModdedWhatCommands.tree() gates itself at LEVEL_GAMEMASTERS; the /iris what overlays are read-only,
-        // so the root builder relaxes the whole subtree here instead of forking that file.
-        root.then(ModdedWhatCommands.tree().requires(READ_ONLY));
+        // ModdedWhatCommands.tree() gates itself at LEVEL_GAMEMASTERS and keeps that gate:
+        // "what markers" drives lease-gated 9x9 mantle scans, and the Bukkit twin puts the
+        // whole tree behind an op-default permission. requires() would overwrite, not AND.
+        root.then(ModdedWhatCommands.tree());
 
         root.then(teleportTree("teleport"));
         root.then(teleportTree("tp"));

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

@@ -285,7 +285,20 @@ public final class ModdedObjectCommands {
             return 0;
         }
         File file = new File(engine.getData().getDataFolder(), "objects" + File.separator + name.replace('/', File.separatorChar) + ".iob");
-        if (file.exists() && !overwrite) {
+        // Atomic path claim ON the server thread: the async write below turned a plain
+        // exists() check into a TOCTOU where two rapid saves interleaved into one file.
+        File parent = file.getParentFile();
+        if (parent != null) {
+            parent.mkdirs();
+        }
+        boolean claimed;
+        try {
+            claimed = file.createNewFile();
+        } catch (IOException e) {
+            IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_OBJECT_COMMANDS_FAILED_SAVE_OBJECT, MessageArgument.untrusted("value", String.valueOf(e.getMessage()))));
+            return 0;
+        }
+        if (!claimed && !overwrite) {
             IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_OBJECT_COMMANDS_FILE_ALREADY_EXISTS_USE_IRIS_OBJECT_SAVE_OVERWRITE, MessageArgument.untrusted("name", name)));
             return 0;
         }
@@ -295,15 +308,16 @@ public final class ModdedObjectCommands {
         // async-safe), but the disk write of a local, unshared object is not tick work.
         IrisObject object = capture(level, min, max, w, h, d, tilesSkipped, tilesSaved);
         MinecraftServer server = source.getServer();
+        boolean finalClaimed = claimed;
         J.a(() -> {
-            File parent = file.getParentFile();
-            if (parent != null) {
-                parent.mkdirs();
-            }
             try {
                 object.write(file);
             } catch (IOException e) {
                 LOGGER.error("Iris object save failed for {}", file.getAbsolutePath(), e);
+                if (finalClaimed) {
+                    // Never leave a 0-byte claim file permanently blocking non-overwrite saves.
+                    file.delete();
+                }
                 server.execute(() -> IrisModdedCommands.fail(source, IrisLanguage.plain(ModdedCommandMessages.MODDED_OBJECT_COMMANDS_FAILED_SAVE_OBJECT, MessageArgument.untrusted("value", String.valueOf(e.getMessage())))));
                 return;
             }

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

@@ -85,13 +85,16 @@ public final class ModdedChunkUpdateService implements ModdedTickableService {
         ExecutorService active = warmupExecutor;
         warmupExecutor = null;
         if (active != null) {
-            // Drop queued warm-ups (pure prefetch) and AWAIT: the very next shutdown stage
-            // closes every Mantle, and an in-flight mantle.getChunk would fault a plate back
-            // in after the close-time flush.
-            active.shutdownNow();
+            // NEVER interrupt first: an interrupt inside a FileChannel plate read closes the
+            // channel (ClosedByInterruptException) and the read-failure fallback installs an
+            // EMPTY plate that the very next shutdown stage flushes over real data. Queued
+            // warm-ups self-cancel (warmupExecutor is already null), so shutdown() + await
+            // only waits on the single in-flight load; escalate only on timeout.
+            active.shutdown();
             try {
                 if (!active.awaitTermination(5L, TimeUnit.SECONDS)) {
-                    IrisLogging.warn("Iris mantle warm-up did not stop before engine close");
+                    IrisLogging.warn("Iris mantle warm-up did not stop before engine close; forcing interrupt");
+                    active.shutdownNow();
                 }
             } catch (InterruptedException e) {
                 Thread.currentThread().interrupt();
@@ -279,6 +282,12 @@ public final class ModdedChunkUpdateService implements ModdedTickableService {
         }
         try {
             active.execute(() -> {
+                // Self-cancel on shutdown: warmupExecutor is nulled first in onDisable, so
+                // queued prefetches no-op instantly and only an in-flight load is awaited.
+                if (warmupExecutor == null || mantle.isClosed()) {
+                    warmupQueue.remove(key);
+                    return;
+                }
                 try {
                     mantle.getChunk(chunkX, chunkZ);
                 } catch (Throwable e) {

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

@@ -492,7 +492,9 @@ public class NoiseExplorerGUI extends JPanel implements MouseWheelListener {
         }
 
         long sleepMs = Math.max(1, 16 - (long) p.getMilliseconds());
-        EventQueue.invokeLater(() -> {
+        // Pace on a worker, not the EDT: a sleep queued on the event thread blocks painting
+        // and input for the whole frame budget. repaint() marshals itself back.
+        J.a(() -> {
             J.sleep(sleepMs);
             repaint();
         });

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

@@ -124,7 +124,16 @@ public class PregeneratorJob implements PregenListener, PregenRenderSource {
             service.shutdown();
             throw new IllegalStateException("An Iris pregeneration job is already running; stop it first.");
         }
+        try {
             worker.start();
+        } catch (Throwable startFailure) {
+            // Un-publish: a worker that never started can never run onClose(), so nothing
+            // else would ever clear this instance via the normal path.
+            instance.compareAndSet(this, null);
+            monitor.close();
+            service.shutdown();
+            throw startFailure;
+        }
     }
 
     private void computeBounds() {

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

@@ -528,14 +528,16 @@ public class VisionGUI extends JPanel implements MouseWheelListener, KeyListener
             });
             return;
         }
+        double frameMs = 0;
         try {
-            paintBody(gx);
+            frameMs = paintBody(gx);
         } catch (Throwable e) {
             IrisLogging.debug("Vision paint failed: " + e.getClass().getSimpleName() + ": " + e.getMessage());
         } finally {
             // The repaint loop is entirely self-driven from here; it must survive any render
-            // exception or the window freezes on a stale frame permanently.
-            long sleepMs = eco ? 32 : 16;
+            // exception or the window freezes on a stale frame permanently. Frame-time
+            // compensated so a slow frame does not stack a full sleep on top of itself.
+            long sleepMs = Math.max(1, (eco ? 32 : 16) - (long) frameMs);
             J.a(() -> {
                 J.sleep(sleepMs);
                 repaint();
@@ -543,7 +545,7 @@ public class VisionGUI extends JPanel implements MouseWheelListener, KeyListener
         }
     }
 
-    private void paintBody(Graphics gx) {
+    private double paintBody(Graphics gx) {
 
         velocity = Math.abs(ox - oxp) * 0.36 + Math.abs(oz - ozp) * 0.36;
         oxp = lerp(oxp, ox, 0.36);
@@ -630,11 +632,7 @@ public class VisionGUI extends JPanel implements MouseWheelListener, KeyListener
 
         handleFollow();
         renderOverlays(g, p.getMilliseconds());
-
-        if (!isVisible() || !getParent().isVisible()) {
-            return;
-        }
-
+        return p.getMilliseconds();
     }
 
     private void renderGrid(Graphics2D g, int tileSize, double offsetX, double offsetZ) {

core/src/main/java/art/arcane/iris/core/lifecycle/BukkitWorldConfiguration.java

@@ -255,6 +255,13 @@ public final class BukkitWorldConfiguration {
                 }
                 Files.move(staged, absoluteTarget, StandardCopyOption.REPLACE_EXISTING);
             }
+            // bukkit.yml is the commit record the bootstrap reconciles against; its rename
+            // needs the same directory-durability barrier the journal and world moves get.
+            if (requireAtomicReplacement) {
+                DirectoryDurability.forceDirectoryRequired(parent);
+            } else {
+                DirectoryDurability.forceDirectoryAfterCommit(parent, "A bukkit.yml world configuration change");
+            }
         } finally {
             Files.deleteIfExists(staged);
         }

core/src/main/java/art/arcane/iris/core/lifecycle/DirectoryDurability.java

@@ -0,0 +1,42 @@
+package art.arcane.iris.core.lifecycle;
+
+import art.arcane.iris.spi.IrisLogging;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+
+/**
+ * Directory-level durability barrier shared by every atomic publication in the
+ * world-replacement protocol (journal writes, world-directory moves, bukkit.yml
+ * saves). A rename is only durable once its parent directory has been fsynced;
+ * skipped on Windows, where directory handles cannot be forced.
+ */
+final class DirectoryDurability {
+    private DirectoryDurability() {
+    }
+
+    static void forceDirectoryRequired(Path directory) throws IOException {
+        if (File.separatorChar == '\\') {
+            return;
+        }
+        try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
+            channel.force(true);
+        } catch (UnsupportedOperationException failure) {
+            throw new IOException("Directory durability sync is unavailable for " + directory + ".", failure);
+        }
+    }
+
+    static void forceDirectoryAfterCommit(Path directory, String context) {
+        try {
+            forceDirectoryRequired(directory);
+        } catch (IOException failure) {
+            IrisLogging.reportError(
+                    context + " completed, but its parent directory could not be durability-synced.",
+                    failure
+            );
+        }
+    }
+}

core/src/main/java/art/arcane/iris/core/lifecycle/WorldLifecycleSupport.java

@@ -15,6 +15,7 @@ import org.bukkit.NamespacedKey;
 import org.bukkit.World;
 import org.bukkit.configuration.ConfigurationSection;
 import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.event.world.WorldUnloadEvent;
 import org.bukkit.generator.ChunkGenerator;
 
 import java.io.File;
@@ -479,6 +480,10 @@ final class WorldLifecycleSupport {
                 }
             }
 
+            if (!announceManualWorldUnload(world)) {
+                return CompletableFuture.completedFuture(false);
+            }
+
             if (save) {
                 world.save();
             }
@@ -496,6 +501,12 @@ final class WorldLifecycleSupport {
         }
     }
 
+    static boolean announceManualWorldUnload(World world) {
+        WorldUnloadEvent unloadEvent = new WorldUnloadEvent(world);
+        Bukkit.getPluginManager().callEvent(unloadEvent);
+        return !unloadEvent.isCancelled();
+    }
+
     private static CompletableFuture<Boolean> unloadWorldViaAsyncApi(CapabilitySnapshot capabilities, World world, boolean save) {
         if (capabilities.unloadWorldAsyncMethod() == null || capabilities.bukkitServer() == null) {
             return null;
@@ -597,9 +608,11 @@ final class WorldLifecycleSupport {
         Field worldsField = CapabilityResolution.resolveField(bukkitServer.getClass(), "worlds");
         Object rawWorlds = worldsField.get(bukkitServer);
         if (rawWorlds instanceof Map map) {
-            map.remove(WorldIdentity.key(world));
-            map.remove(WorldIdentity.serialize(world));
-            map.remove(world.getName());
+            boolean removed = map.values().removeIf(candidate -> candidate == world);
+            if (!removed) {
+                throw new IllegalStateException(
+                        "CraftServer world registry did not contain \"" + world.getName() + "\".");
+            }
         }
     }
 

core/src/main/java/art/arcane/iris/core/lifecycle/WorldReplacementBootstrap.java

@@ -38,7 +38,20 @@ public final class WorldReplacementBootstrap {
         int published = 0;
         int rolledBack = 0;
         int retained = 0;
+        int skipped = 0;
         for (Transaction transaction : transactions) {
+            // A journal recorded against another level root or logical world name is not this
+            // boot's transaction; skip it with a pointer instead of aborting the whole startup.
+            if (!WorldReplacementJournal.appliesTo(transaction, requiredLevelRoot)) {
+                skipped++;
+                requiredFeedback.accept("Skipping pending world replacement " + transaction.id()
+                        + " for " + transaction.worldKey() + ": it was staged against level root "
+                        + transaction.levelRoot() + " but this server now uses " + requiredLevelRoot
+                        + ". Remove " + requiredDataDirectory.resolve(WorldReplacementJournal.DIRECTORY_NAME)
+                        .resolve(transaction.id() + ".properties")
+                        + " or restore the previous level-name to resolve it.");
+                continue;
+            }
             ReconcileAction action = reconcileTransaction(
                     requiredDataDirectory,
                     requiredLevelRoot,
@@ -52,7 +65,7 @@ public final class WorldReplacementBootstrap {
                 case RETAINED -> retained++;
             }
         }
-        return new ReconcileResult(transactions.size(), published, rolledBack, retained);
+        return new ReconcileResult(transactions.size(), published, rolledBack, retained, skipped);
     }
 
     public static WorldGeneratorSnapshot replacementSnapshot(Transaction transaction) {
@@ -124,11 +137,20 @@ public final class WorldReplacementBootstrap {
                 }
                 throw conflict(active, "bukkit.yml matches neither the replacement nor its retained original state.");
             }
+            try {
                 WorldReplacementFilesystem.publish(
                         paths,
                         active.originalTargetPresent(),
                         active.packFingerprint()
                 );
+            } catch (IOException publishFailure) {
+                throw new IOException("Pending replacement for " + active.worldKey()
+                        + " cannot be published: " + publishFailure.getMessage()
+                        + " To recover, restore the original generator entry for \"" + active.worldName()
+                        + "\" in bukkit.yml (the next boot rolls the replacement back), or delete the journal at "
+                        + dataDirectory.resolve(WorldReplacementJournal.DIRECTORY_NAME).resolve(active.id() + ".properties")
+                        + ".", publishFailure);
+            }
             active = active.withPhase(Phase.PUBLISHED);
             WorldReplacementJournal.write(dataDirectory, active);
             feedback.accept("Published Iris world replacement for " + active.worldKey()
@@ -227,7 +249,7 @@ public final class WorldReplacementBootstrap {
         return new IOException("Pending replacement for " + transaction.worldKey() + " is blocked: " + detail);
     }
 
-    public record ReconcileResult(int transactions, int published, int rolledBack, int retained) {
+    public record ReconcileResult(int transactions, int published, int rolledBack, int retained, int skipped) {
     }
 
     private enum ReconcileAction {

core/src/main/java/art/arcane/iris/core/lifecycle/WorldReplacementFilesystem.java

@@ -2,9 +2,7 @@ package art.arcane.iris.core.lifecycle;
 
 import art.arcane.iris.core.ExactWorldSlotPathPolicy;
 import art.arcane.iris.core.SnapshotDirectoryTreeDeleter;
-import art.arcane.iris.spi.IrisLogging;
 
-import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
@@ -13,6 +11,7 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.AtomicMoveNotSupportedException;
 import java.nio.file.Files;
 import java.nio.file.LinkOption;
+import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.StandardCopyOption;
 import java.nio.file.StandardOpenOption;
@@ -61,6 +60,26 @@ public final class WorldReplacementFilesystem {
         if (state.stagePresent() || state.backupPresent()) {
             throw new IOException("A replacement artifact already exists for this transaction.");
         }
+        requireMigratedRetainedWorld(requiredPaths.target());
+    }
+
+    public static void requireMigratedRetainedWorld(Path retainedWorld) throws IOException {
+        try {
+            requireDirectory(retainedWorld, "retained world");
+            requireDirectory(retainedWorld.resolve("data"), "retained world data");
+            requireDirectory(retainedWorld.resolve("data/paper"), "retained Paper data");
+            requireDirectory(retainedWorld.resolve("data/minecraft"), "retained Minecraft data");
+            for (Path relative : PAPER_WORLD_METADATA) {
+                BasicFileAttributes sourceAttributes = requireSafeEntry(retainedWorld.resolve(relative));
+                if (!sourceAttributes.isRegularFile()) {
+                    throw new IOException("Retained Paper world metadata is not a regular file: " + relative);
+                }
+            }
+        } catch (NoSuchFileException e) {
+            throw new IOException("World slot " + retainedWorld.getFileName()
+                    + " is missing Paper world metadata (" + e.getFile()
+                    + "); load the world once on this server before replacing it.", e);
+        }
     }
 
     public static void publish(
@@ -328,17 +347,8 @@ public final class WorldReplacementFilesystem {
     }
 
     private static void preservePaperWorldMetadata(Path retainedWorld, Path replacementWorld) throws IOException {
-        requireDirectory(retainedWorld, "retained world");
+        requireMigratedRetainedWorld(retainedWorld);
         requireDirectory(replacementWorld, "replacement world");
-        requireDirectory(retainedWorld.resolve("data"), "retained world data");
-        requireDirectory(retainedWorld.resolve("data/paper"), "retained Paper data");
-        requireDirectory(retainedWorld.resolve("data/minecraft"), "retained Minecraft data");
-        for (Path relative : PAPER_WORLD_METADATA) {
-            BasicFileAttributes sourceAttributes = requireSafeEntry(retainedWorld.resolve(relative));
-            if (!sourceAttributes.isRegularFile()) {
-                throw new IOException("Retained Paper world metadata is not a regular file: " + relative);
-            }
-        }
         ensureDirectory(replacementWorld.resolve("data"), "replacement world data");
         ensureDirectory(replacementWorld.resolve("data/paper"), "replacement Paper data");
         ensureDirectory(replacementWorld.resolve("data/minecraft"), "replacement Minecraft data");
@@ -420,25 +430,11 @@ public final class WorldReplacementFilesystem {
     }
 
     private static void forceDirectoryRequired(Path directory) throws IOException {
-        if (File.separatorChar == '\\') {
-            return;
-        }
-        try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
-        } catch (UnsupportedOperationException failure) {
-            throw new IOException("Directory durability sync is unavailable for " + directory + ".", failure);
-        }
+        DirectoryDurability.forceDirectoryRequired(directory);
     }
 
     private static void forceDirectoryAfterCommit(Path directory) {
-        try {
-            forceDirectoryRequired(directory);
-        } catch (IOException failure) {
-            IrisLogging.reportError(
-                    "A world-replacement move completed, but its parent directory could not be durability-synced.",
-                    failure
-            );
-        }
+        DirectoryDurability.forceDirectoryAfterCommit(directory, "A world-replacement move");
     }
 
     public record ReplacementPaths(Path target, Path stage, Path backup) {

core/src/main/java/art/arcane/iris/core/lifecycle/WorldReplacementJournal.java

@@ -3,10 +3,8 @@ package art.arcane.iris.core.lifecycle;
 import art.arcane.iris.core.ExactWorldSlotPathPolicy;
 import art.arcane.iris.core.WorldSlotKey;
 import art.arcane.iris.core.lifecycle.BukkitWorldConfiguration.WorldGeneratorSnapshot;
-import art.arcane.iris.spi.IrisLogging;
 
 import java.io.ByteArrayOutputStream;
-import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
@@ -46,19 +44,50 @@ public final class WorldReplacementJournal {
                 if (Files.isSymbolicLink(file) || !Files.isRegularFile(file, LinkOption.NOFOLLOW_LINKS)) {
                     throw new IOException("Replacement journal entry is unsafe: " + file);
                 }
-                transactions.add(read(file, currentLevelRoot));
+                try {
+                    transactions.add(read(file));
+                } catch (IOException failure) {
+                    throw new IOException("Invalid replacement journal " + file + ": " + failure.getMessage(), failure);
+                }
             }
         }
         transactions.sort(Comparator.comparing(transaction -> transaction.id().toString()));
+        // Only transactions that target the current level root compete for a slot; a stale
+        // journal recorded against another level root must not collide with a live one.
         Set<WorldSlotKey> worldKeys = new HashSet<>();
         for (Transaction transaction : transactions) {
-            if (!worldKeys.add(transaction.worldKey())) {
+            if (appliesTo(transaction, currentLevelRoot) && !worldKeys.add(transaction.worldKey())) {
                 throw new IOException("Multiple replacement journals target " + transaction.worldKey() + ".");
             }
         }
         return List.copyOf(transactions);
     }
 
+    /**
+     * Whether this journal entry targets the current level root and logical world name. A
+     * mismatch means the operator changed level-name or world container after the replacement
+     * was staged; such entries are skipped at bootstrap instead of aborting the whole boot.
+     */
+    public static boolean appliesTo(Transaction transaction, Path currentLevelRoot) {
+        Transaction requiredTransaction = Objects.requireNonNull(transaction, "transaction");
+        ExactWorldSlotPathPolicy.Target target;
+        try {
+            target = ExactWorldSlotPathPolicy.resolve(currentLevelRoot, requiredTransaction.worldKey());
+        } catch (RuntimeException failure) {
+            return false;
+        }
+        if (!target.levelRoot().equals(requiredTransaction.levelRoot())) {
+            return false;
+        }
+        String expectedWorldName;
+        try {
+            expectedWorldName = logicalWorldName(target.levelRoot(), requiredTransaction.worldKey());
+        } catch (IllegalArgumentException failure) {
+            return false;
+        }
+        return expectedWorldName.equals(requiredTransaction.worldName());
+    }
+
     public static void write(Path dataDirectory, Transaction transaction) throws IOException {
         Transaction requiredTransaction = Objects.requireNonNull(transaction, "transaction");
         Path directory = Objects.requireNonNull(directory(dataDirectory, true));
@@ -145,7 +174,7 @@ public final class WorldReplacementJournal {
         throw new IllegalArgumentException("World key is not an exact replaceable world slot: " + requiredWorldKey);
     }
 
-    private static Transaction read(Path file, Path currentLevelRoot) throws IOException {
+    private static Transaction read(Path file) throws IOException {
         Properties properties = new Properties();
         try (InputStream input = Files.newInputStream(file)) {
             properties.load(input);
@@ -196,7 +225,6 @@ public final class WorldReplacementJournal {
                 originalTargetPresent,
                 phase
         );
-        resolveTarget(transaction, currentLevelRoot);
         return transaction;
     }
 
@@ -342,25 +370,11 @@ public final class WorldReplacementJournal {
     }
 
     private static void forceDirectoryRequired(Path directory) throws IOException {
-        if (File.separatorChar == '\\') {
-            return;
-        }
-        try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
-        } catch (UnsupportedOperationException failure) {
-            throw new IOException("Directory durability sync is unavailable for " + directory + ".", failure);
-        }
+        DirectoryDurability.forceDirectoryRequired(directory);
     }
 
     private static void forceDirectoryAfterCommit(Path directory) {
-        try {
-            forceDirectoryRequired(directory);
-        } catch (IOException failure) {
-            IrisLogging.reportError(
-                    "A world-replacement journal change completed, but its parent directory could not be durability-synced.",
-                    failure
-            );
-        }
+        DirectoryDurability.forceDirectoryAfterCommit(directory, "A world-replacement journal change");
     }
 
     public record Transaction(

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

@@ -507,6 +507,14 @@ public final class BukkitCommandMessagesExtended {
             "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks",
             C.RED + "Pregen radius must be greater than zero blocks."
     );
+    public static final TextKey COMMAND_STUDIO_REGIONS_RADIUS_OUT_OF_RANGE = TextKey.of(
+            "iris.bukkit.commandstudio.regions_radius_out_of_range",
+            C.RED + "Radius must be between 1 and 2048 chunks."
+    );
+    public static final TextKey COMMAND_STUDIO_REGIONS_SCAN_FAILED = TextKey.of(
+            "iris.bukkit.commandstudio.regions_scan_failed",
+            C.RED + "Region scan failed: {value}"
+    );
     public static final TextKey COMMAND_PREGEN_STRICT_SERIAL_PREGENERATION_REQUIRES_PAPER_PAPER_COMPATIBLE_SERVER = TextKey.of(
             "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server",
             C.RED + "Strict serial pregeneration requires Paper or a Paper-compatible server."
@@ -965,6 +973,8 @@ public final class BukkitCommandMessagesExtended {
             COMMAND_OBJECT_NO_AREA_SELECTED_4,
             COMMAND_OBJECT_AUTO_SELECT_COMPLETE_2,
             COMMAND_PREGEN_PREGEN_RADIUS_MUST_BE_GREATER_THAN_ZERO_BLOCKS,
+            COMMAND_STUDIO_REGIONS_RADIUS_OUT_OF_RANGE,
+            COMMAND_STUDIO_REGIONS_SCAN_FAILED,
             COMMAND_PREGEN_STRICT_SERIAL_PREGENERATION_REQUIRES_PAPER_PAPER_COMPATIBLE_SERVER,
             COMMAND_PREGEN_ENGINE_ACCESS_THIS_WORLD_IS_NULL,
             COMMAND_PREGEN_PLEASE_MAKE_SURE_WORLD_IS_LOADED_ENGINE_IS_INITIALIZED_GENERATE,

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

@@ -23,6 +23,7 @@ import art.arcane.iris.spi.IrisServices;
 import art.arcane.iris.core.loader.IrisData;
 import art.arcane.iris.core.tools.IrisToolbelt;
 import art.arcane.iris.engine.framework.Engine;
+import art.arcane.iris.engine.framework.EngineLifecycleTasks;
 import art.arcane.iris.engine.framework.TreeBlockMaterial;
 import art.arcane.iris.engine.object.IObjectPlacer;
 import art.arcane.iris.engine.object.IrisBiome;
@@ -270,6 +271,9 @@ public class TreeSVC implements IrisService {
                         IrisServices.get(ExternalDataSVC.class).processUpdate(engine, block, data.getCustom());
                     } else block.setBlockData(d, false);
                     int mantleY = block.getY() - event.getWorld().getMinHeight();
+                    // Lease-gated: the grow task can land after the engine started closing, and
+                    // an unleased mantle write would race the region flush.
+                    EngineLifecycleTasks.run(engine, "tree_grow_mantle", () -> {
                         engine.getMantle().getMantle().set(block.getX(), mantleY, block.getZ(), treeMarker);
                         engine.getMantle().getMantle().set(
                                 block.getX(),
@@ -277,6 +281,7 @@ public class TreeSVC implements IrisService {
                                 block.getZ(),
                                 TreeBlockMaterial.of(block.getBlockData().getAsString())
                         );
+                    });
                 }
             }
         };

core/src/main/java/art/arcane/iris/core/splash/IrisSplashPackScanner.java

@@ -1,6 +1,7 @@
 package art.arcane.iris.core.splash;
 
 import art.arcane.iris.core.pack.PackDirectoryResolver;
+import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParseException;
 import com.google.gson.JsonParser;
@@ -51,12 +52,13 @@ public final class IrisSplashPackScanner {
 
         try (FileReader reader = new FileReader(dimensionFile)) {
             JsonObject json = JsonParser.parseReader(reader).getAsJsonObject();
-            if (!json.has("version")) {
+            JsonElement version = json.get("version");
+            if (version == null || !version.isJsonPrimitive()) {
                 return null;
             }
 
-            return new SplashPackMetadata(dimName, json.get("version").getAsString());
-        } catch (IOException | JsonParseException | IllegalStateException error) {
+            return new SplashPackMetadata(dimName, version.getAsString());
+        } catch (IOException | JsonParseException | IllegalStateException | UnsupportedOperationException error) {
             report(reporter, "Failed to read splash metadata for dimension pack \"" + dimName + "\".", error);
             return null;
         }

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

@@ -198,6 +198,9 @@ public class IrisConverter {
                 sender.sendMessage(IrisLanguage.text(BukkitRuntimeMessages.IRIS_CONVERTER_SOME_SCHEMATICS_FAILED_CONVERT_CHECK_CONSOLE_DETAILS));
             }
         });
+        // Single-use pool: retire the worker once the queued conversion finishes instead of
+        // leaking a non-daemon thread per invocation.
+        executorService.shutdown();
     }
 
     private static int resolveVersion(CompoundTag compound) throws Exception {

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

@@ -39,6 +39,7 @@ import art.arcane.iris.core.pregenerator.methods.HybridPregenMethod;
 import art.arcane.iris.core.service.GlobalCacheSVC;
 import art.arcane.iris.core.service.StudioSVC;
 import art.arcane.iris.engine.framework.Engine;
+import art.arcane.iris.engine.framework.EngineLifecycleTasks;
 import art.arcane.iris.engine.object.IrisDimension;
 import art.arcane.iris.engine.object.IrisWorld;
 import art.arcane.iris.engine.platform.BukkitChunkGenerator;
@@ -643,7 +644,10 @@ public class IrisToolbelt {
         if (e == null) {
             return null;
         }
-        return e.getEngine().getMantle().getMantle().get(x, y - world.getMinHeight(), z, of);
+        // Lease-gated so the engine shutdown drain covers these public accessors; a mantle
+        // mid-close refuses the lease instead of racing the region flush.
+        return EngineLifecycleTasks.call(e.getEngine(), "api_mantle_get",
+                () -> e.getEngine().getMantle().getMantle().get(x, y - world.getMinHeight(), z, of), null);
     }
 
     public static <T> void deleteMantleData(World world, int x, int y, int z, Class<T> of) {
@@ -651,7 +655,8 @@ public class IrisToolbelt {
         if (e == null) {
             return;
         }
-        e.getEngine().getMantle().getMantle().remove(x, y - world.getMinHeight(), z, of);
+        EngineLifecycleTasks.run(e.getEngine(), "api_mantle_delete",
+                () -> e.getEngine().getMantle().getMantle().remove(x, y - world.getMinHeight(), z, of));
     }
 
     public static <T> void setMantleData(World world, int x, int y, int z, T data) {
@@ -659,7 +664,8 @@ public class IrisToolbelt {
         if (e == null || data == null) {
             return;
         }
-        e.getEngine().getMantle().getMantle().set(x, y - world.getMinHeight(), z, data);
+        EngineLifecycleTasks.run(e.getEngine(), "api_mantle_set",
+                () -> e.getEngine().getMantle().getMantle().set(x, y - world.getMinHeight(), z, data));
     }
 
     public static boolean removeWorld(World world) throws IOException {

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

@@ -24,9 +24,9 @@ public final class WorldMaintenance {
             return;
         }
 
-        int depth = worldMaintenanceDepth.computeIfAbsent(worldName, k -> new AtomicInteger()).incrementAndGet();
+        int depth = incrementDepth(worldMaintenanceDepth, worldName);
         if (bypassMantleStages) {
-            worldMaintenanceMantleBypassDepth.computeIfAbsent(worldName, k -> new AtomicInteger()).incrementAndGet();
+            incrementDepth(worldMaintenanceMantleBypassDepth, worldName);
         }
         if (IrisSettings.get().getGeneral().isDebug()) {
             IrisLogging.info("World maintenance enter: " + worldName + " reason=" + reason + " depth=" + depth + " bypassMantle=" + bypassMantleStages);
@@ -44,29 +44,17 @@ public final class WorldMaintenance {
             return;
         }
 
-        AtomicInteger depthCounter = worldMaintenanceDepth.get(worldName);
-        if (depthCounter == null) {
+        if (!worldMaintenanceDepth.containsKey(worldName)) {
             return;
         }
 
-        int depth = depthCounter.decrementAndGet();
-        if (depth <= 0) {
-            worldMaintenanceDepth.remove(worldName, depthCounter);
-            depth = 0;
-        }
+        int depth = decrementDepth(worldMaintenanceDepth, worldName);
 
         // Only a bypass-begin's paired end releases bypass credit: a plain end overlapping a
         // bypassing operation stole its credit and re-enabled mantle stages under it.
         int bypassDepth = 0;
         if (bypassMantleStages) {
-            AtomicInteger bypassCounter = worldMaintenanceMantleBypassDepth.get(worldName);
-            if (bypassCounter != null) {
-                bypassDepth = bypassCounter.decrementAndGet();
-                if (bypassDepth <= 0) {
-                    worldMaintenanceMantleBypassDepth.remove(worldName, bypassCounter);
-                    bypassDepth = 0;
-                }
-            }
+            bypassDepth = decrementDepth(worldMaintenanceMantleBypassDepth, worldName);
         }
 
         if (IrisSettings.get().getGeneral().isDebug()) {
@@ -76,6 +64,22 @@ public final class WorldMaintenance {
         }
     }
 
+    // Depth mutations run inside compute() so an identity-based remove can never clear a
+    // registration a concurrent begin just re-incremented.
+    private static int incrementDepth(Map<String, AtomicInteger> depths, String worldName) {
+        return depths.compute(worldName, (key, current) -> {
+            AtomicInteger counter = current == null ? new AtomicInteger() : current;
+            counter.incrementAndGet();
+            return counter;
+        }).get();
+    }
+
+    private static int decrementDepth(Map<String, AtomicInteger> depths, String worldName) {
+        AtomicInteger remaining = depths.computeIfPresent(
+                worldName, (key, current) -> current.decrementAndGet() <= 0 ? null : current);
+        return remaining == null ? 0 : Math.max(0, remaining.get());
+    }
+
     public static boolean isWorldMaintenanceActive(String worldName) {
         if (worldName == null) {
             return false;

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

@@ -34,7 +34,6 @@ import art.arcane.iris.spi.IrisServices;
 import art.arcane.iris.spi.protocol.IrisMessage;
 import art.arcane.iris.util.project.context.IrisContext;
 import art.arcane.volmlib.util.localization.MessageArgument;
-import art.arcane.volmlib.util.math.RNG;
 
 import static art.arcane.iris.engine.EngineShutdownSequence.runCleanup;
 
@@ -64,7 +63,7 @@ final class EngineHotloader {
             IrisComplex nextComplex = null;
             try {
                 engine.sealForTransition("complex hotload", false);
-                RuntimeAssembly assembly = new RuntimeAssembly(RNG.r.nextInt(), previous.target());
+                RuntimeAssembly assembly = new RuntimeAssembly(RuntimeAssembly.nextRuntimeId(), previous.target());
                 engine.runtimeAssembly.set(assembly);
                 EngineRuntime next;
                 try (IrisContext.Scope ignored = IrisContext.open(engine, engine.getGenerationSessions().currentSessionId(), null)) {

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

@@ -40,10 +40,10 @@ import art.arcane.iris.spi.IrisServices;
 import art.arcane.iris.util.project.context.IrisContext;
 import art.arcane.volmlib.util.io.IO;
 import art.arcane.volmlib.util.math.M;
-import art.arcane.volmlib.util.math.RNG;
 
 import java.io.File;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import static art.arcane.iris.engine.EngineShutdownSequence.propagate;
 
@@ -65,7 +65,7 @@ final class EngineRuntimeBuilder {
     }
 
     EngineRuntime buildRuntime(EngineTarget runtimeTarget) {
-        RuntimeAssembly assembly = new RuntimeAssembly(RNG.r.nextInt(), runtimeTarget);
+        RuntimeAssembly assembly = new RuntimeAssembly(RuntimeAssembly.nextRuntimeId(), runtimeTarget);
         engine.runtimeAssembly.set(assembly);
         try (IrisContext.Scope ignored = IrisContext.open(engine, engine.getGenerationSessions().currentSessionId(), null)) {
             IrisLogging.debug("Setup Engine " + assembly.cacheId);
@@ -279,8 +279,14 @@ final class EngineRuntimeBuilder {
     }
 
     static final class RuntimeAssembly {
+        private static final AtomicInteger RUNTIME_IDS = new AtomicInteger();
+
         final int cacheId;
         final EngineTarget target;
+
+        static int nextRuntimeId() {
+            return RUNTIME_IDS.incrementAndGet();
+        }
         IrisComplex complex;
         UpperDimensionContext upperContext;
         EngineEffects effects;

core/src/main/java/art/arcane/iris/engine/data/chunk/LinkedTerrainChunk.java

@@ -97,7 +97,11 @@ public class LinkedTerrainChunk implements TerrainChunk {
 
     @Override
     public synchronized void setRegion(int xMin, int yMin, int zMin, int xMax, int yMax, int zMax, PlatformBlockState state) {
-        rawChunkData.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, (BlockData) state.nativeHandle());
+        BlockData blockData = (BlockData) state.nativeHandle();
+        if (blockData instanceof IrisCustomData data) {
+            blockData = data.getBase();
+        }
+        rawChunkData.setRegion(xMin, yMin, zMin, xMax, yMax, zMax, blockData);
     }
 
     @Override

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

@@ -33,7 +33,44 @@ public record NativeStructureVolume(
         int maxY,
         int maxZ
 ) {
-    public static final KList<NativeStructureVolume> NONE = new KList<>();
+    // Shared empty sentinel handed to every engine and memoized by the volume caches; a silent
+    // add()/clear() here would corrupt them all globally, so mutation fails loudly instead.
+    public static final KList<NativeStructureVolume> NONE = new KList<>() {
+        @Override
+        public boolean add(NativeStructureVolume volume) {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+
+        @Override
+        public void add(int index, NativeStructureVolume volume) {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+
+        @Override
+        public boolean addAll(java.util.Collection<? extends NativeStructureVolume> volumes) {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+
+        @Override
+        public boolean addAll(int index, java.util.Collection<? extends NativeStructureVolume> volumes) {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+
+        @Override
+        public void clear() {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+
+        @Override
+        public NativeStructureVolume remove(int index) {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+
+        @Override
+        public boolean remove(Object volume) {
+            throw new UnsupportedOperationException("NativeStructureVolume.NONE is immutable");
+        }
+    };
 
     public static NativeStructureVolume of(String structure, int aX, int aY, int aZ, int bX, int bY, int bZ) {
         return new NativeStructureVolume(

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

@@ -231,6 +231,10 @@ public final class IrisObjectIO {
 
     static void write(IrisObject self, OutputStream o) throws IOException {
         validateWritable(self);
+        writeValidated(self, o);
+    }
+
+    private static void writeValidated(IrisObject self, OutputStream o) throws IOException {
         DataOutputStream dos = new DataOutputStream(o);
         dos.writeInt(self.w);
         dos.writeInt(self.h);
@@ -270,6 +274,10 @@ public final class IrisObjectIO {
 
     static void write(IrisObject self, OutputStream o, VolmitSender sender) throws IOException {
         validateWritable(self);
+        writeValidated(self, o, sender);
+    }
+
+    private static void writeValidated(IrisObject self, OutputStream o, VolmitSender sender) throws IOException {
         AtomicReference<IOException> ref = new AtomicReference<>();
         CountDownLatch latch = new CountDownLatch(1);
         new Job() {
@@ -365,7 +373,7 @@ public final class IrisObjectIO {
         // object must leave the existing .iob untouched.
         validateWritable(self);
         try (FileOutputStream out = new FileOutputStream(file)) {
-            write(self, out);
+            writeValidated(self, out);
         }
     }
 
@@ -376,7 +384,7 @@ public final class IrisObjectIO {
 
         validateWritable(self);
         try (FileOutputStream out = new FileOutputStream(file)) {
-            write(self, out, sender);
+            writeValidated(self, out, sender);
         }
     }
 

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

@@ -482,9 +482,10 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
             if (throwable == null) {
                 future.complete(null);
             } else {
+                // The close body already ran and tore the engine down; unlike the pre-dispatch
+                // failure above, resetting the gate here would advertise a healthy generator
+                // over a CLOSED or FAILED engine. Stay latched and surface the failure.
                 future.completeExceptionally(throwable);
-                closeFuture.compareAndSet(future, null);
-                closing = false;
             }
         });
         return future;

core/src/main/java/art/arcane/iris/util/common/math/VectorMath.java

@@ -75,19 +75,4 @@ public class VectorMath extends art.arcane.volmlib.util.math.VectorMath {
         return v;
     }
 
-    public static Vector getAxis(Direction current, Direction to) {
-        if (current.equals(Direction.U) || current.equals(Direction.D)) {
-            if (to.equals(Direction.U) || to.equals(Direction.D)) {
-                return new Vector(1, 0, 0);
-            } else {
-                if (current.equals(Direction.N) || current.equals(Direction.S)) {
-                    return Direction.E.toVector();
-                } else {
-                    return Direction.S.toVector();
-                }
-            }
-        }
-
-        return new Vector(0, 1, 0);
-    }
 }

core/src/main/java/art/arcane/iris/util/common/parallel/BurstExecutor.java

@@ -3,9 +3,14 @@ package art.arcane.iris.util.common.parallel;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.volmlib.util.parallel.BurstExecutorSupport;
 import java.util.concurrent.ExecutorService;
+import java.util.function.Supplier;
 
 public class BurstExecutor extends BurstExecutorSupport {
     public BurstExecutor(ExecutorService executor, int burstSizeEstimate) {
         super(executor, burstSizeEstimate, IrisLogging::reportError);
     }
+
+    public BurstExecutor(Supplier<ExecutorService> executorSource, int burstSizeEstimate) {
+        super(executorSource, burstSizeEstimate, IrisLogging::reportError);
+    }
 }

core/src/main/java/art/arcane/iris/util/common/parallel/MultiBurst.java

@@ -72,7 +72,7 @@ public class MultiBurst extends MultiBurstSupport {
 
     @Override
     public BurstExecutor burst(int estimate) {
-        return new BurstExecutor(service(), estimate);
+        return new BurstExecutor(this::service, estimate);
     }
 
     @Override

core/src/main/java/art/arcane/iris/util/project/hunk/view/ChunkDataHunkHolder.java

@@ -21,6 +21,7 @@ package art.arcane.iris.util.project.hunk.view;
 import art.arcane.iris.core.nms.INMS;
 import art.arcane.iris.spi.PlatformBlockState;
 import art.arcane.iris.util.common.data.B;
+import art.arcane.iris.util.common.data.IrisCustomData;
 import art.arcane.iris.util.project.hunk.storage.AtomicHunk;
 import org.bukkit.block.data.BlockData;
 import org.bukkit.generator.ChunkGenerator.ChunkData;
@@ -88,6 +89,11 @@ public class ChunkDataHunkHolder extends AtomicHunk<PlatformBlockState> {
                 for (int y = 0; y < height; y++) {
                     PlatformBlockState state = super.getRaw(x, y, z);
                     BlockData block = state == null ? null : (BlockData) state.nativeHandle();
+                    // Custom wrappers are not real Bukkit data; write the vanilla base like the
+                    // NMS fast path (NMSBinding.applyChunkDataBlocks) does.
+                    if (block instanceof IrisCustomData custom) {
+                        block = custom.getBase();
+                    }
                     if (block == null) {
                         flushRun(x, z, runStart, y, activeBlock);
                         activeBlock = null;

core/src/main/resources/languages/de_DE.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Kein Bereich ausgewählt.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aAutomatische Auswahl abgeschlossen!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cDer Vorgenerierungsradius muss größer als null Blöcke sein.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cDer Radius muss zwischen 1 und 2048 Chunks liegen.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cRegion-Scan fehlgeschlagen: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cDie strikt serielle Vorgenerierung erfordert Paper oder einen Paper-kompatiblen Server.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cDer Engine-Zugriff für diese Welt ist null!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cStelle sicher, dass die Welt geladen und die Engine initialisiert ist. Generiere zum Beispiel einen neuen Chunk.",

core/src/main/resources/languages/es_ES.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "No hay ningún área seleccionada.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§a¡Selección automática completada!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cEl radio de pregen debe ser mayor que cero bloques.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cEl radio debe estar entre 1 y 2048 chunks.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cError al escanear regiones: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cLa pregeneración estrictamente secuencial requiere Paper o un servidor compatible con Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§c¡El acceso al motor de este mundo es nulo!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cAsegúrate de que el mundo esté cargado y el motor inicializado. Por ejemplo, genera un chunk nuevo.",

core/src/main/resources/languages/fi_FI.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Aluetta ei ole valittu.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aAutomaattivalinta valmis!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen-säteen on oltava suurempi kuin nolla lohkoa.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cSäteen on oltava 1 ja 2048 chunkin välillä.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cAlueskannaus epäonnistui: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cTiukasti sarjallinen esigenerointi vaatii Paperin tai Paper-yhteensopivan palvelimen.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cTämän maailman moottorit eivät toimi!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cVarmista, että maailma on ladattu. & Moottori on alustettu.  Luo esimerkiksi uusi pala.",

core/src/main/resources/languages/fr_FR.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Aucune zone sélectionnée.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aSélection automatique terminée !",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cLe rayon de pregen doit être supérieur à zéro bloc.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cLe rayon doit être compris entre 1 et 2048 chunks.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cÉchec de l'analyse des régions : {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cLa prégénération strictement séquentielle nécessite Paper ou un serveur compatible avec Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cL'accès au moteur de ce monde est nul !",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cVérifiez que le monde est chargé et que le moteur est initialisé. Générez par exemple un nouveau chunk.",

core/src/main/resources/languages/he_IL.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "שום אזור לא נבחר.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aבחירה אוטומטית הושלם!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cרדיוס Pregen חייב להיות גדול יותר מאשר אפס בלוקים.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cהרדיוס חייב להיות בין 1 ל-2048 צ'אנקים.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cסריקת האזורים נכשלה: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cקדם-יצירה טורית קפדנית דורשת Paper או שרת תואם Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cהגישה של המנוע לעולם הזה היא אפס!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cודא שהעולם טעון & המנוע הוא ראשוני.  ליצור נתח חדש, למשל.",

core/src/main/resources/languages/it_IT.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Nessuna area selezionata.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aAuto-selezione completa!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cIl raggio di pregenerazione deve essere maggiore di zero blocchi.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cIl raggio deve essere compreso tra 1 e 2048 chunk.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cScansione delle regioni non riuscita: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cLa pregenerazione strettamente seriale richiede Paper o un server compatibile con Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cL'accesso all'engine per questo mondo è nullo!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cAssicurati che il mondo sia caricato e che l'engine sia inizializzato. Ad esempio, genera un nuovo chunk.",

core/src/main/resources/languages/ja-JP.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "範囲が選択されていません。",
     "iris.bukkit.commandobject.auto_select_complete_2": "§a自動選択完了!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§c事前生成の半径は 0 ブロックより大きくなければなりません。",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§c半径は1から2048チャンクの範囲で指定してください。",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cリージョンスキャンに失敗しました: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§c厳密な直列事前生成には Paper または Paper 互換サーバーが必要です。",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cこのワールドのエンジンにアクセスできません!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cワールドが読み込まれ、エンジンが初期化されていることを確認してください。たとえば、新しいチャンクを生成してください。",

core/src/main/resources/languages/ko_KR.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "선택 없음.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§a자동 선택 완료!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen 반경은 0 개 이상의 블록이 있어야합니다.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§c반경은 1~2048 청크 사이여야 합니다.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§c지역 스캔에 실패했습니다: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§c엄격한 순차 사전 생성에는 Paper 또는 Paper 호환 서버가 필요합니다.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§c이 세상의 엔진 접근은 null입니다!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§c세상이 로드되었는지 확인하십시오. & 엔진은 초기화됩니다.  새로운 청크 생성, 예를 들어.",

core/src/main/resources/languages/lt_LT.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Nepasirinkta sritis.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aAuto-pasirinkite baigtas!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen spindulys turi būti didesnis nei nulis blokų.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cSpindulys turi būti nuo 1 iki 2048 gabalų.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cRegionų nuskaitymas nepavyko: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cGriežtai nuosekliam išankstiniam generavimui reikia Paper arba su Paper suderinamo serverio.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cVariklio pasiekiamumas šiam pasauliui nulinis!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cĮsitikinkite, kad pasaulis įkeltas & variklis įjungiamas.  Pavyzdžiui, generuoti naują gabalą.",

core/src/main/resources/languages/nl_NL.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Geen gebied geselecteerd.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aAutomatisch selecteren voltooid!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen radius moet groter zijn dan nul blokken.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cDe radius moet tussen 1 en 2048 chunks liggen.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cRegioscan mislukt: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cStrikt seriële pregeneratie vereist Paper of een Paper-compatibele server.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cDe toegang tot de motor voor deze wereld is nul!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cZorg ervoor dat de wereld geladen is & de motor is geïnitialiseerd.  Genereer bijvoorbeeld een nieuwe chunk.",

core/src/main/resources/languages/pl_PL.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Nie wybrano obszaru.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aAuto- select zakończone!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPromień pregen musi być większy niż zero bloków.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cPromień musi mieścić się w zakresie od 1 do 2048 chunków.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cSkanowanie regionów nie powiodło się: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cŚciśle szeregowa pregeneracja wymaga Paper lub serwera zgodnego z Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cSilnik dostępu dla tego świata jest zerowy!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cUpewnij się, że świat jest załadowany. & silnik jest inicjalizowany.  Na przykład wygenerować nowy kawałek.",

core/src/main/resources/languages/pt_PT.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Nenhuma área selecionada.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aSelecção automática completa!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cO raio de Pregen deve ser superior a zero blocos.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cO raio deve estar entre 1 e 2048 chunks.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cFalha ao analisar regiões: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cA pré-geração estritamente sequencial requer Paper ou um servidor compatível com Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cO acesso do motor para este mundo é nulo!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cPor favor, certifique-se que o mundo está carregado & O motor está inicializado.  Gerar um novo chunk, por exemplo.",

core/src/main/resources/languages/ru_RU.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Никакой области не выбрано.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aАвтовыбор завершен!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cРадиус прегена должен быть больше нуля блоков.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cРадиус должен быть от 1 до 2048 чанков.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cНе удалось просканировать регионы: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cСтрого последовательная прегенерация требует Paper или Paper-совместимый сервер.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cДоступ к двигателю для этого мира недействителен!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cУбедитесь, что мир загружен & Двигатель инициализируется.  Например, создать новый чанк.",

core/src/main/resources/languages/tr_TR.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Hiçbir alan seçilmiş değildir.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aotomatik seçim tamamen!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen radius sıfır bloklardan daha büyük olmalıdır.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cYarıçap 1 ile 2048 chunk arasında olmalıdır.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cBölge taraması başarısız oldu: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cKesin sıralı ön oluşturma Paper veya Paper uyumlu bir sunucu gerektirir.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cBu dünya için motor erişimi çıplak!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cLütfen dünyanın yüklendiğinden emin olun & Motor başlangıçlı.  Örneğin yeni bir chunk.",

core/src/main/resources/languages/vi_VI.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "Chưa chọn diện tích.",
     "iris.bukkit.commandobject.auto_select_complete_2": "§aTự động chọn hoàn tất!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cBán kính Pregen phải lớn hơn không khối.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§cBán kính phải nằm trong khoảng từ 1 đến 2048 chunk.",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§cQuét khu vực thất bại: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§cTiền tạo tuần tự nghiêm ngặt yêu cầu Paper hoặc máy chủ tương thích với Paper.",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§cĐộng cơ truy cập thế giới này là vô ích!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§cHãy chắc chắn rằng thế giới đã lên đạn. & Động cơ đã khởi động.  Chẳng hạn như tạo ra một mảng mới.",

core/src/main/resources/languages/zh_CN.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "未选择区域 。",
     "iris.bukkit.commandobject.auto_select_complete_2": "§a自动选择完成!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen半径必须大于零块.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§c半径必须在 1 到 2048 区块之间。",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§c区域扫描失败: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§c严格的序列预生成要求 Paper 或一个 Paper- 兼容服务器。",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§c这个世界的引擎是无效的!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§c请确保世界充满 & 引擎已经初始化。  例如, 生成一个新的块 。",

core/src/main/resources/languages/zh_TW.json

@@ -232,6 +232,8 @@
     "iris.bukkit.commandobject.no_area_selected_4": "未選擇區域 。",
     "iris.bukkit.commandobject.auto_select_complete_2": "§a自動選擇完成!",
     "iris.bukkit.commandpregen.pregen_radius_must_be_greater_than_zero_blocks": "§cPregen半徑必須大於零塊.",
+    "iris.bukkit.commandstudio.regions_radius_out_of_range": "§c半徑必須介於 1 到 2048 區塊之間。",
+    "iris.bukkit.commandstudio.regions_scan_failed": "§c區域掃描失敗: {value}",
     "iris.bukkit.commandpregen.strict_serial_pregeneration_requires_paper_paper_compatible_server": "§c嚴格的序列預生成要求 Paper 或一個 Paper- 相容伺服器。",
     "iris.bukkit.commandpregen.engine_access_this_world_is_null": "§c這個世界的引擎是無效的!",
     "iris.bukkit.commandpregen.please_make_sure_world_is_loaded_engine_is_initialized_generate": "§c請確保世界充滿 & 引擎已經初始化。  例如, 生成一個新的塊 。",

core/src/test/java/art/arcane/iris/core/lifecycle/WorldLifecycleUnloadAsyncTest.java

@@ -1,9 +1,13 @@
 package art.arcane.iris.core.lifecycle;
 
 import art.arcane.volmlib.util.bukkit.WorldIdentity;
+import org.bukkit.Bukkit;
 import org.bukkit.NamespacedKey;
 import org.bukkit.World;
+import org.bukkit.event.world.WorldUnloadEvent;
+import org.bukkit.plugin.PluginManager;
 import org.junit.Test;
+import org.mockito.MockedStatic;
 
 import java.lang.reflect.Method;
 import java.util.concurrent.CompletableFuture;
@@ -16,10 +20,43 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.doAnswer;
 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 WorldLifecycleUnloadAsyncTest {
+    @Test
+    public void manualUnloadFallbackDispatchesWorldUnloadEvent() {
+        World world = mock(World.class);
+        PluginManager pluginManager = mock(PluginManager.class);
+
+        try (MockedStatic<Bukkit> bukkit = mockStatic(Bukkit.class)) {
+            bukkit.when(Bukkit::getPluginManager).thenReturn(pluginManager);
+            assertTrue(WorldLifecycleSupport.announceManualWorldUnload(world));
+        }
+
+        verify(pluginManager).callEvent(any(WorldUnloadEvent.class));
+    }
+
+    @Test
+    public void manualUnloadFallbackHonorsCancelledWorldUnloadEvent() {
+        World world = mock(World.class);
+        PluginManager pluginManager = mock(PluginManager.class);
+        doAnswer(invocation -> {
+            WorldUnloadEvent event = invocation.getArgument(0);
+            event.setCancelled(true);
+            return null;
+        }).when(pluginManager).callEvent(any(WorldUnloadEvent.class));
+
+        try (MockedStatic<Bukkit> bukkit = mockStatic(Bukkit.class)) {
+            bukkit.when(Bukkit::getPluginManager).thenReturn(pluginManager);
+            assertFalse(WorldLifecycleSupport.announceManualWorldUnload(world));
+        }
+    }
+
     @Test
     public void reflectedAsyncUnloadWaitsForTrueCallback() throws Exception {
         CallbackServer server = new CallbackServer();

core/src/test/java/art/arcane/iris/core/lifecycle/WorldReplacementBootstrapTest.java

@@ -192,22 +192,22 @@ public class WorldReplacementBootstrapTest {
     }
 
     @Test
-    public void rejectsChangedLevelRootBeforeTouchingStagedStorage() throws Exception {
+    public void skipsChangedLevelRootWithoutTouchingStagedStorage() throws Exception {
         Transaction transaction = stagedTransaction(Phase.ARMED, true, "original");
         configureReplacement(transaction);
         Path otherLevelRoot = Files.createDirectories(serverRoot.resolve("renamed-world"));
 
-        assertThrows(
-                IOException.class,
-                () -> WorldReplacementBootstrap.reconcile(
+        WorldReplacementBootstrap.ReconcileResult result = WorldReplacementBootstrap.reconcile(
                 dataDirectory,
                 otherLevelRoot,
                 bukkitConfiguration,
                 ignored -> {
                 }
-                )
         );
 
+        assertEquals(1, result.skipped());
+        assertEquals(0, result.published());
+        assertEquals(0, result.rolledBack());
         assertEquals("original", Files.readString(target.worldDirectory().resolve("original.txt")));
         assertTrue(Files.isDirectory(paths(transaction).stage()));
         assertFalse(Files.exists(paths(transaction).backup()));
@@ -280,6 +280,28 @@ public class WorldReplacementBootstrapTest {
         }
     }
 
+    @Test
+    public void skipsJournalStagedAgainstAnotherLevelRootInsteadOfAborting() throws Exception {
+        Transaction transaction = stagedTransaction(Phase.CLEANUP_PENDING, true, "original");
+        Path otherLevelRoot = Files.createDirectories(serverRoot.resolve("renamed-world"));
+
+        WorldReplacementBootstrap.ReconcileResult result = WorldReplacementBootstrap.reconcile(
+                dataDirectory,
+                otherLevelRoot,
+                bukkitConfiguration,
+                ignored -> {
+                }
+        );
+
+        assertEquals(1, result.skipped());
+        assertEquals(0, result.published());
+        assertEquals(0, result.rolledBack());
+        assertEquals(0, result.retained());
+        assertTrue(Files.exists(dataDirectory
+                .resolve(WorldReplacementJournal.DIRECTORY_NAME)
+                .resolve(transaction.id() + ".properties")));
+    }
+
     private WorldReplacementBootstrap.ReconcileResult reconcile() throws Exception {
         return WorldReplacementBootstrap.reconcile(
                 dataDirectory,

core/src/test/java/art/arcane/iris/core/lifecycle/WorldReplacementFilesystemTest.java

@@ -108,6 +108,23 @@ public class WorldReplacementFilesystemTest {
         assertFalse(Files.exists(paths.backup()));
     }
 
+    @Test
+    public void rejectsUnmigratedRetainedWorldAtAdmission() throws Exception {
+        WorldReplacementFilesystem.ReplacementPaths paths = paths("admit-missing-paper-metadata", TRANSACTION_ID);
+        Files.createDirectories(paths.target());
+        Files.writeString(paths.target().resolve("original.txt"), "original");
+
+        IOException failure = assertThrows(
+                IOException.class,
+                () -> WorldReplacementFilesystem.requireExistingTarget(paths)
+        );
+
+        assertTrue(failure.getMessage().contains("missing Paper world metadata"));
+        assertTrue(failure.getMessage().contains("load the world once on this server"));
+        assertFalse(Files.exists(paths.stage()));
+        assertFalse(Files.exists(paths.backup()));
+    }
+
     @Test
     public void publishesReplacementWithoutCreatingBackupForAbsentTarget() throws Exception {
         WorldReplacementFilesystem.ReplacementPaths paths = paths("publish-absent", TRANSACTION_ID);

core/src/test/java/art/arcane/iris/spi/IrisLoggingTest.java

@@ -8,7 +8,9 @@ import java.io.ByteArrayOutputStream;
 import java.io.PrintStream;
 import java.nio.charset.StandardCharsets;
 
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.CALLS_REAL_METHODS;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
@@ -25,7 +27,7 @@ public class IrisLoggingTest {
 
     @Test
     public void contextualReportPrintsFullStacktraceWithBoundPlatform() {
-        IrisPlatform platform = mock(IrisPlatform.class);
+        IrisPlatform platform = mock(IrisPlatform.class, CALLS_REAL_METHODS);
         IrisPlatforms.bind(platform);
         IllegalStateException failure = new IllegalStateException("outer", new IllegalArgumentException("inner"));
         ByteArrayOutputStream output = new ByteArrayOutputStream();
@@ -38,10 +40,29 @@ public class IrisLoggingTest {
         }
 
         verify(platform).log(LogLevel.ERROR, "Runtime world creation failed.");
+        verify(platform).reportError("Runtime world creation failed.", failure);
         verify(platform).reportError(failure);
         String text = output.toString(StandardCharsets.UTF_8);
         assertTrue(text.contains("IllegalStateException"));
         assertTrue(text.contains("IllegalArgumentException"));
         assertTrue(text.contains("inner"));
     }
+
+    @Test
+    public void contextualReportHonorsPlatformOverrideSuppression() {
+        IrisPlatform platform = mock(IrisPlatform.class);
+        IrisPlatforms.bind(platform);
+        IllegalStateException failure = new IllegalStateException("suppressed");
+        ByteArrayOutputStream output = new ByteArrayOutputStream();
+        PrintStream originalErr = System.err;
+        System.setErr(new PrintStream(output, true, StandardCharsets.UTF_8));
+        try {
+            IrisLogging.reportError("Throttled failure.", failure);
+        } finally {
+            System.setErr(originalErr);
+        }
+
+        verify(platform).reportError("Throttled failure.", failure);
+        assertFalse(output.toString(StandardCharsets.UTF_8).contains("suppressed"));
+    }
 }

probe/src/main/java/art/arcane/iris/probe/StubTileData.java

@@ -19,6 +19,7 @@ public final class StubTileData extends TileData {
     private static final Gson GSON = new GsonBuilder()
             .disableHtmlEscaping()
             .setStrictness(Strictness.LENIENT)
+            .setObjectToNumberStrategy(com.google.gson.ToNumberPolicy.LONG_OR_DOUBLE)
             .create();
 
     private final String blockKey;

probe/src/test/java/art/arcane/iris/probe/StubTileDataTest.java

@@ -32,6 +32,24 @@ public class StubTileDataTest {
         assertEquals("minecraft:chests/ancient_city", decoded.getProperties().get("LootTable"));
     }
 
+    @Test
+    public void modernIntegralPropertiesReencodeByteIdentical() throws Exception {
+        KMap<String, Object> properties = new KMap<>();
+        properties.put("LootTable", "minecraft:chests/ancient_city");
+        properties.put("LootTableSeed", -7205759403792793599L);
+        StubTileData original = StubTileData.fromProperties(
+                StubPlatform.blockStateForTest("minecraft:chest[facing=north]"), properties);
+        byte[] encoded = encode(original::toBinary);
+
+        StubTileData decoded;
+        try (DataInputStream input = new DataInputStream(new ByteArrayInputStream(encoded))) {
+            decoded = StubTileData.read(input);
+        }
+
+        assertArrayEquals(encoded, encode(decoded::toBinary));
+        assertEquals(-7205759403792793599L, decoded.getProperties().get("LootTableSeed"));
+    }
+
     @Test
     public void legacyLootablePayloadPreservesItsCompleteFrame() throws Exception {
         byte[] payload = encode(output -> {

spi/src/main/java/art/arcane/iris/spi/IrisLogging.java

@@ -97,6 +97,11 @@ public final class IrisLogging {
             inner.printStackTrace(System.err);
         }
 
+        if (IrisPlatforms.isBound()) {
+            IrisPlatforms.get().reportError(message, cause);
+            return;
+        }
+
         reportError(cause);
         cause.printStackTrace(System.err);
     }

spi/src/main/java/art/arcane/iris/spi/IrisPlatform.java

@@ -195,4 +195,17 @@ public interface IrisPlatform {
      * Hands a throwable to the host's error reporting. Safe from any thread; must not rethrow.
      */
     void reportError(Throwable error);
+
+    /**
+     * Contextual variant of {@link #reportError(Throwable)}. The platform owns trace emission so
+     * each adapter prints exactly one copy and its own suppression (throttles, debug gates) is
+     * honored; the default preserves the historical behavior of reporting plus an unconditional
+     * stack trace on stderr.
+     */
+    default void reportError(String context, Throwable error) {
+        reportError(error);
+        if (error != null) {
+            error.printStackTrace(System.err);
+        }
+    }
 }