d

adapters/bukkit/nms/v26_2_R1/src/test/java/art/arcane/iris/nativegen/NativeStructurePostProcessorSurfaceTerrainTest.java

@@ -100,13 +100,17 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
     }
 
     @Test
-    public void sourceBeardAdjustmentsPrepareTerrainAcrossDeclaredSteps() {
+    public void sourceBeardAdjustmentsPrepareOnlyAtTheSurfaceStructuresStep() {
         assertTrue(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
                 TerrainAdjustment.BEARD_THIN, GenerationStep.Decoration.SURFACE_STRUCTURES));
-        assertTrue(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
+        assertFalse(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
                 TerrainAdjustment.BEARD_BOX, GenerationStep.Decoration.FLUID_SPRINGS));
-        assertTrue(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
+        assertFalse(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
                 TerrainAdjustment.BEARD_THIN, GenerationStep.Decoration.UNDERGROUND_STRUCTURES));
+        assertFalse(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
+                TerrainAdjustment.BEARD_BOX, GenerationStep.Decoration.UNDERGROUND_DECORATION));
+        assertFalse(NativeStructureSurfaceFitter.shouldPrepareSurfaceTerrain(
+                TerrainAdjustment.BEARD_THIN, GenerationStep.Decoration.STRONGHOLDS));
     }
 
     @Test
@@ -119,6 +123,31 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
                 TerrainAdjustment.NONE, GenerationStep.Decoration.FLUID_SPRINGS));
     }
 
+    @Test
+    public void shallowUndergroundBeardBoxDoesNotMutateTheTopSurface() throws Exception {
+        PoolElementStructurePiece piece = rigidTemplatePiece(
+                new InlineSinglePoolElement(template(List.of(
+                        block(0, 1, 0, Blocks.DEEPSLATE_BRICKS.defaultBlockState())))),
+                new BoundingBox(0, 67, 0, 0, 74, 0), 1, Rotation.NONE);
+        Structure structure = new DesertPyramidStructure(
+                new Structure.StructureSettings(
+                        HolderSet.empty(), Map.of(),
+                        GenerationStep.Decoration.UNDERGROUND_DECORATION,
+                        TerrainAdjustment.BEARD_BOX));
+        StructureStart start = new StructureStart(
+                structure, new ChunkPos(0, 0), 0,
+                new PiecesContainer(List.of(piece)));
+        BoundingBox area = new BoundingBox(0, 48, 0, 0, 80, 0);
+        Map<BlockPos, BlockState> blocks = flatTerrain(area, 64);
+        Map<BlockPos, BlockState> before = new HashMap<>(blocks);
+
+        NativeStructureSurfaceFitter.prepareSurfaceStructures(
+                world(blocks), area, List.of(surfaceTarget(start)),
+                (x, z) -> 64);
+
+        assertEquals(before, blocks);
+    }
+
     @Test
     public void explicitTerrainOverrideDisablesSourceBeardFitting() {
         StructureStart start = desertStart(TerrainAdjustment.BEARD_BOX);
@@ -158,85 +187,70 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
     }
 
     @Test
-    public void beardBoxUsesTheFullRigidHeightWhileBeardThinUsesTheGroundPlane() {
-        NativeStructureSurfaceFitter.SurfaceAnchor thin =
-                new NativeStructureSurfaceFitter.SurfaceAnchor(0, 4, 0, 4, 64, 2);
-        NativeStructureSurfaceFitter.SurfaceAnchor box =
-                new NativeStructureSurfaceFitter.SurfaceAnchor(
-                        0, 4, 0, 4, 64, 2, 65, 90);
-
-        assertEquals(80, NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(thin), 2, 2, 80));
-        assertEquals(64, NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(box), 2, 2, 80));
-    }
-
-    @Test
-    public void beardInfluenceBeginsAtGroundYRatherThanTheSurfaceBlock() {
+    public void sourceSurfaceAnchorMeetsOneBlockBelowTheAuthoredGroundPlane() {
         BoundingBox bounds = new BoundingBox(0, 64, 0, 4, 90, 4);
-        NativeStructureSurfaceFitter.SurfaceAnchor thin =
-                NativeStructureSurfaceFitter.surfaceAnchor(
-                        bounds, 68, 2, TerrainAdjustment.BEARD_THIN);
-        NativeStructureSurfaceFitter.SurfaceAnchor box =
-                NativeStructureSurfaceFitter.surfaceAnchor(
-                        bounds, 68, 2, TerrainAdjustment.BEARD_BOX);
+        NativeStructureSurfaceFitter.SurfaceAnchor anchor =
+                NativeStructureSurfaceFitter.surfaceAnchor(bounds, 68, 2);
 
-        assertEquals(67, thin.meetY());
-        assertEquals(0, thin.verticalDistance(68));
-        assertEquals(1, thin.verticalDistance(67));
-        assertEquals(0, box.verticalDistance(68));
-        assertEquals(1, box.verticalDistance(67));
-        assertEquals(0, box.verticalDistance(90));
-        assertEquals(1, box.verticalDistance(91));
+        assertEquals(67, anchor.meetY());
+        assertEquals(0, anchor.minX());
+        assertEquals(4, anchor.maxX());
+        assertEquals(0, anchor.minZ());
+        assertEquals(4, anchor.maxZ());
     }
 
     @Test
-    public void rigidFootprintsRaiseTerrainAcrossGapsLargerThanTheBeardKernel() {
+    public void rigidFootprintsBoundTerrainAcrossGapsLargerThanTheBeardKernel() {
         NativeStructureSurfaceFitter.SurfaceAnchor rigid = anchor(72, 2);
         NativeStructureSurfaceFitter.SurfaceAnchor junction = anchor(72, 1);
 
-        assertEquals(72, NativeStructureSurfaceFitter.resolveSurfaceTarget(
+        assertEquals(46, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(rigid), 2, 2, 40));
-        assertEquals(40, NativeStructureSurfaceFitter.resolveSurfaceTarget(
+        assertEquals(46, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(junction), 2, 2, 40));
     }
 
     @Test
-    public void elevatedRigidFootprintsBlendIntoAHorizontalRescueTaper() {
-        int originalY = 40;
-        int kernelEdge = NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(51, 2)), 5, 2, originalY);
-        int gapThirteen = NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(52, 2)), 5, 2, originalY);
-        int gapEighteen = NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(57, 2)), 5, 2, originalY);
-        int gapTwentyFour = NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(63, 2)), 5, 2, originalY);
+    public void beardSkirtBoundsAndGradesUpwardAndDownwardSymmetrically() {
+        int originalY = 64;
+        NativeStructureSurfaceFitter.SurfaceAnchor high = anchor(96, 2);
+        NativeStructureSurfaceFitter.SurfaceAnchor low = anchor(32, 2);
+        int[] raised = new int[13];
+        int[] lowered = new int[13];
+        for (int outset = 0; outset <= 12; outset++) {
+            int x = 4 + outset;
+            raised[outset] = NativeStructureSurfaceFitter.resolveSurfaceTarget(
+                    List.of(high), x, 2, originalY);
+            lowered[outset] = NativeStructureSurfaceFitter.resolveSurfaceTarget(
+                    List.of(low), x, 2, originalY);
+        }
 
-        assertEquals(originalY, kernelEdge);
-        assertTrue(gapThirteen >= kernelEdge);
-        assertTrue(gapEighteen > gapThirteen);
-        assertTrue(gapTwentyFour > gapEighteen);
-        assertTrue(gapTwentyFour < 63);
-        assertEquals(originalY, NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(63, 2)), 16, 2, originalY));
-        assertEquals(originalY, NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(63, 1)), 5, 2, originalY));
-        assertEquals(80, NativeStructureSurfaceFitter.resolveSurfaceTarget(
-                List.of(anchor(64, 2)), 5, 2, 80));
+        assertArrayEquals(
+                new int[]{70, 69, 68, 67, 67, 66, 66, 65, 65, 64, 64, 64, 64},
+                raised);
+        assertArrayEquals(
+                new int[]{58, 59, 60, 61, 61, 62, 62, 63, 63, 64, 64, 64, 64},
+                lowered);
+        for (int outset = 0; outset <= 12; outset++) {
+            assertEquals(raised[outset] - originalY, originalY - lowered[outset]);
+        }
     }
 
     @Test
-    public void projectedCenterAndRigidChildrenShareTerrainSupportAcrossTheAssembly() {
+    public void projectedCenterAndRigidChildrenUseProcessedFoundationCells() throws Exception {
         Structure structure = new DesertPyramidStructure(
                 new Structure.StructureSettings(
                         HolderSet.empty(), Map.of(),
                         GenerationStep.Decoration.SURFACE_STRUCTURES,
                         TerrainAdjustment.BEARD_BOX));
-        PoolElementStructurePiece center = rigidPiece(
-                new BoundingBox(0, 71, 0, 3, 80, 3), 1);
-        PoolElementStructurePiece child = rigidPiece(
-                new BoundingBox(10, 65, 0, 13, 76, 3), 7);
+        PoolElementStructurePiece center = rigidTemplatePiece(
+                new InlineSinglePoolElement(template(List.of(
+                        block(1, 1, 1, Blocks.COBBLESTONE.defaultBlockState())))),
+                new BoundingBox(0, 71, 0, 3, 80, 3), 1, Rotation.NONE);
+        PoolElementStructurePiece child = rigidTemplatePiece(
+                new InlineSinglePoolElement(template(List.of(
+                        block(1, 7, 1, Blocks.COBBLESTONE.defaultBlockState())))),
+                new BoundingBox(10, 65, 0, 13, 76, 3), 7, Rotation.NONE);
         StructureStart start = new StructureStart(
                 structure, new ChunkPos(0, 0), 0,
                 new PiecesContainer(List.of(center, child)));
@@ -244,8 +258,8 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
         Map<BlockPos, BlockState> blocks = new HashMap<>();
         for (int x = area.minX(); x <= area.maxX(); x++) {
             for (int z = area.minZ(); z <= area.maxZ(); z++) {
-                put(blocks, x, 63, z, Blocks.DIRT.defaultBlockState());
-                put(blocks, x, 64, z, Blocks.GRASS_BLOCK.defaultBlockState());
+                put(blocks, x, 64, z, Blocks.DIRT.defaultBlockState());
+                put(blocks, x, 65, z, Blocks.GRASS_BLOCK.defaultBlockState());
             }
         }
 
@@ -255,21 +269,66 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
                         new IrisStructureTerrain().setMode(IrisStructureTerrainMode.SOURCE)));
         NativeStructureSurfaceFitter.prepareSurfaceStructures(
                 world(blocks), area, targets,
-                (x, z) -> 64);
+                (x, z) -> 65);
 
         assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 1, 71, 1));
         assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 11, 71, 1));
         assertEquals(Blocks.DIRT.defaultBlockState(), state(blocks, 11, 70, 1));
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 2, 65, 2));
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 12, 65, 2));
     }
 
     @Test
-    public void terrainMatchingFootprintsRaiseAndLowerOnlyLowestSolidColumns() throws Exception {
+    public void sparseRigidFootprintsIgnoreAirAndSolidsAboveTheGroundPlane() throws Exception {
+        StructureTemplate sparseTemplate = template(List.of(
+                block(0, 1, 0, Blocks.COBBLESTONE.defaultBlockState()),
+                block(15, 1, 0, Blocks.AIR.defaultBlockState()),
+                block(30, 5, 0, Blocks.STONE.defaultBlockState())));
+        PoolElementStructurePiece piece = rigidTemplatePiece(
+                new InlineSinglePoolElement(sparseTemplate),
+                new BoundingBox(0, 68, 0, 30, 76, 0), 1, Rotation.NONE);
+        StructureStart start = rigidSurfaceStart(
+                List.of(piece), TerrainAdjustment.BEARD_THIN);
+        BoundingBox area = new BoundingBox(0, 52, 0, 30, 80, 0);
+        Map<BlockPos, BlockState> blocks = flatTerrain(area, 64);
+
+        NativeStructureSurfaceFitter.prepareSurfaceStructures(
+                world(blocks), area, List.of(surfaceTarget(start)),
+                (x, z) -> 64);
+
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 0, 68, 0));
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 15, 64, 0));
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 30, 64, 0));
+    }
+
+    @Test
+    public void extremeRigidFoundationGapDoesNotCreateATerrainPillar() throws Exception {
+        StructureTemplate template = template(List.of(
+                block(0, 1, 0, Blocks.COBBLESTONE.defaultBlockState())));
+        PoolElementStructurePiece piece = rigidTemplatePiece(
+                new InlineSinglePoolElement(template),
+                new BoundingBox(0, 90, 0, 0, 96, 0), 1, Rotation.NONE);
+        StructureStart start = rigidSurfaceStart(
+                List.of(piece), TerrainAdjustment.BEARD_THIN);
+        BoundingBox area = new BoundingBox(0, 30, 0, 0, 100, 0);
+        Map<BlockPos, BlockState> blocks = flatTerrain(area, 40);
+
+        NativeStructureSurfaceFitter.prepareSurfaceStructures(
+                world(blocks), area, List.of(surfaceTarget(start)),
+                (x, z) -> 40);
+
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 0, 46, 0));
+        assertEquals(Blocks.AIR.defaultBlockState(), state(blocks, 0, 47, 0));
+        assertEquals(Blocks.AIR.defaultBlockState(), state(blocks, 0, 89, 0));
+    }
+
+    @Test
+    public void terrainMatchingFootprintsFollowProcessedLowestSolidColumns() throws Exception {
         StructureTemplate pathTemplate = template(List.of(
                 block(0, 0, 0, Blocks.AIR.defaultBlockState()),
-                block(0, 1, 0, Blocks.DIRT_PATH.defaultBlockState()),
+                block(0, 2, 0, Blocks.DIRT.defaultBlockState()),
                 block(15, 0, 0, Blocks.AIR.defaultBlockState()),
-                block(30, 0, 0, Blocks.AIR.defaultBlockState()),
-                block(30, 1, 0, Blocks.DIRT_PATH.defaultBlockState()),
+                block(30, 0, 0, Blocks.DIRT.defaultBlockState()),
                 block(45, 0, 0, Blocks.DANDELION.defaultBlockState())));
         InlineSinglePoolElement element = new InlineSinglePoolElement(
                 pathTemplate, List.of(), StructureTemplatePool.Projection.TERRAIN_MATCHING);
@@ -290,8 +349,8 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
                 world(blocks), area, List.of(surfaceTarget(start)),
                 (x, z) -> x == 0 ? 60 : x == 30 ? 72 : 64);
 
-        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 0, 68, 0));
-        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 30, 68, 0));
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 0, 61, 0));
+        assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 30, 71, 0));
         assertEquals(Blocks.AIR.defaultBlockState(), state(blocks, 30, 72, 0));
         assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(blocks, 15, 64, 0));
         assertEquals(Blocks.AIR.defaultBlockState(), state(blocks, 15, 65, 0));
@@ -770,10 +829,10 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
     }
 
     @Test
-    public void surfaceAnchorIsFlushInsideAndUnchangedAtRadius() {
+    public void surfaceAnchorCapsInsideAndIsUnchangedAtRadius() {
         NativeStructureSurfaceFitter.SurfaceAnchor anchor = anchor(72, 2);
 
-        assertEquals(72, NativeStructureSurfaceFitter.resolveSurfaceTarget(
+        assertEquals(70, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(anchor), 2, 2, 64));
         assertEquals(64, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(anchor), 16, 2, 64));
@@ -786,7 +845,7 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
         NativeStructureSurfaceFitter.SurfaceAnchor raised = anchor(68, 2);
         NativeStructureSurfaceFitter.SurfaceAnchor lowered = anchor(64, 2);
 
-        assertEquals(64, NativeStructureSurfaceFitter.resolveSurfaceTarget(
+        assertEquals(65, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(raised), 10, 2, 64));
         assertEquals(67, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(lowered), 10, 2, 68));
@@ -1197,16 +1256,20 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
     }
 
     @Test
-    public void stackedRigidPiecesPreserveTheLowerAuthoredSurface() {
+    public void stackedRigidPiecesPreserveTheLowerProcessedFoundation() throws Exception {
         Structure structure = new DesertPyramidStructure(
                 new Structure.StructureSettings(
                         HolderSet.empty(), Map.of(),
                         GenerationStep.Decoration.SURFACE_STRUCTURES,
                         TerrainAdjustment.BEARD_BOX));
-        PoolElementStructurePiece lower = rigidPiece(
-                new BoundingBox(0, 62, 0, 4, 65, 4), 1);
-        PoolElementStructurePiece upper = rigidPiece(
-                new BoundingBox(0, 66, 0, 4, 78, 4), 1);
+        PoolElementStructurePiece lower = rigidTemplatePiece(
+                new InlineSinglePoolElement(template(List.of(
+                        block(2, 1, 2, Blocks.COBBLESTONE.defaultBlockState())))),
+                new BoundingBox(0, 62, 0, 4, 65, 4), 1, Rotation.NONE);
+        PoolElementStructurePiece upper = rigidTemplatePiece(
+                new InlineSinglePoolElement(template(List.of(
+                        block(2, 1, 2, Blocks.COBBLESTONE.defaultBlockState())))),
+                new BoundingBox(0, 66, 0, 4, 78, 4), 1, Rotation.NONE);
         StructureStart start = new StructureStart(
                 structure, new ChunkPos(0, 0), 0,
                 new PiecesContainer(List.of(upper, lower)));
@@ -1236,7 +1299,7 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
         NativeStructureSurfaceFitter.SurfaceAnchor adjacent =
                 new NativeStructureSurfaceFitter.SurfaceAnchor(5, 9, 0, 4, 70, 2);
 
-        assertEquals(65, NativeStructureSurfaceFitter.resolveSurfaceTarget(
+        assertEquals(69, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(adjacent), 4, 2, 64));
         assertEquals(66, NativeStructureSurfaceFitter.resolveSurfaceTarget(
                 List.of(local, adjacent), 4, 2, 64));

adapters/bukkit/plugin/build.gradle

@@ -3,7 +3,7 @@ def mainClass = 'art.arcane.iris.Iris'
 def bootstrapperClass = 'art.arcane.iris.IrisBootstrap'
 
 String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate')
-    .orElse('com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522')
+    .orElse('com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186')
     .get()
 
 dependencies {

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

@@ -669,7 +669,7 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
                 watch::readSettingsContent,
                 watch::normalizeSettingsContent
         );
-        configHotloadEngine.configure(3_000L, List.of(watch.settingsFile()), List.of());
+        configHotloadEngine.configure(500L, 3_000L, List.of(watch.settingsFile()), List.of());
         // Stale-temp cleanup must complete before services enable: StudioSVC.onEnable downloads
         // packs through cache/temp on an async thread, and a concurrent delete of that folder
         // truncated pack imports mid-copy (partial packs/<key> without dimensions/).
@@ -714,7 +714,7 @@ public class Iris extends VolmitPlugin implements Listener, ReloadAware {
             pendingWorldReplacements.captureVanillaLevelContext();
             pendingWorldReplacements.verifyLoadedPublishedWorlds();
             J.a(this::bstats);
-            J.ar(() -> settingsHotloadWatch.checkConfigHotload(configHotloadEngine), 60);
+            J.ar(() -> settingsHotloadWatch.checkConfigHotload(configHotloadEngine), 10);
             J.sr(this::tickQueue, 0);
             J.s(this::setupPapi);
             if (IrisStartupValidation.isReady()) {

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

@@ -21,9 +21,12 @@ package art.arcane.iris.core;
 import art.arcane.iris.Iris;
 import art.arcane.iris.core.localization.IrisLanguage;
 import art.arcane.volmlib.util.hotload.ConfigHotloadEngine;
-import art.arcane.volmlib.util.io.IO;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.util.List;
 
 /**
@@ -31,6 +34,8 @@ import java.util.List;
  * {@link ConfigHotloadEngine} is built from and drains the touched-file queue.
  */
 public final class SettingsHotloadWatch {
+    private static final int MAX_SETTINGS_BYTES = 2 * 1024 * 1024;
+
     private final File settingsFile;
 
     public SettingsHotloadWatch(File settingsFile) {
@@ -46,13 +51,17 @@ public final class SettingsHotloadWatch {
             return;
         }
 
-        for (File file : engine.pollTouchedFiles()) {
-            engine.processFileChange(file, ignored -> {
-                IrisSettings.invalidate();
-                IrisSettings.get();
-                IrisLanguage.reload();
-                return true;
-            }, ignored -> Iris.info("Hotloaded settings.json "));
+        for (ConfigHotloadEngine.StableContentSnapshot snapshot : engine.pollTouchedSnapshots()) {
+            if ("missing".equals(snapshot.signature())) {
+                engine.processSnapshotChange(snapshot, ignored -> true, null);
+                Iris.warn("settings.json was removed; retaining the last valid runtime settings.");
+                continue;
+            }
+            engine.processSnapshotChange(
+                    snapshot,
+                    stable -> applySettingsSnapshot(stable.file(), stable.normalizedContent()),
+                    ignored -> Iris.info("Hotloaded settings.json ")
+            );
         }
         IrisLanguage.update();
     }
@@ -76,8 +85,12 @@ public final class SettingsHotloadWatch {
             return null;
         }
 
-        try {
-            return IO.readAll(file);
+        try (InputStream input = Files.newInputStream(file.toPath())) {
+            byte[] content = input.readNBytes(MAX_SETTINGS_BYTES + 1);
+            if (content.length > MAX_SETTINGS_BYTES) {
+                throw new IOException("Settings exceed " + MAX_SETTINGS_BYTES + " bytes: " + file);
+            }
+            return new String(content, StandardCharsets.UTF_8);
         } catch (Throwable ex) {
             Iris.warn("Failed to read settings file %s: %s%s",
                     file.getAbsolutePath(),
@@ -95,4 +108,19 @@ public final class SettingsHotloadWatch {
 
         return text.replace("\r\n", "\n").trim();
     }
+
+    private boolean applySettingsSnapshot(File file, String content) {
+        if (content == null) {
+            return false;
+        }
+        try {
+            return IrisSettings.applyHotloadSnapshot(content, IrisLanguage::reload);
+        } catch (RuntimeException failure) {
+            Iris.warn("Rejected invalid settings hotload from %s: %s",
+                    file.getAbsolutePath(),
+                    failure.getMessage() == null ? failure.getClass().getSimpleName() : failure.getMessage());
+            Iris.reportError(failure);
+            return false;
+        }
+    }
 }

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

@@ -2,6 +2,7 @@ package art.arcane.iris.core.commands;
 
 import art.arcane.iris.Iris;
 import art.arcane.iris.core.loader.IrisData;
+import art.arcane.iris.core.pack.BrokenPackException;
 import art.arcane.iris.core.runtime.WorldRuntimeControlService;
 import art.arcane.iris.core.runtime.StudioOpenCoordinator;
 import art.arcane.iris.core.runtime.jigsaw.JigsawPlanarArchetype;
@@ -960,6 +961,11 @@ public class CommandJigsaw implements DirectorExecutor {
         Throwable failure = unwrapCompletionFailure(throwable == null
                 ? new IllegalStateException("Studio open completed without a result")
                 : throwable);
+        if (isExpectedOpenDenial(failure)) {
+            Iris.warn("Jigsaw Studio open for '%s' was denied: %s",
+                    structureKey, failure.getMessage());
+            return;
+        }
         Iris.reportError("Failed to open Jigsaw Studio for '" + structureKey + "'.", failure);
         sendError(commandSender, "Jigsaw Studio open failed: " + failure.getMessage());
     }
@@ -1022,6 +1028,10 @@ public class CommandJigsaw implements DirectorExecutor {
         return current;
     }
 
+    static boolean isExpectedOpenDenial(Throwable failure) {
+        return unwrapCompletionFailure(failure) instanceof BrokenPackException;
+    }
+
     private void sendError(String message) {
         sender().sendMessage(C.RED + message);
     }

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

@@ -101,7 +101,7 @@ public class WandSVC implements IrisService {
             var latch = new CountDownLatch(1);
             var holder = Iris.tickets.getHolder(p.getWorld());
             new Job() {
-                private int i;
+                private volatile int i;
                 private Chunk chunk;
 
                 @Override

adapters/bukkit/plugin/src/test/java/art/arcane/iris/core/commands/CommandJigsawContractTest.java

@@ -1,5 +1,6 @@
 package art.arcane.iris.core.commands;
 
+import art.arcane.iris.core.pack.BrokenPackException;
 import art.arcane.iris.core.runtime.StudioOpenCoordinator;
 import art.arcane.iris.core.runtime.jigsaw.JigsawPlanarArchetype;
 import art.arcane.iris.core.runtime.jigsaw.JigsawStudioCellDimensions;
@@ -7,6 +8,7 @@ import art.arcane.iris.core.runtime.jigsaw.JigsawStudioLayout;
 import art.arcane.iris.core.runtime.jigsaw.JigsawStudioMode;
 import art.arcane.iris.core.runtime.jigsaw.JigsawStudioVariantCatalog;
 import art.arcane.iris.core.runtime.jigsaw.JigsawStudioWorkcellSpec;
+import art.arcane.iris.core.service.JigsawStudioService;
 import art.arcane.iris.core.structure.authoring.StructureBackend;
 import art.arcane.iris.core.structure.authoring.StructureCapability;
 import art.arcane.iris.core.structure.authoring.StructureHash;
@@ -17,7 +19,6 @@ import art.arcane.iris.core.structure.authoring.StructureTransactionWriter;
 import art.arcane.iris.core.structure.conversion.IrisStructureAdoptionInputKind;
 import art.arcane.iris.core.structure.export.VanillaJigsawExportFormat;
 import art.arcane.iris.core.tools.IrisCreator;
-import art.arcane.iris.core.service.JigsawStudioService;
 import art.arcane.iris.engine.object.IrisDimension;
 import art.arcane.iris.engine.object.IrisDirection;
 import art.arcane.iris.engine.object.IrisJigsawConnector;
@@ -44,6 +45,7 @@ import java.nio.file.Path;
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.CompletionException;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static org.junit.Assert.assertEquals;
@@ -101,6 +103,18 @@ public class CommandJigsawContractTest {
                 CommandJigsaw.STUDIO_OPEN_KIND.datapackPreparation());
     }
 
+    @Test
+    public void packValidationDenialsAreExpectedOpenFailures() {
+        BrokenPackException failure = new BrokenPackException(
+                "overworld", List.of("Biome 'broken' has no resolvable regions."));
+
+        assertTrue(CommandJigsaw.isExpectedOpenDenial(failure));
+        assertTrue(CommandJigsaw.isExpectedOpenDenial(
+                new CompletionException(failure)));
+        assertFalse(CommandJigsaw.isExpectedOpenDenial(
+                new IllegalStateException("Unexpected Studio failure")));
+    }
+
     @Test
     public void committedActivationStartsInitialEvaluationBeforePlayerBinding() throws Exception {
         String source = Files.readString(Path.of(
@@ -129,6 +143,10 @@ public class CommandJigsawContractTest {
         NamespacedKey source = CommandJigsaw.parseRegisteredStructureKey("minecraft:village_plains");
         assertEquals("minecraft_village_plains", CommandJigsaw.resolveConversionTarget(source, "auto"));
         assertEquals("villages/plains", CommandJigsaw.resolveConversionTarget(source, "iris:villages/plains"));
+        NamespacedKey ancientCity = CommandJigsaw.parseRegisteredStructureKey(
+                "minecraft:ancient_city");
+        assertEquals("minecraft_ancient_city",
+                CommandJigsaw.resolveConversionTarget(ancientCity, "auto"));
         assertThrows(IllegalArgumentException.class,
                 () -> CommandJigsaw.resolveConversionTarget(source, "custom:village"));
     }

adapters/fabric/build.gradle

@@ -31,7 +31,7 @@ file('../../gradle.properties').withInputStream { InputStream stream -> rootProp
 String irisVersion = providers.gradleProperty('irisVersion').getOrElse(rootProperties.getProperty('irisVersion', '4.0.0-26.2'))
 String minecraftVersion = providers.gradleProperty('minecraftVersion').getOrElse(rootProperties.getProperty('minecraftVersion', '26.2'))
 String fabricLoaderVersion = providers.gradleProperty('fabricLoaderVersion').getOrElse(rootProperties.getProperty('fabricLoaderVersion', '0.19.3'))
-String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate').getOrElse(rootProperties.getProperty('volmLibCoordinate', 'com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522'))
+String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate').getOrElse(rootProperties.getProperty('volmLibCoordinate', 'com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186'))
 Closure<String> irisArtifactName = { String platform, String targetVersion ->
     return "Iris v${project.version} [${platform}] ${targetVersion}.jar"
 }

adapters/forge/build.gradle

@@ -31,7 +31,7 @@ file('../../gradle.properties').withInputStream { InputStream stream -> rootProp
 String irisVersion = providers.gradleProperty('irisVersion').getOrElse(rootProperties.getProperty('irisVersion', '4.0.0-26.2'))
 String minecraftVersion = providers.gradleProperty('minecraftVersion').getOrElse(rootProperties.getProperty('minecraftVersion', '26.2'))
 String forgeVersion = providers.gradleProperty('forgeVersion').getOrElse(rootProperties.getProperty('forgeVersion', '26.2-65.1.1'))
-String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate').getOrElse(rootProperties.getProperty('volmLibCoordinate', 'com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522'))
+String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate').getOrElse(rootProperties.getProperty('volmLibCoordinate', 'com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186'))
 Closure<String> loaderDisplayVersion = { String loaderVersion ->
     String coordinatePrefix = "${minecraftVersion}-"
     if (loaderVersion.startsWith(coordinatePrefix)) {

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

@@ -33,6 +33,7 @@ public final class NativeStructureSurfaceFitter {
     private static final double SURFACE_TERRAIN_FALLOFF = 2.0;
     private static final long SURFACE_TERRAIN_INFLUENCE_SCALE = 1_000_000L;
     private static final int SURFACE_TERRAIN_RADIUS = 12;
+    private static final int MAX_SOURCE_SURFACE_DELTA = 6;
     private static final int MAX_SURFACE_TEMPLATE_CELLS = 4_194_304;
     private static final Set<String> WARNED_SOURCE_BUDGET =
             ConcurrentHashMap.newKeySet();
@@ -113,8 +114,9 @@ public final class NativeStructureSurfaceFitter {
 
     static boolean shouldPrepareSurfaceTerrain(TerrainAdjustment adjustment,
                                                GenerationStep.Decoration step) {
-        return adjustment == TerrainAdjustment.BEARD_THIN
-                || adjustment == TerrainAdjustment.BEARD_BOX;
+        return step == GenerationStep.Decoration.SURFACE_STRUCTURES
+                && (adjustment == TerrainAdjustment.BEARD_THIN
+                || adjustment == TerrainAdjustment.BEARD_BOX);
     }
 
     static int surfaceTerrainRadius() {
@@ -131,50 +133,27 @@ public final class NativeStructureSurfaceFitter {
         int localTargetY = originalY;
         SurfaceAnchor selectedLocal = null;
         long totalInfluence = 0L;
-        long weightedMeetY = 0L;
+        long weightedTargetY = 0L;
         long maximumInfluence = 0L;
         for (SurfaceAnchor anchor : anchors) {
             int outX = IrisObjectVacuum.outset(worldX, anchor.minX(), anchor.maxX());
             int outZ = IrisObjectVacuum.outset(worldZ, anchor.minZ(), anchor.maxZ());
             boolean containsColumn = outX == 0 && outZ == 0;
-            if (containsColumn && anchor.strength() > 1 && originalY < anchor.meetY()) {
-                if (precedes(anchor, selectedLocal)) {
-                    localTargetY = anchor.meetY();
-                    selectedLocal = anchor;
-                }
+            long distanceSquared = (long) outX * outX + (long) outZ * outZ;
+            long radiusSquared = (long) SURFACE_TERRAIN_RADIUS * SURFACE_TERRAIN_RADIUS;
+            if (distanceSquared > radiusSquared) {
                 continue;
             }
-            int verticalDistance = anchor.verticalDistance(originalY);
-            long horizontalDistanceSquared = (long) outX * outX + (long) outZ * outZ;
-            long distanceSquared = (long) outX * outX + (long) outZ * outZ
-                    + (long) verticalDistance * verticalDistance;
-            double factor = 0D;
-            long radiusSquared = (long) SURFACE_TERRAIN_RADIUS * SURFACE_TERRAIN_RADIUS;
-            if (distanceSquared <= radiusSquared) {
             double distance = Math.sqrt(distanceSquared);
-                factor = Math.pow(
+            double factor = Math.pow(
                     1D - distance / SURFACE_TERRAIN_RADIUS, SURFACE_TERRAIN_FALLOFF);
-            }
-            if (anchor.strength() > 1 && originalY < anchor.meetY()
-                    && verticalDistance > SURFACE_TERRAIN_RADIUS
-                    && horizontalDistanceSquared <= radiusSquared) {
-                double horizontalDistance = Math.sqrt(horizontalDistanceSquared);
-                double horizontalFactor = Math.pow(
-                        1D - horizontalDistance / SURFACE_TERRAIN_RADIUS,
-                        SURFACE_TERRAIN_FALLOFF);
-                double rescueProgress = Math.min(1D,
-                        (verticalDistance - SURFACE_TERRAIN_RADIUS)
-                                / (double) SURFACE_TERRAIN_RADIUS);
-                double rescueWeight = rescueProgress * rescueProgress
-                        * (3D - 2D * rescueProgress);
-                factor = Math.max(factor, horizontalFactor * rescueWeight);
-            }
             if (factor <= 0D) {
                 continue;
             }
+            int boundedTargetY = boundedSurfaceTarget(originalY, anchor.meetY());
             if (containsColumn) {
                 if (precedes(anchor, selectedLocal)) {
-                    localTargetY = anchor.meetY();
+                    localTargetY = boundedTargetY;
                     selectedLocal = anchor;
                 }
                 continue;
@@ -185,19 +164,35 @@ public final class NativeStructureSurfaceFitter {
             }
             long weightedInfluence = influence * Math.max(1, anchor.strength());
             totalInfluence += weightedInfluence;
-            weightedMeetY += weightedInfluence * anchor.meetY();
+            weightedTargetY += weightedInfluence * boundedTargetY;
             maximumInfluence = Math.max(maximumInfluence, influence);
         }
         if (selectedLocal != null) {
-            return new SurfaceResolution(localTargetY, selectedLocal.strength() > 1);
+            return new SurfaceResolution(
+                    localTargetY,
+                    selectedLocal.strength() > 1
+                            && localTargetY == selectedLocal.meetY());
         }
         if (totalInfluence == 0L) {
             return new SurfaceResolution(originalY, false);
         }
-        double blendedMeetY = weightedMeetY / (double) totalInfluence;
+        double blendedTargetY = weightedTargetY / (double) totalInfluence;
         double factor = maximumInfluence / (double) SURFACE_TERRAIN_INFLUENCE_SCALE;
         return new SurfaceResolution(
-                (int) Math.round(originalY + ((blendedMeetY - originalY) * factor)), false);
+                blendSurfaceTarget(originalY, blendedTargetY, factor), false);
+    }
+
+    private static int boundedSurfaceTarget(int originalY, int meetY) {
+        int delta = Math.max(
+                -MAX_SOURCE_SURFACE_DELTA,
+                Math.min(MAX_SOURCE_SURFACE_DELTA, meetY - originalY));
+        return originalY + delta;
+    }
+
+    private static int blendSurfaceTarget(int originalY, double targetY, double factor) {
+        double delta = (targetY - originalY) * factor;
+        int magnitude = (int) Math.round(Math.abs(delta));
+        return originalY + (delta < 0D ? -magnitude : magnitude);
     }
 
     private static boolean precedes(SurfaceAnchor candidate, SurfaceAnchor selected) {
@@ -235,12 +230,16 @@ public final class NativeStructureSurfaceFitter {
                 area.maxX() + SURFACE_TERRAIN_RADIUS, area.maxY(),
                 area.maxZ() + SURFACE_TERRAIN_RADIUS);
         List<SurfaceAnchor> anchors = new ArrayList<>();
+        Set<StructureStart> seenStarts = Collections.newSetFromMap(
+                new IdentityHashMap<>());
         for (NativeStructureTerrainIntegrator.TerrainTarget target : targets) {
             if (!requiresSourceSurfaceTerrain(target)) {
                 continue;
             }
             StructureStart start = target.start();
-            TerrainAdjustment adjustment = start.getStructure().terrainAdaptation();
+            if (!seenStarts.add(start)) {
+                continue;
+            }
             BoundingBox firstBounds = start.getPieces().getFirst().getBoundingBox();
             BlockPos firstCenter = firstBounds.getCenter();
             BlockPos referencePosition = new BlockPos(
@@ -251,19 +250,15 @@ public final class NativeStructureSurfaceFitter {
                 if (piece instanceof PoolElementStructurePiece poolPiece) {
                     StructureTemplatePool.Projection projection =
                             poolPiece.getElement().getProjection();
-                    if (projection == StructureTemplatePool.Projection.RIGID) {
-                        BoundingBox bounds = poolPiece.getBoundingBox();
-                        anchors.add(surfaceAnchor(
-                                bounds, bounds.minY() + poolPiece.getGroundLevelDelta(),
-                                2, adjustment));
-                    } else if (!budgetExceeded
-                            && projection == StructureTemplatePool.Projection.TERRAIN_MATCHING
+                    if (!budgetExceeded
+                            && (projection == StructureTemplatePool.Projection.RIGID
+                            || projection == StructureTemplatePool.Projection.TERRAIN_MATCHING)
                             && intersectsHorizontally(poolPiece.getBoundingBox(), influenceArea)) {
                         try {
                             List<SurfaceAnchor> pieceAnchors = new ArrayList<>();
-                            addTerrainMatchingSurfaceAnchors(
+                            addProcessedSurfaceAnchors(
                                     world, influenceArea, poolPiece, referencePosition,
-                                    adjustment, budget, pieceAnchors);
+                                    projection, budget, pieceAnchors);
                             anchors.addAll(pieceAnchors);
                         } catch (TemplateBudgetExceeded ignored) {
                             budgetExceeded = true;
@@ -274,22 +269,22 @@ public final class NativeStructureSurfaceFitter {
                         anchors.add(new SurfaceAnchor(
                                 junction.getSourceX(), junction.getSourceX(),
                                 junction.getSourceZ(), junction.getSourceZ(),
-                                junction.getSourceGroundY() - 1, 1,
-                                junction.getSourceGroundY(), junction.getSourceGroundY()));
+                                junction.getSourceGroundY() - 1, 1));
                     }
                     continue;
                 }
                 BoundingBox bounds = piece.getBoundingBox();
-                anchors.add(surfaceAnchor(bounds, bounds.minY(), 2, adjustment));
+                anchors.add(surfaceAnchor(bounds, bounds.minY(), 2));
             }
         }
         return List.copyOf(anchors);
     }
 
-    private static void addTerrainMatchingSurfaceAnchors(
+    private static void addProcessedSurfaceAnchors(
             WorldGenLevel world, BoundingBox influenceArea,
             PoolElementStructurePiece piece, BlockPos referencePosition,
-            TerrainAdjustment adjustment, TemplateCellBudget budget,
+            StructureTemplatePool.Projection projection,
+            TemplateCellBudget budget,
             List<SurfaceAnchor> anchors) {
         NativeStructureTemplateOccupancy.OccupancyResult occupancy =
                 NativeStructureTemplateOccupancy.resolve(
@@ -299,14 +294,21 @@ public final class NativeStructureSurfaceFitter {
         if (!occupancy.resolved()) {
             return;
         }
-        int groundY = piece.getBoundingBox().minY() + piece.getGroundLevelDelta();
+        int maximumFoundationY = piece.getBoundingBox().minY()
+                + piece.getGroundLevelDelta();
         Map<Long, NativeStructureTemplateOccupancy.LowestCell> lowest =
                 NativeStructureTemplateOccupancy.lowestProcessedSolidCells(occupancy.cells());
         for (NativeStructureTemplateOccupancy.LowestCell cell : lowest.values()) {
             budget.consume(1);
+            if (projection == StructureTemplatePool.Projection.RIGID
+                    && cell.y() > maximumFoundationY) {
+                continue;
+            }
+            int groundY = projection == StructureTemplatePool.Projection.RIGID
+                    ? maximumFoundationY : cell.y();
             BoundingBox column = new BoundingBox(
                     cell.x(), groundY, cell.z(), cell.x(), groundY, cell.z());
-            anchors.add(surfaceAnchor(column, groundY, 2, adjustment));
+            anchors.add(surfaceAnchor(column, groundY, 2));
         }
     }
 
@@ -318,7 +320,7 @@ public final class NativeStructureSurfaceFitter {
         if (WARNED_SOURCE_BUDGET.add(structureId)) {
             IrisLogging.warn("Native structure SOURCE fitting for '"
                     + structureId + "' exceeded its bounded template budget; "
-                    + "skipping remaining terrain-matching footprints for this start");
+                    + "skipping remaining processed footprints for this start");
         }
     }
 
@@ -462,16 +464,9 @@ public final class NativeStructureSurfaceFitter {
         return first.surfaceY() <= second.surfaceY() ? first : second;
     }
 
-    static SurfaceAnchor surfaceAnchor(BoundingBox bounds, int groundY, int strength,
-                                       TerrainAdjustment adjustment) {
-        int meetY = groundY - 1;
-        if (adjustment == TerrainAdjustment.BEARD_BOX) {
-            return new SurfaceAnchor(
-                    bounds.minX(), bounds.maxX(), bounds.minZ(), bounds.maxZ(),
-                    meetY, strength, groundY, bounds.maxY());
-        }
+    static SurfaceAnchor surfaceAnchor(BoundingBox bounds, int groundY, int strength) {
         return new SurfaceAnchor(bounds.minX(), bounds.maxX(), bounds.minZ(), bounds.maxZ(),
-                meetY, strength, groundY, groundY);
+                groundY - 1, strength);
     }
 
     static boolean requiresSurfaceTerrain(StructureStart start) {
@@ -823,16 +818,7 @@ public final class NativeStructureSurfaceFitter {
         return state.isSolid() && !NativeStructureVegetationClearer.isTreeBlock(state);
     }
 
-    record SurfaceAnchor(int minX, int maxX, int minZ, int maxZ, int meetY, int strength,
-                         int minInfluenceY, int maxInfluenceY) {
-        SurfaceAnchor(int minX, int maxX, int minZ, int maxZ, int meetY, int strength) {
-            this(minX, maxX, minZ, maxZ, meetY, strength, meetY + 1, meetY + 1);
-        }
-
-        int verticalDistance(int y) {
-            return IrisObjectVacuum.outset(y, minInfluenceY, maxInfluenceY);
-        }
-
+    record SurfaceAnchor(int minX, int maxX, int minZ, int maxZ, int meetY, int strength) {
     }
 
     private record SurfaceMaterials(BlockState surface, BlockState subsurface) {

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

@@ -21,48 +21,118 @@ package art.arcane.iris.modded.service;
 import art.arcane.iris.core.IrisSettings;
 import art.arcane.iris.core.localization.IrisLanguage;
 import art.arcane.iris.spi.IrisPlatforms;
+import art.arcane.volmlib.util.hotload.ConfigHotloadEngine;
 import net.minecraft.server.MinecraftServer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
 
 public final class ModdedSettingsHotloadService implements ModdedTickableService {
     private static final Logger LOGGER = LoggerFactory.getLogger("Iris");
-    private static final long POLL_PERIOD_MILLIS = 3_000L;
+    private static final long POLL_PERIOD_MILLIS = 500L;
+    private static final long HOTLOAD_COOLDOWN_MILLIS = 3_000L;
+    private static final int MAX_SETTINGS_BYTES = 2 * 1024 * 1024;
 
-    private long lastPollAt;
-    private long lastModified;
+    private ConfigHotloadEngine hotloadEngine;
+    private long lastPollAtNanos;
 
     @Override
     public void onEnable() {
-        lastPollAt = 0L;
-        lastModified = settingsFile().lastModified();
+        File settingsFile = settingsFile();
+        hotloadEngine = new ConfigHotloadEngine(
+                this::isSettingsFile,
+                () -> List.of(settingsFile),
+                this::readSettings,
+                this::normalizeSettings
+        );
+        hotloadEngine.configure(
+                POLL_PERIOD_MILLIS,
+                HOTLOAD_COOLDOWN_MILLIS,
+                List.of(settingsFile),
+                List.of()
+        );
+        lastPollAtNanos = 0L;
     }
 
     @Override
     public void onDisable() {
+        ConfigHotloadEngine active = hotloadEngine;
+        hotloadEngine = null;
+        if (active != null) {
+            active.clear();
+        }
     }
 
     @Override
     public void onServerTick(MinecraftServer server) {
-        long now = System.currentTimeMillis();
-        if (now - lastPollAt < POLL_PERIOD_MILLIS) {
+        ConfigHotloadEngine active = hotloadEngine;
+        if (active == null) {
             return;
         }
-        lastPollAt = now;
-        long modified = settingsFile().lastModified();
-        if (modified == lastModified) {
+
+        long now = System.nanoTime();
+        if (now - lastPollAtNanos < TimeUnit.MILLISECONDS.toNanos(POLL_PERIOD_MILLIS)) {
+            return;
+        }
+        lastPollAtNanos = now;
+
+        try {
+            for (ConfigHotloadEngine.StableContentSnapshot snapshot : active.pollTouchedSnapshots()) {
+                if ("missing".equals(snapshot.signature())) {
+                    active.processSnapshotChange(snapshot, ignored -> true, null);
+                    LOGGER.warn("settings.json was removed; retaining the last valid runtime settings");
+                    continue;
+                }
+                active.processSnapshotChange(snapshot, this::reloadSettings, ignored -> LOGGER.info("Hotloaded settings.json"));
+            }
             IrisLanguage.update();
-            return;
+        } catch (RuntimeException failure) {
+            LOGGER.error("Iris settings hotload watcher failed", failure);
         }
-        if (IrisSettings.settings != null) {
-            IrisSettings.invalidate();
     }
-        IrisSettings.get();
-        IrisLanguage.reload();
-        lastModified = settingsFile().lastModified();
-        LOGGER.info("Hotloaded settings.json");
+
+    private boolean reloadSettings(ConfigHotloadEngine.StableContentSnapshot snapshot) {
+        try {
+            String content = snapshot.normalizedContent();
+            if (content == null) {
+                return false;
+            }
+            return IrisSettings.applyHotloadSnapshot(content, IrisLanguage::reload);
+        } catch (RuntimeException failure) {
+            LOGGER.error("Iris settings hotload failed; keeping the previous runtime settings", failure);
+            return false;
+        }
+    }
+
+    private boolean isSettingsFile(File file) {
+        return file != null && settingsFile().getAbsoluteFile().equals(file.getAbsoluteFile());
+    }
+
+    private String readSettings(File file) {
+        if (file == null || !file.isFile()) {
+            return null;
+        }
+        try (InputStream input = Files.newInputStream(file.toPath())) {
+            byte[] content = input.readNBytes(MAX_SETTINGS_BYTES + 1);
+            if (content.length > MAX_SETTINGS_BYTES) {
+                throw new IOException("Settings exceed " + MAX_SETTINGS_BYTES + " bytes: " + file);
+            }
+            return new String(content, StandardCharsets.UTF_8);
+        } catch (IOException failure) {
+            throw new UncheckedIOException("Failed to read Iris settings from " + file, failure);
+        }
+    }
+
+    private String normalizeSettings(String content) {
+        return content == null ? null : content.replace("\r\n", "\n").trim();
     }
 
     private static File settingsFile() {

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

@@ -43,6 +43,7 @@ import org.slf4j.LoggerFactory;
 import java.io.File;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
@@ -82,6 +83,9 @@ public final class ModdedStudioHotloadService implements ModdedTickableService,
         if (active != null) {
             active.shutdownNow();
         }
+        for (Watch watch : watches.values()) {
+            watch.close();
+        }
         watches.clear();
     }
 
@@ -172,7 +176,13 @@ public final class ModdedStudioHotloadService implements ModdedTickableService,
         }
         if (!watches.isEmpty()) {
             Set<String> keep = seen == null ? Set.of() : seen;
-            watches.keySet().removeIf((String key) -> !keep.contains(key));
+            watches.entrySet().removeIf((Map.Entry<String, Watch> entry) -> {
+                if (keep.contains(entry.getKey())) {
+                    return false;
+                }
+                entry.getValue().close();
+                return true;
+            });
         }
     }
 
@@ -212,6 +222,7 @@ public final class ModdedStudioHotloadService implements ModdedTickableService,
     private void poll(String dimensionId, Watch watch, IrisModdedChunkGenerator generator, Engine engine) {
         try {
             if (watch.engine != engine) {
+                watch.close();
                 watch.engine = engine;
                 watch.folder = new ReactiveFolder(
                         engine.getData().getDataFolder(),
@@ -241,6 +252,7 @@ public final class ModdedStudioHotloadService implements ModdedTickableService,
             LOGGER.info("Iris studio hotload {} pack={} {}ms", dimensionId, engine.getDimension().getLoadKey(), System.currentTimeMillis() - start);
         } catch (Throwable e) {
             LOGGER.error("Iris studio hotload failed for {}", dimensionId, e);
+            throw new IllegalStateException("Iris studio hotload failed for " + dimensionId, e);
         }
     }
 
@@ -272,5 +284,14 @@ public final class ModdedStudioHotloadService implements ModdedTickableService,
         private final AtomicBoolean busy = new AtomicBoolean(false);
         private volatile Engine engine;
         private volatile ReactiveFolder folder;
+
+        private void close() {
+            ReactiveFolder active = folder;
+            folder = null;
+            if (active != null) {
+                active.clear();
+            }
+            engine = null;
+        }
     }
 }

adapters/neoforge/build.gradle

@@ -31,7 +31,7 @@ file('../../gradle.properties').withInputStream { InputStream stream -> rootProp
 String irisVersion = providers.gradleProperty('irisVersion').getOrElse(rootProperties.getProperty('irisVersion', '4.0.0-26.2'))
 String minecraftVersion = providers.gradleProperty('minecraftVersion').getOrElse(rootProperties.getProperty('minecraftVersion', '26.2'))
 String neoForgeVersion = providers.gradleProperty('neoForgeVersion').getOrElse(rootProperties.getProperty('neoForgeVersion', '26.2.0.59'))
-String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate').getOrElse(rootProperties.getProperty('volmLibCoordinate', 'com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522'))
+String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate').getOrElse(rootProperties.getProperty('volmLibCoordinate', 'com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186'))
 Closure<String> irisArtifactName = { String platform, String targetVersion ->
     return "Iris v${project.version} [${platform}] ${targetVersion}.jar"
 }

build.gradle

@@ -54,7 +54,7 @@ String fabricLoaderVersion = providers.gradleProperty('fabricLoaderVersion').get
 String forgeVersion = providers.gradleProperty('forgeVersion').getOrElse('26.2-65.1.1')
 String neoForgeVersion = providers.gradleProperty('neoForgeVersion').getOrElse('26.2.0.59')
 String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate')
-    .orElse('com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522')
+    .orElse('com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186')
     .get()
 String useLocalVolmLib = providers.gradleProperty('useLocalVolmLib').getOrElse('true')
 String localVolmLibDirectory = providers.gradleProperty('localVolmLibDirectory').getOrNull()

core/build.gradle

@@ -37,7 +37,7 @@ plugins {
 
 def lib = 'art.arcane.iris.util'
 String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate')
-    .orElse('com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522')
+    .orElse('com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186')
     .get()
 String sentryAuthToken = findProperty('sentry.auth.token') as String ?: System.getenv('SENTRY_AUTH_TOKEN')
 boolean hasSentryAuthToken = sentryAuthToken != null && !sentryAuthToken.isBlank()

core/purity-allowlist.txt

@@ -63,7 +63,6 @@ art/arcane/iris/core/service/ExternalDataSVC.java
 art/arcane/iris/core/service/GlobalCacheSVC.java
 art/arcane/iris/core/service/JigsawStudioMarkerParser.java
 art/arcane/iris/core/service/JigsawStudioMenuController.java
-art/arcane/iris/core/service/JigsawStudioBoundsRenderer.java
 art/arcane/iris/core/service/JigsawStudioPreviewRenderer.java
 art/arcane/iris/core/service/JigsawStudioService.java
 art/arcane/iris/core/service/JigsawStudioToolCodec.java

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

@@ -30,6 +30,8 @@ import lombok.Data;
 
 import java.io.File;
 import java.io.IOException;
+import java.util.Objects;
+import java.util.function.Predicate;
 
 @Data
 public class IrisSettings {
@@ -136,6 +138,46 @@ public class IrisSettings {
         }
     }
 
+    public static IrisSettings installHotloadSnapshot(String rawJson) {
+        IrisSettings parsed = parseHotloadSnapshot(rawJson);
+        synchronized (SETTINGS_LOCK) {
+            settings = parsed;
+        }
+        return parsed;
+    }
+
+    public static boolean applyHotloadSnapshot(String rawJson, Predicate<IrisSettings> candidateActivation) {
+        Objects.requireNonNull(candidateActivation, "candidateActivation");
+        IrisSettings parsed = parseHotloadSnapshot(rawJson);
+        if (!candidateActivation.test(parsed)) {
+            return false;
+        }
+        synchronized (SETTINGS_LOCK) {
+            settings = parsed;
+        }
+        return true;
+    }
+
+    public static IrisSettings parseHotloadSnapshot(String rawJson) {
+        if (rawJson == null || rawJson.isBlank()) {
+            throw new IllegalArgumentException("Iris settings snapshot is empty");
+        }
+
+        IrisSettings parsed;
+        try {
+            parsed = new Gson().fromJson(rawJson, IrisSettings.class);
+            if (parsed == null) {
+                throw new IllegalArgumentException("Iris settings snapshot did not contain an object");
+            }
+            migrateLegacyKeys(parsed, rawJson);
+        } catch (RuntimeException failure) {
+            throw new IllegalArgumentException("Iris settings snapshot is invalid", failure);
+        }
+
+        parsed.fillMissingSections();
+        return parsed;
+    }
+
     public void forceSave() {
         File s = IrisPlatforms.get().dataFile("settings.json");
 
@@ -147,6 +189,20 @@ public class IrisSettings {
         }
     }
 
+    private void fillMissingSections() {
+        general = general == null ? new IrisSettingsGeneral() : general;
+        world = world == null ? new IrisSettingsWorld() : world;
+        gui = gui == null ? new IrisSettingsGUI() : gui;
+        autoConfiguration = autoConfiguration == null ? new IrisSettingsAutoconfiguration() : autoConfiguration;
+        generator = generator == null ? new IrisSettingsGenerator() : generator;
+        concurrency = concurrency == null ? new IrisSettingsConcurrency() : concurrency;
+        studio = studio == null ? new IrisSettingsStudio() : studio;
+        performance = performance == null ? new IrisSettingsPerformance() : performance;
+        pregen = pregen == null ? new IrisSettingsPregen() : pregen;
+        sentry = sentry == null ? new IrisSettingsSentry() : sentry;
+        treeFeller = treeFeller == null ? new IrisSettingsTreeFeller() : treeFeller;
+    }
+
     @Data
     public static class IrisSettingsAutoconfiguration {
         public boolean configureSpigotTimeoutTime = true;
@@ -273,6 +329,11 @@ public class IrisSettings {
         public boolean splashLogoStartup = true;
         public boolean useConsoleCustomColors = true;
         public boolean useCustomColorsIngame = true;
+        /**
+         * Boss bar progress loaders for jobs, studio opens, world creation, chunk jobs and pack
+         * downloads. Turning this off keeps the action bar progress line; only the bar goes away.
+         */
+        public boolean progressBossBar = true;
         public boolean adjustVanillaHeight = false;
         public boolean autoIngestDatapacks = true;
         /**

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

@@ -28,19 +28,32 @@ import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
+import java.nio.ByteBuffer;
+import java.nio.charset.CharacterCodingException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
+import java.util.HexFormat;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.regex.Pattern;
 
 public final class IrisLanguage {
     private static final long MAX_LOCALE_BYTES = 2L * 1024L * 1024L;
+    private static final long HOTLOAD_CONTENT_STABILITY_NANOS = TimeUnit.MILLISECONDS.toNanos(250L);
+    private static final long HOTLOAD_DELETION_GRACE_NANOS = TimeUnit.SECONDS.toNanos(3L);
+    private static final long HOTLOAD_COOLDOWN_NANOS = TimeUnit.SECONDS.toNanos(3L);
     private static final int MAX_REPORTED_ISSUES = 12;
     private static final Pattern LOCALE_NAME = Pattern.compile("[A-Za-z0-9_-]+");
     private static final Pattern LEGACY_COLOR = Pattern.compile("(?i)\\u00a7[0-9A-FK-ORX]");
@@ -55,10 +68,17 @@ public final class IrisLanguage {
      * new snapshot and the whole memo is discarded. Bounded by the catalog size.
      */
     private static final AtomicReference<PlainMemo> PLAIN_MEMO = new AtomicReference<>(null);
+    private static final LocaleHotloadGate HOTLOAD_GATE = new LocaleHotloadGate(
+            new LocaleHotloadGate.Timing(
+                    HOTLOAD_CONTENT_STABILITY_NANOS,
+                    HOTLOAD_DELETION_GRACE_NANOS,
+                    HOTLOAD_COOLDOWN_NANOS
+            )
+    );
 
     private static volatile File dataFolder;
-    private static volatile File watchedFile;
-    private static volatile long watchedSignature = Long.MIN_VALUE;
+    private static volatile String lastCaptureFailureKey;
+    private static volatile String lastInvalidHotloadLocale;
     private static volatile String activeLocale = CATALOG.englishLocale();
 
     private IrisLanguage() {
@@ -82,6 +102,20 @@ public final class IrisLanguage {
         return reload(root, configuredLocale());
     }
 
+    public static synchronized boolean reload(IrisSettings candidate) {
+        IrisSettings resolvedCandidate = Objects.requireNonNull(candidate, "Candidate settings cannot be null");
+        File root = dataFolder;
+        if (root == null && IrisPlatforms.isBound()) {
+            root = IrisPlatforms.get().dataFolder();
+        }
+        if (root == null) {
+            return false;
+        }
+        IrisSettings.IrisSettingsGeneral general = resolvedCandidate.getGeneral();
+        String locale = general == null ? CATALOG.englishLocale() : general.getLanguage();
+        return reload(root, locale);
+    }
+
     public static synchronized boolean reload(File root, String locale) {
         File resolvedRoot = root == null ? null : root.getAbsoluteFile();
         if (resolvedRoot == null) {
@@ -92,16 +126,26 @@ public final class IrisLanguage {
             requestedLocale = normalizeLocale(locale);
         } catch (RuntimeException exception) {
             dataFolder = resolvedRoot;
+            HOTLOAD_GATE.reset(null);
             IrisLogging.error("Rejected locale setting '" + locale + "'; continuing with " + activeLocale + ".");
             IrisLogging.reportError(exception);
             exception.printStackTrace();
             return false;
         }
-        LocalizationReloadResult result = MANAGER.reload(() -> loadCandidate(resolvedRoot, requestedLocale));
-        dataFolder = resolvedRoot;
+
         File override = overrideFile(resolvedRoot, requestedLocale);
-        watchedFile = override;
-        watchedSignature = signature(override);
+        SnapshotCapture capture = captureForReload(override, requestedLocale);
+        LocalizationReloadResult result;
+        if (capture.failure() == null) {
+            result = MANAGER.reload(() -> loadCandidate(resolvedRoot, requestedLocale, capture.snapshot()));
+        } else {
+            result = MANAGER.reload(() -> {
+                throw capture.failure();
+            });
+        }
+        dataFolder = resolvedRoot;
+        HOTLOAD_GATE.reset(capture.snapshot());
+        lastCaptureFailureKey = null;
         if (!result.applied()) {
             reportRejectedReload(requestedLocale, result);
             return false;
@@ -123,14 +167,47 @@ public final class IrisLanguage {
         try {
             locale = normalizeLocale(configuredLocale());
         } catch (RuntimeException exception) {
-            return reload(root, configuredLocale());
+            String invalidLocale = configuredLocale();
+            if (Objects.equals(lastInvalidHotloadLocale, invalidLocale)) {
+                return false;
             }
+            lastInvalidHotloadLocale = invalidLocale;
+            return reload(root, invalidLocale);
+        }
+        lastInvalidHotloadLocale = null;
         File expected = overrideFile(root, locale);
-        long signature = signature(expected);
-        if (expected.equals(watchedFile) && signature == watchedSignature) {
+        LocaleHotloadSnapshot snapshot;
+        try {
+            snapshot = captureHotloadSnapshot(expected, locale);
+        } catch (IOException | RuntimeException failure) {
+            HOTLOAD_GATE.unavailable();
+            reportCaptureFailure(expected, failure);
+            return false;
+        }
+        if (snapshot == null) {
+            HOTLOAD_GATE.unavailable();
             return true;
         }
-        return reload(root, locale);
+        lastCaptureFailureKey = null;
+
+        LocaleHotloadGate.Attempt attempt = HOTLOAD_GATE.observe(snapshot, System.nanoTime());
+        if (attempt == null) {
+            return true;
+        }
+
+        LocalizationReloadResult result = MANAGER.reload(() -> loadCandidate(root, locale, attempt.snapshot()));
+        boolean applied = result.applied();
+        HOTLOAD_GATE.complete(attempt, System.nanoTime(), applied);
+        if (!applied) {
+            reportRejectedReload(locale, result);
+            return false;
+        }
+
+        activeLocale = locale;
+        int warnings = result.validation().warnings().size();
+        IrisLogging.info("Loaded locale " + locale + " with " + warnings + " fallback "
+                + (warnings == 1 ? "entry" : "entries") + ".");
+        return true;
     }
 
     public static String activeLocale() {
@@ -229,13 +306,16 @@ public final class IrisLanguage {
         throw new IllegalArgumentException("Unsupported Iris message key: " + key.id());
     }
 
-    private static LocalizationCandidate loadCandidate(File root, String locale) throws Exception {
+    private static LocalizationCandidate loadCandidate(
+            File root,
+            String locale,
+            LocaleHotloadSnapshot snapshot
+    ) throws Exception {
         File folder = new File(root, "languages/overrides");
         Files.createDirectories(folder.toPath());
         List<LocaleOverlay> overlays = new ArrayList<>(2);
-        File override = overrideFile(root, locale);
-        if (override.exists()) {
-            overlays.add(loadFileOverlay(override, locale));
+        if (!snapshot.missing()) {
+            overlays.add(parseOverlay(snapshot.file().getPath(), locale, snapshot.content()));
         }
 
         if (!CATALOG.englishLocale().equals(locale)) {
@@ -269,17 +349,6 @@ public final class IrisLanguage {
         }
     }
 
-    private static LocaleOverlay loadFileOverlay(File override, String locale) throws Exception {
-        if (!override.isFile()) {
-            throw new IllegalArgumentException("Locale override is not a regular file: " + override.getPath());
-        }
-        if (override.length() > MAX_LOCALE_BYTES) {
-            throw new IllegalArgumentException("Locale override is too large: " + override.getPath());
-        }
-        String raw = Files.readString(override.toPath(), StandardCharsets.UTF_8);
-        return parseOverlay(override.getPath(), locale, raw);
-    }
-
     private static LocaleOverlay parseOverlay(String source, String locale, String raw) {
         JsonElement parsed = JsonParser.parseString(raw == null || raw.isBlank() ? "{}" : raw);
         if (!parsed.isJsonObject()) {
@@ -461,11 +530,92 @@ public final class IrisLanguage {
         return new File(new File(root, "languages/overrides"), normalizeLocale(locale) + ".json").getAbsoluteFile();
     }
 
-    private static long signature(File file) {
-        if (file == null || !file.exists()) {
-            return 0L;
+    static LocaleHotloadSnapshot captureHotloadSnapshot(File file, String locale) throws IOException {
+        File resolvedFile = Objects.requireNonNull(file, "Locale override file cannot be null").getAbsoluteFile();
+        String resolvedLocale = normalizeLocale(locale);
+        BasicFileAttributes before;
+        try {
+            before = Files.readAttributes(resolvedFile.toPath(), BasicFileAttributes.class);
+        } catch (NoSuchFileException failure) {
+            return LocaleHotloadSnapshot.missing(resolvedFile, resolvedLocale);
         }
-        return file.lastModified() * 31L + file.length();
+        if (!before.isRegularFile()) {
+            throw new IllegalArgumentException("Locale override is not a regular file: " + resolvedFile.getPath());
+        }
+        if (before.size() > MAX_LOCALE_BYTES) {
+            throw new IllegalArgumentException("Locale override is too large: " + resolvedFile.getPath());
+        }
+
+        byte[] bytes;
+        try (InputStream input = Files.newInputStream(resolvedFile.toPath())) {
+            bytes = input.readNBytes((int) MAX_LOCALE_BYTES + 1);
+        } catch (NoSuchFileException failure) {
+            return null;
+        }
+        if (bytes.length > MAX_LOCALE_BYTES) {
+            throw new IllegalArgumentException("Locale override is too large: " + resolvedFile.getPath());
+        }
+
+        BasicFileAttributes after;
+        try {
+            after = Files.readAttributes(resolvedFile.toPath(), BasicFileAttributes.class);
+        } catch (NoSuchFileException failure) {
+            return null;
+        }
+        if (!sameIdentity(before, after) || bytes.length != after.size()) {
+            return null;
+        }
+
+        String content;
+        try {
+            content = StandardCharsets.UTF_8.newDecoder().decode(ByteBuffer.wrap(bytes)).toString();
+        } catch (CharacterCodingException failure) {
+            throw new IOException("Locale override is not valid UTF-8: " + resolvedFile.getPath(), failure);
+        }
+        return LocaleHotloadSnapshot.present(resolvedFile, resolvedLocale, content, sha256(bytes));
+    }
+
+    private static SnapshotCapture captureForReload(File file, String locale) {
+        try {
+            LocaleHotloadSnapshot snapshot = captureHotloadSnapshot(file, locale);
+            if (snapshot == null) {
+                return new SnapshotCapture(
+                        null,
+                        new IOException("Locale override changed while being read: " + file.getPath())
+                );
+            }
+            return new SnapshotCapture(snapshot, null);
+        } catch (Exception failure) {
+            return new SnapshotCapture(null, failure);
+        }
+    }
+
+    private static boolean sameIdentity(BasicFileAttributes before, BasicFileAttributes after) {
+        return before.isRegularFile() == after.isRegularFile()
+                && before.size() == after.size()
+                && before.lastModifiedTime().equals(after.lastModifiedTime())
+                && Objects.equals(before.fileKey(), after.fileKey());
+    }
+
+    private static String sha256(byte[] content) {
+        try {
+            MessageDigest digest = MessageDigest.getInstance("SHA-256");
+            return HexFormat.of().formatHex(digest.digest(content));
+        } catch (NoSuchAlgorithmException failure) {
+            throw new IllegalStateException("SHA-256 is unavailable", failure);
+        }
+    }
+
+    private static void reportCaptureFailure(File file, Exception failure) {
+        String detail = failure.getMessage() == null ? failure.getClass().getSimpleName() : failure.getMessage();
+        String failureKey = file.getAbsolutePath() + ":" + failure.getClass().getName() + ":" + detail;
+        if (Objects.equals(failureKey, lastCaptureFailureKey)) {
+            return;
+        }
+        lastCaptureFailureKey = failureKey;
+        IrisLogging.error("Failed to capture stable locale override " + file.getPath() + ": " + detail);
+        IrisLogging.reportError(failure);
+        failure.printStackTrace();
     }
 
     private static void reportRejectedReload(String locale, LocalizationReloadResult result) {
@@ -489,4 +639,7 @@ public final class IrisLanguage {
 
     private record PlainMemo(LocalizationSnapshot snapshot, Map<String, String> values) {
     }
+
+    private record SnapshotCapture(LocaleHotloadSnapshot snapshot, Exception failure) {
+    }
 }

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

@@ -0,0 +1,100 @@
+package art.arcane.iris.core.localization;
+
+import java.util.Objects;
+
+final class LocaleHotloadGate {
+    private final Timing timing;
+
+    private long generation;
+    private LocaleHotloadSnapshot baseline;
+    private LocaleHotloadSnapshot observed;
+    private long observedSinceNanos;
+    private LocaleHotloadSnapshot pending;
+    private Attempt inFlight;
+    private long lastCompletedAtNanos;
+    private boolean hasCompleted;
+
+    LocaleHotloadGate(Timing timing) {
+        this.timing = Objects.requireNonNull(timing, "Locale hotload timing cannot be null");
+    }
+
+    synchronized Attempt observe(LocaleHotloadSnapshot snapshot, long nowNanos) {
+        LocaleHotloadSnapshot current = Objects.requireNonNull(snapshot, "Locale hotload snapshot cannot be null");
+        if (!current.equals(observed)) {
+            observed = current;
+            observedSinceNanos = nowNanos;
+            return null;
+        }
+
+        long stabilityNanos = current.missing()
+                ? timing.deletionGraceNanos()
+                : timing.contentStabilityNanos();
+        if (!elapsed(nowNanos, observedSinceNanos, stabilityNanos)) {
+            return null;
+        }
+
+        pending = current.equals(baseline) ? null : current;
+        if (pending == null || inFlight != null || !pending.equals(observed)) {
+            return null;
+        }
+        if (hasCompleted && !elapsed(nowNanos, lastCompletedAtNanos, timing.cooldownNanos())) {
+            return null;
+        }
+
+        Attempt attempt = new Attempt(generation, pending);
+        inFlight = attempt;
+        return attempt;
+    }
+
+    synchronized void unavailable() {
+        observed = null;
+        observedSinceNanos = 0L;
+    }
+
+    synchronized void complete(Attempt attempt, long nowNanos, boolean applied) {
+        if (attempt == null || inFlight == null || !inFlight.equals(attempt) || attempt.generation() != generation) {
+            return;
+        }
+
+        inFlight = null;
+        lastCompletedAtNanos = nowNanos;
+        hasCompleted = true;
+        if (!applied) {
+            return;
+        }
+
+        baseline = attempt.snapshot();
+        if (attempt.snapshot().equals(pending)) {
+            pending = null;
+        }
+    }
+
+    synchronized void reset(LocaleHotloadSnapshot snapshot) {
+        generation++;
+        baseline = snapshot;
+        observed = snapshot;
+        observedSinceNanos = 0L;
+        pending = null;
+        inFlight = null;
+        lastCompletedAtNanos = 0L;
+        hasCompleted = false;
+    }
+
+    private boolean elapsed(long nowNanos, long startNanos, long durationNanos) {
+        return nowNanos - startNanos >= durationNanos;
+    }
+
+    record Timing(long contentStabilityNanos, long deletionGraceNanos, long cooldownNanos) {
+        Timing {
+            if (contentStabilityNanos < 0L || deletionGraceNanos < 0L || cooldownNanos < 0L) {
+                throw new IllegalArgumentException("Locale hotload timing cannot be negative");
+            }
+        }
+    }
+
+    record Attempt(long generation, LocaleHotloadSnapshot snapshot) {
+        Attempt {
+            snapshot = Objects.requireNonNull(snapshot, "Locale hotload attempt snapshot cannot be null");
+        }
+    }
+}

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

@@ -0,0 +1,29 @@
+package art.arcane.iris.core.localization;
+
+import java.io.File;
+import java.util.Objects;
+
+record LocaleHotloadSnapshot(File file, String locale, String content, String sha256) {
+    LocaleHotloadSnapshot {
+        file = Objects.requireNonNull(file, "Locale override file cannot be null").getAbsoluteFile();
+        locale = Objects.requireNonNull(locale, "Locale cannot be null");
+        sha256 = Objects.requireNonNull(sha256, "Locale content hash cannot be null");
+    }
+
+    static LocaleHotloadSnapshot missing(File file, String locale) {
+        return new LocaleHotloadSnapshot(file, locale, null, "missing");
+    }
+
+    static LocaleHotloadSnapshot present(File file, String locale, String content, String sha256) {
+        return new LocaleHotloadSnapshot(
+                file,
+                locale,
+                Objects.requireNonNull(content, "Locale content cannot be null"),
+                sha256
+        );
+    }
+
+    boolean missing() {
+        return content == null;
+    }
+}

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

@@ -19,6 +19,7 @@
 package art.arcane.iris.core.project;
 
 import art.arcane.iris.core.localization.BukkitRuntimeMessages;
+import art.arcane.iris.core.IrisSettings;
 import art.arcane.iris.core.localization.IrisLanguage;
 import art.arcane.iris.core.localization.RuntimeProgressMessages;
 import art.arcane.iris.util.common.format.C;
@@ -46,7 +47,8 @@ final class StudioOpenProgressReporter {
         AtomicInteger taskId = new AtomicInteger(-1);
         org.bukkit.boss.BossBar bossBar;
 
-        if (sender.isPlayer() && sender.player() != null) {
+        if (sender.isPlayer() && sender.player() != null
+                && IrisSettings.get().getGeneral().isProgressBossBar()) {
             bossBar = Bukkit.createBossBar(
                     IrisLanguage.text(RuntimeProgressMessages.STUDIO_OPENING),
                     org.bukkit.boss.BarColor.BLUE,

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

@@ -18,6 +18,7 @@
 
 package art.arcane.iris.core.runtime;
 
+import art.arcane.iris.core.IrisSettings;
 import art.arcane.iris.core.localization.IrisLanguage;
 import art.arcane.iris.core.localization.RuntimeProgressMessages;
 import art.arcane.iris.spi.IrisLogging;
@@ -109,8 +110,9 @@ public final class ChunkJobReporter {
     }
 
     private void startReporter() {
-        boolean player = sender.isPlayer() && sender.player() != null;
-        BossBar bossBar = player
+        boolean showBossBar = sender.isPlayer() && sender.player() != null
+                && IrisSettings.get().getGeneral().isProgressBossBar();
+        BossBar bossBar = showBossBar
                 ? Bukkit.createBossBar(IrisLanguage.text(
                         RuntimeProgressMessages.CHUNK_BOSSBAR_WORKING,
                         MessageArgument.trusted("title", title)

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

@@ -1,5 +1,6 @@
 package art.arcane.iris.core.service;
 
+import art.arcane.iris.core.IrisSettings;
 import art.arcane.iris.core.localization.IrisLanguage;
 import art.arcane.iris.core.localization.PackDownloadMessages;
 import art.arcane.iris.core.pack.PackDownloader;
@@ -246,6 +247,7 @@ final class PackDownloadProgressReporter implements PackDownloader.DownloadProgr
 
     private void renderHudPulse(HudSnapshot snapshot) {
         try {
+            if (IrisSettings.get().getGeneral().isProgressBossBar()) {
                 BukkitPlatform.hudLanes().show(
                         player,
                         hudLaneId,
@@ -255,6 +257,7 @@ final class PackDownloadProgressReporter implements PackDownloader.DownloadProgr
                         BarStyle.SEGMENTED_20,
                         1_500L
                 );
+            }
             sender.sendAction(snapshot.line());
         } catch (RuntimeException failure) {
             disableHud(failure);
@@ -310,6 +313,7 @@ final class PackDownloadProgressReporter implements PackDownloader.DownloadProgr
         Runnable retiredCleanup = () -> retireHudLane(cleaned);
         Runnable display = () -> {
             try {
+                if (IrisSettings.get().getGeneral().isProgressBossBar()) {
                     BukkitPlatform.hudLanes().show(
                             player,
                             hudLaneId,
@@ -319,6 +323,7 @@ final class PackDownloadProgressReporter implements PackDownloader.DownloadProgr
                             BarStyle.SOLID,
                             4_000L
                     );
+                }
                 sender.sendAction(message);
             } finally {
                 if (!J.runEntity(player, cleanup, HUD_TERMINAL_TICKS, retiredCleanup)) {

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

@@ -488,33 +488,50 @@ public class StudioSVC implements IrisService {
         }
     }
 
-    private static boolean blockIfPackBroken(VolmitSender sender, String dimm) {
+    private static BrokenPackException reportPackAdmissionFailure(
+            VolmitSender sender, String dimm) {
         Optional<String> startupDenial = IrisStartupValidation.denialReason();
-        if (startupDenial.isPresent()) {
-            sender.sendMessage(startupDenial.get());
-            return true;
-        }
         IrisDimension dimension = IrisToolbelt.getDimension(dimm);
         String packName = dimension == null || dimension.getLoader() == null
                 ? dimm
                 : dimension.getLoader().getDataFolder().getName();
         PackValidationResult validation = PackValidationRegistry.get(packName);
-        if (validation != null && validation.isLoadable()) {
-            return false;
+        BrokenPackException failure = resolvePackAdmissionFailure(
+                packName, startupDenial, validation);
+        if (failure == null) {
+            return null;
+        }
+        if (startupDenial.isPresent()) {
+            sender.sendMessage(startupDenial.get());
+            return failure;
         }
         sender.sendMessage(IrisLanguage.text(BukkitRuntimeMessages.STUDIO_S_V_C_CANNOT_OPEN_STUDIO_PACK_HAS_BLOCKING_ERRORS, MessageArgument.untrusted("dimm", String.valueOf(dimm))));
+        for (String reason : failure.getReasons()) {
+            sender.sendMessage(IrisLanguage.text(BukkitRuntimeMessages.STUDIO_S_V_C_MESSAGE, MessageArgument.untrusted("reason", String.valueOf(reason))));
+        }
+        sender.sendMessage(IrisLanguage.text(BukkitRuntimeMessages.STUDIO_S_V_C_FIX_PACK_RUN_IRIS_PACK_VALIDATE_REVALIDATE, MessageArgument.untrusted("dimm", String.valueOf(packName))));
+        return failure;
+    }
+
+    static BrokenPackException resolvePackAdmissionFailure(
+            String packName,
+            Optional<String> startupDenial,
+            PackValidationResult validation
+    ) {
+        if (startupDenial.isPresent()) {
+            return new BrokenPackException(packName, List.of(startupDenial.get()));
+        }
+        if (validation != null && validation.isLoadable()) {
+            return null;
+        }
         List<String> failures = validation == null
                 ? List.of("Required pack validation has not completed. Studio creation fails closed until validation succeeds.")
                 : validation.getBlockingErrors();
-        for (String reason : failures) {
-            sender.sendMessage(IrisLanguage.text(BukkitRuntimeMessages.STUDIO_S_V_C_MESSAGE, MessageArgument.untrusted("reason", String.valueOf(reason))));
-        }
-        sender.sendMessage(IrisLanguage.text(BukkitRuntimeMessages.STUDIO_S_V_C_FIX_PACK_RUN_IRIS_PACK_VALIDATE_REVALIDATE, MessageArgument.untrusted("dimm", String.valueOf(dimm))));
-        return true;
+        return new BrokenPackException(packName, failures);
     }
 
     public void open(VolmitSender sender, long seed, String dimm, Consumer<World> onDone) throws IrisException {
-        if (blockIfPackBroken(sender, dimm)) {
+        if (reportPackAdmissionFailure(sender, dimm) != null) {
             return;
         }
         studioTransitions.submit(() -> replaceActiveProject(sender, seed, dimm, onDone))
@@ -537,9 +554,9 @@ public class StudioSVC implements IrisService {
             Runnable beforeOpen,
             Consumer<World> onDone
     ) {
-        if (blockIfPackBroken(sender, dimension)) {
-            return CompletableFuture.failedFuture(
-                    new IllegalStateException("Studio pack '" + dimension + "' has blocking validation errors."));
+        BrokenPackException failure = reportPackAdmissionFailure(sender, dimension);
+        if (failure != null) {
+            return CompletableFuture.failedFuture(failure);
         }
         return studioTransitions.submit(() -> replaceActiveProjectTracked(
                 sender,

core/src/main/java/art/arcane/iris/core/structure/VillageImporter.java

@@ -426,7 +426,7 @@ public final class VillageImporter {
                     emittedPools.size(), emittedPieces.size(), losses, true);
         }
 
-        String msg = "Imported village " + structureKey + " as '" + name + "': " + emittedPieces.size() + " pieces, " + emittedPools.size() + " pools, " + pieceBlocks + " blocks";
+        String msg = "Imported jigsaw structure " + structureKey + " as '" + name + "': " + emittedPieces.size() + " pieces, " + emittedPools.size() + " pools, " + pieceBlocks + " blocks";
         if (!losses.isEmpty()) {
             msg += " (" + losses.size() + " fidelity warning(s) recorded)";
         }

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

@@ -624,11 +624,13 @@ public class IrisCreator {
                 return;
             }
             if (showLoaderHud) {
+                if (IrisSettings.get().getGeneral().isProgressBossBar()) {
                     BukkitPlatform.hudLanes().show(sender.player(), "iris:pregen", IrisLanguage.text(
                             RuntimeProgressMessages.WORLD_PREGEN_ACTION,
                             MessageArgument.trusted("bar", ""),
                             MessageArgument.trusted("percent", percent)
                     ), p, BarColor.GREEN, BarStyle.SOLID, 4000L);
+                }
                 int barWidth = 44;
                 int filled = (int) Math.round(Math.max(0.0D, Math.min(1.0D, p)) * barWidth);
                 StringBuilder bar = new StringBuilder(barWidth * 3 + 4);

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

@@ -18,6 +18,7 @@
 
 package art.arcane.iris.core.tools;
 
+import art.arcane.iris.core.IrisSettings;
 import art.arcane.iris.core.localization.IrisLanguage;
 import art.arcane.iris.core.localization.RuntimeProgressMessages;
 import art.arcane.iris.spi.IrisLogging;
@@ -78,7 +79,8 @@ final class WorldCreationProgressReporter {
 
     static WorldCreationProgressReporter start(VolmitSender sender, String worldName) {
         WorldCreationProgressReporter reporter = new WorldCreationProgressReporter(sender, worldName);
-        if (sender.isPlayer() && sender.player() != null) {
+        if (sender.isPlayer() && sender.player() != null
+                && IrisSettings.get().getGeneral().isProgressBossBar()) {
             try {
                 J.sfut(reporter::initializePlayerHud).get(5L, TimeUnit.SECONDS);
             } catch (Throwable failure) {

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

@@ -281,8 +281,8 @@ public final class IrisObjectIO {
         AtomicReference<IOException> ref = new AtomicReference<>();
         CountDownLatch latch = new CountDownLatch(1);
         new Job() {
-            private int total = self.blocks.size() * 3 + self.states.size();
-            private int c = 0;
+            private volatile int total = self.blocks.size() * 3 + self.states.size();
+            private volatile int c = 0;
 
             @Override
             public String getName() {

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

@@ -147,7 +147,7 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
         this.dimensionKey = dimensionKey;
         this.folder = new ReactiveFolder(
                 dataLocation,
-                (_a, _b, _c) -> hotload(),
+                (_a, _b, _c) -> hotloadFromWatcher(),
                 new KList<>(".iob", ".json"),
                 new KList<>(".iris"),
                 new KList<>()
@@ -542,6 +542,13 @@ public class BukkitChunkGenerator extends ChunkGenerator implements PlatformChun
         withExclusiveControl(() -> getEngine().hotload());
     }
 
+    private void hotloadFromWatcher() {
+        if (!shouldRunStudioHotload(isStudio(), closing, jigsawStudioActive)) {
+            return;
+        }
+        withExclusiveControlFuture(() -> getEngine().hotload(), 30L, TimeUnit.SECONDS).join();
+    }
+
     @Override
     public CompletableFuture<Void> hotloadComplexAsync(long acquisitionTimeout, TimeUnit unit) {
         Engine activeEngine = getEngine();

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

@@ -18,6 +18,7 @@
 
 package art.arcane.iris.platform.bukkit;
 
+import art.arcane.iris.core.IrisSettings;
 import art.arcane.iris.core.nms.INMS;
 import art.arcane.iris.core.nms.MinecraftVersion;
 import art.arcane.iris.engine.object.IrisPosition;
@@ -161,6 +162,9 @@ public final class BukkitPlatform implements IrisPlatform {
     }
 
     public static void showProgressLane(Player player, String laneId, String title, double progress, long staleMillis) {
+        if (!IrisSettings.get().getGeneral().isProgressBossBar()) {
+            return;
+        }
         hudLanes().show(player, laneId, title, progress, BarColor.BLUE, BarStyle.SOLID, staleMillis);
     }
 

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

@@ -30,8 +30,8 @@ import java.net.URI;
 
 public class DownloadJob implements Job {
     private final DL.Download download;
-    private int tw;
-    private int cw;
+    private volatile int tw;
+    private volatile int cw;
 
     public DownloadJob(String url, File destination) throws MalformedURLException {
         tw = 1;

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

@@ -23,7 +23,7 @@ import art.arcane.volmlib.util.collection.KList;
 public class JobCollection implements Job {
     private final String name;
     private final KList<Job> jobs;
-    private String status;
+    private volatile String status;
 
     public JobCollection(String name, Job... jobs) {
         this(name, new KList<>(jobs));

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

@@ -25,7 +25,7 @@ import java.util.concurrent.atomic.AtomicInteger;
 public abstract class QueueJob<T> implements Job {
     final KList<T> queue;
     private final AtomicInteger completed;
-    protected int totalWork;
+    protected volatile int totalWork;
 
     public QueueJob() {
         totalWork = 0;

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

@@ -21,7 +21,7 @@ package art.arcane.iris.util.common.scheduling.jobs;
 public class SingleJob implements Job {
     private final String name;
     private final Runnable runnable;
-    private boolean done;
+    private volatile boolean done;
 
     public SingleJob(String name, Runnable runnable) {
         this.name = name;

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

@@ -6,7 +6,10 @@ import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertThrows;
 
 public class IrisSettingsDefaultsTest {
     @Test
@@ -34,4 +37,64 @@ public class IrisSettingsDefaultsTest {
         assertTrue(settings.isAutoIngestDatapacks());
         assertFalse(settings.isAutoImportDatapackStructures());
     }
+
+    @Test
+    public void hotloadSnapshotIsValidatedBeforeReplacingLiveSettings() {
+        IrisSettings previous = IrisSettings.settings;
+        IrisSettings live = new IrisSettings();
+        IrisSettings.settings = live;
+        try {
+            assertThrows(IllegalArgumentException.class,
+                    () -> IrisSettings.installHotloadSnapshot("{\"general\":"));
+            assertSame(live, IrisSettings.settings);
+
+            IrisSettings installed = IrisSettings.installHotloadSnapshot(
+                    "{\"general\":{\"language\":\"fr_FR\"},\"world\":null}");
+            assertSame(installed, IrisSettings.settings);
+            assertEquals("fr_FR", installed.getGeneral().getLanguage());
+            assertNotNull(installed.getWorld());
+        } finally {
+            IrisSettings.settings = previous;
+        }
+    }
+
+    @Test
+    public void rejectedHotloadActivationKeepsPreviousLiveSettings() {
+        IrisSettings previous = IrisSettings.settings;
+        IrisSettings live = new IrisSettings();
+        live.getGeneral().setLanguage("en_US");
+        IrisSettings.settings = live;
+        try {
+            boolean applied = IrisSettings.applyHotloadSnapshot(
+                    "{\"general\":{\"language\":\"de_DE\"}}",
+                    candidate -> false
+            );
+
+            assertFalse(applied);
+            assertSame(live, IrisSettings.settings);
+            assertEquals("en_US", IrisSettings.settings.getGeneral().getLanguage());
+        } finally {
+            IrisSettings.settings = previous;
+        }
+    }
+
+    @Test
+    public void successfulHotloadActivationPublishesCandidateSettings() {
+        IrisSettings previous = IrisSettings.settings;
+        IrisSettings live = new IrisSettings();
+        IrisSettings.settings = live;
+        try {
+            boolean applied = IrisSettings.applyHotloadSnapshot(
+                    "{\"general\":{\"language\":\"de_DE\"},\"world\":null}",
+                    candidate -> "de_DE".equals(candidate.getGeneral().getLanguage())
+            );
+
+            assertTrue(applied);
+            assertNotSame(live, IrisSettings.settings);
+            assertEquals("de_DE", IrisSettings.settings.getGeneral().getLanguage());
+            assertNotNull(IrisSettings.settings.getWorld());
+        } finally {
+            IrisSettings.settings = previous;
+        }
+    }
 }

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

@@ -0,0 +1,89 @@
+package art.arcane.iris.core;
+
+import art.arcane.iris.platform.bukkit.BukkitPlatform;
+import org.junit.Test;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
+
+public class ProgressBossBarToggleTest {
+    @Test
+    public void progressBossBarsAreEnabledByDefault() {
+        assertTrue(new IrisSettings.IrisSettingsGeneral().isProgressBossBar());
+    }
+
+    @Test
+    public void showProgressLaneNeverTouchesTheLaneServiceWhenDisabled() {
+        withProgressBossBar(false, () ->
+                BukkitPlatform.showProgressLane(null, "iris:job", "Working", 0.5D, 4000L));
+    }
+
+    @Test
+    public void showProgressLaneStillReachesTheLaneServiceWhenEnabled() {
+        withProgressBossBar(true, () -> assertThrows(IllegalStateException.class,
+                () -> BukkitPlatform.showProgressLane(null, "iris:job", "Working", 0.5D, 4000L)));
+    }
+
+    @Test
+    public void studioOpenBossBarIsGatedBySettings() throws Exception {
+        assertGated("core/project/StudioOpenProgressReporter.java");
+    }
+
+    @Test
+    public void worldCreationBossBarIsGatedBySettings() throws Exception {
+        assertGated("core/tools/WorldCreationProgressReporter.java");
+    }
+
+    @Test
+    public void chunkJobBossBarIsGatedBySettings() throws Exception {
+        assertGated("core/runtime/ChunkJobReporter.java");
+    }
+
+    @Test
+    public void packDownloadLaneIsGatedWhileTheActionBarSurvives() throws Exception {
+        String source = source("core/service/PackDownloadProgressReporter.java");
+
+        assertTrue(source.contains("isProgressBossBar()"));
+        assertTrue("the action bar must keep reporting when boss bars are off",
+                source.contains("sender.sendAction(snapshot.line())"));
+    }
+
+    @Test
+    public void pregenLaneIsGatedWhileTheActionBarSurvives() throws Exception {
+        String source = source("core/tools/IrisCreator.java");
+        int lane = source.indexOf("\"iris:pregen\"");
+        int gate = source.lastIndexOf("isProgressBossBar()", lane);
+
+        assertTrue("the pregen boss bar lane must sit behind general.progressBossBar",
+                gate > 0 && lane - gate < 200);
+        assertTrue("the action bar must keep reporting when boss bars are off",
+                source.contains("RuntimeProgressMessages.WORLD_PREGEN_ACTION"));
+    }
+
+    private void assertGated(String relativePath) throws Exception {
+        assertTrue(relativePath + " must consult general.progressBossBar before creating a boss bar",
+                source(relativePath).contains("isProgressBossBar()"));
+    }
+
+    private String source(String relativePath) throws Exception {
+        return Files.readString(Path.of("src/main/java/art/arcane/iris").resolve(relativePath));
+    }
+
+    private void withProgressBossBar(boolean enabled, Runnable body) {
+        IrisSettings previous = IrisSettings.settings;
+        try {
+            IrisSettings live = new IrisSettings();
+            live.getGeneral().setProgressBossBar(enabled);
+            IrisSettings.settings = live;
+            assertFalse("another test hosted a HUD; this test needs an unhosted platform",
+                    BukkitPlatform.hasHud());
+            body.run();
+        } finally {
+            IrisSettings.settings = previous;
+        }
+    }
+}

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

@@ -0,0 +1,55 @@
+package art.arcane.iris.core.localization;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.File;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.attribute.FileTime;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
+
+public class IrisLanguageHotloadSnapshotTest {
+    @Rule
+    public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+    @Test
+    public void capturesMissingOverrideAsStableTombstone() throws Exception {
+        File override = new File(temporaryFolder.getRoot(), "languages/overrides/en_US.json");
+
+        LocaleHotloadSnapshot snapshot = IrisLanguage.captureHotloadSnapshot(override, "en_US");
+
+        assertTrue(snapshot.missing());
+        assertEquals("missing", snapshot.sha256());
+    }
+
+    @Test
+    public void detectsSameMetadataContentReplacementBySha256() throws Exception {
+        File override = new File(temporaryFolder.getRoot(), "languages/overrides/en_US.json");
+        Files.createDirectories(override.toPath().getParent());
+        String firstContent = "{\"messages\":{\"a\":\"1\"}}";
+        String secondContent = "{\"messages\":{\"a\":\"2\"}}";
+        Files.writeString(override.toPath(), firstContent, StandardCharsets.UTF_8);
+        FileTime fixedTime = FileTime.fromMillis(10_000L);
+        Files.setLastModifiedTime(override.toPath(), fixedTime);
+        LocaleHotloadSnapshot first = IrisLanguage.captureHotloadSnapshot(override, "en_US");
+
+        Files.writeString(override.toPath(), secondContent, StandardCharsets.UTF_8);
+        Files.setLastModifiedTime(override.toPath(), fixedTime);
+        LocaleHotloadSnapshot second = IrisLanguage.captureHotloadSnapshot(override, "en_US");
+
+        assertFalse(first.missing());
+        assertFalse(second.missing());
+        assertEquals(firstContent.length(), secondContent.length());
+        assertEquals(first.file(), second.file());
+        assertEquals(firstContent, first.content());
+        assertEquals(secondContent, second.content());
+        assertNotEquals(first.sha256(), second.sha256());
+        assertNotEquals(first, second);
+    }
+}

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

@@ -1,5 +1,6 @@
 package art.arcane.iris.core.localization;
 
+import art.arcane.iris.core.IrisSettings;
 import art.arcane.volmlib.util.localization.MessageArgument;
 import art.arcane.volmlib.util.localization.LocaleOverlay;
 import art.arcane.volmlib.util.localization.LocalizationValidationResult;
@@ -35,6 +36,7 @@ import java.util.stream.Stream;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
 public class IrisLanguageTest {
@@ -237,6 +239,26 @@ public class IrisLanguageTest {
         );
     }
 
+    @Test
+    public void rejectedCandidateLocaleLeavesPreviousSettingsAndLanguageActive() {
+        IrisSettings previous = IrisSettings.settings;
+        IrisSettings live = new IrisSettings();
+        live.getGeneral().setLanguage("en_US");
+        IrisSettings.settings = live;
+        try {
+            boolean applied = IrisSettings.applyHotloadSnapshot(
+                    "{\"general\":{\"language\":\"../invalid\"}}",
+                    IrisLanguage::reload
+            );
+
+            assertFalse(applied);
+            assertSame(live, IrisSettings.settings);
+            assertEquals("en_US", IrisLanguage.activeLocale());
+        } finally {
+            IrisSettings.settings = previous;
+        }
+    }
+
     @Test
     public void untrustedArgumentsCannotInjectLegacyOrMiniMessageFormatting() throws Exception {
         writeOverride("de_DE", """

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

@@ -0,0 +1,159 @@
+package art.arcane.iris.core.localization;
+
+import org.junit.Test;
+
+import java.io.File;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+public class LocaleHotloadGateTest {
+    @Test
+    public void anchorsCooldownAtCompletedApplication() {
+        LocaleHotloadGate gate = gate();
+        LocaleHotloadSnapshot initial = snapshot("initial");
+        LocaleHotloadSnapshot first = snapshot("first");
+        LocaleHotloadSnapshot second = snapshot("second");
+        gate.reset(initial);
+
+        assertNull(gate.observe(first, 0L));
+        LocaleHotloadGate.Attempt firstAttempt = gate.observe(first, 100L);
+        assertNotNull(firstAttempt);
+        gate.complete(firstAttempt, 500L, true);
+
+        assertNull(gate.observe(second, 600L));
+        assertNull(gate.observe(second, 700L));
+        assertNull(gate.observe(second, 3_499L));
+        LocaleHotloadGate.Attempt secondAttempt = gate.observe(second, 3_500L);
+
+        assertNotNull(secondAttempt);
+        assertEquals(second, secondAttempt.snapshot());
+    }
+
+    @Test
+    public void coalescesCooldownBurstToLatestStableSnapshot() {
+        LocaleHotloadGate gate = gate();
+        LocaleHotloadSnapshot first = snapshot("first");
+        LocaleHotloadSnapshot intermediate = snapshot("intermediate");
+        LocaleHotloadSnapshot latest = snapshot("latest");
+        gate.reset(snapshot("initial"));
+
+        assertNull(gate.observe(first, 0L));
+        LocaleHotloadGate.Attempt firstAttempt = gate.observe(first, 100L);
+        assertNotNull(firstAttempt);
+        gate.complete(firstAttempt, 200L, true);
+
+        assertNull(gate.observe(intermediate, 250L));
+        assertNull(gate.observe(intermediate, 350L));
+        assertNull(gate.observe(latest, 400L));
+        assertNull(gate.observe(latest, 500L));
+        assertNull(gate.observe(latest, 3_199L));
+        LocaleHotloadGate.Attempt latestAttempt = gate.observe(latest, 3_200L);
+
+        assertNotNull(latestAttempt);
+        assertEquals(latest, latestAttempt.snapshot());
+    }
+
+    @Test
+    public void requiresDeletionGraceAndCancelsTransientMissingSnapshot() {
+        LocaleHotloadGate gate = gate();
+        LocaleHotloadSnapshot initial = snapshot("initial");
+        LocaleHotloadSnapshot replacement = snapshot("replacement");
+        LocaleHotloadSnapshot missing = LocaleHotloadSnapshot.missing(initial.file(), "en_US");
+        gate.reset(initial);
+
+        assertNull(gate.observe(missing, 0L));
+        assertNull(gate.observe(missing, 499L));
+        assertNull(gate.observe(replacement, 500L));
+        LocaleHotloadGate.Attempt replacementAttempt = gate.observe(replacement, 600L);
+        assertNotNull(replacementAttempt);
+        assertEquals(replacement, replacementAttempt.snapshot());
+        gate.complete(replacementAttempt, 600L, true);
+
+        assertNull(gate.observe(missing, 700L));
+        assertNull(gate.observe(missing, 1_199L));
+        assertNull(gate.observe(missing, 1_200L));
+        LocaleHotloadGate.Attempt deletionAttempt = gate.observe(missing, 3_600L);
+
+        assertNotNull(deletionAttempt);
+        assertEquals(missing, deletionAttempt.snapshot());
+    }
+
+    @Test
+    public void unavailableReadBlocksStalePendingSnapshot() {
+        LocaleHotloadGate gate = gate();
+        LocaleHotloadSnapshot first = snapshot("first");
+        LocaleHotloadSnapshot pending = snapshot("pending");
+        gate.reset(snapshot("initial"));
+
+        assertNull(gate.observe(first, 0L));
+        LocaleHotloadGate.Attempt firstAttempt = gate.observe(first, 100L);
+        assertNotNull(firstAttempt);
+        gate.complete(firstAttempt, 200L, true);
+        assertNull(gate.observe(pending, 300L));
+        assertNull(gate.observe(pending, 400L));
+
+        gate.unavailable();
+        assertNull(gate.observe(pending, 3_200L));
+        LocaleHotloadGate.Attempt recoveredAttempt = gate.observe(pending, 3_300L);
+
+        assertNotNull(recoveredAttempt);
+        assertEquals(pending, recoveredAttempt.snapshot());
+    }
+
+    @Test
+    public void failedApplicationRetriesOnlyAfterCooldown() {
+        LocaleHotloadGate gate = gate();
+        LocaleHotloadSnapshot changed = snapshot("changed");
+        gate.reset(snapshot("initial"));
+
+        assertNull(gate.observe(changed, 0L));
+        LocaleHotloadGate.Attempt failedAttempt = gate.observe(changed, 100L);
+        assertNotNull(failedAttempt);
+        gate.complete(failedAttempt, 500L, false);
+
+        assertNull(gate.observe(changed, 3_499L));
+        LocaleHotloadGate.Attempt retryAttempt = gate.observe(changed, 3_500L);
+
+        assertNotNull(retryAttempt);
+        assertEquals(changed, retryAttempt.snapshot());
+    }
+
+    @Test
+    public void manualResetInvalidatesInFlightAutomaticAttempt() {
+        LocaleHotloadGate gate = gate();
+        LocaleHotloadSnapshot automatic = snapshot("automatic");
+        LocaleHotloadSnapshot manual = snapshot("manual");
+        LocaleHotloadSnapshot changed = snapshot("changed");
+        gate.reset(snapshot("initial"));
+
+        assertNull(gate.observe(automatic, 0L));
+        LocaleHotloadGate.Attempt staleAttempt = gate.observe(automatic, 100L);
+        assertNotNull(staleAttempt);
+        gate.reset(manual);
+        gate.complete(staleAttempt, 200L, true);
+
+        assertNull(gate.observe(manual, 200L));
+        assertNull(gate.observe(changed, 300L));
+        LocaleHotloadGate.Attempt currentAttempt = gate.observe(changed, 400L);
+
+        assertNotNull(currentAttempt);
+        assertNotEquals(staleAttempt.generation(), currentAttempt.generation());
+        assertEquals(changed, currentAttempt.snapshot());
+    }
+
+    private LocaleHotloadGate gate() {
+        return new LocaleHotloadGate(new LocaleHotloadGate.Timing(100L, 500L, 3_000L));
+    }
+
+    private LocaleHotloadSnapshot snapshot(String content) {
+        return LocaleHotloadSnapshot.present(
+                new File("locale.json"),
+                "en_US",
+                content,
+                content
+        );
+    }
+}

core/src/test/java/art/arcane/iris/core/service/StudioSVCPackAdmissionTest.java

@@ -0,0 +1,60 @@
+package art.arcane.iris.core.service;
+
+import art.arcane.iris.core.pack.BrokenPackException;
+import art.arcane.iris.core.pack.PackValidationResult;
+import org.junit.Test;
+
+import java.util.List;
+import java.util.Optional;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class StudioSVCPackAdmissionTest {
+    @Test
+    public void loadablePackIsAdmitted() {
+        PackValidationResult validation = new PackValidationResult(
+                "overworld", List.of(), List.of(), 1L);
+
+        assertNull(StudioSVC.resolvePackAdmissionFailure(
+                "overworld", Optional.empty(), validation));
+    }
+
+    @Test
+    public void missingValidationFailsClosedWithTheResolvedPackName() {
+        BrokenPackException failure = StudioSVC.resolvePackAdmissionFailure(
+                "overworld-pack", Optional.empty(), null);
+
+        assertEquals("overworld-pack", failure.getPackName());
+        assertEquals(List.of(
+                "Required pack validation has not completed. Studio creation fails closed until validation succeeds."),
+                failure.getReasons());
+    }
+
+    @Test
+    public void blockingValidationPreservesEveryReasonInOrder() {
+        List<String> reasons = List.of(
+                "Biome 'broken' has no resolvable regions.",
+                "Structure 'castle' references missing pool 'castle/start'.");
+        PackValidationResult validation = new PackValidationResult(
+                "overworld", reasons, List.of(), 1L);
+
+        BrokenPackException failure = StudioSVC.resolvePackAdmissionFailure(
+                "overworld", Optional.empty(), validation);
+
+        assertEquals("overworld", failure.getPackName());
+        assertEquals(reasons, failure.getReasons());
+    }
+
+    @Test
+    public void startupDenialTakesPriorityOverCachedPackValidation() {
+        String denial = "Restart the server after changing external datapacks.";
+        PackValidationResult validation = new PackValidationResult(
+                "overworld", List.of(), List.of(), 1L);
+
+        BrokenPackException failure = StudioSVC.resolvePackAdmissionFailure(
+                "overworld", Optional.of(denial), validation);
+
+        assertEquals(List.of(denial), failure.getReasons());
+    }
+}

core/src/test/java/art/arcane/iris/core/structure/VillageImporterBundleTest.java

@@ -112,9 +112,9 @@ public class VillageImporterBundleTest {
     }
 
     @Test
-    public void nativeMaximumDistanceControlsIrisAssemblyRadius() {
+    public void registeredJigsawMetadataIncludesAncientCitySourceAndAssemblyContract() {
         Map<String, Object> structure = VillageImporter.structureJson(
-                "minecraft:village_plains",
+                "minecraft:ancient_city",
                 "village/pool/minecraft/start",
                 6,
                 81
@@ -122,8 +122,10 @@ public class VillageImporterBundleTest {
 
         assertEquals(6, structure.get("maxDepth"));
         assertEquals(6, structure.get("maxSizeChunks"));
+        assertEquals("STRUCTURE_PIECE", structure.get("placeMode"));
         assertEquals(IrisJigsawBranchFailurePolicy.TERMINATE_BRANCH.name(),
                 structure.get("branchFailurePolicy"));
+        assertEquals("minecraft:ancient_city", structure.get("vanillaSource"));
     }
 
     private StructureResourceBundle bundle(String objectContent) {

gradle.properties

@@ -30,4 +30,4 @@ apiVersion=26.1
 fabricLoaderVersion=0.19.3
 forgeVersion=26.2-65.1.1
 neoForgeVersion=26.2.0.59
-volmLibCoordinate=com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522
+volmLibCoordinate=com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186

probe/build.gradle

@@ -10,7 +10,7 @@ application {
 }
 
 String volmLibCoordinate = providers.gradleProperty('volmLibCoordinate')
-    .orElse('com.github.VolmitSoftware:VolmLib:5486ac97ad6d6833e27275dc768222d377721522')
+    .orElse('com.github.VolmitSoftware:VolmLib:e6574cf814b3dd670385a4d632a63fde2038e186')
     .get()
 
 dependencies {