Fixes

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

@@ -70,10 +70,10 @@ public class CustomBiomeSource extends BiomeSource {
         LinkedHashSet<Holder<Biome>> biomes = new LinkedHashSet<>();
 
         for (IrisBiome i : engine.getAllBiomes()) {
-            Holder<Biome> vanillaHolder = NMSBinding.biomeToBiomeBase(registry, i.getVanillaDerivative());
+            Holder<Biome> vanillaHolder = resolveBiomeHolder(registry, i.getStructureDerivativeKey());
             if (vanillaHolder == null) {
                 throw new IllegalStateException("Iris structure biome derivative '"
-                        + i.getVanillaDerivativeKey() + "' is not registered for biome '" + i.getLoadKey() + "'");
+                        + i.getStructureDerivativeKey() + "' is not registered for biome '" + i.getLoadKey() + "'");
             }
             biomes.add(vanillaHolder);
 
@@ -312,10 +312,10 @@ public class CustomBiomeSource extends BiomeSource {
             throw new IllegalStateException("Iris returned no surface structure biome at block "
                     + blockX + "," + blockZ);
         }
-        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, irisBiome.getVanillaDerivative());
+        Holder<Biome> holder = resolveBiomeHolder(biomeRegistry, irisBiome.getStructureDerivativeKey());
         if (holder == null) {
             throw new IllegalStateException("Iris structure biome derivative '"
-                    + irisBiome.getVanillaDerivativeKey() + "' is not registered at block "
+                    + irisBiome.getStructureDerivativeKey() + "' is not registered at block "
                     + blockX + "," + blockZ);
         }
         return holder;
@@ -371,10 +371,11 @@ public class CustomBiomeSource extends BiomeSource {
                     + x + "," + y + "," + z);
         }
 
-        Holder<Biome> holder = NMSBinding.biomeToBiomeBase(biomeRegistry, resolution.irisBiome.getVanillaDerivative());
+        Holder<Biome> holder = resolveBiomeHolder(
+                biomeRegistry, resolution.irisBiome.getStructureDerivativeKey());
         if (holder == null) {
             throw new IllegalStateException("Iris structure biome derivative '"
-                    + resolution.irisBiome.getVanillaDerivativeKey() + "' is not registered at block "
+                    + resolution.irisBiome.getStructureDerivativeKey() + "' is not registered at block "
                     + resolution.blockX + "," + resolution.blockY + "," + resolution.blockZ);
         }
         return holder;
@@ -505,6 +506,17 @@ public class CustomBiomeSource extends BiomeSource {
         return optionalReferenceHolder.get();
     }
 
+    private static Holder<Biome> resolveBiomeHolder(Registry<Biome> registry, String biomeKey) {
+        if (registry == null || biomeKey == null || biomeKey.isBlank()) {
+            return null;
+        }
+        Identifier identifier = Identifier.tryParse(biomeKey);
+        if (identifier == null) {
+            return null;
+        }
+        return registry.get(ResourceKey.create(Registries.BIOME, identifier)).orElse(null);
+    }
+
     private static Holder<Biome> resolveFallbackBiome(Registry<Biome> registry, Registry<Biome> customRegistry) {
         Holder<Biome> plains = NMSBinding.biomeToBiomeBase(registry, org.bukkit.block.Biome.PLAINS);
         if (plains != null) {

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

@@ -3,7 +3,6 @@ package art.arcane.iris.core.nms.v26_2_R1;
 import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.framework.IrisStructureLocator;
 import art.arcane.iris.engine.framework.NativeStructureGenerationPolicy;
-import art.arcane.iris.core.structure.NativeStructureLocateCapability;
 import art.arcane.iris.engine.object.IrisDimension;
 import art.arcane.iris.engine.object.IrisNativeStructureDecision;
 import art.arcane.iris.engine.object.IrisStructureStiltSettings;
@@ -174,7 +173,7 @@ public class IrisChunkGenerator extends CustomChunkGenerator {
             String key = id.toString();
             IrisNativeStructureDecision decision = NativeStructureGenerationPolicy.resolve(engine,
                     key, NativeStructurePostProcessor.isUndergroundStep(holder.value().step()));
-            if (NativeStructureLocateCapability.isPaperUnavailable(key) || !decision.generate()) {
+            if (!decision.generate()) {
                 continue;
             }
             candidates.add(new NativeLocateCandidate(holder, key));

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

@@ -0,0 +1,22 @@
+package art.arcane.iris.core.nms.v26_2_R1;
+
+import org.junit.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class CustomBiomeSourceStructureContractTest {
+    @Test
+    public void nativeStructuresUseTerrainSafeDerivativeAtEveryBiomeBoundary() throws IOException {
+        String source = Files.readString(Path.of(System.getProperty("iris.customBiomeSource")));
+
+        assertTrue(source.contains("resolveBiomeHolder(registry, i.getStructureDerivativeKey())"));
+        assertTrue(source.contains("resolveBiomeHolder(biomeRegistry, irisBiome.getStructureDerivativeKey())"));
+        assertTrue(source.contains("resolution.irisBiome.getStructureDerivativeKey()"));
+        assertFalse(source.contains("resolution.irisBiome.getVanillaDerivative()"));
+    }
+}

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

@@ -17,7 +17,7 @@ import static org.junit.Assert.assertSame;
 
 public class IrisChunkGeneratorMonumentLocateContractTest {
     @Test
-    public void nativeLocateAllowsExplicitReplacementBeforeNativeCapabilityGate() throws IOException {
+    public void nativeLocateAllowsMonumentsAfterPolicyAndReachabilityChecks() throws IOException {
         String source = Files.readString(Path.of(System.getProperty("iris.nmsChunkGeneratorSource")));
         int findStart = source.indexOf("findNearestMapStructure(ServerLevel level");
         assertTrue(findStart >= 0);
@@ -42,9 +42,9 @@ public class IrisChunkGeneratorMonumentLocateContractTest {
         int reachabilityStart = source.indexOf("private Set<String> reachableStructureKeys", filterStart);
         assertTrue(reachabilityStart > filterStart);
         String filterMethod = source.substring(filterStart, reachabilityStart);
-        int monumentReject = filterMethod.indexOf("if (NativeStructureLocateCapability.isPaperUnavailable(key)");
-        int rejectContinue = filterMethod.indexOf("continue;", monumentReject);
-        int emptyNativePartition = filterMethod.indexOf("if (candidates.isEmpty())", rejectContinue);
+        int policyFilter = filterMethod.indexOf("if (!decision.generate())");
+        int filterContinue = filterMethod.indexOf("continue;", policyFilter);
+        int emptyNativePartition = filterMethod.indexOf("if (candidates.isEmpty())", filterContinue);
         int reachabilityLookup = filterMethod.indexOf("reachableStructureKeys(level)", emptyNativePartition);
 
         assertTrue(policyResolution >= 0);
@@ -58,10 +58,11 @@ public class IrisChunkGeneratorMonumentLocateContractTest {
         assertTrue(nativeFilter >= 0);
         assertTrue(delegateLocate > nativeFilter);
         assertTrue(nearestSelection > delegateLocate);
-        assertTrue(monumentReject >= 0);
-        assertTrue(rejectContinue > monumentReject);
-        assertTrue(emptyNativePartition > rejectContinue);
+        assertTrue(policyFilter >= 0);
+        assertTrue(filterContinue > policyFilter);
+        assertTrue(emptyNativePartition > filterContinue);
         assertTrue(reachabilityLookup > emptyNativePartition);
+        assertFalse(filterMethod.contains("NativeStructureLocateCapability"));
         assertFalse(irisHelper.contains("NativeStructureLocateCapability.isPaperUnavailable(structureId)"));
         assertTrue(irisHelper.contains("new BlockPos(result.originX(), result.baseY(), result.originZ())"));
     }

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

@@ -173,6 +173,24 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
         assertEquals(Blocks.GRASS_BLOCK.defaultBlockState(), state(raised, 0, 68, 0));
     }
 
+    @Test
+    public void raisedSurfaceTerrainDoesNotSliceTreeBlocks() {
+        Map<BlockPos, BlockState> blocks = new HashMap<>();
+        BlockState log = Blocks.OAK_LOG.defaultBlockState();
+        BlockState leaves = Blocks.OAK_LEAVES.defaultBlockState();
+        put(blocks, 0, 63, 0, Blocks.DIRT.defaultBlockState());
+        put(blocks, 0, 64, 0, Blocks.GRASS_BLOCK.defaultBlockState());
+        put(blocks, 0, 66, 0, log);
+        put(blocks, 0, 68, 0, leaves);
+
+        NativeStructurePostProcessor.applySurfaceColumn(
+                world(blocks), new BlockPos.MutableBlockPos(),
+                0, 0, 64, 68, -64, 319);
+
+        assertEquals(log, state(blocks, 0, 66, 0));
+        assertEquals(leaves, state(blocks, 0, 68, 0));
+    }
+
     @Test
     public void loweredFluidColumnsRemainFluidFilled() {
         Map<BlockPos, BlockState> blocks = new HashMap<>();
@@ -266,11 +284,18 @@ public class NativeStructurePostProcessorSurfaceTerrainTest {
     }
 
     @Test
-    public void vegetationCleanupUsesTheSameCircularTaperAsTerrain() {
-        BoundingBox piece = new BoundingBox(0, 60, 0, 4, 80, 4);
+    public void templateAirDoesNotEraseTreesInsideVillagePieces() throws Exception {
+        BlockPos origin = new BlockPos(0, 80, 0);
+        StructureTemplate template = template(List.of(
+                new StructureTemplate.StructureBlockInfo(BlockPos.ZERO, Blocks.AIR.defaultBlockState(), null)));
+        StructurePlaceSettings settings = new StructurePlaceSettings().setRotation(Rotation.NONE);
+        Map<BlockPos, BlockState> blocks = new HashMap<>();
+        BlockState log = Blocks.OAK_LOG.defaultBlockState();
+        blocks.put(origin, log);
 
-        assertTrue(NativeStructurePostProcessor.withinSurfaceTerrainRadius(16, 2, piece, 12));
-        assertFalse(NativeStructurePostProcessor.withinSurfaceTerrainRadius(16, 16, piece, 12));
+        NativeStructurePostProcessor.clearTemplateAir(world(blocks), template, origin, 80, settings);
+
+        assertEquals(log, blocks.get(origin));
     }
 
     private static NativeStructurePostProcessor.SurfaceAnchor anchor(int meetY, int strength) {

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

@@ -27,8 +27,8 @@ public class NativeStructurePostProcessorVegetationTest {
     }
 
     @Test
-    public void surfaceStructuresClearTheirEntireFootprintByDefault() {
-        assertTrue(NativeStructurePostProcessor.shouldClearEntireVegetationFootprint(
+    public void surfaceStructuresPreserveVegetationUnlessConfigured() {
+        assertFalse(NativeStructurePostProcessor.shouldClearEntireVegetationFootprint(
                 GenerationStep.Decoration.SURFACE_STRUCTURES, false));
         assertTrue(NativeStructurePostProcessor.shouldClearEntireVegetationFootprint(
                 GenerationStep.Decoration.SURFACE_STRUCTURES, true));

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

@@ -21,7 +21,6 @@ package art.arcane.iris.core.commands;
 import art.arcane.iris.Iris;
 import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.core.service.ObjectStudioSaveService;
-import art.arcane.iris.core.structure.NativeStructureLocateCapability;
 import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.framework.IrisStructureLocator;
 import art.arcane.iris.engine.framework.NativeStructureGenerationPolicy;
@@ -136,10 +135,6 @@ public class CommandFind implements DirectorExecutor {
                 locateIrisStructure(e, structureKey, commandSender);
                 return;
             }
-            if (NativeStructureLocateCapability.isPaperUnavailable(structureKey)) {
-                commandSender.sendMessage(C.RED + NativeStructureLocateCapability.unavailableMessage());
-                return;
-            }
         }
 
         if (nativeStructure == null && IrisStructureLocator.isPlaced(e, structureKey)) {

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

@@ -21,7 +21,6 @@ package art.arcane.iris.core.commands;
 import art.arcane.iris.Iris;
 import art.arcane.iris.core.loader.IrisData;
 import art.arcane.iris.core.structure.BulkStructureImporter;
-import art.arcane.iris.core.structure.NativeStructureLocateCapability;
 import art.arcane.iris.core.structure.StructureCaptureImporter;
 import art.arcane.iris.core.structure.StructureImporter;
 import art.arcane.iris.core.structure.StructureIndexService;
@@ -185,7 +184,6 @@ public class CommandStructure implements DirectorExecutor {
         int nativeEligible = 0;
         int disabled = 0;
         int unreachable = 0;
-        int unavailable = 0;
         int searchLimited = 0;
         int errors = 0;
         for (String keyName : structureKeys) {
@@ -228,19 +226,12 @@ public class CommandStructure implements DirectorExecutor {
                 continue;
             }
             nativeEligible++;
-            if (NativeStructureLocateCapability.isPaperUnavailable(keyName)) {
-                unavailable++;
-                messages.add(C.YELLOW + "[native-eligible/locate-unavailable] " + C.WHITE + keyName + C.YELLOW + ": "
-                        + NativeStructureLocateCapability.unavailableMessage());
-                continue;
-            }
             messages.add(C.GREEN + "[native-eligible] " + C.WHITE + keyName);
         }
         messages.add(C.GREEN + "Structure verify: " + C.WHITE + located + C.GREEN + " Iris placements located, "
                 + C.WHITE + nativeEligible + C.GREEN + " native structures eligible, "
                 + C.WHITE + disabled + C.GREEN + " disabled by policy, "
                 + C.WHITE + unreachable + C.GREEN + " biome-unreachable, "
-                + C.WHITE + unavailable + C.GREEN + " generation-eligible but unavailable to synchronous locate, "
                 + C.WHITE + searchLimited + C.GREEN + " density searches safety-limited, "
                 + C.WHITE + errors + C.GREEN + " errors. Native eligibility is checked without running blocking live locates.");
         sendVerificationMessages(commandSender, target, messages);

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

@@ -35,18 +35,17 @@ public class IrisStructureLocateCommandContractTest {
         int replacementCheck = method.indexOf(
                 "decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS", policyResolution);
         int replacementLocate = method.indexOf("locateIrisStructure(e, structureKey, commandSender)", replacementCheck);
-        int capabilityCheck = method.indexOf("NativeStructureLocateCapability.isPaperUnavailable(structureKey)", replacementLocate);
         int genericIrisLookup = method.indexOf(
-                "nativeStructure == null && IrisStructureLocator.isPlaced(e, structureKey)", capabilityCheck);
+                "nativeStructure == null && IrisStructureLocator.isPlaced(e, structureKey)", replacementLocate);
         int nativeLocate = method.indexOf("targetWorld.locateNearestStructure(", genericIrisLookup);
         assertTrue(nativeResolution >= 0);
         assertTrue(policyResolution > nativeResolution);
         assertTrue(replacementCheck > policyResolution);
         assertTrue(replacementLocate > replacementCheck);
-        assertTrue(capabilityCheck > replacementLocate);
-        assertTrue(genericIrisLookup > capabilityCheck);
+        assertTrue(genericIrisLookup > replacementLocate);
         assertTrue(nativeLocate > policyResolution);
         assertTrue(method.contains("decision.status() != NativeStructureGenerationStatus.REPLACED_BY_IRIS"));
+        assertFalse(method.contains("NativeStructureLocateCapability"));
     }
 
     @Test