Added 1.21.1 mod targets

- Build Fabric, Forge and NeoForge per target listed in gradle/mod-targets.json (1.21.1, 26.3)
- Add 1.21.1 adapter source overlays under adapters/*/src/versions/1.21.1
- Add verifyModdedMatrix and per-target Java runtime verification of loader jars
- Re-inject persistent dimensions from the levels-ready hook before the watchdog starts
- Wait for queued chunks and the final save before pregen completes
- Add the 1.21.1 data version and datapack supported_formats range
- Cascade regions whose sea or shore pool loses every biome
- Use Gson calls available on the 1.21.1 runtime

core/src/test/java/art/arcane/iris/generation/terrain/IrisRegionCompatPoolTest.java

@@ -23,6 +23,7 @@ import static art.arcane.iris.testsupport.PackCompatFixtures.find;
 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;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -132,6 +133,133 @@ public class IrisRegionCompatPoolTest {
         assertFalse(region.evaluateCompat(gate(report)).excluded());
     }
 
+    @Test
+    public void evaluateCompatExcludesRegionWithNoShoreBiomesLeft() {
+        PackCompatReport report = new PackCompatReport();
+        IrisBiome plains = biome("land/plains");
+        IrisBiome beach = PackCompatFixtures.exclude(biome("swamp/shore/beach"),
+                CompatRegistry.BLOCK, "minecraft:firefly_bush");
+        IrisData data = dataWith(report, plains, beach);
+        IrisRegion region = PackCompatFixtures.region("swamp");
+        region.setLoader(data);
+        region.setLandBiomes(new KList<>("land/plains"));
+        region.setShoreBiomes(new KList<>("swamp/shore/beach"));
+
+        CompatStatus status = region.evaluateCompat(gate(report));
+
+        assertTrue(status.excluded());
+        assertSame(plains, region.getRealLandBiomes(() -> data).getFirst());
+        CompatFinding cascade = find(report, CompatAction.EXCLUDED, "region", "swamp");
+        assertNotNull(cascade);
+        assertEquals("minecraft:firefly_bush", cascade.key());
+        assertEquals("no shore biomes remain", cascade.detail());
+        CompatFinding dropped = find(report, CompatAction.DROPPED, "region", "swamp");
+        assertNotNull(dropped);
+        assertEquals("shoreBiomes[0] swamp/shore/beach", dropped.detail());
+    }
+
+    @Test
+    public void evaluateCompatExcludesRegionWithNoSeaBiomesLeft() {
+        PackCompatReport report = new PackCompatReport();
+        IrisBiome plains = biome("land/plains");
+        IrisBiome sea = excludeBlock(biome("sea/sulfur"));
+        IrisData data = dataWith(report, plains, sea);
+        IrisRegion region = PackCompatFixtures.region("overworld");
+        region.setLoader(data);
+        region.setLandBiomes(new KList<>("land/plains"));
+        region.setSeaBiomes(new KList<>("sea/sulfur"));
+
+        assertTrue(region.evaluateCompat(gate(report)).excluded());
+        CompatFinding cascade = find(report, CompatAction.EXCLUDED, "region", "overworld");
+        assertNotNull(cascade);
+        assertEquals(MISSING_BLOCK, cascade.key());
+        assertEquals("no sea biomes remain", cascade.detail());
+    }
+
+    @Test
+    public void evaluateCompatPreservesSurvivingSurfacePoolOrder() {
+        PackCompatReport report = new PackCompatReport();
+        IrisBiome plains = biome("land/plains");
+        IrisBiome sea = biome("sea/ocean");
+        IrisBiome sand = biome("shore/sand");
+        IrisBiome gravel = biome("shore/gravel");
+        IrisBiome sulfur = excludeBlock(biome("shore/sulfur"));
+        IrisData data = dataWith(report, plains, sea, sand, gravel, sulfur);
+        IrisRegion region = PackCompatFixtures.region("overworld");
+        region.setLoader(data);
+        region.setLandBiomes(new KList<>("land/plains"));
+        region.setSeaBiomes(new KList<>("shore/sulfur", "sea/ocean"));
+        region.setShoreBiomes(new KList<>("shore/sand", "shore/sulfur", "shore/gravel"));
+
+        assertFalse(region.evaluateCompat(gate(report)).excluded());
+        KList<IrisBiome> shores = region.getRealShoreBiomes(() -> data);
+        assertEquals(2, shores.size());
+        assertSame(sand, shores.get(0));
+        assertSame(gravel, shores.get(1));
+        assertSame(sea, region.getRealSeaBiomes(() -> data).getFirst());
+    }
+
+    @Test
+    public void evaluateCompatAllowsOmittedSurfacePoolsAndDepletedCavePool() {
+        PackCompatReport report = new PackCompatReport();
+        IrisBiome plains = biome("land/plains");
+        IrisBiome sulfur = excludeBlock(biome("cave/sulfur"));
+        IrisData data = dataWith(report, plains, sulfur);
+        IrisRegion region = PackCompatFixtures.region("highlands");
+        region.setLoader(data);
+        region.setLandBiomes(new KList<>("land/plains"));
+        region.setCaveBiomes(new KList<>("cave/sulfur"));
+
+        assertFalse(region.evaluateCompat(gate(report)).excluded());
+        assertTrue(region.getRealSeaBiomes(() -> data).isEmpty());
+        assertTrue(region.getRealShoreBiomes(() -> data).isEmpty());
+        assertTrue(region.getRealCaveBiomes(() -> data).isEmpty());
+    }
+
+    @Test
+    public void evaluateCompatDoesNotMisattributeUnresolvedShorePoolToLandDrop() {
+        PackCompatReport report = new PackCompatReport();
+        IrisBiome plains = biome("land/plains");
+        IrisBiome sulfur = excludeBlock(biome("land/sulfur"));
+        IrisData data = dataWith(report, plains, sulfur);
+        IrisRegion region = PackCompatFixtures.region("overworld");
+        region.setLoader(data);
+        region.setLandBiomes(new KList<>("land/plains", "land/sulfur"));
+        region.setShoreBiomes(new KList<>("shore/missing"));
+
+        assertFalse(region.evaluateCompat(gate(report)).excluded());
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void dimensionDropsRegionWhoseDeclaredShorePoolWasExcluded() {
+        PackCompatReport report = new PackCompatReport();
+        IrisBiome plains = biome("land/plains");
+        IrisBiome beach = excludeBlock(biome("shore/sulfur"));
+        IrisData data = dataWith(report, plains, beach);
+        IrisRegion swamp = PackCompatFixtures.region("swamp");
+        swamp.setLoader(data);
+        swamp.setLandBiomes(new KList<>("land/plains"));
+        swamp.setShoreBiomes(new KList<>("shore/sulfur"));
+        swamp.setCompat(swamp.evaluateCompat(gate(report)));
+        IrisRegion highlands = PackCompatFixtures.region("highlands");
+        ResourceLoader<IrisRegion> regions = mock(ResourceLoader.class);
+        when(data.getRegionLoader()).thenReturn(regions);
+        when(regions.load("swamp")).thenReturn(swamp);
+        when(regions.load("highlands")).thenReturn(highlands);
+        IrisDimension dimension = new IrisDimension().setRegions(new KList<>("swamp", "highlands"));
+        dimension.setLoadKey("overworld");
+        dimension.setLoader(data);
+
+        assertFalse(dimension.evaluateCompat(gate(report)).excluded());
+        KList<IrisRegion> surviving = dimension.getAllRegions(() -> data);
+        assertEquals(1, surviving.size());
+        assertSame(highlands, surviving.getFirst());
+        CompatFinding drop = find(report, CompatAction.DROPPED, "dimension", "overworld");
+        assertNotNull(drop);
+        assertEquals("regions[0] swamp", drop.detail());
+    }
+
     @Test
     public void evaluateCompatDoesNotExcludeRegionThatNeverDeclaredLandBiomes() {
         PackCompatReport report = new PackCompatReport();

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

@@ -71,7 +71,15 @@ public class BuiltInPackUpdatesTest {
 
     @Test
     public void boundsReleaseMetadataSize() throws Exception {
-        assertEquals(BuiltInPackUpdates.Update.unavailable(), checkResponse(" ".repeat(1024 * 1024 + 1)));
+        String release = release("4010", "overworld.zip", false);
+        assertEquals(BuiltInPackUpdates.Update.unavailable(),
+                checkResponse(release + " ".repeat(1024 * 1024 - release.length() + 1)));
+    }
+
+    @Test
+    public void acceptsReleaseMetadataAtSizeLimit() throws Exception {
+        String release = release("4010", "overworld.zip", false);
+        assertEquals("4010", checkResponse(release + " ".repeat(1024 * 1024 - release.length())).version());
     }
 
     @Test

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

@@ -58,7 +58,7 @@ public class DefaultPackBootstrapProvisionerTest {
             Path dataDirectory = root.resolve("plugins/Iris");
             writePack(dataDirectory.resolve("packs/overworld"), "overworld", "runtime");
             BukkitStartupPaths startupPaths = BukkitStartupPaths.resolve(root, new String[0]);
-            for (DataVersion version : new DataVersion[]{DataVersion.V26_1_2, DataVersion.V26_2, DataVersion.V26_3}) {
+            for (DataVersion version : new DataVersion[]{DataVersion.V1_21_1, DataVersion.V26_1_2, DataVersion.V26_2, DataVersion.V26_3}) {
                 DefaultPackBootstrapProvisioner.ProvisionResult result = DefaultPackBootstrapProvisioner.provision(
                         new DefaultPackBootstrapProvisioner.BootstrapRequest(dataDirectory, ignored -> {}, startupPaths, version));
                 Path biomeRoot = result.datapackRoot().resolve("data/iris/worldgen/biome/biomes");

core/src/test/java/art/arcane/iris/pack/datapack/DataVersionTest.java

@@ -9,6 +9,7 @@ import static org.junit.Assert.assertSame;
 public class DataVersionTest {
     @Test
     public void runtimeSelectionPreservesEverySupportedVersion() {
+        assertSame(DataVersion.V1_21_1, DataVersion.forMinecraftVersion("1.21.1"));
         assertSame(DataVersion.V26_1_2, DataVersion.forMinecraftVersion("26.1.2"));
         assertSame(DataVersion.V26_2, DataVersion.forMinecraftVersion("26.2"));
         assertSame(DataVersion.V26_2, DataVersion.forMinecraftVersion("26.2.0"));
@@ -24,6 +25,7 @@ public class DataVersionTest {
 
     @Test
     public void packFormatsMatchServerVersionJson() {
+        assertEquals(48, DataVersion.V1_21_1.getPackFormat());
         assertEquals(101, DataVersion.V26_1_2.getPackFormat());
         assertEquals(107, DataVersion.V26_2.getPackFormat());
         assertEquals(121, DataVersion.V26_3.getPackFormat());
@@ -31,7 +33,7 @@ public class DataVersionTest {
 
     @Test
     public void minSupportedPackFormatIsTheOldestSupportedRuntime() {
-        assertEquals(101, DataVersion.minSupportedPackFormat());
+        assertEquals(48, DataVersion.minSupportedPackFormat());
     }
 
     @Test

core/src/test/java/art/arcane/iris/structure/export/VanillaJigsawDatapackExporterTest.java

@@ -142,6 +142,47 @@ public class VanillaJigsawDatapackExporterTest {
         assertEquals("north_up", paletteEntry.getCompoundTag("Properties").getString("orientation"));
     }
 
+    @Test
+    public void exports1211RuntimeBlockStatesAndPackFormat() throws Exception {
+        when(IrisPlatforms.get().minecraftVersion()).thenReturn("1.21.1");
+        try {
+            TestGraph graph = connectorGraph();
+            Path output = temporaryFolder.getRoot().toPath().resolve("village-1211");
+            VanillaJigsawExportSettings settings = VanillaJigsawExportSettings.builder()
+                    .maxDistanceVertical(graph.structure.getMaxSizeChunks() * 16).build();
+            VanillaJigsawExportResult result = new VanillaJigsawDatapackExporter().export(
+                    request(graph, output).namespace("studio").resourcePath("village/test").settings(settings).build());
+            assertTrue(result.diagnostics().toString(), result.isSuccess());
+            JsonObject pack = json(output.resolve("pack.mcmeta")).getAsJsonObject("pack");
+            assertEquals(48, pack.get("pack_format").getAsInt());
+            JsonObject structure = json(output.resolve("data/studio/worldgen/structure/village/test.json"));
+            assertTrue(structure.get("max_distance_from_center").isJsonPrimitive());
+            CompoundTag template = (CompoundTag) NBTUtil.read(output.resolve(
+                    "data/studio/structure/village/test/piece/pieces/start.nbt").toFile()).getTag();
+            assertEquals(3955, template.getInt("DataVersion"));
+            CompoundTag palette = (CompoundTag) template.getListTag("palette").get(0);
+            assertEquals("minecraft:jigsaw", palette.getString("Name"));
+        } finally {
+            when(IrisPlatforms.get().minecraftVersion()).thenReturn("26.2");
+        }
+    }
+
+    @Test
+    public void rejects1211VanillaExportWithDifferentVerticalDistance() throws Exception {
+        when(IrisPlatforms.get().minecraftVersion()).thenReturn("1.21.1");
+        try {
+            Path output = temporaryFolder.getRoot().toPath().resolve("unequal-1211");
+            VanillaJigsawExportResult result = new VanillaJigsawDatapackExporter().export(
+                    request(connectorGraph(), output).settings(VanillaJigsawExportSettings.builder()
+                            .maxDistanceVertical(127).build()).build());
+            assertFalse(result.isSuccess());
+            assertTrue(result.diagnostics().stream().anyMatch(diagnostic ->
+                    diagnostic.code() == VanillaJigsawExportDiagnostic.Code.INVALID_MAX_DISTANCE));
+        } finally {
+            when(IrisPlatforms.get().minecraftVersion()).thenReturn("26.2");
+        }
+    }
+
     @Test
     public void exports26_3RuntimeBlockStatesAndPackFormat() throws Exception {
         when(IrisPlatforms.get().minecraftVersion()).thenReturn("26.3.0");