fix: preserve microblock state dispatch

JAVA_MIGRATION_HANDOFF.md

@@ -16,7 +16,7 @@ migration checkout; `codex/tile-compatibility-fixes` was deleted after its fixes
 
 ## Current state and next target
 
-**523 plain-JVM tests and 237 Java 8 Forge tests pass, with zero failures/errors/skips.** Sources total **224 Java
+**526 plain-JVM tests and 237 Java 8 Forge tests pass, with zero failures/errors/skips.** Sources total **224 Java
 files and 9 Scala files / 747 nonblank Scala lines**. The packaged inventory has 443 classes.
 
 Review follow-up: restored packet-scheduler callback mutation behavior with the original Scala hash-map traversal,

docs/migration/HISTORY.md

@@ -1697,3 +1697,14 @@ differences belong in the [divergence ledger](../../JAVA_MIGRATION_DIVERGENCES.m
   This fixes an extension-contract regression, without claiming a demonstrated current-pack gameplay failure.
   Evidence is under ignored `run/conversion-review/`; migration-plan changes remain deferred until the review fixes
   are complete.
+
+### 2026-09-04 — Microblock state accessor compatibility
+
+- Restored virtual shape/material getters and setters for geometry, material lookup, drops, pick-block, NBT and
+  description/incremental packets. The backing fields, JVM signatures and serialized formats remain unchanged.
+- Three new regression cases compiled against the original Scala jar pass there, fail on the unfixed Java port
+  and pass unchanged after the fix. The test material explicitly implements the original Scala interface defaults
+  and uses the retained registry companion so the same test source compiles against both versions.
+- Build/style checks, 526 JVM tests and 237 Java 8 Forge tests pass. ProjectRed extends `Microblock`, and consumers
+  use its shape/material accessors, but no supplied consumer overriding those accessors was found. Evidence is
+  under ignored `run/conversion-review/`; no migration-plan changes were made.

src/main/scala/codechicken/microblock/Microblock.java

@@ -81,23 +81,23 @@ public abstract class Microblock extends TMultiPart implements TCuboidPart {
     }
 
     public int getSize() {
-        return shape >> 4;
+        return shape() >> 4;
     }
 
     public int getShape() {
-        return shape & 0xF;
+        return shape() & 0xF;
     }
 
     public void setShape(int size, int slot) {
-        shape = (byte) (size << 4 | slot);
+        shape_$eq((byte) (size << 4 | slot));
     }
 
     public int getMaterial() {
-        return material;
+        return material();
     }
 
     public MicroMaterialRegistry.IMicroMaterial getIMaterial() {
-        return MicroMaterialRegistry.getMaterial(material);
+        return MicroMaterialRegistry.getMaterial(material());
     }
 
     public abstract int itemClassID();
@@ -114,7 +114,7 @@ public abstract class Microblock extends TMultiPart implements TCuboidPart {
                         ItemMicroPart.create(
                                 amount,
                                 size | itemClassID() << 8,
-                                MicroMaterialRegistry.materialName(material)));
+                                MicroMaterialRegistry.materialName(material())));
             }
         }
         return items;
@@ -126,7 +126,7 @@ public abstract class Microblock extends TMultiPart implements TCuboidPart {
         for (int itemSize = 4; itemSize > 0; itemSize /= 2) {
             if (size % itemSize == 0 && size / itemSize >= 1) {
                 return ItemMicroPart
-                        .create(itemSize | itemClassID() << 8, MicroMaterialRegistry.materialName(material));
+                        .create(itemSize | itemClassID() << 8, MicroMaterialRegistry.materialName(material()));
             }
         }
         return null;
@@ -134,17 +134,17 @@ public abstract class Microblock extends TMultiPart implements TCuboidPart {
 
     @Override
     public void writeDesc(MCDataOutput packet) {
-        MicroMaterialRegistry.writeMaterialID(packet, material);
-        packet.writeByte(shape);
+        MicroMaterialRegistry.writeMaterialID(packet, material());
+        packet.writeByte(shape());
     }
 
     @Override
     public void readDesc(MCDataInput packet) {
-        shape = packet.readByte();
+        shape_$eq(packet.readByte());
     }
 
     public void sendShapeUpdate() {
-        getWriteStream().writeByte(shape);
+        getWriteStream().writeByte(shape());
     }
 
     @Override
@@ -155,14 +155,14 @@ public abstract class Microblock extends TMultiPart implements TCuboidPart {
 
     @Override
     public void save(NBTTagCompound tag) {
-        tag.setByte("shape", shape);
-        tag.setString("material", MicroMaterialRegistry.materialName(material));
+        tag.setByte("shape", shape());
+        tag.setString("material", MicroMaterialRegistry.materialName(material()));
     }
 
     @Override
     public void load(NBTTagCompound tag) {
-        shape = tag.getByte("shape");
-        material = MicroMaterialRegistry.materialID(tag.getString("material"));
+        shape_$eq(tag.getByte("shape"));
+        material_$eq(MicroMaterialRegistry.materialID(tag.getString("material")));
     }
 
     public boolean isTransparent() {

src/test/java/codechicken/microblock/MicroblockCharacterizationTest.java

@@ -106,7 +106,7 @@ class MicroblockCharacterizationTest {
         if (MicroMaterialRegistry.getMaterial(MATERIAL_NAME) == null) {
             MicroMaterialRegistry.registerMaterial(MATERIAL, MATERIAL_NAME);
         }
-        MicroMaterialRegistry.setupIDMap();
+        MicroMaterialRegistry$.MODULE$.setupIDMap();
         materialId = MicroMaterialRegistry.materialID(MATERIAL_NAME);
         microClass = allocateInstance(TestMicroClass.class);
     }
@@ -247,6 +247,85 @@ class MicroblockCharacterizationTest {
         assertSame(loaded, tile.changedPart);
     }
 
+    @Test
+    void overriddenStateDrivesGeometryMaterialAndItems() {
+        AccessorMicroblock part = new AccessorMicroblock();
+        assertEquals(5, part.getSize());
+        assertEquals(2, part.getShape());
+        assertEquals(materialId, part.getMaterial());
+        assertSame(MATERIAL, part.getIMaterial());
+        assertEquals(2.5f, part.getStrength(null, null));
+        assertTrue(part.isTransparent());
+        assertEquals(11, part.getLightValue());
+        assertEquals(2f, part.explosionResistance(null));
+
+        part.setShape(7, 3);
+        assertEquals((byte) 0x73, part.shape());
+        assertEquals(1, part.shapeWrites);
+        ItemMicroPart previous = MicroblockProxy.itemMicro();
+        ItemMicroPart item = new ItemMicroPart();
+        MicroblockProxy.itemMicro_$eq(item);
+        try {
+            List<ItemStack> drops = part.getDrops();
+            assertEquals(3, drops.size());
+            assertItem(drops.get(0), item, 1, 7 << 8 | 4);
+            assertItem(drops.get(1), item, 1, 7 << 8 | 2);
+            assertItem(drops.get(2), item, 1, 7 << 8 | 1);
+            part.setShape(6, 1);
+            assertItem(part.pickItem(null), item, 1, 7 << 8 | 2);
+        } finally {
+            MicroblockProxy.itemMicro_$eq(previous);
+        }
+        part.setShape(8, 15);
+        assertEquals(-8, part.getSize());
+        assertEquals(15, part.getShape());
+    }
+
+    @Test
+    void overriddenStateIsWrittenToDescriptionsNbtAndUpdates() {
+        AccessorMicroblock part = new AccessorMicroblock();
+        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+        part.writeDesc(output(bytes));
+        assertArrayEquals(new byte[] { (byte) materialId, (byte) 0x52 }, bytes.toByteArray());
+        NBTTagCompound tag = new NBTTagCompound();
+        part.save(tag);
+        assertEquals((byte) 0x52, tag.getByte("shape"));
+        assertEquals(MATERIAL_NAME, tag.getString("material"));
+
+        bytes.reset();
+        RecordingTile tile = new RecordingTile();
+        tile.output = output(bytes);
+        part.bind(tile);
+        part.sendShapeUpdate();
+        assertArrayEquals(new byte[] { (byte) 0x52 }, bytes.toByteArray());
+    }
+
+    @Test
+    void overriddenSettersReceiveLoadedStateAndNetworkUpdates() {
+        AccessorMicroblock part = new AccessorMicroblock();
+        NBTTagCompound tag = new NBTTagCompound();
+        tag.setByte("shape", (byte) 0x31);
+        tag.setString("material", MissingMicroMaterial.key());
+        part.load(tag);
+        assertEquals((byte) 0x31, part.shape());
+        assertEquals(MicroMaterialRegistry.getMissingId(), part.material());
+        assertEquals(1, part.shapeWrites);
+        assertEquals(1, part.materialWrites);
+
+        part.readDesc(input((byte) 0x42));
+        assertEquals((byte) 0x42, part.shape());
+        assertEquals(2, part.shapeWrites);
+        RecordingTile tile = new RecordingTile();
+        part.bind(tile);
+        part.read(input((byte) 0x63));
+        assertEquals((byte) 0x63, part.shape());
+        assertEquals(3, part.shapeWrites);
+        assertEquals(1, part.materialWrites);
+        assertEquals(1, tile.renderMarks);
+        assertEquals(1, tile.partChanges);
+        assertSame(part, tile.changedPart);
+    }
+
     private static void assertTrait(Class<?> type, Class<?>[] interfaces, Set<String> methods) {
         assertTrue(type.isInterface());
         assertArrayEquals(interfaces, type.getInterfaces());
@@ -315,7 +394,7 @@ class MicroblockCharacterizationTest {
         return (T) unsafe.getMethod("allocateInstance", Class.class).invoke(field.get(null), type);
     }
 
-    private static final class TestMicroblock extends Microblock {
+    private static class TestMicroblock extends Microblock {
 
         private static final Cuboid6 BOUNDS = new Cuboid6(0, 0, 0, 0.5, 0.75, 1);
 
@@ -339,6 +418,40 @@ class MicroblockCharacterizationTest {
         }
     }
 
+    private static final class AccessorMicroblock extends TestMicroblock {
+
+        private int overriddenMaterial = materialId;
+        private byte overriddenShape = 0x52;
+        private int materialWrites;
+        private int shapeWrites;
+
+        private AccessorMicroblock() {
+            super(MicroMaterialRegistry.getMissingId());
+        }
+
+        @Override
+        public int material() {
+            return overriddenMaterial;
+        }
+
+        @Override
+        public void material_$eq(int value) {
+            materialWrites++;
+            overriddenMaterial = value;
+        }
+
+        @Override
+        public byte shape() {
+            return overriddenShape;
+        }
+
+        @Override
+        public void shape_$eq(byte value) {
+            shapeWrites++;
+            overriddenShape = value;
+        }
+    }
+
     private static final class TestMicroClass extends MicroblockClass {
 
         @Override
@@ -388,6 +501,19 @@ class MicroblockCharacterizationTest {
 
     private static final class TestMaterial implements IMicroMaterial {
 
+        @Override
+        public boolean isSolid() {
+            return !isTransparent();
+        }
+
+        @Override
+        public void loadIcons() {}
+
+        @Override
+        public boolean canRenderInPass(int pass) {
+            return pass == 0;
+        }
+
         @Override
         public IIcon getBreakingIcon(int side) {
             return null;