fix: reactivate scheduled ticks restored from chunk NBT

docs/migration/DIVERGENCES.md

@@ -16,6 +16,7 @@ audit, before extending this list.
 | --- | --- |
 | Raw microblock recipe material lookup | Skips `MissingMicroMaterial`, whose recovery item is stone, so sawing stone selects the real stone material. Existing missing-material microblocks retain their recovery behavior. This fixes a pre-existing Scala bug. |
 | `BlockMicroMaterial.createAndRegister(Block, Seq, String)` | Registers every supplied metadata value instead of only zero, including dark-oak logs and leaves and their legacy-name remaps. This fixes a pre-existing Scala bug; material IDs are rebuilt through the existing registry mapping. |
+| Chunk scheduled-tick restoration | Reactivates chunks with restored scheduled ticks so their callbacks resume at the saved deadlines. The Scala implementation restored entries without activating their chunk. NBT layout and duplicate-scheduling behavior are unchanged. |
 | `IDWriter` before `setMax` | `read`/`write` throw `IllegalStateException` instead of `NullPointerException`. Uninitialized use is unsupported. |
 | `PacketScheduler` invalid `maskWidth` | Throws `IllegalArgumentException` instead of `scala.MatchError`. Valid widths remain 1, 2, 4 and 8. |
 | `NormalOcclusionTest.apply(Traversable, Traversable)` | Materializes both inputs into Java lists before testing instead of nested Scala `forall`. Finite, side-effect-free collections give the same result; eager traversal can change side effects, failure timing and termination for unusual inputs. |

src/main/scala/codechicken/multipart/TickScheduler.java

@@ -302,6 +302,9 @@ public final class TickScheduler {
                                     false));
                 }
             }
+            if (!tickList.isEmpty()) {
+                scheduler().tickChunks.add(this);
+            }
         }
 
         @Override

src/test/java/codechicken/multipart/TickSchedulerPersistenceRegressionTest.java

@@ -0,0 +1,55 @@
+package codechicken.multipart;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Collections;
+
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.world.ChunkPosition;
+import net.minecraft.world.chunk.Chunk;
+
+import org.junit.jupiter.api.Test;
+
+class TickSchedulerPersistenceRegressionTest {
+
+    @Test
+    void savedTicksResumeAfterChunkReloadAndFireOnlyOnce() {
+        TickScheduler.WorldTickScheduler world = new TickScheduler.WorldTickScheduler(null);
+        Chunk chunk = new Chunk(null, 2, -3);
+        TileMultipart tile = new TileMultipart();
+        tile.xCoord = 35;
+        tile.yCoord = 64;
+        tile.zCoord = -44;
+        int[] calls = { 0 };
+        TMultiPart part = new TMultiPart() {
+
+            @Override
+            public String getType() {
+                return "test:restored-tick";
+            }
+
+            @Override
+            public void scheduledTick() {
+                calls[0]++;
+            }
+        };
+        tile.setPartList(Collections.singletonList(part));
+        part.bind(tile);
+        chunk.chunkTileEntityMap.put(new ChunkPosition(3, 64, 4), tile);
+        TickScheduler.ChunkTickScheduler scheduler = new TickScheduler.ChunkTickScheduler(chunk, world);
+        scheduler.scheduleTick(part, 2, false);
+        NBTTagCompound saved = new NBTTagCompound();
+        scheduler.saveData(saved);
+        assertEquals(1, saved.getTagList("multipartTicks", 10).tagCount());
+        scheduler.unload();
+        TickScheduler.ChunkTickScheduler restored = new TickScheduler.ChunkTickScheduler(chunk, world);
+        restored.loadData(saved);
+        restored.scheduleTick(part, 0, false);
+        for (int tick = 0; tick < 4; tick++) {
+            world.preTick();
+            world.postTick();
+            assertEquals(tick < 2 ? 0 : 1, calls[0]);
+        }
+    }
+
+}