Enforce seed cohesion

- Scope cached generation fields to their seed and context.
- Warm decorators and ores with their canonical generation seeds.
- Stabilize object traversal and procedural placement choices.
- Isolate smart-bore variants from shared source objects.
- Pin noise and full-engine output across generation orders.
- Verify same-jar generation through cold server restarts.

probe/src/main/java/art/arcane/iris/probe/GenerationOrderProbe.java

@@ -326,7 +326,7 @@ public final class GenerationOrderProbe {
         );
     }
 
-    private static ProbeResult run(ProbeConfiguration configuration) throws Exception {
+    static ProbeResult run(ProbeConfiguration configuration) throws Exception {
         System.out.println(LOG_PREFIX + " pack: " + configuration.packSource().getAbsolutePath());
         System.out.println(LOG_PREFIX + " dimension: " + configuration.dimensionKey());
         System.out.println(LOG_PREFIX + " seed: " + configuration.seed());

probe/src/main/java/art/arcane/iris/probe/RealPackProbeSupport.java

@@ -537,7 +537,7 @@ final class RealPackProbeSupport {
     private static File clonePack(File source, File workRoot) throws Exception {
         File destination = new File(workRoot, "pack");
         if (System.getProperty("os.name").startsWith("Mac")) {
-            Process clone = new ProcessBuilder("/bin/cp", "-Rc", source.getAbsolutePath(), destination.getAbsolutePath())
+            Process clone = new ProcessBuilder("/bin/cp", "-RLc", source.getAbsolutePath(), destination.getAbsolutePath())
                     .inheritIO().start();
             if (clone.waitFor() == 0) {
                 return destination;

probe/src/test/java/art/arcane/iris/probe/SeedCohesionProbeTest.java

@@ -0,0 +1,74 @@
+package art.arcane.iris.probe;
+
+import art.arcane.iris.testsupport.IrisRuntimeState;
+import org.junit.AfterClass;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.File;
+import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertNotNull;
+
+public final class SeedCohesionProbeTest {
+    @Rule
+    public TemporaryFolder temporary = new TemporaryFolder();
+
+    @AfterClass
+    public static void releaseRuntime() {
+        IrisRuntimeState.reset();
+    }
+
+    @Test
+    public void linkedPackInputsAreCopiedIntoAnIndependentWorkspace() throws Exception {
+        URL resource = SeedCohesionProbeTest.class.getResource("/seed-cohesion");
+        assertNotNull(resource);
+        Path source = Path.of(resource.toURI());
+        Path link = temporary.getRoot().toPath().resolve("linked-pack");
+        Files.createSymbolicLink(link, source);
+        try (RealPackProbeSupport.Workspace workspace = RealPackProbeSupport.openWorkspace(
+                link.toFile(), "cohesion", "[seed-cohesion-copy]")) {
+            Path copy = workspace.pack().toPath();
+            assertFalse(Files.isSymbolicLink(copy));
+            assertFalse(Files.isSameFile(source, copy));
+            assertEquals(Files.readString(source.resolve("dimensions/cohesion.json")),
+                    Files.readString(copy.resolve("dimensions/cohesion.json")));
+        }
+    }
+
+    @Test(timeout = 180_000L)
+    public void completeChunksRemainStableAcrossSeedOrderThreadsAndRestarts() throws Exception {
+        GenerationOrderProbe.AggregateSignature first = generate(1337L, false);
+        GenerationOrderProbe.AggregateSignature parallel = generate(1337L, true);
+        GenerationOrderProbe.AggregateSignature alternate = generate(-8675309L, true);
+        GenerationOrderProbe.AggregateSignature restarted = generate(1337L, true);
+        assertEquals(first, parallel);
+        assertEquals(first, restarted);
+        assertNotEquals(first.blocks(), alternate.blocks());
+        assertEquals(new GenerationOrderProbe.AggregateSignature(
+                "3ddfe89b98273ec609574918ac461bdd0e15365a2840a8ab73285818981feb74",
+                "0f54e6504dc0b66b3c0d9b9cc4406a07a63d14e5eba4c30db7c3d7f74a5d61c7",
+                "9bcf2d354c6f17849046153c25beeb3ce08b81d3409037d2968f28d30d832253"), first);
+        assertEquals(new GenerationOrderProbe.AggregateSignature(
+                "0ad13dd2ea0d3eb467f1fded74403f7efb5245a3a06799b39c1d1d17dd32b926",
+                "0f54e6504dc0b66b3c0d9b9cc4406a07a63d14e5eba4c30db7c3d7f74a5d61c7",
+                "e4f6fb0c86cae9be76a1e957156e42a762b4d75458fb1483fe856bda1cfd3a1e"), alternate);
+    }
+
+    private static GenerationOrderProbe.AggregateSignature generate(long seed, boolean multicore) throws Exception {
+        URL resource = SeedCohesionProbeTest.class.getResource("/seed-cohesion");
+        assertNotNull(resource);
+        File pack = new File(resource.toURI());
+        GenerationOrderProbe.ProbeConfiguration configuration = new GenerationOrderProbe.ProbeConfiguration(
+                pack, "cohesion", seed, -1, 1, -1, 1, 4, 91L, multicore, false);
+        GenerationOrderProbe.ProbeResult result = GenerationOrderProbe.run(configuration);
+        assertEquals("PASS", result.status());
+        return result.signature();
+    }
+}

probe/src/test/resources/seed-cohesion/biomes/terrain.json

@@ -0,0 +1,18 @@
+{
+  "name": "Terrain",
+  "derivative": "minecraft:plains",
+  "vanillaDerivative": "minecraft:plains",
+  "layers": [{"palette": [{"block": "minecraft:stone"}]}],
+  "generators": [{"generator": "terrain", "min": 20, "max": 30}],
+  "decorators": [{
+    "chance": 0.61,
+    "style": {"style": "SIMPLEX", "zoom": 7},
+    "variance": {"style": "SIMPLEX", "zoom": 4},
+    "heightVariance": {"style": "SIMPLEX", "zoom": 9},
+    "forcePlace": true,
+    "stackMin": 1,
+    "stackMax": 5,
+    "palette": [{"block": "minecraft:stone"}, {"block": "minecraft:dirt"}],
+    "topPalette": [{"block": "minecraft:granite"}, {"block": "minecraft:andesite"}]
+  }]
+}

probe/src/test/resources/seed-cohesion/dimensions/cohesion.json

@@ -0,0 +1,11 @@
+{
+  "name": "Seed cohesion fixture",
+  "version": 1,
+  "mode": {"type": "OVERWORLD"},
+  "regions": ["terrain"],
+  "environment": "NORMAL",
+  "dimensionHeight": {"min": 0, "max": 64},
+  "logicalHeight": 64,
+  "fluidHeight": 10,
+  "caveProfile": {"enabled": false}
+}

probe/src/test/resources/seed-cohesion/generators/terrain.json

@@ -0,0 +1,5 @@
+{
+  "seed": 310,
+  "interpolator": {"function": "NONE", "horizontalScale": 1},
+  "composite": [{"seed": 310, "style": {"style": "SIMPLEX", "zoom": 19}}]
+}

probe/src/test/resources/seed-cohesion/regions/terrain.json

@@ -0,0 +1,6 @@
+{
+  "name": "Terrain",
+  "landBiomes": ["terrain"],
+  "seaBiomes": ["terrain"],
+  "shoreBiomes": ["terrain"]
+}