Added generation history

- World-local pack epochs preserve generated chunks across restart-only updates
- Kernel catalogs and source seals retain executable generation behavior across jar changes
- Crash-safe ownership, boundary, registry, semantic, and mantle records survive activation changes
- New terrain blends lower surfaces and inverted ceilings against frozen historical boundaries
- Cave, object, structure, biome, and hydrology work respects activation ownership
- Find commands merge recorded facts with eligible active predictions for biomes, regions, structures, objects, and rivers
- Bukkit, Fabric, Forge, and NeoForge route generation through retained runtime scopes
- Shutdown ordering preserves class-loader resources until world and service cleanup finishes
- Tests cover activation chains, failure recovery, retained registries, bounded lookup, and transition geometry

spi/src/main/java/art/arcane/iris/spi/PlatformGenerationRegistry.java

@@ -0,0 +1,84 @@
+package art.arcane.iris.spi;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+public interface PlatformGenerationRegistry {
+    Pattern SHA_256_PATTERN = Pattern.compile("[0-9a-f]{64}");
+
+    String runtimeIdentity();
+
+    String generatedDefinitionRendererIdentity();
+
+    default String customBiomeResourceKey(String identitySha256) {
+        return contentAddressedCustomBiomeResourceKey(identitySha256);
+    }
+
+    default List<String> legacyCustomBiomeResourceKeys(
+            String packName,
+            String dimensionKey,
+            String customBiomeId
+    ) {
+        return List.of();
+    }
+
+    String dimensionTypeResourceKey(String packName, String dimensionKey, String dimensionTypeKey);
+
+    Definition definition(String registryKey, String resourceKey);
+
+    default Definition generatedDefinition(String registryKey, String resourceKey) {
+        return definition(registryKey, resourceKey);
+    }
+
+    default Definition canonicalDefinition(String registryKey, String resourceKey, String sourceJson) {
+        return Definition.exactJson(sourceJson);
+    }
+
+    static String contentAddressedCustomBiomeResourceKey(String identitySha256) {
+        String requiredFingerprint = Objects.requireNonNull(identitySha256, "identitySha256");
+        if (!SHA_256_PATTERN.matcher(requiredFingerprint).matches()) {
+            throw new IllegalArgumentException("Custom biome identity fingerprint must be a lowercase SHA-256 value.");
+        }
+        return "iris:biomes/" + requiredFingerprint;
+    }
+
+    enum Encoding {
+        JSON,
+        CONSERVATIVE_IDENTITY
+    }
+
+    record Definition(Encoding encoding, String value) {
+        public Definition {
+            encoding = Objects.requireNonNull(encoding, "encoding");
+            value = Objects.requireNonNull(value, "value");
+            if (value.isBlank()) {
+                throw new IllegalArgumentException("Platform registry definition must not be blank.");
+            }
+        }
+
+        public static Definition exactJson(String json) {
+            return new Definition(Encoding.JSON, json);
+        }
+
+        public static Definition conservativeIdentity(String identity) {
+            return new Definition(Encoding.CONSERVATIVE_IDENTITY, identity);
+        }
+
+        public static Definition resourceIdentity(String registryKey, String resourceKey) {
+            String requiredRegistryKey = requireText(registryKey, "registryKey");
+            String requiredResourceKey = requireText(resourceKey, "resourceKey");
+            return conservativeIdentity(
+                    "registry-resource-key-v1|" + requiredRegistryKey + "|" + requiredResourceKey
+            );
+        }
+
+        private static String requireText(String value, String label) {
+            String required = Objects.requireNonNull(value, label).trim();
+            if (required.isEmpty()) {
+                throw new IllegalArgumentException(label + " must not be blank.");
+            }
+            return required;
+        }
+    }
+}

spi/src/main/java/art/arcane/iris/spi/PlatformRegistries.java

@@ -31,6 +31,12 @@ import java.util.Map;
  * Internal to Iris; not a published integration surface.
  */
 public interface PlatformRegistries {
+    default PlatformGenerationRegistry generationRegistry() {
+        throw new UnsupportedOperationException(
+                "The active platform does not expose generation registry definitions."
+        );
+    }
+
     /**
      * Resolves a block key through the platform's compatibility layer, which rewrites keys that moved between
      * Minecraft versions and consults registered custom-content providers. An unresolvable key is reported and