Retained active generation resources

- Failed planner drains retain mantle and generation data for retry
- Detached runtime cleanup retains its target until runtime teardown succeeds
- Terrain caches clear after hydrology shutdown completes

core/src/main/java/art/arcane/iris/engine/EngineShutdownSequence.java

@@ -192,8 +192,17 @@ final class EngineShutdownSequence {
                 () -> NativeStructureOwnershipStore.close(engine));
         cleanupFailure = appendFailure(cleanupFailure, ownershipFailure);
         if (ownershipFailure == null) {
-            cleanupFailure = closeDetachedGenerationRuntimes(cleanupFailure);
-            cleanupFailure = closeRuntime(engine.runtime, cleanupFailure);
+            Throwable runtimeFailure = closeDetachedGenerationRuntimes(null);
+            if (runtimeFailure == null) {
+                runtimeFailure = closeRuntime(engine.runtime, null);
+            }
+            cleanupFailure = appendFailure(cleanupFailure, runtimeFailure);
+            if (runtimeFailure != null) {
+                if (cleanupFailure != original) {
+                    original.addSuppressed(cleanupFailure);
+                }
+                return;
+            }
             engine.runtime = null;
             cleanupFailure = runCleanup(cleanupFailure, engine.publishedTarget::close);
             cleanupFailure = runCleanup(cleanupFailure, engine.engineDataStore::releaseEngineData);
@@ -229,11 +238,15 @@ final class EngineShutdownSequence {
                 assembly.mode.close();
             }
         });
-        failure = runCleanup(failure, () -> {
+        Throwable complexFailure = runCleanup(null, () -> {
             if (assembly.complex != null) {
                 assembly.complex.close();
             }
         });
+        failure = appendFailure(failure, complexFailure);
+        if (complexFailure != null) {
+            return failure;
+        }
         failure = runCleanup(failure, () -> {
             if (assembly.hash32 != null) {
                 assembly.hash32.cancel(true);
@@ -277,7 +290,11 @@ final class EngineShutdownSequence {
             return failure;
         }
         failure = runCleanup(failure, generationRuntime.mode()::close);
-        failure = runCleanup(failure, generationRuntime.complex()::close);
+        Throwable complexFailure = runCleanup(null, generationRuntime.complex()::close);
+        failure = appendFailure(failure, complexFailure);
+        if (complexFailure != null) {
+            return failure;
+        }
         failure = runCleanup(failure, () -> generationRuntime.hash32().cancel(true));
         if (generationRuntime.mantle() != retainedMantle) {
             failure = runCleanup(failure, generationRuntime.mantle()::saveAllNow);
@@ -290,10 +307,14 @@ final class EngineShutdownSequence {
         IrisEngine.GenerationRuntimeBinding binding = new IrisEngine.GenerationRuntimeBinding(
                 engine,
                 generationRuntime);
+        Throwable runtimeFailure;
         try (IrisEngine.GenerationRuntimeScope ignored = engine.generationRuntimeScopes.open(binding)) {
-            failure = closeGenerationRuntime(generationRuntime, failure);
+            runtimeFailure = closeGenerationRuntime(generationRuntime, null);
         } catch (Throwable scopeFailure) {
-            failure = appendFailure(failure, scopeFailure);
+            runtimeFailure = scopeFailure;
+        }
+        if (runtimeFailure != null) {
+            return appendFailure(failure, runtimeFailure);
         }
         return closeDetachedTarget(generationRuntime.target(), failure);
     }

core/src/main/java/art/arcane/iris/engine/IrisComplex.java

@@ -1783,9 +1783,9 @@ public class IrisComplex implements DataProvider {
     }
 
     public void close() {
-        resolvedTerrain.clear();
         if (hydrologyRuntime != null) {
             hydrologyRuntime.close();
         }
+        resolvedTerrain.clear();
     }
 }

core/src/test/java/art/arcane/iris/engine/EngineShutdownDrainTest.java

@@ -0,0 +1,102 @@
+package art.arcane.iris.engine;
+
+import art.arcane.iris.engine.EngineRuntimeBuilder.RuntimeAssembly;
+import art.arcane.iris.engine.framework.EngineMode;
+import art.arcane.iris.engine.mantle.EngineMantle;
+import art.arcane.iris.spi.IrisPlatform;
+import art.arcane.iris.spi.IrisPlatforms;
+import art.arcane.iris.spi.PlatformBlockState;
+import art.arcane.iris.spi.PlatformRegistries;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.mockito.InOrder;
+
+import java.util.concurrent.CompletableFuture;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.inOrder;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.when;
+
+public class EngineShutdownDrainTest {
+    private static IrisPlatform previousPlatform;
+
+    @BeforeClass
+    public static void bindPlatform() {
+        previousPlatform = IrisPlatforms.isBound() ? IrisPlatforms.get() : null;
+        IrisPlatforms.unbind();
+        IrisPlatform platform = mock(IrisPlatform.class);
+        PlatformRegistries registries = mock(PlatformRegistries.class);
+        when(platform.registries()).thenReturn(registries);
+        when(registries.block(anyString())).thenReturn(mock(PlatformBlockState.class));
+        IrisPlatforms.bind(platform);
+    }
+
+    @AfterClass
+    public static void restorePlatform() {
+        IrisPlatforms.unbind();
+        if (previousPlatform != null) {
+            IrisPlatforms.bind(previousPlatform);
+        }
+    }
+
+    @Test
+    public void failedPlannerDrainRetainsRuntimeStorage() {
+        GenerationRuntime runtime = mock(GenerationRuntime.class);
+        IrisComplex complex = mock(IrisComplex.class);
+        EngineMantle mantle = mock(EngineMantle.class);
+        CompletableFuture<Long> hash = new CompletableFuture<>();
+        when(runtime.mode()).thenReturn(mock(EngineMode.class));
+        when(runtime.complex()).thenReturn(complex);
+        when(runtime.mantle()).thenReturn(mantle);
+        when(runtime.hash32()).thenReturn(hash);
+        IllegalStateException failure = new IllegalStateException("Planner still active");
+        doThrow(failure).when(complex).close();
+
+        assertSame(failure, new EngineShutdownSequence(null).closeGenerationRuntime(runtime, null));
+        verifyNoInteractions(mantle);
+        assertFalse(hash.isCancelled());
+    }
+
+    @Test
+    public void successfulPlannerDrainPrecedesMantleRelease() {
+        GenerationRuntime runtime = mock(GenerationRuntime.class);
+        IrisComplex complex = mock(IrisComplex.class);
+        EngineMantle mantle = mock(EngineMantle.class);
+        CompletableFuture<Long> hash = new CompletableFuture<>();
+        when(runtime.mode()).thenReturn(mock(EngineMode.class));
+        when(runtime.complex()).thenReturn(complex);
+        when(runtime.mantle()).thenReturn(mantle);
+        when(runtime.hash32()).thenReturn(hash);
+
+        assertNull(new EngineShutdownSequence(null).closeGenerationRuntime(runtime, null));
+        InOrder releases = inOrder(complex, mantle);
+        releases.verify(complex).close();
+        releases.verify(mantle).saveAllNow();
+        releases.verify(mantle).close();
+        assertTrue(hash.isCancelled());
+    }
+
+    @Test
+    public void failedAssemblyDrainRetainsMantleOwnership() {
+        RuntimeAssembly assembly = mock(RuntimeAssembly.class);
+        assembly.complex = mock(IrisComplex.class);
+        assembly.mantle = mock(EngineMantle.class);
+        assembly.ownsMantle = true;
+        assembly.hash32 = new CompletableFuture<>();
+        IllegalStateException failure = new IllegalStateException("Planner still active");
+        doThrow(failure).when(assembly.complex).close();
+
+        assertSame(failure, new EngineShutdownSequence(null).closeAssembly(assembly, null));
+        verifyNoInteractions(assembly.mantle);
+        assertTrue(assembly.ownsMantle);
+        assertFalse(assembly.hash32.isCancelled());
+    }
+}

core/src/test/java/art/arcane/iris/engine/EngineShutdownOwnershipContractTest.java

@@ -43,8 +43,8 @@ public class EngineShutdownOwnershipContractTest {
         String cleanup = source.substring(cleanupStart, cleanupEnd);
         int ownershipClose = cleanup.indexOf("NativeStructureOwnershipStore.close(engine)");
         int ownershipGate = cleanup.indexOf("if (ownershipFailure == null)", ownershipClose);
-        int detachedRelease = cleanup.indexOf("closeDetachedGenerationRuntimes(cleanupFailure)", ownershipGate);
-        int runtimeRelease = cleanup.indexOf("closeRuntime(engine.runtime, cleanupFailure)", ownershipGate);
+        int detachedRelease = cleanup.indexOf("closeDetachedGenerationRuntimes(null)", ownershipGate);
+        int runtimeRelease = cleanup.indexOf("closeRuntime(engine.runtime, null)", ownershipGate);
         int closedPublication = cleanup.indexOf("engine.closed = true", ownershipGate);
 
         assertTrue(ownershipClose >= 0);