Replace network save snapshots instead of appending old entries

src/main/java/org/cyclops/integrateddynamics/IntegratedDynamics.java

@@ -260,6 +260,7 @@ public Class<?>[] getGameTestClasses() {
                 GameTestsMechanicalSqueezer.class,
                 GameTestsMenrilLogs.class,
                 GameTestsNetwork.class,
+                GameTestsNetworkSnapshot.class,
                 GameTestsOffsets.class,
                 GameTestsPartGuiRemoval.class,
                 GameTestsParts.class,

src/main/java/org/cyclops/integrateddynamics/core/network/Network.java

@@ -171,7 +171,8 @@ public boolean equals(Object object) {
     }
 
     public NetworkParams toParams() {
-        return new NetworkParams(this.baseCluster.toParams(), this.crashed);
+        // A save can happen before the first network tick completes deferred loading.
+        return this.toRead != null ? this.toRead : new NetworkParams(this.baseCluster.toParams(), this.crashed);
     }
 
     public void fromParams(NetworkParams params) {

src/main/java/org/cyclops/integrateddynamics/core/persist/world/NetworkWorldStorage.java

@@ -88,11 +88,14 @@ public void beforeSave() {
             network.beforeServerStop();
         }
 
-        // Save to params
-        for(Network network : networks) {
-            // Save to params
-            this.networkParams.add(network.toParams());
+        // Build a complete snapshot before replacing the previous serialized state.
+        // Appending here retains stale networks and duplicates them on every save.
+        List<NetworkParams> snapshot = Lists.newArrayList();
+        for (Network network : networks) {
+            snapshot.add(network.toParams());
         }
+        this.networkParams.clear();
+        this.networkParams.addAll(snapshot);
 
         // Consider always dirty
         setDirty();

src/main/java/org/cyclops/integrateddynamics/gametest/GameTestsNetworkSnapshot.java

@@ -0,0 +1,72 @@
+package org.cyclops.integrateddynamics.gametest;
+
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Direction;
+import net.minecraft.gametest.framework.GameTestHelper;
+import net.minecraft.network.chat.Component;
+import org.cyclops.cyclopscore.gametest.GameTest;
+import org.cyclops.integrateddynamics.RegistryEntries;
+import org.cyclops.integrateddynamics.api.path.SidedPathElementParams;
+import org.cyclops.integrateddynamics.core.helper.NetworkHelpers;
+import org.cyclops.integrateddynamics.core.network.Network;
+import org.cyclops.integrateddynamics.core.network.NetworkParams;
+import org.cyclops.integrateddynamics.core.persist.world.NetworkWorldStorage;
+
+import java.util.List;
+import java.util.Optional;
+
+public class GameTestsNetworkSnapshot {
+    @GameTest(template = GameTestsNetwork.TEMPLATE_EMPTY)
+    public void testRepeatedSaveReplacesSnapshot(GameTestHelper helper) {
+        BlockPos pos = BlockPos.ZERO.offset(1, 1, 1);
+        helper.setBlock(pos, RegistryEntries.BLOCK_CABLE.value());
+        helper.setBlock(pos.east(), RegistryEntries.BLOCK_CABLE.value());
+        helper.succeedWhen(() -> {
+            Network network = (Network) NetworkHelpers.getNetworkChecked(helper.getLevel(), helper.absolutePos(pos), null);
+            NetworkParams expected = network.toParams();
+            NetworkWorldStorage storage = new NetworkWorldStorage(List.of(new NetworkParams(List.of(), true)));
+            storage.addNewNetwork(network);
+            for (int i = 0; i < 10; i++) {
+                storage.beforeSave();
+                helper.assertTrue(storage.getNetworkParams().equals(List.of(expected)), Component.literal("Save retained stale or duplicate networks"));
+            }
+            storage.removeInvalidatedNetwork(network);
+            storage.beforeSave();
+            helper.assertTrue(storage.getNetworkParams().isEmpty(), Component.literal("Removed network was resaved"));
+        });
+    }
+
+    @GameTest(template = GameTestsNetwork.TEMPLATE_EMPTY)
+    public void testSaveBeforeDeferredLoad(GameTestHelper helper) {
+        SidedPathElementParams path = new SidedPathElementParams(helper.getLevel().dimension().identifier().toString(), helper.absolutePos(BlockPos.ZERO), Optional.of(Direction.EAST));
+        NetworkParams pending = new NetworkParams(List.of(path), true);
+        Network network = new Network();
+        network.fromParams(pending);
+        NetworkWorldStorage storage = new NetworkWorldStorage(List.of(pending));
+        storage.addNewNetwork(network);
+        storage.beforeSave();
+        storage.beforeSave();
+        helper.assertTrue(storage.getNetworkParams().equals(List.of(pending)), Component.literal("Deferred network data changed before its first tick"));
+        helper.succeed();
+    }
+
+    @GameTest(template = GameTestsNetwork.TEMPLATE_EMPTY)
+    public void testFailedSnapshotPreservesPrevious(GameTestHelper helper) {
+        NetworkParams previous = new NetworkParams(List.of(), true);
+        NetworkWorldStorage storage = new NetworkWorldStorage(List.of(previous));
+        storage.addNewNetwork(new Network() {
+            @Override
+            public void beforeServerStop() {}
+            @Override
+            public NetworkParams toParams() { throw new IllegalStateException("Synthetic snapshot failure"); }
+        });
+        boolean failed = false;
+        try {
+            storage.beforeSave();
+        } catch (IllegalStateException expected) {
+            failed = true;
+        }
+        helper.assertTrue(failed && storage.getNetworkParams().equals(List.of(previous)), Component.literal("Failed snapshot changed previous data"));
+        helper.succeed();
+    }
+}