Fixes

adapters/bukkit/plugin/src/main/java/art/arcane/iris/core/commands/CommandJigsaw.java

@@ -52,6 +52,7 @@ import art.arcane.iris.engine.object.IrisPosition;
 import art.arcane.iris.engine.object.IrisStructure;
 import art.arcane.iris.platform.bukkit.BukkitPlatform;
 import art.arcane.iris.util.common.director.DirectorExecutor;
+import art.arcane.iris.util.common.director.specialhandlers.IrisStructureHandler;
 import art.arcane.iris.util.common.format.C;
 import art.arcane.iris.util.common.plugin.VolmitSender;
 import art.arcane.iris.util.common.scheduling.J;
@@ -118,9 +119,9 @@ public class CommandJigsaw implements DirectorExecutor {
                     customHandler = JigsawModeHandler.class) String mode,
             @Param(description = "iris or vanilla", defaultValue = "iris",
                     customHandler = JigsawCompatibilityHandler.class) String compatibility,
-            @Param(description = "Cell width", defaultValue = "16") int width,
-            @Param(description = "Cell height", defaultValue = "16") int height,
-            @Param(description = "Cell depth", defaultValue = "16") int depth,
+            @Param(description = "Cell width", defaultValue = "15") int width,
+            @Param(description = "Cell height", defaultValue = "15") int height,
+            @Param(description = "Cell depth", defaultValue = "15") int depth,
             @Param(description = "Studio world seed", defaultValue = "1337") long seed
     ) {
         IrisData data = requireData(dimension);
@@ -157,6 +158,16 @@ public class CommandJigsaw implements DirectorExecutor {
             }
             return;
         }
+        try {
+            JigsawStudioService.clearAutosaveHistory(
+                    data.getDataFolder().toPath(),
+                    structure);
+        } catch (IOException exception) {
+            Iris.reportError("Failed to clear stale Jigsaw Studio history for '" + structure + "'.", exception);
+            sendError("Jigsaw project was created, but stale autosave history could not be cleared: "
+                    + exception.getMessage());
+            return;
+        }
         data.invalidateStructureResources();
         sender().sendMessage(C.GREEN + "Created Jigsaw project '" + structure + "' atomically.");
         open(dimension, structure, seed);
@@ -208,7 +219,8 @@ public class CommandJigsaw implements DirectorExecutor {
     public void open(
             @Param(description = "Pack dimension") IrisDimension dimension,
             @Param(name = "key", aliases = {"structure", "name"},
-                    description = "Existing key loaded from structures/<key>.json") String structure,
+                    description = "Existing key loaded from structures/<key>.json",
+                    customHandler = IrisStructureHandler.class) String structure,
             @Param(description = "Studio world seed", defaultValue = "1337") long seed
     ) {
         openProject(player(), sender(), dimension, structure, seed);

adapters/bukkit/plugin/src/main/java/art/arcane/iris/core/commands/CommandObject.java

@@ -202,7 +202,7 @@ public class CommandObject implements DirectorExecutor {
                 //Prevent blocks being set in or bellow bedrock
                 if (y <= world.getMinHeight() || block.getType() == Material.BEDROCK) return;
 
-                futureBlockChanges.put(block, block.getBlockData());
+                futureBlockChanges.putIfAbsent(block, block.getBlockData());
 
                 if (d instanceof IrisCustomData data) {
                     block.setBlockData(data.getBase(), false);

adapters/bukkit/plugin/src/main/java/art/arcane/iris/core/commands/CommandStructure.java

@@ -369,7 +369,24 @@ public class CommandStructure implements DirectorExecutor {
             }
             p.getObject().place(p.getX(), p.getY(), p.getZ(), placer, config, rng, null, null, data);
         }
-        sender().sendMessage(IrisLanguage.text(BukkitCommandMessagesExtended.COMMAND_STRUCTURE_PLACED_PIECES_AT_YOUR_LOCATION, MessageArgument.untrusted("structure", structure), MessageArgument.untrusted("value", pieces.size())));
+        int blockChanges = 0;
+        for (Map.Entry<Block, BlockData> entry : future.entrySet()) {
+            if (!entry.getKey().getBlockData().equals(entry.getValue())) {
+                blockChanges++;
+            }
+        }
+        if (blockChanges == 0) {
+            sender().sendMessage(IrisLanguage.text(
+                    BukkitCommandMessagesExtended.COMMAND_STRUCTURE_PLACEMENT_CHANGED_NO_BLOCKS,
+                    MessageArgument.untrusted("structure", structure),
+                    MessageArgument.untrusted("value", pieces.size())));
+            return;
+        }
+        sender().sendMessage(IrisLanguage.text(
+                BukkitCommandMessagesExtended.COMMAND_STRUCTURE_PLACED_PIECES_AT_YOUR_LOCATION,
+                MessageArgument.untrusted("structure", structure),
+                MessageArgument.untrusted("value", pieces.size()),
+                MessageArgument.untrusted("value2", blockChanges)));
     }
 
 }