d

d

adapters/modded-common/src/main/java/art/arcane/iris/modded/ModdedStructureHooks.java

@@ -19,6 +19,7 @@
 package art.arcane.iris.modded;
 
 import art.arcane.iris.nativegen.NativeStructureGenerationException;
+import art.arcane.iris.nativegen.NativeStructureGenerationKeys;
 import art.arcane.iris.nativegen.NativeStructureFactory;
 import art.arcane.iris.spi.IrisLogging;
 import art.arcane.iris.spi.PlatformStructureHooks;
@@ -225,22 +226,15 @@ public final class ModdedStructureHooks implements PlatformStructureHooks {
 
     @Override
     public List<String> reachableStructureKeys(PlatformWorld world) {
-        List<String> keys = new ArrayList<>();
         ServerLevel level = requireLevel(world, "resolve reachable structures");
         try {
             BiomeSource source = level.getChunkSource().getGenerator().getBiomeSource();
             Set<String> possibleBiomes = possibleBiomeKeys(source);
-            Registry<Structure> registry = level.registryAccess().lookupOrThrow(Registries.STRUCTURE);
-            for (Map.Entry<ResourceKey<Structure>, Structure> entry : registry.entrySet()) {
-                if (hasPossibleBiome(entry.getValue(), possibleBiomes)) {
-                    keys.add(entry.getKey().identifier().toString());
-                }
-            }
+            return new ArrayList<>(NativeStructureGenerationKeys.reachable(level, possibleBiomes));
         } catch (RuntimeException error) {
             throw new IllegalStateException("Iris failed to resolve reachable structures for modded level '"
                     + level.dimension().identifier() + "'", error);
         }
-        return keys;
     }
 
     @Override
@@ -401,16 +395,6 @@ public final class ModdedStructureHooks implements PlatformStructureHooks {
         return keys;
     }
 
-    private static boolean hasPossibleBiome(Structure structure, Set<String> possibleBiomeKeys) {
-        for (Holder<Biome> holder : structure.biomes()) {
-            Optional<ResourceKey<Biome>> key = holder.unwrapKey();
-            if (key.isPresent() && possibleBiomeKeys.contains(key.get().identifier().toString())) {
-                return true;
-            }
-        }
-        return false;
-    }
-
     private static ServerLevel level(PlatformWorld world) {
         return world instanceof ModdedPlatformWorld moddedWorld ? moddedWorld.level() : null;
     }

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedCommandHelp.java

@@ -54,6 +54,9 @@ import static art.arcane.iris.modded.command.ModdedCommandFeedback.USAGE_ICON;
 final class ModdedCommandHelp {
     private static final int PAGE_SIZE = 17;
     private static final int PAGE_BUTTON_WIDTH = 10;
+    private static final TextKey COMMAND_UNREGISTERED = TextKey.of(
+            "iris.modded.help.entry.command.unregistered",
+            "Print every structure excluded from goto completion and its exact reason to the server console");
     private static final Map<String, List<Entry>> SECTIONS = new LinkedHashMap<>();
 
     static {
@@ -98,6 +101,7 @@ final class ModdedCommandHelp {
                 Entry.command("biome", "<key>", ModdedHelpMessages.COMMAND_BIOME_FIND_AN_IRIS_BIOME),
                 Entry.command("region", "<key>", ModdedHelpMessages.COMMAND_REGION_FIND_AN_IRIS_REGION),
                 Entry.command("object", "<key>", ModdedHelpMessages.COMMAND_OBJECT_FIND_AN_OBJECT_PLACEMENT),
+                Entry.command("unregistered", "", COMMAND_UNREGISTERED),
                 Entry.command("structure", "<key>", ModdedHelpMessages.COMMAND_STRUCTURE_FIND_AN_IRIS_PLACED_OR_NATIVE_DATAPACK_STRUCTURE),
                 Entry.command("poi", "<type>", ModdedHelpMessages.COMMAND_POI_FIND_A_SUPPORTED_POINT_OF_INTEREST)
         ));

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedCommandSuggestions.java

@@ -21,6 +21,10 @@ package art.arcane.iris.modded.command;
 import art.arcane.iris.core.pack.PackDirectoryResolver;
 import art.arcane.iris.engine.framework.Engine;
 import art.arcane.iris.engine.framework.IrisStructureLocator;
+import art.arcane.iris.engine.framework.NativeStructureGenerationPolicy;
+import art.arcane.iris.engine.framework.StructureReachability;
+import art.arcane.iris.engine.object.IrisNativeStructureDecision;
+import art.arcane.iris.engine.object.NativeStructureGenerationStatus;
 import art.arcane.iris.modded.IrisModdedChunkGenerator;
 import art.arcane.iris.modded.ModdedEngineBootstrap;
 import art.arcane.iris.modded.ModdedServerLevels;
@@ -41,11 +45,16 @@ import org.slf4j.LoggerFactory;
 import java.io.File;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
+import java.util.Map;
 import java.util.Set;
+import java.util.TreeMap;
 import java.util.TreeSet;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Predicate;
 
 final class ModdedCommandSuggestions {
     static final SuggestionProvider<CommandSourceStack> BIOME_KEYS = (CommandContext<CommandSourceStack> context, SuggestionsBuilder builder) -> suggestBiomeKeys(context, builder);
@@ -103,22 +112,62 @@ final class ModdedCommandSuggestions {
     }
 
     static CompletableFuture<Suggestions> suggestStructureKeys(CommandContext<CommandSourceStack> context, SuggestionsBuilder builder) {
-        ModdedCommandFeedback.tab(context.getSource());
+        CommandSourceStack source = context.getSource();
+        ModdedCommandFeedback.tab(source);
         try {
-            Engine engine = IrisModdedCommands.engineFor(context.getSource().getLevel());
-            Collection<String> irisKeys = engine == null ? List.of() : IrisStructureLocator.placedKeys(engine);
-            Registry<Structure> registry = context.getSource().getServer().registryAccess().lookupOrThrow(Registries.STRUCTURE);
-            List<String> nativeKeys = new ArrayList<>(registry.keySet().size());
-            for (Identifier identifier : registry.keySet()) {
-                nativeKeys.add(identifier.toString());
+            ServerLevel level = source.getLevel();
+            Engine engine = IrisModdedCommands.engineFor(level);
+            if (engine == null) {
+                return builder.buildFuture();
             }
-            return SharedSuggestionProvider.suggest(combineStructureKeys(irisKeys, nativeKeys), builder);
+            boolean nativeGenerationEnabled =
+                    source.getServer().getWorldGenSettings().options().generateStructures();
+            Collection<String> irisKeys = IrisStructureLocator.locatableEditableKeys(engine);
+            Set<String> reachableNativeKeys = StructureReachability.reachableKeys(engine);
+            Registry<Structure> registry = source.getServer().registryAccess().lookupOrThrow(Registries.STRUCTURE);
+            List<String> nativeKeys = new ArrayList<>(registry.keySet().size());
+            Set<String> registeredKeys = new HashSet<>(registry.keySet().size());
+            for (Identifier identifier : registry.keySet()) {
+                String key = identifier.toString();
+                registeredKeys.add(normalizeKey(key));
+                IrisNativeStructureDecision decision = NativeStructureGenerationPolicy.resolve(engine, key, false);
+                boolean nativePlacement = IrisStructureLocator.hasNativePlacement(engine, key);
+                boolean locatableNativePlacement = nativePlacement
+                        && IrisStructureLocator.hasLocatableNativePlacement(engine, key);
+                boolean locatableEditableReplacement = !nativePlacement
+                        && decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS
+                        && IrisStructureLocator.hasLocatableEditablePlacement(engine, key);
+                if (isEligibleRegisteredStructure(decision, nativePlacement,
+                        locatableNativePlacement, locatableEditableReplacement,
+                        reachableNativeKeys.contains(normalizeKey(key)), nativeGenerationEnabled)) {
+                    nativeKeys.add(key);
+                }
+            }
+            Collection<String> unregisteredIrisKeys = eligibleUnregisteredEditableKeys(
+                    irisKeys, registeredKeys,
+                    (String candidate) -> IrisStructureLocator.hasNativePlacement(engine, candidate));
+            return SharedSuggestionProvider.suggest(
+                    combineStructureKeys(unregisteredIrisKeys, nativeKeys), builder);
         } catch (Throwable e) {
-            warnTabFailure("structure keys", context.getSource(), e);
+            warnTabFailure("structure keys", source, e);
         }
         return builder.buildFuture();
     }
 
+    static boolean isEligibleRegisteredStructure(IrisNativeStructureDecision decision,
+                                                 boolean nativePlacement,
+                                                 boolean locatableNativePlacement,
+                                                 boolean locatableEditableReplacement,
+                                                 boolean reachable,
+                                                 boolean nativeGenerationEnabled) {
+        if (decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS) {
+            return locatableEditableReplacement
+                    || nativeGenerationEnabled && nativePlacement && locatableNativePlacement;
+        }
+        return nativeGenerationEnabled && decision.generate()
+                && (reachable || nativePlacement && locatableNativePlacement);
+    }
+
     static void warnTabFailure(String suggestion, CommandSourceStack source, Throwable error) {
         String origin = tabOrigin(source);
         if (!REPORTED_TAB_FAILURES.add(suggestion + '|' + origin + '|' + error.getClass().getName())) {
@@ -142,10 +191,38 @@ final class ModdedCommandSuggestions {
     }
 
     static List<String> combineStructureKeys(Collection<String> irisKeys, Collection<String> nativeKeys) {
-        Set<String> combined = new TreeSet<>();
-        combined.addAll(irisKeys);
-        combined.addAll(nativeKeys);
-        return List.copyOf(combined);
+        Map<String, String> combined = new TreeMap<>();
+        addStructureKeys(combined, irisKeys);
+        addStructureKeys(combined, nativeKeys);
+        return List.copyOf(combined.values());
+    }
+
+    static List<String> eligibleUnregisteredEditableKeys(
+            Collection<String> irisKeys, Set<String> normalizedRegisteredKeys,
+            Predicate<String> nativePlacement) {
+        List<String> filtered = new ArrayList<>(irisKeys.size());
+        for (String key : irisKeys) {
+            String normalizedKey = normalizeKey(key);
+            if (!normalizedKey.isEmpty()
+                    && !normalizedRegisteredKeys.contains(normalizedKey)
+                    && !nativePlacement.test(key)) {
+                filtered.add(key.trim());
+            }
+        }
+        return List.copyOf(filtered);
+    }
+
+    private static void addStructureKeys(Map<String, String> combined, Collection<String> keys) {
+        for (String key : keys) {
+            String normalizedKey = normalizeKey(key);
+            if (!normalizedKey.isEmpty()) {
+                combined.putIfAbsent(normalizedKey, key.trim());
+            }
+        }
+    }
+
+    static String normalizeKey(String key) {
+        return key == null ? "" : key.trim().toLowerCase(Locale.ROOT);
     }
 
     private static CompletableFuture<Suggestions> suggestPackNames(CommandContext<CommandSourceStack> context, SuggestionsBuilder builder) {

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedCommandTree.java

@@ -242,6 +242,9 @@ final class ModdedCommandTree {
                 .then(Commands.literal("object")
                         .then(Commands.argument("key", StringArgumentType.greedyString()).suggests(ModdedCommandSuggestions.OBJECT_KEYS)
                                 .executes((CommandContext<CommandSourceStack> context) -> ModdedLocateCommands.gotoObject(context.getSource(), StringArgumentType.getString(context, "key")))))
+                .then(Commands.literal("unregistered")
+                        .executes((CommandContext<CommandSourceStack> context) ->
+                                ModdedUnregisteredStructures.print(context.getSource())))
                 .then(Commands.literal("structure")
                         .then(Commands.argument("key", StringArgumentType.greedyString()).suggests(ModdedCommandSuggestions.STRUCTURE_KEYS)
                                 .executes((CommandContext<CommandSourceStack> context) -> ModdedLocateCommands.gotoStructure(context.getSource(), StringArgumentType.getString(context, "key")))))

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedLocateCommands.java

@@ -26,6 +26,7 @@ import art.arcane.iris.engine.framework.GenerationSessionLease;
 import art.arcane.iris.engine.framework.IrisStructureLocator;
 import art.arcane.iris.engine.framework.Locator;
 import art.arcane.iris.engine.framework.NativeStructureGenerationPolicy;
+import art.arcane.iris.engine.framework.StructureReachability;
 import art.arcane.iris.engine.framework.WrongEngineBroException;
 import art.arcane.iris.engine.object.IrisBiome;
 import art.arcane.iris.engine.object.IrisNativeStructureDecision;
@@ -157,7 +158,8 @@ final class ModdedLocateCommands {
         }
         Optional<NativeStructureTarget> resolved = resolveNativeStructure(source, level, engine, key);
         if (resolved.isEmpty()) {
-            if (IrisStructureLocator.isPlaced(engine, key)) {
+            if (!IrisStructureLocator.hasNativePlacement(engine, key)
+                    && IrisStructureLocator.hasLocatableEditablePlacement(engine, key)) {
                 locateIrisStructure(source, level, engine, player, key);
                 return 1;
             }
@@ -166,31 +168,74 @@ final class ModdedLocateCommands {
         }
         NativeStructureTarget target = resolved.get();
         IrisNativeStructureDecision decision = NativeStructureGenerationPolicy.resolve(engine, target.key(), false);
-        if (!decision.generate()
-                && decision.status() != NativeStructureGenerationStatus.REPLACED_BY_IRIS) {
-            IrisModdedCommands.fail(source, NativeStructureGenerationPolicy.generationStatusMessage(
-                    target.key(), decision.status()));
+        boolean nativeGenerationEnabled =
+                source.getServer().getWorldGenSettings().options().generateStructures();
+        boolean nativePlacement = IrisStructureLocator.hasNativePlacement(engine, target.key());
+        boolean locatableNativePlacement = nativePlacement
+                && IrisStructureLocator.hasLocatableNativePlacement(engine, target.key());
+        boolean locatableEditableReplacement = !nativePlacement
+                && decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS
+                && IrisStructureLocator.hasLocatableEditablePlacement(engine, target.key());
+        boolean reachable = StructureReachability.isReachable(engine, target.key());
+        if (!ModdedCommandSuggestions.isEligibleRegisteredStructure(
+                decision, nativePlacement, locatableNativePlacement, locatableEditableReplacement,
+                reachable, nativeGenerationEnabled)) {
+            IrisModdedCommands.fail(source, registeredStructureUnavailableMessage(
+                    target.key(), target.availability(), decision,
+                    nativePlacement, locatableNativePlacement,
+                    nativeGenerationEnabled, reachable));
             return 0;
         }
-        if (decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS) {
-            if (!IrisStructureLocator.hasNativePlacement(engine, target.key())) {
-                locateIrisStructure(source, level, engine, player, target.key());
-                return 1;
-            }
-            IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.IRIS_MODDED_COMMANDS_SEARCHING_NATIVE_STRUCTURE_WITHIN_CHUNKS, MessageArgument.untrusted("value", target.key()), MessageArgument.untrusted("NATIVESTRUCTURELOCATERADIUS", NATIVE_STRUCTURE_LOCATE_RADIUS)));
-            runNativeStructureLocate(source, level, player, target);
+        if (locatableEditableReplacement) {
+            locateIrisStructure(source, level, engine, player, target.key());
             return 1;
         }
-        if (!IrisStructureLocator.hasNativePlacement(engine, target.key())
-                && target.availability() != NativeStructureAvailability.AVAILABLE) {
-            IrisModdedCommands.fail(source, nativeUnavailableMessage(target.key(), target.availability()));
-            return 0;
-        }
         IrisModdedCommands.ok(source, IrisLanguage.plain(ModdedCommandMessages.IRIS_MODDED_COMMANDS_SEARCHING_NATIVE_STRUCTURE_WITHIN_CHUNKS, MessageArgument.untrusted("value", target.key()), MessageArgument.untrusted("NATIVESTRUCTURELOCATERADIUS", NATIVE_STRUCTURE_LOCATE_RADIUS)));
         runNativeStructureLocate(source, level, player, target);
         return 1;
     }
 
+    static String registeredStructureUnavailableMessage(
+            String key, NativeStructureAvailability nativeAvailability,
+            IrisNativeStructureDecision decision,
+            boolean nativePlacement, boolean locatableNativePlacement,
+            boolean nativeGenerationEnabled, boolean reachable) {
+        if (!decision.generate()
+                && decision.status() != NativeStructureGenerationStatus.REPLACED_BY_IRIS) {
+            return NativeStructureGenerationPolicy.generationStatusMessage(key, decision.status());
+        }
+        if (decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS) {
+            if (nativePlacement && !nativeGenerationEnabled) {
+                return withInactiveNativePlacement(
+                        nativeUnavailableMessage(key, NativeStructureAvailability.WORLD_DISABLED),
+                        nativePlacement, locatableNativePlacement);
+            }
+            return "Iris replacement " + key
+                    + " is configured, but every matching placement has non-positive density or a Y band "
+                    + "outside this world's height range.";
+        }
+        if (!nativeGenerationEnabled) {
+            return withInactiveNativePlacement(
+                    nativeUnavailableMessage(key, NativeStructureAvailability.WORLD_DISABLED),
+                    nativePlacement, locatableNativePlacement);
+        }
+        NativeStructureAvailability availability = nativeAvailability;
+        if (availability == NativeStructureAvailability.AVAILABLE && !reachable) {
+            availability = NativeStructureAvailability.NO_PLACEMENT;
+        }
+        return withInactiveNativePlacement(
+                nativeUnavailableMessage(key, availability), nativePlacement, locatableNativePlacement);
+    }
+
+    private static String withInactiveNativePlacement(
+            String reason, boolean nativePlacement, boolean locatableNativePlacement) {
+        if (!nativePlacement || locatableNativePlacement) {
+            return reason;
+        }
+        return reason + " A matching Iris nativeStructures placement is also configured, but has non-positive "
+                + "density or a Y band outside this world's height range.";
+    }
+
     private static void locateIrisStructure(CommandSourceStack source, ServerLevel level, Engine engine,
                                             ServerPlayer player, String key) {
         MinecraftServer server = source.getServer();
@@ -311,7 +356,7 @@ final class ModdedLocateCommands {
                 case AVAILABLE -> available++;
                 case WORLD_DISABLED, FILTERED -> disabled++;
                 case IRIS_SUPPRESSED -> suppressed++;
-                case BIOME_UNREACHABLE -> unreachableBiomes++;
+                case EMPTY_BIOME_FILTER, BIOME_UNREACHABLE -> unreachableBiomes++;
                 case NO_PLACEMENT -> unsupported++;
             }
         }
@@ -361,25 +406,28 @@ final class ModdedLocateCommands {
         return Optional.of(new NativeStructureTarget(key, holder.get(), availability));
     }
 
-    private static NativeStructureAvailability nativeAvailability(CommandSourceStack source, ServerLevel level,
-                                                                   Engine engine, String key,
-                                                                   Holder.Reference<Structure> holder) {
+    static NativeStructureAvailability nativeAvailability(CommandSourceStack source, ServerLevel level,
+                                                           Engine engine, String key,
+                                                           Holder.Reference<Structure> holder) {
         boolean worldEnabled = source.getServer().getWorldGenSettings().options().generateStructures();
         IrisNativeStructureDecision decision = NativeStructureGenerationPolicy.resolve(engine, key, false);
         boolean selected = decision.status() != NativeStructureGenerationStatus.DISABLED_BY_PACK;
         boolean suppressed = decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS;
+        boolean biomeFilterEmpty = holder.value().biomes().stream().findAny().isEmpty();
         ChunkGenerator chunkGenerator = level.getChunkSource().getGenerator();
         boolean biomeReachable = chunkGenerator instanceof IrisModdedChunkGenerator irisGenerator
                 && irisGenerator.isNativeStructureReachable(holder);
         boolean hasPlacement = false;
-        if (worldEnabled && selected && !suppressed && biomeReachable) {
+        if (worldEnabled && selected && !suppressed && !biomeFilterEmpty && biomeReachable) {
             hasPlacement = !level.getChunkSource().getGeneratorState().getPlacementsForStructure(holder).isEmpty();
         }
-        return classifyNativeAvailability(worldEnabled, selected, suppressed, biomeReachable, hasPlacement);
+        return classifyNativeAvailability(
+                worldEnabled, selected, suppressed, biomeFilterEmpty, biomeReachable, hasPlacement);
     }
 
     static NativeStructureAvailability classifyNativeAvailability(boolean worldEnabled, boolean selected,
-                                                                   boolean suppressed, boolean biomeReachable,
+                                                                   boolean suppressed, boolean biomeFilterEmpty,
+                                                                   boolean biomeReachable,
                                                                    boolean hasPlacement) {
         if (!worldEnabled) {
             return NativeStructureAvailability.WORLD_DISABLED;
@@ -390,6 +438,9 @@ final class ModdedLocateCommands {
         if (suppressed) {
             return NativeStructureAvailability.IRIS_SUPPRESSED;
         }
+        if (biomeFilterEmpty) {
+            return NativeStructureAvailability.EMPTY_BIOME_FILTER;
+        }
         if (!biomeReachable) {
             return NativeStructureAvailability.BIOME_UNREACHABLE;
         }
@@ -399,15 +450,19 @@ final class ModdedLocateCommands {
         return NativeStructureAvailability.AVAILABLE;
     }
 
-    private static String nativeUnavailableMessage(String key, NativeStructureAvailability availability) {
+    static String nativeUnavailableMessage(String key, NativeStructureAvailability availability) {
         return switch (availability) {
             case WORLD_DISABLED -> "Native structure generation is disabled for this world, so " + key + " cannot generate or be located.";
             case FILTERED -> NativeStructureGenerationPolicy.generationStatusMessage(
                     key, NativeStructureGenerationStatus.DISABLED_BY_PACK);
             case IRIS_SUPPRESSED -> NativeStructureGenerationPolicy.generationStatusMessage(
                     key, NativeStructureGenerationStatus.REPLACED_BY_IRIS);
+            case EMPTY_BIOME_FILTER -> "Native structure " + key
+                    + " has a biome tag or filter that resolves to zero registered biomes.";
             case BIOME_UNREACHABLE -> "Native structure " + key + " cannot generate because none of its required biomes are produced by this Iris pack.";
-            case NO_PLACEMENT -> "Native structure " + key + " is registered, but its structure set has no placement supported by this dimension's generator state.";
+            case NO_PLACEMENT -> "Native structure " + key
+                    + " is registered and biome-compatible, but has no active positive-weight, "
+                    + "positive-frequency structure-set placement in this dimension's generator state.";
             case AVAILABLE -> "Native structure " + key + " is available.";
         };
     }
@@ -531,6 +586,7 @@ final class ModdedLocateCommands {
         WORLD_DISABLED,
         FILTERED,
         IRIS_SUPPRESSED,
+        EMPTY_BIOME_FILTER,
         BIOME_UNREACHABLE,
         NO_PLACEMENT
     }

adapters/modded-common/src/main/java/art/arcane/iris/modded/command/ModdedUnregisteredStructures.java

@@ -0,0 +1,204 @@
+/*
+ * Iris is a World Generator for Minecraft Servers
+ * Copyright (c) 2026 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package art.arcane.iris.modded.command;
+
+import art.arcane.iris.engine.framework.Engine;
+import art.arcane.iris.engine.framework.IrisStructureLocator;
+import art.arcane.iris.engine.framework.NativeStructureGenerationPolicy;
+import art.arcane.iris.engine.framework.StructureReachability;
+import art.arcane.iris.engine.object.IrisNativeStructureDecision;
+import art.arcane.iris.engine.object.NativeStructureGenerationStatus;
+import net.minecraft.commands.CommandSourceStack;
+import net.minecraft.core.Holder;
+import net.minecraft.core.Registry;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.resources.Identifier;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.world.level.levelgen.structure.Structure;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.function.Predicate;
+
+final class ModdedUnregisteredStructures {
+    private static final Logger LOGGER = LoggerFactory.getLogger("Iris");
+
+    private ModdedUnregisteredStructures() {
+    }
+
+    static int print(CommandSourceStack source) {
+        ServerLevel level = source.getLevel();
+        Engine engine = IrisModdedCommands.engineFor(level);
+        if (engine == null) {
+            IrisModdedCommands.fail(source,
+                    "This dimension is not generated by Iris, so it has no Iris structure eligibility report.");
+            return 0;
+        }
+        try {
+            List<ExcludedStructure> excluded = collect(source, level, engine);
+            String dimension = level.dimension().identifier().toString();
+            long unregistered = excluded.stream()
+                    .filter((ExcludedStructure entry) -> entry.status() == ReportStatus.UNREGISTERED)
+                    .count();
+            long unplaced = excluded.stream()
+                    .filter((ExcludedStructure entry) -> entry.status() == ReportStatus.UNPLACED)
+                    .count();
+            long hidden = excluded.size() - unregistered - unplaced;
+            LOGGER.info("[Iris goto unregistered] {} structure candidate(s) excluded from /iris goto structure in {}",
+                    excluded.size(), dimension);
+            for (ExcludedStructure entry : excluded) {
+                LOGGER.info("[Iris goto unregistered] [{}] {} - {}",
+                        entry.status().label(), entry.key(), entry.reason());
+            }
+            LOGGER.info("[Iris goto unregistered] Inventory scope is the live registry, this pack's "
+                    + "nativeStructures placements, and structureLoader editable resources. This is deterministic "
+                    + "eligibility analysis and performs no chunk search; absent unmanaged datapack resources "
+                    + "cannot be inferred after registry loading.");
+            IrisModdedCommands.ok(source, "Iris wrote " + excluded.size() + " structure candidate(s) for "
+                    + dimension + " to the server console (" + hidden + " excluded, "
+                    + unregistered + " unregistered, " + unplaced + " unplaced).");
+            return 1;
+        } catch (Throwable error) {
+            LOGGER.error("Iris failed to build the excluded structure report for {}",
+                    level.dimension().identifier(), error);
+            IrisModdedCommands.fail(source,
+                    "Iris could not build the excluded structure report; see the server console.");
+            return 0;
+        }
+    }
+
+    static List<ExcludedStructure> collect(CommandSourceStack source, ServerLevel level, Engine engine) {
+        boolean nativeGenerationEnabled =
+                source.getServer().getWorldGenSettings().options().generateStructures();
+        Set<String> reachableNativeKeys = StructureReachability.reachableKeys(engine);
+        Registry<Structure> registry = source.getServer().registryAccess().lookupOrThrow(Registries.STRUCTURE);
+        Map<String, ExcludedStructure> excluded = new TreeMap<>();
+        Set<String> registeredKeys = new HashSet<>(registry.keySet().size());
+        Set<String> eligibleRegisteredKeys = new HashSet<>(registry.keySet().size());
+        for (Identifier identifier : registry.keySet()) {
+            String key = identifier.toString();
+            String normalizedKey = ModdedCommandSuggestions.normalizeKey(key);
+            registeredKeys.add(normalizedKey);
+            Optional<Holder.Reference<Structure>> holder = registry.get(identifier);
+            if (holder.isEmpty()) {
+                excluded.put(normalizedKey, new ExcludedStructure(ReportStatus.EXCLUDED,
+                        key, "The live structure registry contains this key but has no bound structure holder."));
+                continue;
+            }
+            IrisNativeStructureDecision decision = NativeStructureGenerationPolicy.resolve(engine, key, false);
+            boolean nativePlacement = IrisStructureLocator.hasNativePlacement(engine, key);
+            boolean locatableNativePlacement = nativePlacement
+                    && IrisStructureLocator.hasLocatableNativePlacement(engine, key);
+            boolean locatableEditableReplacement = !nativePlacement
+                    && decision.status() == NativeStructureGenerationStatus.REPLACED_BY_IRIS
+                    && IrisStructureLocator.hasLocatableEditablePlacement(engine, key);
+            boolean reachable = reachableNativeKeys.contains(normalizedKey);
+            if (ModdedCommandSuggestions.isEligibleRegisteredStructure(
+                    decision, nativePlacement, locatableNativePlacement,
+                    locatableEditableReplacement, reachable, nativeGenerationEnabled)) {
+                eligibleRegisteredKeys.add(normalizedKey);
+                continue;
+            }
+            ModdedLocateCommands.NativeStructureAvailability availability =
+                    ModdedLocateCommands.nativeAvailability(source, level, engine, key, holder.get());
+            String reason = ModdedLocateCommands.registeredStructureUnavailableMessage(
+                    key, availability, decision, nativePlacement, locatableNativePlacement,
+                    nativeGenerationEnabled, reachable);
+            excluded.put(normalizedKey, new ExcludedStructure(ReportStatus.EXCLUDED, key, reason));
+        }
+        List<String> absentNativeKeys = missingConfiguredNativeKeys(
+                IrisStructureLocator.placedKeys(engine), registeredKeys,
+                (String key) -> IrisStructureLocator.hasNativePlacement(engine, key));
+        for (String key : absentNativeKeys) {
+            String normalizedKey = ModdedCommandSuggestions.normalizeKey(key);
+            excluded.putIfAbsent(normalizedKey, new ExcludedStructure(ReportStatus.UNREGISTERED, key,
+                    "Configured by an Iris nativeStructures placement, but absent from the live structure registry; "
+                            + "install or enable the datapack or mod that provides this key."));
+        }
+        if (engine.getData().getStructureLoader() != null) {
+            for (String key : engine.getData().getStructureLoader().getPossibleKeys()) {
+                String normalizedKey = ModdedCommandSuggestions.normalizeKey(key);
+                if (normalizedKey.isEmpty() || eligibleRegisteredKeys.contains(normalizedKey)
+                        || excluded.containsKey(normalizedKey)) {
+                    continue;
+                }
+                boolean registered = registeredKeys.contains(normalizedKey);
+                boolean nativePlacement = IrisStructureLocator.hasNativePlacement(engine, key);
+                boolean locatableEditable = IrisStructureLocator.hasLocatableEditablePlacement(engine, key);
+                if (!registered && !nativePlacement && locatableEditable) {
+                    continue;
+                }
+                boolean configured = IrisStructureLocator.hasEditablePlacement(engine, key);
+                excluded.putIfAbsent(normalizedKey, new ExcludedStructure(
+                        ReportStatus.UNPLACED, key.trim(), editableExclusionReason(configured)));
+            }
+        }
+        return List.copyOf(excluded.values());
+    }
+
+    static List<String> missingConfiguredNativeKeys(
+            Collection<String> placedKeys, Set<String> normalizedRegisteredKeys,
+            Predicate<String> nativePlacement) {
+        Map<String, String> missing = new TreeMap<>();
+        for (String key : placedKeys) {
+            String normalizedKey = ModdedCommandSuggestions.normalizeKey(key);
+            if (!normalizedKey.isEmpty()
+                    && !normalizedRegisteredKeys.contains(normalizedKey)
+                    && nativePlacement.test(key)) {
+                missing.putIfAbsent(normalizedKey, key.trim());
+            }
+        }
+        return List.copyOf(missing.values());
+    }
+
+    static String editableExclusionReason(boolean configured) {
+        if (!configured) {
+            return "Editable Iris structure resource is loaded, but no biome, region, or dimension structure "
+                    + "placement references it.";
+        }
+        return "Editable Iris structure resource is referenced by a placement, but every matching placement "
+                + "has non-positive density or a Y band outside this world's height range.";
+    }
+
+    enum ReportStatus {
+        EXCLUDED("excluded"),
+        UNREGISTERED("unregistered"),
+        UNPLACED("unplaced");
+
+        private final String label;
+
+        ReportStatus(String label) {
+            this.label = label;
+        }
+
+        String label() {
+            return label;
+        }
+    }
+
+    record ExcludedStructure(ReportStatus status, String key, String reason) {
+    }
+}