Add client-side recipe loading for servers without recipe sync

api/src/main/java/me/shedaniel/rei/api/client/config/ConfigObject.java

@@ -288,6 +288,16 @@ default boolean isLeftHandSidePanel() {
     @ApiStatus.Experimental
     boolean doesCacheDisplayLookup();
 
+    /**
+     * Returns whether REI should force loading recipes from local client data
+     * instead of waiting for server synchronization.
+     * Useful for multiplayer servers that do not send recipe data.
+     *
+     * @return whether force local recipes is enabled
+     */
+    @ApiStatus.Experimental
+    boolean isForceLocalRecipes();
+
     boolean doDebugRenderTimeRequired();
 
     boolean doMergeDisplayUnderOne();

runtime/src/main/java/me/shedaniel/rei/RoughlyEnoughItemsCoreClient.java

@@ -92,6 +92,7 @@
 import me.shedaniel.rei.impl.common.networking.DisplaySyncPacket;
 import me.shedaniel.rei.impl.common.plugins.PluginManagerImpl;
 import me.shedaniel.rei.impl.common.plugins.ReloadManagerImpl;
+import me.shedaniel.rei.impl.common.registry.displays.ServerDisplayRegistryImpl;
 import me.shedaniel.rei.impl.common.util.InstanceHelper;
 import me.shedaniel.rei.impl.common.util.IssuesDetector;
 import me.shedaniel.rei.plugin.test.REITestCommonPlugin;
@@ -117,14 +118,22 @@
 import net.minecraft.world.item.Item;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.TooltipFlag;
+import net.minecraft.core.HolderLookup;
+import net.minecraft.server.packs.PackResources;
+import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.resources.MultiPackResourceManager;
+import net.minecraft.tags.TagLoader;
 import net.minecraft.world.item.crafting.RecipeAccess;
+import net.minecraft.world.item.crafting.RecipeHolder;
+import net.minecraft.world.item.crafting.RecipeManager;
 import net.minecraft.world.item.crafting.display.RecipeDisplayEntry;
 import net.minecraft.world.item.crafting.display.RecipeDisplayId;
 import org.apache.commons.lang3.mutable.MutableLong;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
+import java.util.concurrent.CompletableFuture;
 import java.util.function.*;
 import java.util.stream.Stream;
 
@@ -311,13 +320,22 @@ private void registerEvents() {
         Minecraft client = Minecraft.getInstance();
         final ResourceLocation recipeButtonTex = ResourceLocation.withDefaultNamespace("textures/gui/recipe_button.png");
         MutableLong endReload = new MutableLong(-1);
+        // Set up client-side recipe loading for forceLocalRecipes mode.
+        // When on a remote server with no integrated server, ServerDisplayRegistryImpl
+        // cannot access GameInstance.getServer().getRecipeManager(). This supplier
+        // provides recipes loaded from the client's vanilla data pack instead.
+        ServerDisplayRegistryImpl.setClientRecipeSupplier(RoughlyEnoughItemsCoreClient::loadRecipesFromClientDataPacks);
         PRE_UPDATE_RECIPES.register((recipeAccess, registryAccess) -> {
             reloadPlugins(null, ReloadStage.START, registryAccess);
         });
         ClientRecipeUpdateEvent.EVENT.register(recipeManager -> {
             reloadPlugins(endReload, ReloadStage.END);
         });
         ClientRecipeUpdateEvent.ADD.register((recipeAccess, entries) -> {
+            if (ConfigObject.getInstance().isForceLocalRecipes() && !Minecraft.getInstance().isLocalServer()) {
+                InternalLogger.getInstance().debug("Ignoring server recipe ADD (%d entries) because forceLocalRecipes is enabled.", entries.size());
+                return;
+            }
             if (ClientHelperImpl.getInstance().canUsePackets()) {
                 return;
             }
@@ -328,6 +346,10 @@ private void registerEvents() {
             registry.addJob(() -> registry.addRecipes(mapped));
         });
         ClientRecipeUpdateEvent.REMOVE.register((recipeAccess, entries) -> {
+            if (ConfigObject.getInstance().isForceLocalRecipes() && !Minecraft.getInstance().isLocalServer()) {
+                InternalLogger.getInstance().debug("Ignoring server recipe REMOVE (%d entries) because forceLocalRecipes is enabled.", entries.size());
+                return;
+            }
             if (ClientHelperImpl.getInstance().canUsePackets()) {
                 return;
             }
@@ -500,4 +522,70 @@ public static void reloadPlugins(MutableLong lastReload, @Nullable ReloadStage s
         }
         ReloadManagerImpl.reloadPlugins(start, () -> InstanceHelper.connectionFromClient() == null);
     }
+
+    private static List<RecipeHolder<?>> loadRecipesFromClientDataPacks() {
+        try {
+            Minecraft mc = Minecraft.getInstance();
+            if (mc.getConnection() == null) return Collections.emptyList();
+            if (mc.isLocalServer()) return Collections.emptyList();
+            if (!ConfigObject.getInstance().isForceLocalRecipes()) return Collections.emptyList();
+
+            InternalLogger.getInstance().info("[Force Local Recipes] Loading recipes from client data packs...");
+
+            RegistryAccess registryAccess = mc.getConnection().registryAccess();
+
+            // Create a data resource manager from the vanilla pack.
+            // The vanilla JAR contains all recipe JSONs under data/<namespace>/recipe/.
+            List<PackResources> packResourcesList = new ArrayList<>();
+            packResourcesList.add(mc.getVanillaPackResources());
+
+            List<RecipeHolder<?>> result;
+            try (MultiPackResourceManager dataManager = new MultiPackResourceManager(PackType.SERVER_DATA, packResourcesList)) {
+                // Load tags for ALL builtin registries (items, blocks, fluids, etc.)
+                // from the vanilla data pack. The connection's registryAccess only contains
+                // dynamic registries, but recipe ingredients reference tags from builtin
+                // registries like minecraft:item (e.g. #minecraft:bundles, #minecraft:planks).
+                int tagCount = 0;
+                for (net.minecraft.core.Registry<?> registry : net.minecraft.core.registries.BuiltInRegistries.REGISTRY) {
+                    if (registry instanceof net.minecraft.core.WritableRegistry) {
+                        try {
+                            @SuppressWarnings({"unchecked", "rawtypes"})
+                            net.minecraft.core.WritableRegistry writable = (net.minecraft.core.WritableRegistry) registry;
+                            TagLoader.loadTagsForRegistry(dataManager, writable);
+                            tagCount++;
+                        } catch (Exception e) {
+                            // Some registries might not have tag directories, skip silently
+                        }
+                    }
+                }
+                InternalLogger.getInstance().info("[Force Local Recipes] Loaded tags for %d builtin registries from client data packs", tagCount);
+
+                // Also load tags for dynamic registries from the connection's registryAccess
+                List<net.minecraft.core.Registry.PendingTags<?>> pendingTags =
+                        TagLoader.loadTagsForExistingRegistries(dataManager, registryAccess);
+                for (net.minecraft.core.Registry.PendingTags<?> pt : pendingTags) {
+                    pt.apply();
+                }
+                if (!pendingTags.isEmpty()) {
+                    InternalLogger.getInstance().info("[Force Local Recipes] Loaded and applied %d dynamic registry tag sets", pendingTags.size());
+                }
+
+                // Now load recipes — tag references will resolve correctly.
+                RecipeManager recipeManager = new RecipeManager(registryAccess);
+                recipeManager.reload(
+                    CompletableFuture::completedFuture,
+                    dataManager,
+                    Runnable::run,
+                    Runnable::run
+                ).join();
+                result = new ArrayList<>(recipeManager.getRecipes());
+            }
+
+            InternalLogger.getInstance().info("[Force Local Recipes] Loaded %d recipes from client data packs", result.size());
+            return result;
+        } catch (Exception e) {
+            InternalLogger.getInstance().error("[Force Local Recipes] Failed to load recipes from client data packs", e);
+            return Collections.emptyList();
+        }
+    }
 }

runtime/src/main/java/me/shedaniel/rei/impl/client/config/ConfigObjectImpl.java

@@ -313,6 +313,11 @@ public boolean doesCacheDisplayLookup() {
         return advanced.miscellaneous.cachingDisplayLookup;
     }
 
+    @Override
+    public boolean isForceLocalRecipes() {
+        return advanced.miscellaneous.forceLocalRecipes;
+    }
+
     @Override
     public boolean doDebugRenderTimeRequired() {
         return advanced.layout.debugRenderTimeRequired;
@@ -739,6 +744,8 @@ public static class Miscellaneous {
             public boolean newFastEntryRendering = true;
             public boolean cachingFastEntryRendering = false;
             public boolean cachingDisplayLookup = true;
+            @Comment("Forces REI to load recipes from local client data instead of waiting for server synchronization. Useful for servers that do not send recipe data.")
+            public boolean forceLocalRecipes = false;
             public CategorySettings categorySettings = new CategorySettings();
 
             public static class CategorySettings {

runtime/src/main/java/me/shedaniel/rei/impl/client/gui/config/options/AllREIConfigGroups.java

@@ -80,7 +80,8 @@ static <T> OptionGroup make(String id) {
             .add(CUSTOMIZED_FILTERING);
     OptionGroup FILTERING_ADVANCED = make("filtering.advanced")
             .add(FILTER_DISPLAYS)
-            .add(MERGE_DISPLAYS);
+            .add(MERGE_DISPLAYS)
+            .add(FORCE_LOCAL_RECIPES);
     OptionGroup LIST_ENTRIES = make("list.entries")
             .add(DISPLAY_MODE)
             .add(ORDERING)

runtime/src/main/java/me/shedaniel/rei/impl/client/gui/config/options/AllREIConfigOptions.java

@@ -256,6 +256,8 @@ static ComparableValue<Double>[] doubleRange(double start, double end, double st
             .ofBoolean(translatable("config.rei.values.performance.reload_thread.main_thread"), translatable("config.rei.values.performance.reload_thread.rei_thread"));
     CompositeOption<Boolean> CACHED_DISPLAY_LOOKUP = make("performance.cached_display_lookup", i -> i.advanced.miscellaneous.cachingDisplayLookup, (i, v) -> i.advanced.miscellaneous.cachingDisplayLookup = v)
             .enabledDisabled();
+    CompositeOption<Boolean> FORCE_LOCAL_RECIPES = make("filtering.force_local_recipes", i -> i.advanced.miscellaneous.forceLocalRecipes, (i, v) -> i.advanced.miscellaneous.forceLocalRecipes = v)
+            .enabledDisabled();
     CompositeOption<Object> PLUGINS_PERFORMANCE = make("debug.plugins_performance", i -> null, (i, v) -> new Object())
             .details((access, option, onClose) -> Minecraft.getInstance().setScreen(new PerformanceScreen(onClose)))
             .requiresLevel();

runtime/src/main/java/me/shedaniel/rei/impl/client/gui/hints/ImportantWarningsWidget.java

@@ -26,6 +26,7 @@
 import me.shedaniel.math.Rectangle;
 import me.shedaniel.rei.RoughlyEnoughItemsCoreClient;
 import me.shedaniel.rei.api.client.ClientHelper;
+import me.shedaniel.rei.api.client.config.ConfigObject;
 import me.shedaniel.rei.api.client.gui.config.DisplayPanelLocation;
 import me.shedaniel.rei.api.client.gui.widgets.WidgetWithBounds;
 import me.shedaniel.rei.api.client.gui.widgets.Widgets;
@@ -63,7 +64,7 @@ public ImportantWarningsWidget() {
                 prevId = newId;
                 dirty = true;
             }
-            dirty = dirty && !ClientHelper.getInstance().canUseMovePackets();
+            dirty = dirty && !ClientHelper.getInstance().canUseMovePackets() && !ConfigObject.getInstance().isForceLocalRecipes();
         }
 
         this.visible = dirty;

runtime/src/main/java/me/shedaniel/rei/impl/client/registry/display/DisplayRegistryImpl.java

@@ -156,6 +156,15 @@ public void startReload() {
 
     @Override
     public void endReload() {
+        // Inject force-local recipe displays from ServerDisplayRegistryImpl
+        List<Display> forceLocalDisplays = me.shedaniel.rei.impl.common.registry.displays.ServerDisplayRegistryImpl.consumePendingForceLocalDisplays();
+        if (forceLocalDisplays != null && !forceLocalDisplays.isEmpty()) {
+            InternalLogger.getInstance().info("[Force Local Recipes] Injecting %d displays into client registry", forceLocalDisplays.size());
+            for (Display display : forceLocalDisplays) {
+                super.add(display, SYNCED);
+            }
+        }
+
         InternalLogger.getInstance().debug("Found %d displays", size());
 
         for (CategoryIdentifier<?> identifier : getAll().keySet()) {

runtime/src/main/java/me/shedaniel/rei/impl/common/networking/DisplaySyncPacket.java

@@ -28,6 +28,7 @@
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
 import me.shedaniel.rei.RoughlyEnoughItemsNetwork;
+import me.shedaniel.rei.api.client.config.ConfigObject;
 import me.shedaniel.rei.api.client.registry.display.DisplayRegistry;
 import me.shedaniel.rei.api.common.display.Display;
 import me.shedaniel.rei.impl.client.registry.display.DisplayRegistryImpl;
@@ -102,6 +103,10 @@ public Type<? extends CustomPacketPayload> type() {
 
     @Environment(EnvType.CLIENT)
     public void handle(NetworkManager.PacketContext context) {
+        if (ConfigObject.getInstance().isForceLocalRecipes() && !net.minecraft.client.Minecraft.getInstance().isLocalServer()) {
+            InternalLogger.getInstance().info("[REI Server Display Sync] Ignoring server display sync because forceLocalRecipes is enabled.");
+            return;
+        }
         DisplayRegistryImpl registry = (DisplayRegistryImpl) DisplayRegistry.getInstance();
         if (syncType() == SyncType.SET) {
             InternalLogger.getInstance().info("[REI Server Display Sync] Received server's request to set %d recipes.", displays().size());

runtime/src/main/java/me/shedaniel/rei/impl/common/registry/displays/ServerDisplayRegistryImpl.java

@@ -57,6 +57,21 @@ public class ServerDisplayRegistryImpl extends AbstractDisplayRegistry<REICommon
     private static final Comparator<RecipeHolder<?>> RECIPE_COMPARATOR = Comparator.comparing((RecipeHolder<?> o) -> o.id().location().getNamespace()).thenComparing(o -> o.id().location().getPath());
     private final Object2LongMap<UUID> playerVersionMap = new Object2LongOpenHashMap<>();
     private int reloadVersionHash = UUID.randomUUID().hashCode();
+    @Nullable
+    private static java.util.function.Supplier<List<RecipeHolder<?>>> clientRecipeSupplier;
+    @Nullable
+    private static List<Display> pendingForceLocalDisplays;
+
+    public static void setClientRecipeSupplier(@Nullable java.util.function.Supplier<List<RecipeHolder<?>>> supplier) {
+        clientRecipeSupplier = supplier;
+    }
+
+    @Nullable
+    public static List<Display> consumePendingForceLocalDisplays() {
+        List<Display> displays = pendingForceLocalDisplays;
+        pendingForceLocalDisplays = null;
+        return displays;
+    }
 
     public ServerDisplayRegistryImpl() {
         super(ServerDisplaysHolder::new);
@@ -207,6 +222,24 @@ public boolean add(Display display, @Nullable Object origin) {
     public void endReload() {
         InternalLogger.getInstance().debug("Found preliminary %d displays", size());
         fillRecipes();
+
+        // If force-local recipes were loaded, store displays for client registry injection
+        // On a remote server with forceLocalRecipes, the normal DisplaySyncPacket path won't work,
+        // so we need to pass displays directly to the client DisplayRegistryImpl.
+        try {
+            if (me.shedaniel.rei.api.client.config.ConfigObject.getInstance().isForceLocalRecipes()
+                    && !net.minecraft.client.Minecraft.getInstance().isLocalServer()
+                    && size() > 0) {
+                List<Display> allDisplays = new ArrayList<>();
+                for (List<Display> displays : getAll().values()) {
+                    allDisplays.addAll(displays);
+                }
+                pendingForceLocalDisplays = allDisplays;
+                InternalLogger.getInstance().info("[Force Local Recipes] Stored %d displays for client registry injection", allDisplays.size());
+            }
+        } catch (Exception e) {
+            InternalLogger.getInstance().debug("[Force Local Recipes] Could not check force-local state: %s", e.getMessage());
+        }
     }
 
     private void fillRecipes() {
@@ -227,7 +260,27 @@ private void fillRecipes() {
     }
 
     private List<RecipeHolder<?>> getAllSortedRecipes() {
-        return GameInstance.getServer().getRecipeManager().getRecipes().parallelStream().sorted(RECIPE_COMPARATOR).toList();
+        try {
+            var server = GameInstance.getServer();
+            if (server != null) {
+                return server.getRecipeManager().getRecipes()
+                    .parallelStream().sorted(RECIPE_COMPARATOR).toList();
+            }
+        } catch (Exception e) {
+            InternalLogger.getInstance().error("Failed to get recipes from server: %s", e.getMessage());
+        }
+        if (clientRecipeSupplier != null) {
+            try {
+                List<RecipeHolder<?>> recipes = clientRecipeSupplier.get();
+                if (!recipes.isEmpty()) {
+                    InternalLogger.getInstance().info("[Force Local Recipes] Loaded %d recipes from client-side provider", recipes.size());
+                }
+                return recipes;
+            } catch (Exception e) {
+                InternalLogger.getInstance().error("[Force Local Recipes] Failed to get client-side recipes", e);
+            }
+        }
+        return Collections.emptyList();
     }
 
     public static class ServerDisplaysHolder extends DisplaysHolderImpl {

runtime/src/main/resources/assets/roughlyenoughitems/lang/en_us.json

@@ -436,6 +436,8 @@
   "config.rei.options.filtering.filter_displays.desc": "Apply filtering rules to determine the visibility of displays. Displays with all entries filtered will be hidden.",
   "config.rei.options.filtering.merge_displays": "Merge Displays",
   "config.rei.options.filtering.merge_displays.desc": "Merge displays with the same recipe. This is useful for unifying recipes.",
+  "config.rei.options.filtering.force_local_recipes": "Force Local Recipes (Ignore Server Sync)",
+  "config.rei.options.filtering.force_local_recipes.desc": "Loads recipes from client resources instead of waiting for server synchronization. Useful for multiplayer servers (e.g. 2b2t) that do not send recipe data. §eWarning: Some recipes may not exist on the server. §eRequires reconnecting to the server after toggling.",
   "config.rei.options.groups.list.entries": "Entries",
   "config.rei.options.list.display_mode": "Display Mode",
   "config.rei.options.list.display_mode.desc": "The way entries are laid out. Paginated mode displays entries in pages, where there are buttons to traverse the different pages. Scrolled mode displays entries in a vertical list.",