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Build and maintain Architectury-based Minecraft 26.x or 1.21.x mods that share one codebase across NeoForge and Fabric. Use only when both loaders are required; use minecraft-modding for a single-loader project.
npx skill4agent add jahrome907/minecraft-agent-skills minecraft-multiloader@ExpectPlatformUse whenDo not use whenminecraft-moddingDo not use whenminecraft-plugin-dev| Component | Purpose |
|---|---|
| Gradle plugin — extends Fabric Loom for multiloader support |
| Runtime library — abstractions over both platforms |
| Annotation marking methods with platform-specific implementations |
| Shared code (no loader-specific APIs) |
| Fabric-specific code + entrypoint |
| NeoForge-specific code + entrypoint |
# gradle.properties property names used by this skill's static helper.
# Get every tool version from the exact generated or known-working project.
mod_version=1.0.0
minecraft_version=1.21.11
enabled_platforms=fabric,neoforge
architectury_version=<project pin>
fabric_loader_version=<project pin>
fabric_api_version=<project pin ending in +1.21.11>
neoforge_version=<project pin in the 21.11.x family>
loom_version=<project pin>architectury_versionloom_versionminecraft_versionreferences/architectury-reference.md./scripts/check-version-sanity.sh --root <project>gradle.propertiesfabricneoforgemy-mod/
├── build.gradle ← root build (shared config)
├── settings.gradle
├── gradle.properties
├── common/
│ ├── build.gradle
│ └── src/main/java/com/example/mymod/
│ ├── MyMod.java ← shared init
│ ├── registry/
│ │ └── ModItems.java ← shared registry declarations
│ └── platform/
│ └── PlatformHelper.java ← @ExpectPlatform methods
├── fabric/
│ ├── build.gradle
│ └── src/main/
│ ├── java/com/example/mymod/fabric/
│ │ ├── MyModFabric.java ← Fabric entrypoint
│ ├── java/com/example/mymod/platform/
│ │ └── PlatformHelperImpl.java ← Fabric @ExpectPlatform implementation
│ └── resources/
│ ├── fabric.mod.json
│ └── assets/...
└── neoforge/
├── build.gradle
└── src/main/
├── java/com/example/mymod/neoforge/
│ ├── MyModNeoForge.java ← NeoForge @Mod entry
├── java/com/example/mymod/platform/
│ └── PlatformHelperImpl.java ← NeoForge @ExpectPlatform implementation
└── resources/
├── META-INF/neoforge.mods.toml
└── assets/...references/legacy-1.21.11-template.mdreferences/architectury-reference.mdcommon/.../MyMod.javapackage com.example.mymod;
import dev.architectury.registry.registries.DeferredRegister;
import dev.architectury.registry.registries.RegistrySupplier;
import net.minecraft.core.registries.Registries;
import net.minecraft.resources.Identifier;
import net.minecraft.resources.ResourceKey;
import net.minecraft.world.item.Item;
public class MyMod {
public static final String MOD_ID = "mymod";
// Architectury's DeferredRegister — works on both platforms
public static final DeferredRegister<Item> ITEMS =
DeferredRegister.create(MOD_ID, Registries.ITEM);
public static final RegistrySupplier<Item> MY_ITEM =
ITEMS.register("my_item", () -> new Item(new Item.Properties().setId(
ResourceKey.create(Registries.ITEM,
Identifier.fromNamespaceAndPath(MOD_ID, "my_item"))
)));
public static void init() {
ITEMS.register(); // registers with both platforms
}
}@ExpectPlatformcommon/package com.example.mymod.platform;
import dev.architectury.injectables.annotations.ExpectPlatform;
import net.minecraft.world.level.material.Fluid;
public class PlatformHelper {
@ExpectPlatform
public static boolean isModLoaded(String modId) {
// This body is replaced at compile time by the platform implementation
throw new AssertionError("ExpectPlatform implementation not found");
}
@ExpectPlatform
public static boolean isClient() {
throw new AssertionError();
}
}@ExpectPlatformcommon/fabric/neoforge/fabric/.../platform/PlatformHelperImpl.javapackage com.example.mymod.platform;
import net.fabricmc.loader.api.FabricLoader;
// Class name must match: <common class name>Impl
public class PlatformHelperImpl {
public static boolean isModLoaded(String modId) {
return FabricLoader.getInstance().isModLoaded(modId);
}
public static boolean isClient() {
return FabricLoader.getInstance().getEnvironmentType() ==
net.fabricmc.api.EnvType.CLIENT;
}
}neoforge/.../platform/PlatformHelperImpl.javapackage com.example.mymod.platform;
import net.neoforged.fml.ModList;
import net.neoforged.fml.loading.FMLEnvironment;
public class PlatformHelperImpl {
public static boolean isModLoaded(String modId) {
return ModList.get().isLoaded(modId);
}
public static boolean isClient() {
return FMLEnvironment.dist.isClient();
}
}fabric/.../MyModFabric.javapackage com.example.mymod.fabric;
import com.example.mymod.MyMod;
import net.fabricmc.api.ModInitializer;
public class MyModFabric implements ModInitializer {
@Override
public void onInitialize() {
MyMod.init();
}
}fabric/.../resources/fabric.mod.json{
"schemaVersion": 1,
"id": "mymod",
"version": "${version}",
"name": "My Mod",
"description": "A multiloader example mod",
"license": "MIT",
"environment": "*",
"entrypoints": {
"main": ["com.example.mymod.fabric.MyModFabric"]
},
"depends": {
"fabricloader": ">=0.18.2",
"fabric-api": ">=0.139.4+1.21.11",
"architectury": ">=19.0",
"minecraft": "~1.21.11"
}
}neoforge/.../MyModNeoForge.javapackage com.example.mymod.neoforge;
import com.example.mymod.MyMod;
import net.neoforged.bus.api.IEventBus;
import net.neoforged.fml.common.Mod;
@Mod(MyMod.MOD_ID)
public class MyModNeoForge {
public MyModNeoForge(IEventBus modEventBus) {
MyMod.init();
}
}neoforge/.../resources/META-INF/neoforge.mods.tomlmodLoader = "javafml"
loaderVersion = "[1,)"
license = "MIT"
[[mods]]
modId = "mymod"
version = "${file.jarVersion}"
displayName = "My Mod"
description = "A multiloader example mod"
[[dependencies.mymod]]
modId = "neoforge"
type = "required"
versionRange = "[21.11,)"
ordering = "NONE"
side = "BOTH"
[[dependencies.mymod]]
modId = "minecraft"
type = "required"
versionRange = "[1.21.11,1.22)"
ordering = "NONE"
side = "BOTH"# Build both JARs simultaneously
./gradlew build
# Inspect the project's actual outputs. Generated templates choose their own
# archive base name and version convention:
find fabric/build/libs neoforge/build/libs -maxdepth 1 -type f -name '*.jar' \
! -name '*-sources.jar' ! -name '*-dev.jar' ! -name '*-javadoc.jar'
# Run in dev environment
./gradlew :fabric:runClient
./gradlew :neoforge:runClient
./gradlew :neoforge:runServer
# Datagen (if applicable)
./gradlew :neoforge:runData| Pitfall | Solution |
|---|---|
Using | Only use vanilla MC and Architectury APIs in common |
Direct field access on | Use Architectury's |
| Constructing a 26.x item without a registry key | Create its |
Forgetting | Both |
| Assets duplicated in fabric/ and neoforge/ | Keep assets in |
| A common Mixin imports a loader API or targets one loader's side | Put it in that platform subproject; loader-neutral Mixins may be common when both generated platform configurations include them |
| Accessing world/registry on mod init thread | Use |