Setting up

You need JDK 25 and Git. Gradle comes with the project (./gradlew).

Create the project

Use the addon template (GitHub’s Use this template), or clone it.

Rename it

the mod id my-addon in src/main/resources/fabric.mod.json, in settings.gradle, and in the mixin config’s file name (my-addon.mixins.json);
the package com.example.addon and the class MyAddon;
maven_group and archives_base_name in gradle.properties.

Run it


./gradlew runClient

Minecraft starts with Myriad, Essentials and your addon, the menu open.

Build it


./gradlew build

The jar is in build/libs/.

The build

build.gradle (the parts that matter)


repositories {
    exclusiveContent {
        forRepositories(maven {
            name = "Myriad"
            url = "https://maven.myriadclient.dev/releases"
        })
        filter { includeGroup "dev.myriadclient" }
    }
}
 
dependencies {
    minecraft "com.mojang:minecraft:${project.minecraft_version}"
    implementation "net.fabricmc:fabric-loader:${project.loader_version}"
    implementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_api_version}"
 
    implementation "dev.myriadclient:myriad:${project.myriad_version}"
    // Only in the dev client, to test next to the stock modules. Don't use its classes: players can remove it.
    localRuntime "dev.myriadclient:myriad-essentials:${project.essentials_version}"
}

Myriad’s artifacts (dev.myriadclient:myriad, with sources and javadoc, and dev.myriadclient:myriad-essentials) are on https://maven.myriadclient.dev/releases. Your IDE shows the javadoc of every API class: it’s written to be read.

To build against Myriad changes that aren’t released yet: run ./gradlew publishToMavenLocal in a Myriad checkout and add mavenLocal() to forRepositories(...).

`fabric.mod.json`


{
  "schemaVersion": 1,
  "id": "my-addon",
  "version": "${version}",
  "name": "My Addon",
  "description": "What it does, in one line.",
  "authors": ["You"],
  "icon": "assets/my-addon/icon.png",
  "contact": {
    "sources": "https://github.com/you/my-addon",
    "issues": "https://github.com/you/my-addon/issues"
  },
  "environment": "client",
  "entrypoints": { "myriad": ["com.example.addon.MyAddon"] },
  "mixins": ["my-addon.mixins.json"],
  "depends": { "myriad": ">=0.3.0", "minecraft": "~26.2" }
}

entrypoints.myriad is your MyriadAddon.
contact.sources pointing at your GitHub repository lets Myriad update your addon.
depends.myriad is the oldest Myriad you support (see Compatibility).

The dev client

The template’s loom.runs.client sets Myriad’s dev options as system properties. Add the ones you want:

build.gradle


loom {
    runs {
        client {
            property("myriad.openDesktop", "true")                 // the menu open on start
            property("myriad.devConsole", "run/myriad-dev-inbox")  // scripted steps (below)
            property("myriad.auditMixins", "true")                 // apply every mixin at start, so a bad target fails at once
            property("myriad.screenshotEvery", "10")               // a screenshot every 10 s into run/screenshots
            programArgs("--quickPlaySingleplayer", "New World")    // straight into a world
        }
    }
}

The dev console reads commands from the inbox file (one per line) and logs what happens: Myriad commands, hold forward,sprint 20, look <yaw> <pitch>, wait <ticks>, screenshot <name>, menu open, panel <id>, and selftest (turns every module on and off and reports any that throw). See Testing.

Only use dev.myriadclient.api. Anything in dev.myriadclient.impl is internal and changes without notice; an addon that touches it breaks on the next release.