Set up CI/CD pipelines, automated publishing, and release workflows for Minecraft mods and plugins for 1.21.x. Covers GitHub Actions matrix builds for NeoForge and Fabric, automated publishing to Modrinth (via minotaur Gradle plugin) and CurseForge (via curseforgegradle), GitHub Releases with JAR artifacts, semantic versioning conventions for Minecraft mods, CHANGELOG generation, Dependabot for Gradle wrapper and plugin updates, build caching with gradle/actions/setup-gradle, pull request checks, and release tag workflows. Also covers Paper plugin CI with shadow JAR builds.

Write Minecraft vanilla commands, NBT scripts, scoreboards, and complex execute chains for use in command blocks, chat, or .mcfunction files. Covers full execute subcommand reference (as/at/in/positioned/rotated/facing/anchored/if/unless/store/run), selector arguments with all filter options, scoreboard objectives and operations, NBT path syntax for entities/blocks/storage, schedule and forceload commands, tellraw/title JSON text components, bossbar, team management, item modification commands, attribute commands, particle/playsound effects, and RCON scripting. Targets Minecraft 1.21.x Java Edition. Use for command-only work; for full function/advancement/recipe systems use the minecraft-datapack skill instead.

Operate EssentialsX on Minecraft 1.21.x servers with safe, practical admin workflows. Covers module scope, install and version-alignment checks, Vault economy integration, kits/warps/homes/spawn operations, permissions patterns, moderation workflows (mute, jail, tempban), and common config pitfalls. Use for EssentialsX operations, not plugin development.

Generate Minecraft-focused raster assets with Codex's built-in image generation tool, including pack icons, promo art, concept textures, thumbnails, server banners, and UI mockups. Use when the deliverable should be a bitmap image rather than JSON models, SVG, or code-native assets.

Full-stack Minecraft mod development skill for both NeoForge (1.21+) and Fabric (1.21+). Scaffolds new mods, adds custom blocks, items, entities, recipes, commands, GUIs, dimensions, and data generation. Knows the NeoForge DeferredRegister + event-bus system and the Fabric Registry + ModInitializer system. Use when the user asks to create a Minecraft mod, add a feature to an existing mod, fix a mod bug, generate JSON assets/data, or migrate between modding platforms. Prefer NeoForge unless the user specifies Fabric or Multiloader.

Build Minecraft mods targeting both NeoForge and Fabric simultaneously using the Architectury framework for Minecraft 1.21.x. Covers Architectury project structure (common/neoforge/fabric subprojects), ExpectPlatform annotation for platform-specific implementations, shared registry via Architectury's registration API, platform-specific entrypoints, architectury-loom Gradle plugin configuration, gradle.properties for both loaders, multi-jar publishing to Modrinth and CurseForge, and avoiding common pitfalls when sharing code. Use this skill when building a mod that must run on both NeoForge and Fabric with a single shared codebase.

Develop Minecraft server plugins using the Paper/Bukkit/Spigot API for Minecraft 1.21.x. Handles creating Paper plugins with JavaPlugin, event listeners with @EventHandler, commands, schedulers (sync/async/Folia-safe), Persistent Data Container (PDC), Adventure text components, Vault economy integration, BungeeCord/Velocity messaging, plugin.yml and paper-plugin.yml configuration, YAML config management, and Paper-specific enhancement APIs. Always targets Paper API 1.21.x (Java 21) with Gradle (Kotlin DSL). Distinguishes plugin development from mod development: plugins run server-side only and do not require client installation.

Create and edit Minecraft resource packs for 1.21.x including custom block models, item models, blockstate definitions, textures (PNG format requirements), sounds.json, custom fonts, MCMETA animation files, OptiFine CIT (Custom Item Textures), and pack.mcmeta format. Covers the full block/item model JSON schema (parent, textures, elements, display, overrides), multi-layer items, GUI textures, GUI sprites, language files, shader integration (core shaders, Iris), and the pack format numbers for each 1.21.x version. Use to customize how Minecraft looks and sounds without mods.

Set up, configure, and operate Minecraft Java Edition servers for 1.21.x across Paper, Purpur, Folia, Velocity networks, and modded (Fabric/NeoForge) deployments. Covers deployment selection, performance tuning playbooks, plugin operations, proxy/forwarding setup, backup and recovery runbooks, live incident troubleshooting, Docker/Pterodactyl patterns, and security hardening. Use for server infrastructure and operations, not plugin or mod feature development.

Write automated tests for Minecraft mods and plugins for 1.21.x. Covers NeoForge GameTests (@GameTest annotation, GameTestHelper assertions, test structure placement), Fabric game tests (fabric-gametest-api-v1), unit testing non-Minecraft logic with JUnit 5, MockBukkit for Paper/Bukkit plugin testing (mock server, mock player, event dispatching, inventory checking), integration testing with a test server via Gradle, and GitHub Actions CI workflows that run GameTests headlessly. Includes patterns for mocking registries, testing event handlers, testing commands, and test-driven development for Minecraft projects.

Operate WorldEdit safely and efficiently for Minecraft 1.21.x server build/admin workflows. Covers selection mechanics, region operations, masks and patterns, clipboards and schematics, brushes and terraforming, undo/history safety, and practical runbooks for spawn edits, arena resets, block cleanup, and path shaping. Use for command-driven world operations, not plugin development.