Useful Autocrafter Plugin

Autocrafter inventory protection for Minecraft servers.
Prevents autocrafters from depleting ingredient slots below 1 item.

            

Useful Autocrafter is an open-source Paper plugin that fixes a common autocrafter problem: the vanilla autocrafter consumes all items in a slot and stops, leaving the recipe unfillable until the slot is manually restocked. This plugin intercepts every craft attempt and cancels it if any enabled slot is down to its last item, ensuring autocrafters always retain at least 1 item per slot as a buffer. Enabled by default with no configuration required.

Core Features

• Last-item protection: Cancels any crafting attempt where at least one enabled slot holds exactly 1 item, guaranteeing a minimum of 1 item is always retained per slot
• Per-slot awareness: Respects the vanilla crafter's disabled-slot toggle - only enabled slots are checked, disabled slots are ignored
• Runtime toggle: Enable or disable protection on a running server without a restart using /usefulcrafter on|off
• Zero configuration: No config.yml required - the plugin works immediately after installation with sensible defaults

Supported Platforms

• Server Software: Paper only (CrafterCraftEvent and Crafter block state API are Paper-exclusive)
• Minecraft Versions: 1.21 and higher (autocrafter block requires 1.21+)
• Java Requirements: Java 21+
• Dependencies: None - no external plugins required

Table of Contents

1. Getting Started
   • Prerequisites
   • Installation Steps
   • Verifying Installation
2. How It Works
3. Commands
   • Command Reference
4. Permissions
5. Building from Source
6. License

Getting Started

Prerequisites

Before installing Useful Autocrafter, confirm the following requirements are met:

• A Minecraft server running Paper or a Paper fork (Purpur, etc.)
• Server version 1.21 or higher
• Java 21 or newer installed on the machine running the server
• Operator or console access to install plugin files

Spigot and CraftBukkit are not supported - the plugin relies on Paper's CrafterCraftEvent and Crafter inventory API which are Paper-only.

Installation Steps

1. Download the latest Useful-Autocrafters-x.x.x.jar from the Releases page
2. Stop your server completely before placing any files
3. Copy the .jar into your server's plugins/ directory
4. Start the server - protection is active immediately, no configuration needed

Verifying Installation

• Run /plugins in-game - Useful-Autocrafters should appear green in the list
• Run /usefulcrafter to confirm the plugin reports ENABLED status
• Place an autocrafter with a crafting recipe and fill ingredient slots with exactly 1 item each - crafting should be blocked
• Fill ingredient slots with 2+ items each - crafting should proceed normally

How It Works

The plugin listens to Paper's CrafterCraftEvent at HIGHEST priority. Every time an autocrafter attempts to produce an output item, the event handler:

1. Retrieves the Crafter block state from the event's block
2. Iterates all 9 crafting slots (indices 0-8)
3. For each slot that is not disabled in the crafter UI, checks if the slot holds exactly 1 item
4. If any enabled slot is at exactly 1 item, the event is cancelled and no output is produced
5. If all enabled slots have 2 or more items (or are empty), crafting proceeds normally

When protection fires, the autocrafter silently skips the craft cycle. No message is sent to players. The autocrafter will resume crafting automatically once the slot is restocked above 1 item.

Important: The plugin state (enabled/disabled) is not persisted across server restarts. The plugin always starts in the enabled state. If you need protection disabled permanently, use /usefulcrafter off after each restart or remove the plugin.

Commands

All commands require the usefulautocrafters.toggle permission (operator by default).

Root command: /usefulcrafter
Aliases: /uac, /ucraft

Command Reference

Command	Description
/usefulcrafter	Show current enabled/disabled status
/usefulcrafter on	Enable last-item protection (also accepts enable)
/usefulcrafter off	Disable last-item protection (also accepts disable)

Permissions

Permission	Description	Default
usefulautocrafters.toggle	Toggle protection on or off via /usefulcrafter	op

Building from Source

Useful Autocrafter uses Apache Maven as its build system.

Requirements:

• Java 21 or newer
• Apache Maven 3.6 or newer

Steps:

# Clone the repository
git clone https://github.com/Cobbleworks/Useful-Autocrafter-Plugin.git
cd Useful-Autocrafter-Plugin

# Compile and package
mvn clean package

The output JAR is written to target/Useful-Autocrafters-x.x.x.jar. Copy it into your server's plugins/ folder as described in the Installation Steps section.

Project Structure:

src/main/
├── java/com/usefulautocrafters/
│   ├── UsefulAutocrafters.java        - Plugin entry point (onEnable / onDisable)
│   ├── AutocrafterListener.java       - CrafterCraftEvent handler, last-item check logic
│   └── UsefulCrafterCommand.java      - /usefulcrafter command + tab completion
└── resources/
    └── plugin.yml                     - Plugin metadata, commands, permissions

License

This project is licensed under the MIT License - see the LICENSE file for details.