Chest Loader

Chest Loader

Chest Loader is a server-side Fabric mod that turns a chest or barrel into a chunk loader made from vanilla items. Vanilla clients can join without installing the mod.

This document is also available in 中文.

Minecraft version

• 26.2

Installation

Download the JAR from the releases page or CurseForge.

Install Fabric Loader on the server, then put Fabric API and the Chest Loader JAR in the server's mods directory. Clients do not need Chest Loader or Fabric API.

For single-player use, install the same files in the local game instance.

Usage

Place the configured pattern in a chest or barrel, then open the container. The default pattern uses at least ten obsidian, at least four powered rails in one slot, and one minecart:

O O O O
O R M O
O O O O

O is obsidian, R is powered rail, and M is a minecart. Every slot outside the pattern must be empty. The pattern may start in any column where it fits. The rail and minecart may trade places.

The loader keeps a 7×7 chunk area loaded in its own dimension. The central 3×3 chunks process entities. The loader remains active after a server restart.

Removing an item from the pattern deactivates the loader when the container closes. Hopper changes may take up to one scan interval to register.

Configuration

Chest Loader creates config/chestloader.json on the first start:

{
  "patterns": [
    {
      "name": "obsidian-frame",
      "dimensions": ["minecraft:overworld", "minecraft:the_nether"],
      "shape": [
        "OOOO",
        "ORMO",
        "OOOO"
      ],
      "keys": {
        "O": { "items": ["minecraft:obsidian"], "min": 1 },
        "R": { "items": ["minecraft:powered_rail"], "min": 4 },
        "M": {
          "items": [
            "minecraft:minecart",
            "minecraft:chest_minecart",
            "minecraft:hopper_minecart",
            "minecraft:furnace_minecart"
          ],
          "min": 1,
          "max": 1
        }
      },
      "slide": true,
      "mirror": true
    }
  ],
  "ticketLevel": 30,
  "scanIntervalTicks": 200,
  "maxLoadersPerDimension": 32,
  "maxLoadersTotal": 128,
  "notifyOnActivate": true,
  "particleOnActive": true
}

Each entry in patterns defines one accepted layout.

• shape draws the layout one row at a time. A . or space requires an empty slot. Other characters refer to entries in keys.
• keys lists the accepted items and the minimum and maximum count for each slot.
• slide lets the pattern start at any position where it fits. Slots outside the pattern must stay empty.
• mirror also accepts a left-to-right reflection of the pattern.
• dimensions lists where the pattern works. Add minecraft:the_end to enable it in the End.

You can add more entries to patterns for other layouts or dimensions.

ticketLevel controls the loaded range. The default value, 30, loads a 7×7 area with a 3×3 entity-processing center. Values 32 and 33 do not process entities in the center.

scanIntervalTicks controls how often the mod checks active loaders for hopper changes. maxLoadersPerDimension and maxLoadersTotal cap the number of active loaders. The two feedback options control activation messages and portal particles.

Commands

/chestloader list
/chestloader disable <x> <y> <z> [dimension]
/chestloader enable <x> <y> <z> [dimension]
/chestloader check <x> <y> <z>

list shows every tracked loader and provides clickable enable or disable buttons in chat. disable releases its chunks but keeps the loader on the list. enable restores it from any location. These commands require permission level 1.

check evaluates the container at the given position. It requires permission level 2.

Limits

• An active loader uses the whole container, so you cannot use that container for storage.
• Chunk loading does not bypass Minecraft's mob spawning and despawning distance rules. The loader cannot run a mob farm without a nearby player.
• Keep a machine inside the central 3×3 chunks if it needs entity processing.
• A disabled loader broken while its chunk is unloaded may remain in list until the chunk loads or someone tries to enable it.

Build and test

Install JDK 25, then run:

./gradlew test
./gradlew runGameTest
./gradlew build

The built JAR is written to build/libs/.

License

Apache License 2.0