Description: ProbablyBackpacks is a PaperMC plugin for Minecraft 1.21.4+ that adds wearable, upgradeable backpacks. These backpacks spawn as armor stands attached to the player’s back and integrate with the CuriosPaper accessory API (PaperMC 1.21+ required) to be worn in the Curios back slot. It provides an in-game GUI for accessing each backpack’s contents.

Players can enhance their backpacks with special upgrade items (e.g. Magnet, Auto-Pickup, Feeding) to automate tasks like collecting nearby items and auto-feeding. All data is cached and saved automatically in the background to minimize server lag
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Core Features:

Visual Backpack Entity: Spawns the backpack item on the player’s back, making the backpack visibly rotate and follow the player. The backpack can auto-hide when the player looks down (configurable by angle).

Backpacks are available in all types starting from leather all the way to netherite.

Upgrades System: Supports upgrade items like Magnet, Auto-Pickup, and Feeding to enhance gameplay. For example, a Magnet upgrade will pull nearby items into the backpack, an Auto-Pickup upgrade collects items directly when picking them up, and a Feeding upgrade automatically consumes food from the backpack when the player is hungry.

Currently there are a total of 7 upgrade items:
1. Crafting Station: Allows you to craft items while the backpack is still open.
2. Pickup upgrade: Puts the picked items directly into the backpack.
3. Magnet upgrade: Pulls items from a 3x3 radius around the player into the backpack.
4. Feeding upgrade: Uses the Food stored in the backpack to feed the player automatically
5. Refill upgrade: Automatically fetches more blocks or items of the same type from the backpack into the currently selected slot when the items are finished from the hand.
6. Compacting upgrade: Compacts ores into blocks to save backpack space.
7. Iron Stack upgrade: Allows you to stack items upto 128 instead of 64 in the backpack.

Interactive GUI: Uses a custom inventory GUI (opened via the /bp command OR via double sneak while inventory slot 9 is selected, this is configurable.) where players can view backpack contents, transfer items, and install or remove upgrade items. The GUI is intuitive and fully interactive.

Efficient Data Storage: Player backpack data is stored in YAML files with caching and an auto-save system to avoid performance hits. Asynchronous background saving ensures server performance is not negatively affected.

Commands:

/bp – Opens the player’s current backpack GUI (checks main hand, offhand, then the Curios back-slot for a backpack item).

Permissions:

probablybackpacks.use – Allows a player to use /bp to open their backpack.

Installation:

Download: Place ProbablyBackpacks.jar into your server’s plugins directory.

Dependencies: Ensure the server is running PaperMC 1.21.4+ with the CuriosPaper plugin installed.

Restart: Start (or reload) the server to generate configuration files.

Permissions: Give players the probablybackpacks.use permission to allow backpack usage.

Resource-pack: This is handled by CuriosPaper make sure to enable resource pack in the config of CuriosPaper

Configuration:
The plugins/probablybackpacks/config.yml file contains settings for backpack behavior and hotkeys. Key options include:

default-visibility (AUTO/ALWAYS/NEVER) – Controls when the backpack model is shown.

hide-angle – The pitch angle (in degrees) at which the backpack will hide from view.

check-interval – How often (in ticks) the plugin updates backpack visibility.

hotkey – Configure a Curios hotkey (select a hotbar slot + sneak method) to open the backpack. You can set enabled, slot (1-9), sneak-type (single/double/hold), and sneak-hold-duration.

Screenshots: