BackPackSSS

BackPackSSS is a lightweight, survival-friendly backpack plugin for PaperMC 1.21+.
It features a 3-tier crafting progression system, custom 3D resource-pack models,
SQLite persistence, and robust anti-dupe protection — with minimal server overhead.

Current version: 1.9

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Features

Feature	Details
3 backpack tiers	Weak (18 slots) → Good (27 slots) → Strong (54 slots)
Tier upgrade crafting	Craft a higher tier using the previous tier as center ingredient
3D resource pack	Custom bundle model per tier (brown / yellow / red)
SQLite persistence	Data survives restarts; async dirty-flag saves, sync save on shutdown
Anti-dupe protection	Session lock, opening cooldown, death/quit save
Nesting prevention	Blocks backpacks, shulker boxes, and bundles inside backpacks
Item filter	Explicitly blocks armor, tools, weapons, and enchanted books
Max backpack limit	Configurable per-player limit (default: 1)
Permission-based admin	backpack.admin for give/reload; works with LuckPerms etc.

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Requirements

• Server: PaperMC 1.21 or later
• Java: 21+
• SQLite JDBC: bundled by PaperMC — no extra jars needed

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Building from Source

git clone <repo-url>
cd BackPackSSS
mvn clean package
# Output: target/BackPackSSS-1.9.jar

Requires Maven 3.8+ and JDK 21.

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Installation

1. Drop BackPackSSS-1.9.jar into your server's plugins/ folder.
2. Restart (or reload) the server.
3. (Optional) Copy resource-pack/ contents, host the pack, and set it as your
   server resource pack in server.properties.

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Commands

Command	Permission	Description
/backpack or /bp	backpack.use	Show craft reminder
/bp give <tier>	backpack.admin	Give yourself a backpack (tier 1–3)
/bp give <tier> <player>	backpack.admin	Give a backpack to another online player
/bp reload	backpack.admin	Reload config without restarting

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Permissions

Node	Default	Description
backpack.use	everyone	Allows opening a backpack
backpack.admin	OP	Access to give and reload sub-commands

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Crafting Recipes

Tier 1 — Weak Backpack (18 slots)

[L][L][L]
[L][C][L]
[L][L][L]
L = Leather  |  C = Chest

Tier 2 — Good Backpack (27 slots)

[I][R][I]
[R][B1][R]
[I][R][I]
I = Iron Ingot  |  R = Redstone  |  B1 = Tier 1 Backpack

Tier 3 — Strong Backpack (54 slots)

[S][D][S]
[D][B2][D]
[S][D][S]
S = Shulker Shell  |  D = Diamond  |  B2 = Tier 2 Backpack

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Configuration (config.yml)

auto-discover-recipes: true   # Show recipes in recipe book on join

restrictions:
  max-backpacks: 1            # Max backpacks per player inventory (0 = unlimited)
  allow-nesting: false        # Block backpacks/shulkers/bundles inside backpacks
  filter-special-items: true  # Block armor, tools, weapons, enchanted books

tiers:
  1:
    name: "&fWeak Backpack"
    size: 18                  # Must be a multiple of 9 (max 54)
    cmd: 10101                # CustomModelData matching your resource pack
    lore:
      - "&7Level: &fWeak"
      - "&7Capacity: &b18 slots"
      - ""
      - "&aRight-click to open!"
  # tiers 2 and 3 follow the same structure

Notes on size: Changing a tier's size after players have already stored items is
safe — the plugin will trim excess items and log a warning rather than crash.

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Item Filter (filter-special-items)

When enabled, the following item categories cannot be placed inside a backpack:

• Armor (helmets, chestplates, leggings, boots — all materials)
• Melee weapons (swords — all materials)
• Tools (axes, pickaxes, shovels, hoes — all materials)
• Ranged weapons (bows, crossbows, tridents)
• Shields, elytras, shears, flint and steel
• Enchanted books
• Totems of undying

Regular items with a stack size of 1 from other plugins are not blocked unless they
match one of the categories above.

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Changelog

See CHANGELOG.md for the full history of changes.

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Author

Duong2012G — feedback and bug reports welcome.