SellMulti

SellMulti is an advanced, high-performance economy plugin built for Minecraft 1.21+ servers running Paper or Purpur. It provides an end-to-end dynamic market economy, 9-category progression multipliers, drop-in auto-sell containers, a real-time Action Bar HUD, and an interactive Admin Price Editor GUI.

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Dependencies & Requirements

Required Dependencies

1. Server Platform: Paper or Purpur 1.21.x (Running on Java 21 or newer)
2. Vault: Economy abstraction layer API (Download Vault)
3. Economy Provider: Any Vault-compatible economy plugin, such as:
   • EssentialsX (Recommended)
   • CMI
   • Treasury
   • CoinsEngine

Recommended Plugins

• LuckPerms: Permission management for player and administrative access.
• PlaceholderAPI: Placeholder expansion support for Scoreboards, TAB, and chat formatting.
• DecentHolograms / FancyHolograms: For displaying top seller leaderboards.

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Features

1. Drop-In Sell Container (/sell)

• Clean, 4-row (36 slots) virtual chest container.
• Drop items directly into the inventory.
• ESC Auto-Sell: Closing the container or pressing ESC automatically calculates payouts, credits player balance, updates multiplier EXP, and sends a single-line summary message.
• Automatic Item Refund: Unsellable items and protected containers are immediately returned to the player.

2. 9-Category Multiplier Progression (/sellmulti)

Categorizes over 1,300+ Minecraft 1.21 items into 9 distinct categories:

• CROPS: Agricultural harvests, seeds, fruits, and farming crops.

• MINERALS: Raw ores, ingots, gems, diamonds, and netherite materials.

• MOB_DROPS: Monster loot, boss drops, mob materials, and mob meats.

• EQUIPMENT: Weapons, armor, tools, bows, shields, and gear.

• NATURAL: Raw environmental blocks, dirt, stone, sand, logs, and leaves.

• FISHING: Fish species, nautilus shells, kelp, and aquatic catches.

• ENCHANTED: Enchanted books, golden apples, and enhanced consumable items.

• ALCHEMY: Potions, brewing ingredients, and chemical components.

• MISC: Decorative blocks, glass, wool, terracotta, and construction blocks.

• Exponential Scaling Curve: Progression requirement scales exponentially, particularly from 2.0x to 3.0x (ranging from billions up to 1.5 Trillion currency).

• Hard Multiplier Ceiling: Multiplier strictly caps at 3.0x (MAX LEVEL).

3. 30-Day Dynamic Market Cycles

• Every 30 days, the market engine automatically applies randomized market factors (between 0.8x and 1.5x) to all items.
• Staged prices configured by administrators via /selladmin automatically take effect during the next 30-day market reset cycle.

4. Real-Time Action Bar Live Price HUD

• Displays instant unit price, active category multiplier, and stack total payout above the hotbar when switching to or holding any sellable item:
  • Single item: Sell: 1.5 [Currency] (1x)
  • Stack (>1): Sell: 1.5 [Currency] (1x) | Total: +96 [Currency]
• 100% Vanilla NBT Purity: Does not alter physical item lore, ensuring flawless block stacking, crafting recipes, and hopper sorting compatibility.

5. Interactive Admin Price Editor GUI (/selladmin)

• Overview menu displaying all 9 categories with total registered items.
• Paginated category editor sorted by staged price descending.
• Configured Item Highlighting: Configured items display in bold green with (Configured) status.
• Search System: Built-in search dialog to filter items by keyword, with right-click to clear filter.
• Administrative Action Controls: Dedicated buttons to reset all staged prices across all categories to 1.0 currency or apply staged prices and reroll market factors immediately.

6. Security & Anti-Exploit Invariants

• Atomic Session Locks: Prevents race conditions, double-processing, and packet spam exploits during batch transactions.
• Shulker Box & Bundle Protection: Strictly prohibits selling Shulker Boxes and Bundles, preventing accidental loss of container contents.
• Named & Enchanted Item Safety: The /sell all command automatically excludes custom-named items and enchanted gear.
• Numeric Overflow Guard: Rejects non-positive prices and caps values at 1 Trillion to prevent 64-bit integer and double memory overflow.

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Commands & Permissions

Command	Permission	Description
/sell	sell.use	Open 4-row drop-in sell container (Auto-sells on close)
/sell hand	sell.use	Sell item currently held in main hand
/sell all	sell.use	Sell all valid items in inventory (Protects shulkers and enchanted gear)
/sellmulti	sell.use	Open Multiplier Overview GUI and Category Price Lists
/selladmin	sell.admin	Open Interactive Admin Price Editor GUI
/selladmin reroll	sell.admin	Apply staged prices and reroll 30-day market factors immediately
/selladmin reload	sell.admin	Reload configuration files and item catalog
/selladmin reset	sell.admin	Reset all staged prices across all categories to 1.0 currency
/selladmin setmulti <player> <category> <multiplier>	sell.admin	Set specific player multiplier for a category
/selladmin resetplayer <player>	sell.admin	Reset all multipliers and EXP for a specific player

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Configuration (config.yml)

# Prefix and Currency Symbol
prefix: "&8[&6✦ &e&lSell&8]&r "
currency_symbol: "⛃"

# Market Reroll Interval in Seconds (2592000 = 30 Days)
market_reroll_interval: 2592000

# Action Bar HUD Display
hud:
  enabled: true

# Multiplier Progression Settings
multiplier:
  max: 3.0
  increment: 0.1
  levels:
    1: 1000000          # 1.0M  -> 1.1x
    2: 3000000          # 3.0M  -> 1.2x
    3: 8000000          # 8.0M  -> 1.3x
    4: 20000000         # 20M   -> 1.4x
    5: 50000000         # 50M   -> 1.5x
    6: 100000000        # 100M  -> 1.6x
    7: 200000000        # 200M  -> 1.7x
    8: 350000000        # 350M  -> 1.8x
    9: 550000000        # 550M  -> 1.9x
    10: 800000000       # 800M  -> 2.0x
    11: 2500000000      # 2.5B  -> 2.1x
    12: 6000000000      # 6.0B  -> 2.2x
    13: 15000000000     # 15B   -> 2.3x
    14: 35000000000     # 35B   -> 2.4x
    15: 75000000000     # 75B   -> 2.5x
    16: 150000000000    # 150B  -> 2.6x
    17: 280000000000    # 280B  -> 2.7x
    18: 500000000000    # 500B  -> 2.8x
    19: 850000000000    # 850B  -> 2.9x
    20: 1500000000000   # 1.5T  -> 3.0x (MAX LEVEL)

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Building from Source

Prerequisites

• Java Development Kit (JDK) 21 or newer
• Apache Maven 3.8+

# 1. Clone the repository
git clone https://github.com/egade369/sellmulti.git

# 2. Navigate into project directory
cd sellmulti

# 3. Build the JAR file
mvn clean package

The compiled JAR file will be generated at target/sellmulti-1.0.0.jar.

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Author & License

• Author: egade369
• Repository: https://github.com/egade369/sellmulti
• License: Custom Non-Commercial License (Free for private server use. Commercial resale or paid redistribution is strictly prohibited. See LICENSE for details.)