Item Ledger & anti-dupe#

How the ledger works#

Identity. Valuable unstackable items (elytra, totems, tridents, maces, netherite gear, and every enchanted unstackable item by default) get a random UUID in their persistent data. Players cannot see it, and stacking is unaffected.
Sightings. Online inventories, ender chests, cursors and the contents of shulkers and bundles are scanned in the background, spread over scan-interval-seconds. Containers are scanned when opened and closed.
Detection.
- The same identity twice in one holder is a certain dupe.
- The same identity in two holders within the window is checked again on each holder's own thread. On Folia this happens twice, one second apart, so an item that is simply being moved never counts as a dupe.
Action. ALERT (default) or REMOVE_COPY (confiscates the copy that showed up last).

Chain of custody#

Each identity remembers its last custody-depth holders. Dupe alerts (in game, log file and Discord) include the chain, e.g. player Steve → chest world 10 64 -3 → player Alex. Use /og ledger trace to look at any item.

Creative and kits#

Items handled by creative-mode players get a fresh identity, so creative cloning is never reported.

Kit and crate plugins that saved one tracked item hand out identical copies. When the same identity is confirmed in template-threshold (3) different holders, OmniGuard treats it as a template: it stops alerting and tells you once. /og ledger unignore <uid> reverses that, and /og ledger ignore <uid> does it by hand.

Gain monitor#

For stackable valuables (gain-monitor.thresholds), OmniGuard compares inventory + ender chest + shulker contents over a window, minus gains that a legitimate source explains: pickups, crafting, furnaces, trades and container withdrawals. It is alert-only.

Known dupe patches (`dupe-patches`)#

Inventory entities (chest donkeys, llamas, chest minecarts and boats) cannot go through portals while loaded.
Inventories close safely on quit, world change, owner death, vehicle break, block break/explosion and chunk unload.
No inventory actions while dead.
Drop-spam rate limit.

Illegal items (`illegal-items`)#

Survival items with enchantments above max-enchant-level (30), stacks larger than allowed, or (optionally) unbreakable flags are reported on join, inventory close, container open and pickup. The check is alert-only by default (fix: false). Items made by plugins (custom name, lore, model data or another plugin's data) are skipped, so nothing a server sells is ever changed without the owner deciding so.