NBTShield

## [2.1.1] - 2026-03-25

### Added

- **Whitelist Unicode Detection** — New detection system that only allows Latin characters, common symbols, and emoji in user input. Blocks Korean, CJK, PUA, Braille, zero-width, and all other non-Latin scripts

- **System Item Protection** — Items with `CustomModelData` (server/resource pack textures) are now exempt from ALL size checks and removal

- **New config**: `skip-custom-model-data-items: true` — Prevents deletion of server-created textured items

- **Debug toggle**: `/nbts debug` command to enable/disable verbose logging (disabled by default)

- **Paper AsyncChatEvent** — Separate `PaperChatListener` class for Paper-specific chat handling (fails gracefully on non-Paper servers)

### Changed

- **Unicode detection switched from blacklist to whitelist** — Only whitelisted characters are allowed in user input (chat, commands, signs, books, anvil renames)

- **All debug/verbose logs gated behind `/nbts debug`** — No more console spam from chat codepoints, packet inspection, or injection messages

### Fixed

- **Chests with textures no longer deleted** — `enforceChunkNbtLimit()` now skips containers holding system items

- **`isContainerOversized()` / `isShulkerBoxOversized()`** — Skip system items in size calculations

- **Serialization failure no longer auto-deletes items** — `getItemByteSize()` returning `-1` no longer flags items as oversized

- **PacketProtection** — Now extracts actual message field from packets instead of using `toString()`

### Performance

- **Fast-path for vanilla items** — Items without `ItemMeta` skip serialization entirely (~90% reduction in serialization calls)

- **Size cache** — `getItemByteSize()` caches results for 5 seconds to avoid repeated serialization

- **Interact cooldown** — `onPlayerInteract` rate-limited to 1 check every 2 seconds per player

### Removed

- Inventory scanning for Unicode characters (items in player inventory no longer deleted)

- Item frame scanning for Unicode characters

- Join/slot change/hand swap/inventory close Unicode scanning

- Old detection methods: `hasIllegalUnicode()`, `objectContainsPua()`, `componentContainsPua()`