Major Fixes

Multiplayer Network Stability

• Added maximum list-length limits for network packets involving dragged slots, feature panels, JEI ingredients, and similar data.

• Added validation for oversized stack counts sent by clients, preventing negative values, invalid quantities, and excessive memory allocation.

• Unknown operation types are no longer treated as normal click actions.

• Added rate limiting to forced full-sync requests, reducing the risk of packet spam from malicious or malfunctioning clients.

• Client and server protocol versions must now match exactly. Incompatible versions will be rejected during connection.

Reduced Multiplayer Synchronization Traffic

Previously, while the feature panel was open, a full backpack data packet could also be sent every 5 ticks. This has now been optimized:

• Periodic feature panel refreshes no longer force a full backpack synchronization.

• Full backpack snapshots are no longer resent when the backpack contents have not changed.

• Routine background backpack synchronization has been reduced from once every 10 ticks to once every 20 ticks.

• Player actions such as clicking, transferring, and sorting still trigger an immediate synchronization.

Safer Double-Click Transfers

Double-click transfers from containers, the player inventory, and the hotbar are still supported, with improved server-side handling:

• The server now checks whether the player is allowed to remove items from the selected slot.

• The slot’s original onTake logic is preserved.

• Standard player inventory slots now support proper partial transfers.

• Special slots, including machine output slots, furnace output slots, and crafting result slots, will only transfer when the entire stack can fit inside the backpack.

• This prevents partial removal from special output slots from causing incorrect recipe consumption, experience rewards, or machine processing counts.

Oversized Stack Optimizations

Optimizations have been added for Sophisticated Backpacks stack upgrades and StackableItems:

• Stack counts above 999 are now abbreviated using K, M, and B.

• Long stack-count numbers no longer overlap adjacent slots.

• Vanilla ItemStack data inside network packets now uses a safe display count.

• The actual oversized stack count is transmitted and restored through an additional integer field.

• Click-and-drag distribution no longer loops once for every individual item.

For example, distributing hundreds of thousands of items by dragging will no longer perform hundreds of thousands of loop iterations, significantly reducing the risk of client and server lag.

Feature Panel and Furnace Optimizations

• The embedded furnace now writes backpack NBT immediately only when fuel is consumed or smelting is completed.

• Smelting progress is now saved periodically instead of writing backpack NBT every tick.

• Item-return checks when removing upgrade components now run only when the upgrade state changes.

• Empty crafting table, anvil, and smithing table states are no longer read repeatedly every tick.

• Removed the obsolete temporary furnace implementation and its event listeners, which were no longer accessible through any active feature.

GUI and Compatibility Optimizations

• Added caching for search results. Backpack contents are no longer filtered again when neither the inventory nor the search text has changed.

• Hovered-slot fields are now cached separately for different vanilla and modded containers, preventing incorrect field access after switching GUIs.

• Curios slots are now sorted by identifier, reducing changes to the ordering of virtual backpack slots in accessory inventories.

• Some Sophisticated Backpacks and Curios reflection methods are now cached, reducing repeated reflection lookups.

• Large item tooltips will continue to render above the backpack GUI.