In Episode 03 of my Ultra Modular Inventory + Interaction System series for UE 5.4, I fix a really annoying edge case from earlier: when your stack is capped (like my carrot max stack of 50), the extra items shouldn’t just disappear. I go back into the Item Container Component and refactor my original “Try Add Item to Inventory” flow by building a couple helper functions (like adding at an index and finding a valid slot), then I wrap the logic in a while loop that keeps adding one item at a time until either the quantity is fully placed or we run out of space. The big takeaway is the system now automatically finds a new slot and handles stacking without you babysitting it. After that, I move into UI: drag and drop. I set up a DragDropOperation blueprint with a source container and source index, detect drag from the item widget, spawn an item preview widget, and then handle OnDrop by switching slots. Then I push it further: if you drop an item onto the same tag, I don’t want a swap—I want a merge, so I hook the “try add already existing item” logic into slot switching. Finally, I start wiring up storage: a basic chest with its own storage container component, gameplay tags to open the storage UI, and UI manager events to show/hide inventories cleanly.