Initial commit: Item Interaction Ecosystem plugin (UE5.7)

Server-authoritative, data-driven item/inventory/interaction/carry/equipment/
world-slot/placement/crafting framework. 8 modules, compiles against UE 5.7.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Source/ItemInventory/Public/ReplicatedInventoryList.h

@@ -0,0 +1,84 @@
+// Copyright ExByte Studios. Item Interaction Ecosystem.
+
+#pragma once
+
+#include "CoreMinimal.h"
+#include "Net/Serialization/FastArraySerializer.h"
+#include "ItemInstanceData.h"
+#include "ReplicatedInventoryList.generated.h"
+
+class UInventoryComponent;
+
+/**
+ * One replicated item slot (section 7.3). The item carries its own ContainerId /
+ * SlotIndex inside FItemInstanceData, but they are mirrored here so the FastArray
+ * delta only needs the entry, and so clients can route OnRep callbacks per slot.
+ */
+USTRUCT()
+struct ITEMINVENTORY_API FRepInventoryEntry : public FFastArraySerializerItem
+{
+	GENERATED_BODY()
+
+	UPROPERTY()
+	FGuid ContainerId;
+
+	UPROPERTY()
+	int32 SlotIndex = INDEX_NONE;
+
+	UPROPERTY()
+	FItemInstanceData Item;
+
+	FRepInventoryEntry() = default;
+	FRepInventoryEntry(const FGuid& InContainer, int32 InSlot, const FItemInstanceData& InItem)
+		: ContainerId(InContainer), SlotIndex(InSlot), Item(InItem) {}
+};
+
+/**
+ * FastArraySerializer carrying every item the inventory owns across all containers
+ * (section 7.3 / 32). One list per component delta-replicates only changed entries.
+ */
+USTRUCT()
+struct ITEMINVENTORY_API FReplicatedInventoryList : public FFastArraySerializer
+{
+	GENERATED_BODY()
+
+	UPROPERTY()
+	TArray<FRepInventoryEntry> Entries;
+
+	/** Not replicated - set by the owning component so callbacks can broadcast. */
+	UPROPERTY(NotReplicated)
+	TObjectPtr<UInventoryComponent> OwnerComponent = nullptr;
+
+	bool NetDeltaSerialize(FNetDeltaSerializeInfo& DeltaParms)
+	{
+		return FFastArraySerializer::FastArrayDeltaSerialize<FRepInventoryEntry, FReplicatedInventoryList>(Entries, DeltaParms, *this);
+	}
+
+	//~ FFastArraySerializer client callbacks
+	void PostReplicatedAdd(const TArrayView<int32>& AddedIndices, int32 FinalSize);
+	void PostReplicatedChange(const TArrayView<int32>& ChangedIndices, int32 FinalSize);
+	void PreReplicatedRemove(const TArrayView<int32>& RemovedIndices, int32 FinalSize);
+
+	// --- Server-side mutation helpers (mark dirty for delta replication) ---
+
+	/** Adds or replaces the entry occupying (Container, Slot). Returns the live entry. */
+	FRepInventoryEntry& AddOrUpdate(const FGuid& Container, int32 Slot, const FItemInstanceData& Item);
+
+	/** Removes the entry with the given instance id. Returns true if one was removed. */
+	bool RemoveByInstanceId(const FGuid& InstanceId);
+
+	/** Marks an existing entry dirty after its Item was mutated in place. */
+	void MarkEntryDirtyByInstanceId(const FGuid& InstanceId);
+
+	FRepInventoryEntry* FindByInstanceId(const FGuid& InstanceId);
+	const FRepInventoryEntry* FindByInstanceId(const FGuid& InstanceId) const;
+};
+
+template<>
+struct TStructOpsTypeTraits<FReplicatedInventoryList> : public TStructOpsTypeTraitsBase2<FReplicatedInventoryList>
+{
+	enum
+	{
+		WithNetDeltaSerializer = true
+	};
+};