add blueprints

docs/blueprints/04-inventory/26_BPC_ActiveItemSystem.md

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+# BPC_ActiveItemSystem — Active Item System
+
+**Parent Class:** `ActorComponent`
+**Category:** Inventory
+**Target UE Version:** 5.5–5.7
+**Build Phase:** 3 — Inventory
+
+---
+
+## 1. Overview
+
+`BPC_ActiveItemSystem` manages the player's currently selected/active item and quick slot assignments. It reads from [`BPC_InventorySystem`](BPC_InventorySystem.md) and maps up to 8 quick slots to inventory items, handling hotkey input, item switching, and active item context (usable, throwable, consumable).
+
+---
+
+## 2. Enums
+
+### `E_QuickSlot`
+
+| Value | Description |
+|-------|-------------|
+| `Slot_1` | Hotkey 1 |
+| `Slot_2` | Hotkey 2 |
+| `Slot_3` | Hotkey 3 |
+| `Slot_4` | Hotkey 4 |
+| `Slot_5` | Hotkey 5 |
+| `Slot_6` | Hotkey 6 |
+| `Slot_7` | Hotkey 7 |
+| `Slot_8` | Hotkey 8 |
+
+---
+
+## 3. Variables
+
+| Variable | Type | Description |
+|----------|------|-------------|
+| `QuickSlots` | `TMap<E_QuickSlot, FGuid>` | Hotkey → Inventory Item ID mapping |
+| `ActiveSlot` | `E_QuickSlot` | Currently selected quick slot |
+| `ActiveItem` | `S_InventoryEntry` | Currently active item data |
+| `bHasActiveItem` | `bool` | An item is currently selected |
+| `bCanSwitchItems` | `bool` | Item switching allowed (not during anim) |
+| `SwitchCooldown` | `float` | Min time between item switches |
+
+---
+
+## 4. Functions
+
+| Function | Description |
+|----------|-------------|
+| `SetQuickSlot` | Assigns an inventory item to a quick slot |
+| `ClearQuickSlot` | Clears a quick slot assignment |
+| `SelectSlot` | Sets the active quick slot by key press |
+| `GetActiveItem` | Returns current `S_InventoryEntry` |
+| `UseActiveItem` | Uses/consumes the active item |
+| `CycleNextItem` | Selects the next populated quick slot |
+| `CyclePreviousItem` | Selects the previous populated quick slot |
+| `IsQuickSlotEmpty` | Returns true if quick slot has no item |
+| `GetQuickSlotItem` | Returns item in a specific quick slot |
+
+---
+
+## 5. Event Dispatchers
+
+| Dispatcher | Payload | Description |
+|------------|---------|-------------|
+| `OnActiveItemChanged` | `S_InventoryEntry NewItem`, `E_QuickSlot Slot` | Active item switched |
+| `OnQuickSlotAssigned` | `E_QuickSlot Slot`, `FGuid ItemID` | Item assigned to quick slot |
+| `OnQuickSlotCleared` | `E_QuickSlot Slot` | Quick slot cleared |
+| `OnActiveItemUsed` | `S_InventoryEntry Item` | Active item consumed |
+
+---
+
+## 6. Dependencies & Communication
+
+| System | Relationship |
+|--------|--------------|
+| `BPC_InventorySystem` | Reads inventory slots; source of truth for items |
+| `BPC_EquipmentSlotSystem` | Automatically updates quick slots on equipment change |
+| `WBP_HUDController` | Displays active item in HUD |
+| `BPC_HealthSystem` | Consumed health items trigger healing |
+
+---
+
+## 7. Reuse Notes
+- Quick slots are configurable per project (4-8 slots)
+- Active item system is the bridge between inventory data and gameplay input