add some impl comments

code/foundation/src/ecs/components.h

@@ -103,20 +103,18 @@ typedef struct {
 } Item;
 
 typedef struct {
-    uint64_t ent;
-} ItemSlot;
-
-typedef struct {
-    ItemSlot items[ITEMS_CONTAINER_SIZE];
+    // TODO: we now hold a ref to an item, instead of representing an item slot,
+    // so that we can let the item entity keep its own components and also handle merging ops on its own.
+    ecs_entity_t items[ITEMS_CONTAINER_SIZE];
     float pickup_time;
 } Inventory;
 
 typedef struct {
-    ItemSlot items[ITEMS_CONTAINER_SIZE];
+    ecs_entity_t items[ITEMS_CONTAINER_SIZE];
 } ItemContainer;
 
 typedef struct {
-    ItemSlot processed_item;
+    ecs_entity_t processed_item;
     float cook_time;
     float burn_time;
 } Furnace;

code/foundation/src/ents/items.h

@@ -48,6 +48,11 @@ void item_show(uint64_t ent, bool show);
 uint64_t item_spawn(asset_id kind, uint32_t qty);
 void item_despawn(uint64_t id);
 
+// NOTE: item ops
+void item_pickup(uint64_t ent, uint64_t item);
+void item_drop(uint64_t ent, uint64_t item);
+void item_merge(uint64_t item1, uint64_t item2);
+
 // NOTE(zaklaus): items
 item_id item_find(asset_id kind);
 void item_use(ecs_world_t *ecs, ItemSlot *it, Position p, uint64_t udata);