Stacks inserted into storages will now try to fill other stacks first

code/game/objects/items/storage/storage.dm

@@ -395,8 +395,19 @@ GLOBAL_LIST_EMPTY_TYPED(item_storage_box_cache, /datum/item_storage_box)
 
 ///Returns TRUE if there is room for the given item. W_class_override allows checking for just a generic W_class, meant for checking shotgun handfuls without having to spawn and delete one just to check.
 /obj/item/storage/proc/has_room(obj/item/new_item, W_class_override = null)
+	for(var/obj/item/cur_item in contents)
+		if(!istype(cur_item, /obj/item/stack) || !istype(new_item, /obj/item/stack))
+			continue
+
+		var/obj/item/stack/cur_stack = cur_item
+		var/obj/item/stack/new_stack = new_item
+
+		if(cur_stack.amount < cur_stack.max_amount && new_stack.stack_id == cur_stack.stack_id)
+			return TRUE
+
 	if(storage_slots != null && length(contents) < storage_slots)
 		return TRUE //At least one open slot.
+
 	//calculate storage space only for containers that don't have slots
 	if (storage_slots == null)
 		var/sum_storage_cost = W_class_override ? W_class_override : new_item.get_storage_cost() //Takes the override if there is one, the given item otherwise.
@@ -490,7 +501,27 @@ user can be null, it refers to the potential mob doing the insertion.**/
 /obj/item/storage/proc/handle_item_insertion(obj/item/new_item, prevent_warning = FALSE, mob/user)
 	if(!istype(new_item))
 		return FALSE
+
 	if(user && new_item.loc == user)
+		if(istype(new_item, /obj/item/stack))
+			var/obj/item/stack/new_stack = new_item
+
+			for(var/obj/item/cur_item in contents)
+				if(!istype(cur_item, /obj/item/stack))
+					continue
+				var/obj/item/stack/cur_stack = cur_item
+
+				if(cur_stack.amount < cur_stack.max_amount && new_stack.stack_id == cur_stack.stack_id)
+					var/amount = min(cur_stack.max_amount - cur_stack.amount, new_stack.amount)
+					new_stack.use(amount)
+					cur_stack.add(amount)
+
+			if(!QDELETED(new_stack) && can_be_inserted(new_stack, user))
+				if(!user.drop_inv_item_to_loc(new_item, src))
+					return FALSE
+			else
+				return TRUE
+
 		if(!user.drop_inv_item_to_loc(new_item, src))
 			return FALSE
 	else

code/modules/mob/living/carbon/human/inventory.dm

@@ -215,32 +215,46 @@
 	if(!has_limb_for_slot(slot))
 		return
 
-	if(equipping_item == l_hand)
-		if(equipping_item.flags_item & NODROP)
-			return
-		l_hand = null
-		update_inv_l_hand()
-		//removes item's actions, may be readded once re-equipped to the new slot
-		for(var/item_actions in equipping_item.actions)
-			var/datum/action/action = item_actions
-			action.remove_from(src)
-
-	else if(equipping_item == r_hand)
-		if(equipping_item.flags_item & NODROP)
-			return
-		r_hand = null
-		update_inv_r_hand()
-		//removes item's actions, may be readded once re-equipped to the new slot
-		for(var/item_actions in equipping_item.actions)
-			var/datum/action/action = item_actions
-			action.remove_from(src)
-
-	equipping_item.screen_loc = null
-	if(equipping_item.loc != src)
-		equipping_item.pickup(src, disable_warning)
-	equipping_item.forceMove(src)
-	equipping_item.layer = ABOVE_HUD_LAYER
-	equipping_item.plane = ABOVE_HUD_PLANE
+	// Already handled within the proc, usually storages that force move the item themselves
+	var/static/list/no_update = list(
+		WEAR_IN_BACK,
+		WEAR_IN_SCABBARD,
+		WEAR_IN_JACKET,
+		WEAR_IN_HELMET,
+		WEAR_IN_ACCESSORY,
+		WEAR_IN_BELT,
+		WEAR_IN_J_STORE,
+		WEAR_IN_L_STORE,
+		WEAR_IN_R_STORE
+	)
+
+	if(!(slot in no_update))
+		if(equipping_item == l_hand)
+			if(equipping_item.flags_item & NODROP)
+				return
+			l_hand = null
+			update_inv_l_hand()
+			//removes item's actions, may be readded once re-equipped to the new slot
+			for(var/item_actions in equipping_item.actions)
+				var/datum/action/action = item_actions
+				action.remove_from(src)
+
+		else if(equipping_item == r_hand)
+			if(equipping_item.flags_item & NODROP)
+				return
+			r_hand = null
+			update_inv_r_hand()
+			//removes item's actions, may be readded once re-equipped to the new slot
+			for(var/item_actions in equipping_item.actions)
+				var/datum/action/action = item_actions
+				action.remove_from(src)
+
+		equipping_item.screen_loc = null
+		if(equipping_item.loc != src)
+			equipping_item.pickup(src, disable_warning)
+		equipping_item.forceMove(src)
+		equipping_item.layer = ABOVE_HUD_LAYER
+		equipping_item.plane = ABOVE_HUD_PLANE
 
 	switch(slot)
 		if(WEAR_BACK)