The functionality gave ability to put on hold necessary product items without actual
changing stock record values.
Product stock level was then calculated as number of available items in stock minus items "on hold".
Staff users also could remove item from holding and put it back to the stock.
We implemented "sale" functionality, which is actually in-store purchase, submitted by the staff user through the dashboard. Thus, we replicated and re-integrated basket and checkout functionality to the dashboard. This functionality allowed to add any product to the sale from the dashboard products list page. If product had variants — it allowed to select necessary child product in order to add to the active sale.