Found a bug in the Swift (both in 1.20 & 1.22).
When you are in the product details and entering a product to cart (e.g. 10092 which has by default "4 in stock"), the quantity specified in the quantity box is added UNCONDITIONALLY to the cart. To test this, go to product 10092 details and type 100 in the quantity box and then either hit Enter or click "Add to cart". You will see that 100 items will be added to the cart even though the available stock is only 4.
Moreover, when you go to the cart summary, you will see that the quantity box correctly shows the maximum available quantity of 4 for item 10092 but the total amount for that line will be the quantity entered (e.g. 100 x 14.39 = 1439.00). End result is that customer when checking out will end up paying for 100 units even though only 4 are registered in the cart.
The logic that checks the available quantity doesn't seem to be working. You can check this yourself using https://swiftdemo.dynamicweb-cms.com demo website.