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This functionality supports preventing a guest from adding to cart past the allowed window, and also prevents the scenario where if a guest adds to the cart during a valid time and then leaves the item in the cart past the allowed window they are prevented from checking out past the blackout window.
For example: Guest puts a product with date 2/16 in their cart on 2/15 but doesn't check out until 2/16. On 2/16 the product is no longer available on the PDP but since the guest already has it in their cart they can still check out.
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