Should I not use a CDN if I need to check for out of stock products in real time in e-Commerce?

Hey folks - quick question about using sanityClient with, and without a CDN. Working on an e-commerce store and as part of the checkout process I check the stock/inventory server side to make sure the product is actually still in stock. This has to be perfectly up to date. So that once a sale is completed the stock is reduced by 1, and once there is 0 stock the product can no longer be sold. I need to avoid user A buying the last product and then 2 seconds later user B also purchasing the product.
I assume in this use case I should NOT use the CDN?

Are you keeping track of stock counts for products in sanity and doing a patch event or something to update stock on a purchase?

Yes - exactly. Just firing off a patch event based on a webhook from Stripe.

That's what I'd do! Maybe make two instances of your client - one with CDN and one without, that way the bulk of your requests can be quicker & cheaper but you can still get up-to-date data for the crucial ones