How Scaling Only Cart and Checkout on Black Friday Cut Our Marketplace Infrastructure Bill

https://papa-wiki.win/index.php/When_a_Retail_CTO_Watches_Millions_Slip_Away:_David%27s_Story

After three failed marketplace projects, one sharp pull request on a Black Friday weekend taught me which parts of a platform truly need to scale. We used to spin up every service, every database replica, every cache cluster when traffic spiked