Non-technical founder here, built my whole product with Claude Code. Everyone in this forum keeps saying the same thing UI and analytics get the "looks fine, ship it" treatment, but billing and auth get the paranoid line-by-line review. I've lived that.
Here's the twist though: my product IS the billing edge case. It's a tool that recovers failed subscription payments, so the entire thing lives in the messy world of declined cards expired cards, insufficient funds, bank 3-D Secure/SCA challenges that all look similar in the data but need completely different handling. Vibe-coding something where a wrong branch means someone gets emailed "your card was declined" when it actually went through was genuinely terrifying. I couldn't just trust the vibes.
