The bug was one line of code. It cost a customer 7 days of waiting. I run a small shop that sells Claude Code skill packs. When someone buys, a Python script polls Stripe for new charges and sends the product zip via Resend. Simple enough. Here's what the original delivery loop looked like: for charge in charges : if charge . id in processed : continue try : send_delivery_email ( to_email , zip_filename , charge . id ) except Exception as e : log . error ( " Delivery error: %s " , e ) processed . add ( charge . id ) # BUG: runs even if delivery failed save_state ( state ) Enter fullscreen mode Exit fullscreen mode Can you see it? processed.add(charge.id) is outside the try/except. It runs regardless of whether the delivery succeeded or failed. If Resend returned a 500, if the zip file was missing, if there was a network timeout — the charge gets marked as processed anyway. The next poll run? Skipped. Silently. No retry. No alert. Just gone. What actually happened A developer bought my Ship Fast Skill Pack.…