The Bug That Slept for 6 Months

Six months. That’s how long the bug lived in our production system before anyone noticed it. Not a crash. Not an error. Not a red alert in monitoring. Just a quiet little bug… slowly waiting. And the worst part? I wrote it. The Confident Commit It was a normal Friday afternoon. You know the type. Everyone wants to push their code before the weekend. Pull requests start getting approved faster than usual. I had just finished implementing a small feature in our backend. The task was simple: Calculate a discount for returning customers. The logic looked clean. The tests passed. Everything worked locally. So I pushed the commit with a message that looked like this: feat: add loyalty discount logic Approved. Merged. Deployed. And just like that, the code went to production. I closed my laptop and went into the weekend feeling productive. The Invisible Bug The system ran smoothly for months. Orders were processed. Payments worked. Customers kept using the platform. Nothing seemed wrong. But