Book: Event-Driven Architecture Pocket Guide My project: Hermes IDE | GitHub — an IDE for developers who ship with Claude Code and other AI coding tools Me: xgabriel.com | GitHub Picture it: 5:47 PM on a Friday, the on-call phone vibrates. A single payment event with a malformed currency field, "USD " with a trailing space your parser hates, has been retrying since 4:12 PM. Each retry blocks the partition behind it. Six thousand orders are now stuck waiting on one rotten apple. Your consumer's lag chart looks like a staircase going up. You did not have a dead letter queue. That is the entire problem. The DLQ pattern is one of those ideas that sounds boring in a system-design interview and saves your weekend in production. The shape is simple: when a message fails N times, stop hammering it, set it aside in a separate queue, and move on. The implementation is small enough to fit in 200 lines.…