5 Silent Architecture Killers That Pass Code Review Every Time

Last month, I approved a pull request that looked perfectly fine. Clean code, tests passing, no obvious issues. Three weeks later, that same change triggered a cascade of problems that took two developers three days to untangle.

The code wasn’t broken. The architecture was.

After seven years of building and maintaining backend systems, I’ve realized something unsettling: the changes that destroy architecture rarely look dangerous in code review. They pass CI/CD. They solve immediate problems. They even follow best practices.

But they slowly poison the system.

Here are the five silent killers I’ve learned to watch for, and what they actually cost when left unchecked.

1. Just One More Parameter

This one sneaks up on everyone. You start with a clean function signature. Then business requirements shift. Instead of rethinking the design, you add a parameter. Then another. Then “just one more for this edge case.”

Here’s how it typically evolves:

// Week 1: Simple and clear
async function sendNotification(userId, message) {
  const user = await getUser(userId);
  await emailService.send(user.email, message);
}
// Week 4: New requirement
async…