Shotgun Surgery

Symptom

A single conceptual change forces edits in many small places — adding a logging field means touching 17 files.

Goal

All code that varies together lives together. Adding a new field is one change in one module.

Smellier version

// Five files each have:
log(`event=${event}, user=${user}`);

Fresher version

// One file:
function logEvent({ event, user }) {
  // one place to evolve
}

Savings

Change cost becomes proportional to the conceptual change, not to how widely the concept was scattered.

Note

Easy to miss a site; reviewers can't easily verify completeness; small changes feel disproportionately risky.