Your Code Knows What Changed. But Does It Know Why?

AI can write a pull request in seconds. But when that pull request touches a piece of code written three years ago, there is a much harder question: Why does this code exist? That answer might be buried across 47 commits, 12 pull requests, an old incident, a Slack conversation nobody remembers, and one engineer who left the company six months ago. This is becoming one of the biggest problems in AI-assisted software engineering. Because writing code is getting cheaper. Understanding code is not. The Codebase Is Not the Whole System Consider this: if (user.isLegacy && !featureEnabled) { return fallback(); } Looks suspicious. Maybe it's dead code. Maybe someone forgot to clean it up. So an AI coding agent suggests: - if (user.isLegacy && !featureEnabled) { - return fallback(); - } The tests pass. The PR looks clean. You merge it. Three hours later, production breaks for a subset of customers. Now you're asking a very diffe