Intro
Ask an AI assistant to "handle the checkout flow" and it will hand you a working function in about four seconds. Validate the cart, call three different APIs, format a receipt, log the analytics event, catch whatever errors show up, all in one block, three levels of nesting deep. It runs. It passes the one test anyone bothered to write. And it is, structurally, a small readability crisis waiting for whoever opens that file next.
That gap, between code that works and code a human can actually follow six months later, is where most of the real cost of AI-assisted development quietly accumulates. Here's where it actually shows up. (Illustrative composites drawn from common patterns, not specific incidents.)
The function that does six things because nobody told it not to
A generated function rarely sets out to do too much. It just keeps absorbing responsibility one prompt at a time: first it validates input, then someone asks it to also handle a retry, then to also log the outcome, then to also format the response for the frontend. Each addition looks reasonable in isolation. Read top to bottom six weeks later, it's a single function holding four unrelated jobs, and splitting it back apart means first reverse-engineering which lines belong to which job.
