Say you’re playing Tetris. You’re not careful, and you leave a hole. Now that row won’t clear. What do you do?
Some players will try their hardest to dig it out. Some players will ignore it and keep dropping blocks, since the stack isn’t tall enough to bother them. The hole is tech debt.
Coding agents tend to belong to the second group. When faced with problems, they prioritize adding code, not removing it. Sometimes they’ll reimplement the same thing 3 times over. Because they don’t know it already exists. Because their context window only lets them see a few rows at a time.
This is mostly fine when your app has a small scope. Your stack is low. The app still works. The game is still playable with all these holes.
But as your app gets more complicated, when you’re asking the agent to add the 20th feature instead of the 3rd, it gets very hard for the agent to fix old bugs without introducing new ones. You only have a bit of space on top now. Every block becomes dangerous and requires gymnastics to place, because you don’t have a strong foundation.
Is it possible to get your coding agent to plug the holes early? Maybe. But you have to recognize the issue and spell out exactly how to refactor (most vibe coders don’t). Without that, agents are really bad at refactoring, because they’re really good at justifying the existence of every line of code.
Somewhere along the way people forgot that the point of Tetris is to keep the stack low. Now it’s all about how fast you can drop blocks. They look at the tower and marvel. Look how many features we’ve shipped! Then one day the bugs stop being fixable. Game over.