What breaks first when scaling vibe-coded apps?

Building a functional MVP over a weekend using tools like Lovable or Cursor is easy, but adding features later gets messy. Small edits in one file often break unrelated logic, mostly because you don't fully track how data moves through the app.

I found that pasting a short plain-text system flow at the start of every prompt and committing code after every single change completely stopped the silent breaks.

When your AI-generated code started breaking, what simple habit saved your project?