Why AI-Generated Apps Break After Every Change — The Structural Mechanism

"Every time we add something, something else breaks." If you've built an application with AI tools — Cursor, Lovable, Bolt.new, Replit, v0 — and you're past the first few months of development, there's a good chance you've heard this sentence. Maybe you've said it yourself. This post breaks down the structural mechanism behind this pattern, how to detect it in your own codebase, and what the fix actually looks like. The Pattern Here's what we typically see in AI-generated codebases past month 3: Files that have grown past 500–800 lines Circular dependency chains between modules Business logic in unexpected places (route handlers, UI components, utility files) Less than 10% test coverage Every "simple" change requires extensive manual testing This isn't bad code. It's structurally incoherent code. The Mechanism: Architecture Drift AI-assisted development optimizes locally. Each prompt solves the immediate problem without awareness of the broader architecture. Session 1 establishes a cle