AI now writes over **25% of Google’s** and as much as **90% of Anthropic’s** code. That’s not a trend—it’s a regime change. Still, the mess in large public systems reminds us: clever analysis isn’t enough. Complex systems don’t behave; they misbehave. When the machines are churning out code, the smarter move is to evolve from working systems—not architect them from scratch. Bottom-up beats big plans.