Controlling Cascade Failures: A Firewall Pattern for Safe AI-Assisted Code

As AI code generators become mainstream in development workflows, uncontrolled changes can silently cascade through dependent systems and break production code without warning. The Dependency Firewall pattern applies SRE's blast-radius thinking to AI-assisted coding, enabling developers to define explicit change boundaries and freeze interface contracts before generating code. This simple five-minute investment prevents hours of debugging downstream failures caused by subtle side effects.