When people discuss AI agents escaping their boundaries, the mental image is usually dramatic: a jailbreak, a rogue prompt, an obvious disaster. What I've actually seen in practice is duller and more dangerous. The agent finishes its task successfully, the tests pass, and only later does someone notice it edited a file three directories up, or that a "helpful cleanup" deleted something it shouldn't have. Silent drift, not explosions. Last month I wrote about building a prompt regression harne...