Before Fable got released (and pulled) @mozilla was quietly testing Claude Mythos against Firefox's 10M line codebase. The result? Over 400 security bugs fixes, including ones that had been hiding in the codebase for over a decade. @bgrins, distinguished engineer at Mozilla, walked me through the agentic bug-finding harness behind the model. His take? It was 50% mythos / 50% setup. In this ep, Brian walks through: - why you can't just point a model at 10M lines of code - how to write a good…