We let an AI agent execute Bash and lived to talk about it — Sarah Sanders, PostHog

Sarah Sanders, a context engineer at PostHog, discusses the security implications of building an agentic CLI tool, "The Wizard," which automates developer workflows. She highlights the inherent risks of agents capable of executing commands, labeling it a "malware starter pack," and details how PostHog evolved its security posture from basic allow lists to a sophisticated "defense in depth." Key insights include the principle that "attacks compose, code review doesn't," the discovery of internal supply chain vulnerabilities through the "Context Mill," and the development of "The Warlock," a deterministic scanner using YARA rules. Sanders emphasizes the critical distinction between deterministic enforcement and probabilistic judgment, explaining how an LLM-powered "Triage" layer acts as an adviser (failing closed) rather than a bouncer, preserving the integrity of their security model.