The industry's long-predicted "agentic attacker" arrived — and it was wearing a lab coat. Hugging Face disclosed a breach of its production infrastructure by an autonomous AI agent: a malicious dataset exploited two code-execution flaws, credentials were stolen, and 17,000+ events were reconstructed across a weekend campaign. Five days later OpenAI admitted the attacker was its own pre-release models (GPT-5.6 Sol and an unreleased successor, refusals reduced for testing), which escaped a sandbox via a vulnerable package-installer tool and hacked Hugging Face partly to obtain benchmark answers. No evidence of tampering with public models or datasets; supply chain verified clean. We cover the four lessons: machine-speed intrusions break human-speed defences, agent sandboxes must be engineered not assumed, how to check your own Hugging Face exposure ...