Beyond security hardening, OpenAI greatly expanded the coverage of its chain-of-thought monitoring system. Previously, monitoring was mainly focused on internal deployments of frontier models and frontier reinforcement learning training, because these workloads combine advanced model capabilities with access to tools, sensitive systems, and networks, but it did not cover all inference and training runs that use tools.
The new monitoring system uses a multi-stage architecture: first, activation classifiers run at every sampled token to detect anomalous signals in the model's internal activity; after potential problems are found, they escalate step by step to more computationally intensive and more sophisticated automated investigation systems. These systems examine tool calls, reasoning processes, and complete activity sequences, looking for signs of unauthorized access, data theft, destructive behavior, and attempts to defeat security measures.
OpenAI's goal is to issue an alert within 30 minutes after the monitoring system detects suspicious activity. If a possible critical security boundary violation is determined, a highest-priority alert is generated, and security and research teams are immediately called; if it cannot be confirmed as a false positive within 30 minutes, the relevant activity will be paused. The cost of this system is not small: OpenAI estimates that monitoring overhead accounts for roughly 20% of monitored inference compute, with the specific proportion varying by training and evaluation workload. After confirming on August 7 that Astra may possess critical cyber capabilities, the monitoring requirement expanded from "RL training and evaluation only" to "all Astra inference using tools."