{"slug": "sapien-a-stateful-policy-engine-for-autonomous-ai-agents", "title": "Sapien: A Stateful Policy Engine for Autonomous AI Agents", "summary": "Researchers introduced Sapien, a stateful policy engine that enforces contextual security policies on autonomous AI agents' tool calls by specifying permitted tool-call sequences with regular expressions extended with stateful predicates, deferred policy generation, and scoped semantic checks. According to the arXiv paper 2610.00797v1, Sapien stays within a few percent of an unconstrained agent's utility while ruling out 93-95% of attacks on AgentDojo and 62-85% on Toolathlon even when the agent is fully hijacked, roughly twice as many as tool allowlists on long-horizon tasks.", "body_md": "arXiv:2610.00797v1 Announce Type: new \nAbstract: Contextual security defenses prevent AI agents from taking rogue actions by synthesizing a task-specific policy and enforcing it on the agent's tool calls. In multi-step tasks, however, which actions are valid often depends on what the agent has already done and learned. We present Sapien, a policy engine for enforcing stateful contextual policies. A Sapien policy specifies permitted tool-call sequences using a regular expression extended with stateful predicates, deferred policy generation, and scoped semantic checks. We show that Sapien stays within a few percent of an unconstrained agent's utility. Even if the agent is fully hijacked, Sapien's policies rule out 93-95% of attacks on AgentDojo and 62-85% on Toolathlon (twice as many as tool allowlists on long-horizon tasks).", "url": "https://wpnews.pro/news/sapien-a-stateful-policy-engine-for-autonomous-ai-agents", "canonical_source": "https://www.machinebrief.com/news/sapien-a-stateful-policy-engine-for-autonomous-ai-agents-r98x", "published_at": "2026-10-02 04:00:00+00:00", "updated_at": "2026-10-02 07:07:14.993435+00:00", "lang": "en", "topics": ["ai-agents", "ai-safety", "artificial-intelligence", "ai-research"], "entities": ["Sapien", "AgentDojo", "Toolathlon", "arXiv"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/sapien-a-stateful-policy-engine-for-autonomous-ai-agents", "markdown": "https://wpnews.pro/news/sapien-a-stateful-policy-engine-for-autonomous-ai-agents.md", "text": "https://wpnews.pro/news/sapien-a-stateful-policy-engine-for-autonomous-ai-agents.txt", "jsonld": "https://wpnews.pro/news/sapien-a-stateful-policy-engine-for-autonomous-ai-agents.jsonld"}}