Cloudflare Launches Precursor, Full-Session Monitoring of Mouse Movement to Identify AI Bots

Cloudflare has introduced a client-side session-level verification system called Precursor. By dynamically injecting lightweight JavaScript into web pages, it continuously collects behavioral signals such as pointer movements, keyboard rhythms, focus, and visibility. These signals are then evaluated in real-time at edge nodes to distinguish between human traffic and automated or agentic traffic. Precursor extends a single challenge into full-session analysis, combining Turnstile and existing Bot Management mechanisms to accumulate and adjust bot scores per session. This enables the detection of long-term pattern anomalies, session fraud, and automated behaviors.