Beyond Injection Detection: A Positive-Security Prompt Firewall that Closes the Scope and PHI Gap SOTA Classifiers Miss in Healthcare

Abstract

Presents QFIRE, an inline, provider-agnostic prompt firewall for healthcare AI agents that combines positive-security scope constraints, an asynchronous detector graph, and de-obfuscation — and releases QFIRE-HealthBench, where generic injection detectors recover only 0.40 recall while QFIRE's scope+PHI chain reaches 0.83.