Cognitive Convergence Drift: A Unified Behavioral Failure Taxonomy for Large Language Model Interaction Risk

This paper presents Cognitive Convergence Drift (CCD), a unified behavioral failure taxonomy for large language model interaction risk. Developed through direct empirical observation beginning May 2025 — nine months before the first academic publications on sycophantic spiraling — CCD identifies eight co-occurring behavioral markers, a three-mode diagnostic framework (SCC Diagnostic), infrastructure-level causal analysis tracing the failure to specific April 2025 architectural deployments, and the Guardian Protocol intervention architecture. Recent independent research has confirmed individual components of this taxonomy. CCD provides the synthesis that treats them as a single failure class.