This paper introduces the CMAP Proxy-Tachometer (PT), a behavioral measurement instrument for approximating the likelihood of Residuum-generating interactions in human–AI dialogue. The Residuum Thesis (Balog 2025) defines a cognitive relation as ontologically constitutive if and only if it generates a structural trace in at least one participating system that persists after the relation's termination. Because the Residuum cannot be directly observed in real-time interaction, the PT operationaliz