D4: Two-Layer Machine (Understanding + State-Estimation)

The machine requires two layers, both necessary, neither sufficient alone. The understanding layer (AI comprehension of values, context, narrative) enables the machine to recognize when current behavior diverges from long-term commitments and to contextualize observations. The state-estimation layer (real-time physiological + behavioral monitoring) enables the machine to detect when the human's capacity to access their own evaluative processes is degraded.

Without state-estimation, the understanding layer interacts with degraded humans without knowing it. Without understanding, the state-estimation layer can detect stress but cannot determine what constitutes helpful versus harmful intervention.

This design requirement is derived from the premises: if agency is state-dependent (F1) and state changes exceed unaided perception (F2), then an agency-supporting system must estimate state; if the objective is capacity for self-directed action (D2), then the system must understand what self-directed action means for this person.