Retention Without Dynamics: A Lagrangian Model of Post-Event Stability

This work introduces a minimal variational framework for describing retention as a physical mode of stability emerging after the cessation of external dynamics. A Lagrangian model is formulated in terms of a retentional difference and an autonomous retentional node evolving in pseudo-time. The study derives strict threshold conditions for self-sustaining retentional states, demonstrates neutral stability and hysteresis, and defines operational exit conditions without invoking energy flow, learning, or dissipative dynamics. The framework establishes retention as an ontologically distinct post-dynamical regime, providing a foundational basis for the physics and philosophy of persistence.