Spectrally Selected Causal Self-Memory in Open Quantum Dynamics: An Interventional Criterion and Ternary Examples

Spectrally Selected Causal Self-Memory (SCSM) introduces an interventional criterion for a restricted form of same-sector causal memory in open quantum dynamics. Memory effects are commonly described through non-Markovianity, information backflow, memory kernels, or multitime process tensors. These approaches establish that the past can influence the future, but they do not by themselves isolate the case in which information about an intrinsically selected sector of the system is stored and later acts back on that same sector. In SCSM, the target sector is selected spectrally from the reduced dynamics. The system is encoded into a memory, and two interventions are then compared: one leaves the relevant memory record intact, while the other erases that record without changing the reduced system state at the intervention time. The difference in later trace-norm distinguishability defines an operational causal witness. Positive, zero, and negative values of this witness correspond respectively to protective, neutral, and dissipative self-memory for the selected mode. The paper includes an exactly solvable ternary qutrit model exhibiting open protective and dissipative regions separated by an analytic phase boundary, together with a numerical benchmark on a regular graded SU(2) tower. The deposit also contains the LaTeX source, symbolic and numerical reproduction code, CSV data, figures, and an interactive demonstrator. The qutrit result is reconstructed directly from the channel operators by the supplied Python script. SCSM is not proposed as a criterion for consciousness and is not a replacement for existing descriptions of non-Markovianity. It is intended as a same-sector interventional refinement for isolating reflexive memory effects in open dynamical systems.