Navigational Cybernetics 2.5: Structural Axioms of Drift, Admissibility, and Long-Horizon Viability

This work presents a formally closed architectural framework defining Navigational Cybernetics 2.5 - a distinct class of long-horizon adaptive systems in which intelligence is characterized not by avoidance of collapse, but by the capacity to navigate how collapse unfolds under irreversible drift.The framework establishes drift as an unavoidable structural medium rather than an error to be corrected, and introduces admissibility as a non-causal exclusion relation over admissible futures, categorically separated from action selection, optimization, or control. Long-horizon viability is shown to depend on architectural structuring of drift through regime dynamics, phase consistency, and admissible continuation, rather than on performance metrics, penalties, or reward maximization.The document provides:a closed axiomatic system defining drift, admissibility, identity continuity, internal time, and structural collapse;explicit architectural exclusion criteria distinguishing cybernetics of order 2, 2.5, and 3;formal treatment of drift navigability as dominance of internally generated drift structures over externally imposed drift;positive and negative hypothetical examples, including learning-based and control-based systems, enabling falsifiable classification;a comprehensive glossary establishing a canonical vocabulary for the school.This release represents a classification and falsification framework, not an implementation guide or optimization method. It is intentionally pre-constructive: architectures are evaluated by structural properties and exclusion criteria rather than by algorithmic prescriptions.The canonical and continuously evolving repository of this work is maintained on Zenodo (https://zenodo.org/communities/d3a-architecture/records?q=&l=list&p=1&s=10&sort=newest), where versioning, archival continuity, and long-term preservation are anchored. This Figshare record serves as a redundant publication channel (“backup runway”), ensuring accessibility, citation stability, and institutional visibility across platforms.