This repository accompanies the paper “Why the Odd-Only Collatz Map Lacks Persistent Growth Tubes”. The work presents an empirical and structural analysis of the odd-only Collatz map,focusing on the stability of growth-supporting residue structures under 2-adic refinement.Rather than claiming convergence or a proof of the Collatz conjecture,the paper isolates refinement stability as a diagnostic criterion. Empirically, residue classes that exhibit positive expected log-drift at a coarse modulus(e.g. mod 36) fail to remain dominant when refined to mod 72 for the map n ↦ 3n + 1,while the variant n ↦ 3n + 5 exhibits stable lifting of its dominant structure. The repository includes the paper, the analysis code, and the residue-conditioneddrift data used to generate the figures.The results are intended as a structural perspective on the difficulty of sustainingpersistent growth in Collatz-type dynamics.