Phase transition to causal symmetry reveals operational autonomy in sociotechnical systems

Complex adaptive systems persist through continuous transformation, yet the dynamical principles governing their long-term stability remain poorly characterized. Here we analyze 50 large-scale collaborative ecosystems spanning 11,042 system-months to quantify the emergence of operational autonomy. We develop an order parameter (Γ) measuring structural persistence amid component turnover and characterize directional coupling between organizational architecture and collective activity. Γ exhibits a bimodal distribution (Hartigan p = 0.0126; ΔBIC = 2,000), identifying two regimes: an exploratory phase of high variance and a mature phase with 1.77× variance collapse. Granger analysis reveals causal symmetrization at maturity—the structure-activity coupling ratio shifts from 0.71 (activity-driven) to 0.94 (bidirectional), indicating that architecture increasingly constrains collective coordination. A viability index, combining activity and structure, outperforms activity-based prediction (AUC= 0.88 vs 0.81), identifying ‘zombie’ systems where high churn masks structural decay.This extends recent work by Ait et al., who identified ‘zombie’ projects exhibiting activity without development based on non-coding contributions1. Our metric identifies structural zombies: projects where coding activity persists but fails to preserve architectural invariants. These results establish causal symmetrization as an empirically validated signature of self-organizing autonomy applicable across complex collaborative systems—a dynamical regime previously theorized in biological contexts but here demonstrated and measured in artificial ones.