When Worlds Outlive Scars: How Persistent Environments Carry History Across Agent Resets

Resetting an agent does not necessarily reset its learning process. If an earlier policy changed a persistent environment, a fresh policy can inherit a different training distribution even after capability, memory, replay, and parameters have been restored or cleared. We trace the resulting channel from past capability, through a constructed world and fresh post-reset experience, into newly learned parameters and later behavior. Rather than infer this pathway from endpoint correlations, we exchange the intermediate carriers: fresh behavior follows assigned worlds, learned effects follow assigned replay, equalizing full replay removes the parameter contrast, and removing the world after practice preserves it. The inherited contrast is neither intrinsically beneficial nor harmful. Holding the learned snapshots fixed while changing only future task geometry yields positive, negative, and approximately cancelling consequences. An exact model gives a finite regime in which capability composition selects construction, and controlled learned systems realize the pathway without capability labels. The complete lifecycle is established in one designed Fork family; other structures expose explicit failure conditions, so broader carrier validity remains open. Persistent environmental state can therefore act as a hidden history channel even when agent-side state is reset.