BDPD² — Governance of Nested Commons: Four Vignettes

Governance of nested commons — multiple shared resources coexisting under overlapping institutional structures — requires substrate-level tools that prior single-arena frameworks do not provide. This paper surveys the BDPD platform's governance affordances through four vignettes, each posing one research question at N=5 seeds with deterministic heuristic agents and DeepSeek-flash LLM players. Two cross-cutting findings recur. First, the qualitative direction of governance effects (collapse yes/no, sanction-ladder ordering) is robust to seed variation under 3% observation noise; the quantitative depth near the collapse threshold is not. Second, and more consequential, the survey separates what an institution does to the world from what it does through the agent's reading of it: the first is real and identifiable — a treaty cap set below the sum of the individual caps charges the players who obeyed rather than the designated defector, and coercive exclusion captures whoever is defecting when the rule fires, conformists included — while the second is not found. The institution never reaches the text these agents read, so sanctioner cells that appear to differ cannot be attributed to the agents' perception, and every earlier reading that had the agents decoding a signal is withdrawn. The identifiable half is a property of substrate and rule together; the perceptual half is unmeasured, which is itself the argument for studying governance on the interaction between rules and agent realism.