Computational social choice and algorithmic decision theory offer rich aggregation theory but no comprehensive process for egalitarian self-governance: aggregation, deliberation, amendment, and consensus are each considered in isolation, with key metric-space aggregators being NP-hard. Here, we propose constitutional governance in metric spaces, integrating these stages into a coherent polynomial-time protocol for constitutional governance. The constitution assigns, per amendable component including itself, a metric space, aggregation rule, and supermajority threshold. Amendments proceed by members voting with their ideal elements, followed by members submitting public proposals carrying supermajority public support under the revealed votes. Public proposals can be sourced from deliberation among members, vote aggregation, or AI mediation. The constitutional rule adopts a supported proposal with positive maximal score, if there is one, else retains the status quo. With Constitutional Consensus, a community can run the constitutional governance protocol on members' personal computing devices (e.g., smartphones), achieving digital sovereignty. We focus on the utility of the generalised median, prove that at majority threshold no misreport weakly dominates sincere voting, and study the compromise gap between best peak and unconstrained optimum. We instantiate the framework to seven canonical settings -- electing officers, setting rates, allocating budgets, ranking priorities, selecting boards, drafting bylaws, and amending the constitution. By unifying metric-space aggregation, reality-aware social choice, supermajority amendment, constitutional consensus, deliberative coalition formation, and AI mediation, this work delivers a comprehensive solution to the constitutional governance of digital communities and organisations.

翻译：计算社会选择与算法决策理论提供了丰富的聚合理论，但缺乏一套完整的用于平等自治的流程：聚合、商议、修正和共识被孤立地考虑，而关键的度量空间聚合器是NP难的。本文提出了度量空间中的宪政治理，将这些阶段整合为一个连贯的多项式时间协议。宪法为每个可修正的构成部分（包括自身）分配一个度量空间、一个聚合规则和一个超级多数阈值。修正过程由成员投票表达其理想元素开始，随后成员提交公开提案，这些提案在公开投票下获得超级多数的支持。公开提案可来源于成员间的商议、投票聚合或AI调解。宪法规则采纳一个获支持且得分最高的提案（若有），否则维持现状。通过宪政共识，社区可在成员的个人计算设备（如智能手机）上运行宪政治理协议，实现数字主权。我们聚焦于广义中位数的效用，证明在多数阈值下不存在弱占优的真实投票误报，并研究了最佳峰值与无约束最优之间的妥协差距。我们将该框架实例化为七个经典场景——选举官员、设定费率、分配预算、排序优先级、遴选委员会、起草章程和修正宪法。通过统一度量空间聚合、现实意识的社会选择、超级多数修正、宪政共识、协商联盟形成和AI调解，本工作为数字社区和组织的宪政治理提供了综合性解决方案。