Abstract: Myceloom serves as infrastructure for coalition formation, drawing on political science theory, biological market dynamics, and commons-based peer production to articulate principles for multi-stakeholder digital alliances. Where previous analyses addressed myceloom's philosophical foundations, community governance, collective intelligence, network architecture, and interface design, this investigation fills a critical gap: the political economy of coalition—how heterogeneous actors with divergent interests find common ground, overcome free-rider problems, and sustain collective action within distributed digital systems. By synthesizing Mancur Olson's logic of collective action, William Riker's coalition formation theory, Robert Axelrod's evolution of cooperation, and biological market theory with platform cooperativism and federated governance innovations, this analysis reveals myceloom not merely as technical infrastructure but as coalition substrate: the political architecture enabling genuinely multi-stakeholder alliances in the digital age. This establishes the Coalition layer of the Myceloom Protocol, defining how diverse stakeholders can form and sustain collaborative alliances. Keywords: Myceloom, Coalition Formation, Political Economy, Collective Action, Platform Cooperativism, Federated Governance, Biological Markets, Free-Rider Problem, Multi-Stakeholder Alliances, Digital Solidarity