Boundary spanners in co-design networks: Modulating tension and structuring informal power

In community-based co-design for social innovation, cross-community collaboration is marked by structural fragility, behavioral tension, and evolving informal power. While designers are often framed as facilitators, this study foregrounds the role of boundary spanners—community-embedded actors who sustain collaboration by modulating boundaries and shaping influence through strategic behaviors. Combining grounded theory with agent-based modeling (ABM), this study identifies five key boundary-spanning behaviors—scouting, negotiating, maintaining, trust-building, and guarding—and simulates their dynamic interplay to examine how different behavioral configurations affect boundary openness, internal cohesion, and informal power accumulation. Findings challenge the assumption that openness alone guarantees resilience. Instead, sustainable collaboration emerges from the strategic modulation of behavioral tensions between exploration and protection. Mixed behavioral strategies—rather than maximal openness—yield greater structural adaptability and collaborative continuity. Informal power, likewise, does not stem from formal authority but evolves through phased behavioral patterns: early-stage bridging, mid-term embedding, and late-stage guarding. This mechanism-based understanding reveals how collaboration infrastructures are not merely built but continuously governed through micro-level actions. The study contributes a mechanism–behavior–structure modeling framework that bridges qualitative insight with computational simulation. It redefines boundary governance as a behavioral design task and advances a dynamic theory of informal power in collaborative systems—providing both a theoretical lens and methodological platform for studying how design navigates participation, positionality, and institutional emergence. • Identifies five key spanning behaviors of boundary spanners in co-design networks. • Proposes an agent-based model linking behaviors, boundary openness, and power dynamics. • Reveals that dynamic balance between exploring and guarding fosters boundary resilience. • Demonstrates that informal power emerges via phased behavioral strategies over time. • Offers a “mechanism–behavior–structure” framework for modeling relational infrastructures.