Public–private partnerships (PPPs) are commonly analyzed through contracts, financing, risk transfer, and project delivery, yet innovation-intensive partnerships increasingly depend on knowledge and resources distributed across organizations whose goals, authority, incentives, and time horizons differ. This article develops an original non-empirical boundary-spanning ecosystem model that reframes selected PPPs as innovation ecosystems when their functioning depends on complementarities, interdependence, continuing knowledge integration, and adaptive coordination beyond the bilateral contract. The synthesis distinguishes six connected but analytically separate elements: heterogeneous actor resources, boundary-spanning mechanisms, knowledge integration, public-value protection, risk–reward alignment, and collaborative adaptation. It argues that boundary spanning does not itself generate integration; translation devices, shared interpretive structures, and organizational integration capabilities are required, while excessive or poorly governed spanning can create attention and coordination costs. Public value is treated as a contested ecosystem-level outcome rather than a presumed consequence of collaboration, and risk allocation is recast as an evolving governance problem rather than a one-time contractual transfer. The proposed model also incorporates feedback, ecosystem failure, temporal change, and institutional contingencies. Its principal contribution is to connect PPP research with innovation-ecosystem and knowledge-integration theory without claiming that PPPs are inherently ecosystems or that the proposed relationships are empirically validated. The model is intended as a theoretically bounded basis for comparative, longitudinal, and multilevel testing across sectors and institutional settings.
