Regenerative transitions demand sustained, multi-stakeholder participation across timescales and institutional levels, beyond conventional design disciplines. Drawing on five embedded case studies — post-conflict territorial development in Nariño (Colombia); co-design with collectives at risk of exclusion in Valencia; an international design cohort (WDO-YDC); institutional co-design at CDTM Valencia; and the citizen-driven legal recognition of the Mar Menor lagoon as a subject of rights — we ask how participation is sustained over time and across nested scales. Through retroductive cross-case thematic analysis, we find five empirical patterns: (i) fractal participation architecture; (ii) attuning, trust and material conditions; (iii) translation as a participatory-design competency distinct from facilitation; (iv) endurance portfolio with capacity-building, narrative-relational or legal-institutional mechanisms, among others; and (v) agonism and agency gradient extending to more-than-human stakeholders. We read these through temporal (infrastructuring) and spatial (institutioning) lenses, with implications for facilitators, institutional sponsors and design educators. The framework is extended in a companion paper.