Biodesign projects often stall between promising material prototypes – bacterial cellulose textiles, mycelium composites and algae-derived materials – and scalable, economically viable production systems. This gap emerges from fragmented decision-making across material design, cultivation processes and techno-economic evaluation, since each domain operates with distinct metrics, vocabularies and decision thresholds – making cross-domain reasoning difficult to formalize and transfer. We present agents.design.bio, a decision-support framework that enables students, designers, educators and founders to engage interdisciplinary expertise through structured reasoning. The platform offers a unified conversational interface in which users interact with domain-specific agents: Designer (@designer), Farmer (@farmer) and CFO (@cfo). Together, they operate on a shared knowledge base, manufacturing datasets and techno-economic models. Rather than generating speculative ideas, the agents evaluate user-defined scenarios and highlight trade-offs, sensitivities and risks – making cross-domain dependencies explicit and testable. The demonstration walks through four phases – material evaluation, process optimization, scale-up stress testing and trade-off analysis – reframing scale-up as a structured learning process rather than a late-stage financial constraint.