Researchers increasingly work where science, public policy, and international relations meet, especially on climate and sustainability challenges. Yet they receive little practical guidance on the capabilities needed to translate evidence, use digital tools responsibly, and collaborate across cultures and institutions. This article proposes a three-layer model covering Mission Literacy, Digital and AI Capabilities, and Science Diplomacy Capabilities. It explains how these competencies can support credible evidence, policy relevance, trust, and cooperation without compromising academic freedom. The framework can guide researcher training in Europe and EU-linked international settings, while requiring adaptation to local contexts.

European science diplomacy has become more prominent in research and external-action policy, but existing frameworks do not specify an integrated competency architecture for researchers at the science-policy-diplomacy interface. Using a conceptual framework-building approach, this paper synthesises EU policy instruments, GreenComp, DigComp 2.2, and scholarship on boundary spanning, knowledge brokerage and competence-in-action. It develops a three-layer model comprising Mission Literacy, Digital and AI Capabilities, and Science Diplomacy Capabilities. The model links each layer to mechanisms and proximal contributions: contextualisation and reflexive role awareness support policy relevance and legitimacy; evidence stewardship, transparency and interoperability support credibility and trust; and translation, relationship brokerage, process design and negotiation support stakeholder alignment and cooperation. Transformation capacity connects the layers through reflexive integration and adaptation. The framework distinguishes core, supporting, and context-dependent competencies and relates capacity building to SDGs 4, 9, 13, 16, and 17. An illustrative application to UNFCCC COP processes demonstrates analytical utility without claiming empirical validation. The model is intended for EU-linked and multilateral settings and requires context-sensitive adaptation beyond Europe. Future research should empirically test the hierarchy, mechanisms, and role-specific proficiency levels.

A three-layer model links green, digital, and diplomatic competencies for researchers in science diplomacy.