The expansion of the OpenAIRE Graph through the EOSC Federation crystallises a decisive movement from fragmented scholarly visibility towards a federated epistemic infrastructure. Rather than functioning as a passive index, the Graph operates as an intelligent connective tissue, linking publications, datasets, software, grants, affiliations and indicators across more than 400 million metadata records from over 100,000 trusted sources. Its integration within EOSC’s build-up phase demonstrates how shared standards, particularly the OpenAIRE Guidelines v4, convert institutional catalogues into interoperable research assets. This is not merely technical harmonisation; it is a politics of discoverability, whereby national repositories such as Research.fi, rUMBA and BERD, and thematic infrastructures such as CERN Open Data and the Blue-Cloud Catalogue, become visible within a common European research horizon. The case of EOSC Node Italy, SURF Netherlands, Poland’s RePOD, PaNOSC, EUDAT, EuropePMC and Data Terra shows that prior OpenAIRE compliance substantially eases federation, while newer adopters extend disciplinary and geographical coverage into previously underrepresented domains. The synthesis is therefore clear: interoperability precedes impact. When repositories adopt common metadata protocols, their outputs cease to be isolated institutional deposits and become reusable components of a transnational knowledge commons. Consequently, the OpenAIRE Graph exemplifies a sustainable architecture for open science: expansive enough to absorb diversity, rigorous enough to preserve trust, and relational enough to provoke unforeseen interdisciplinary discovery.