BioRelay: Multi-Agent Orchestration with Evidence Continuity for Biomedical Knowledge Discovery

Biomedical deep-research agents retrieve evidence from literature and databases, reason over it, and synthesize conclusions into static reports. Yet whether the evidence needed to support those conclusions survives the intermediate stages from retrieval to final output remains largely unmeasured. We formalize this property as evidence continuity and introduce ProteInsight, a benchmark of 2,796 tasks over 699 disease–protein cases with typed evidence assembled from biomedical databases and literature. We find that evidence omission, rather than unsupported generation, is the dominant failure mode: GPT-4o produces grounded answers in 98.7% of cases but with omission accounting for 90.7% of failures and worsening as tasks require more heterogeneous evidence. To preserve evidence across stages, we develop BioRELAY, a multi-agent system that maintains a shared typed evidence state across search, reasoning, and synthesis, with deterministic gates enforcing evidence linkage and state consistency, supporting narrative report and interactive interface. BioRELAY performs strongly on standardized biomedical QA, challenging protein-function reasoning, and end-to-end evidence synthesis. Ablations further show that evidence continuity is distinct from schema validity and model capability, establishing evidence continuity as a measurable failure for multi-agent system and providing a mechanism to localize where evidence is lost.