Reliable access to laboratory and diagnostic data is essential for safe and equitable healthcare, yet laboratory data exchange remains fragmented across institution-specific infrastructures. Laboratory Information Management Systems (LIMS) and electronic health records often rely on bespoke interfaces that limit interoperability, scalability, and governance transparency. This paper is presented as a position and design paper that argues for an annotation-driven middleware (ADM) paradigm to support federated laboratory data exchange. In the proposed approach, machine-readable annotations express governance rules, provenance, data-quality indicators, and privacy constraints, which are dynamically interpreted by a cloud-native orchestration layer to guide routing, transformation, and policy enforcement. By decoupling governance intent from technical integration logic, the ADM paradigm enables declarative configuration by domain experts and supports modular, standards-agnostic interoperability. Illustrative scenarios are used to reason about feasibility rather than to provide empirical validation. This position aims to inform future implementations and evaluation of transparent, governable, and federated laboratory data-exchange infrastructures.