The rapid proliferation of heterogeneous electronic health record (EHR) systems has exacerbated challenges in achieving seamless interoperability, particularly in the alignment of clinical vocabularies for procedure code mapping across disparate platforms. This conceptual manuscript introduces a formal harmonization theory tailored to large-scale clinical environments, emphasizing theoretical constructs for vocabulary alignment without reliance on empirical data or model evaluations. Grounded in systems architecture principles, we propose the vocabulary harmonization orchestration lattice (VHOL), a novel framework comprising layered modules for semantic mapping, contextual reconciliation, and governance oversight. VHOL integrates feedback topologies to mitigate alignment drifts theoretically, incorporating interpretive formulas for risk propagation and decision confidence in cross-system interactions. By synthesizing literature on clinical AI architectures, healthcare analytics infrastructures, and interoperability frameworks, this theory addresses gaps in procedure code harmonization, offering architectural blueprints for scalable deployment. The framework’s unique lattice structure facilitates modular integration into EHR ecosystems, enhancing theoretical robustness against vocabulary discrepancies. Implications extend to improved decision support pipelines and governance in multi-system healthcare settings, fostering a unified semantic foundation for procedure representations. This work advances conceptual discourse on clinical vocabulary management, providing a scalable theoretical lens for future infrastructural innovations in healthcare analytics.