Andrea Tozzi, Anna Brucalassi, Matteo Munari, Simone D'Auria, Andrea Bianco, Giorgio Pariani, Ciro Del Vecchio, Paolo Picchi, Roland Bacon, Bernard Delabre, David Lee, Sofia Randich, Will Saunders

The Wide-field Spectroscopic Telescope (WST) is a planned 12-meter class dedicated spectroscopic facility for massive spectroscopic surveys. This paper presents the current status of Work Package 4.5, the High Resolution Multi-Object Spectrograph (HR-MOS) module. We describe the international team organization and optical design resulting from extensive trade-off studies, presenting its evolution driven by scientific requirements and technical constraints. Design parameters derived from science cases and astronomical community requirements are detailed. Given the critical importance of mass and volume budgets, we present envelope dimensions and mass estimates for HR-MOS. The spectrograph constructive parameters are defined, including optical fiber specifications, multiplex capability, and modular architecture. Finally, we present the structural analysis addressing mechanical stability and performance requirements for this high-resolution multi-object spectrograph.