Abstract: To meet the engineering demands of deep bedded-salt gas storage in China, improve site utilization, enhance operational efficiency, and ensure long-term stability, a full-scale three-dimensional geomechanical model of a four cavern salt cluster is established with consideration of temperature effects induced by injection–production operations. The influences of cavern layout (rectangular vs triangular) and operating mode (synchronous vs asynchronous) on long-term mechanical response and deformation evolution are analyzed, and the stability response of the cavern cluster under single- cavern abnormal conditions is evaluated. The results indicate that long-term stability and deformation uniformity are significantly affected by the cavern layout. A more balanced stress distribution and better deformation compatibility are provided by the rectangular layout, which is favorable for stability optimization. A triangular layout can be adopted under spatial constraints; however, local increases in deviatoric stress and reduced deformation compatibility are caused by its geometric asymmetry. Distinct differences in stress and deformation evolution are exhibited between the operating modes. Synchronous operation is beneficial for maintaining a symmetric overall load-bearing pattern and preventing the formation of local high-stress zones around individual caverns during low-pressure stages, whereas the spatiotemporal non-uniformity of the stress field is increased by asynchronous operation, although the overall peak displacement is slightly reduced. Disturbance from single-cavern extreme failure is observed to be generally localized. When the salt pillar width is 2D, a deformation-affected radius of approximately one-quarter of the pillar width is produced by the depressurization of a single cavern to 0 MPa; the disturbance does not penetrate the pillar, deformation increments in adjacent caverns are kept controllable, and neither global instability nor cascading failure is triggered within the cavern cluster. The shrinkage of the failed cavern is suppressed by brine reinjection for pressure maintenance, but only limited improvement is yielded in the deformation characteristics of the adjacent caverns and the overall cluster. When sufficient pillar-width redundancy exists, either brine reinjection or abandonment of the failed cavern is considered feasible. The findings are expected to provide a reference for layout optimization, operational regulation, and risk mitigation of deep bedded salt cavern clusters under long-term service conditions.