Selecting and Maintaining Boundary Models: Access Conditions and Resource Limits

This working paper specifies a selection and maintenance contract for replacing an internal subsystem with a boundary model. It connects declared targets and construction access to static elimination, memory-bearing models, and input-output identification. Conditional analyses address singular boundary relations, initialization and forcing, identifiable risk quantities, resource caps, and the composition of exact or approximate reductions. The methods are not treated as mutually exclusive model families. Six prospective tests compare the contract with access-aware adaptive selection pipelines. Earlier numerical comparisons are excluded for lack of original generators and per-system records; the work establishes neither a new reduction theorem nor empirical superiority.