Complete Physical Interface of the Neutrino Propagation Role Complex

Neutrino carrier ARC and HNL prediction 2/18 This paper determines the complete carrier-neutral physical interface required by any lawful realization of the neutrino propagation role complex established in the preceding target-fixed analysis. The work begins from the experimentally realized neutrino source–propagation–detection interface and its two nested target-specific roles: interaction–propagation nonalignment and boundary-visible response multiplicity. It does not assume a neutrino mass mechanism, PMNS matrix, right-handed neutrino, Weinberg operator, sterile sector, defect, generalized symmetry, or other microscopic carrier. A canonical physical interface is constructed for simultaneous same-target completions. Its core components include the charged-current preparation and detection boundary, a record-relevant effective propagation channel, cross-boundary support transfer, the finite boundary-visible response-mode packet, mode-to-boundary incidence, environment and record transport, and the strict nesting of the underlying physical roles. The paper also formalizes the physical attachment data required for one coherent realization. These include locality, causal support, electroweak boundary structure, gauge quotient, representation and charge data, anomaly compatibility, vacuum structure, deformation behavior, operator availability, and RG/EFT transport. Global-form, higher-form, higher-group, defect, and non-invertible structures are included only when activated by an admitted target probe or attachment condition. A central result is target-relative interface completeness. An independently defined target-facing trace and saturated semantic evaluator structure show that every target-admitted physical use is determined by a finite collection of trace factors. The resulting carrier-neutral profile recovers the target-facing trace, and equality of complete interface packets is equivalent to indistinguishability under every semantic evaluator admitted by the target. The construction further proves that simultaneous physical realizability, active constraints, and lawful equivalence descend correctly to the admissible quotient. Interface adequacy is therefore characterized without selecting a microscopic occupant. The conclusion is deliberately bounded. The paper establishes completeness of the physical interface relative to the declared neutrino target and comparison class. It does not establish full-theory identity, role-occupancy uniqueness, particle identity, a particular mass mechanism, or a unique neutrino carrier. Those questions remain downstream realization problems.