What architecture would close the coverage gap to the 73-93% sitting outside Tier 2?

A subsidiary question under Q-0002. Q-0029 named what Tier 2 covers; Q-0030 named how Tier 2 fails; Q-0031 names what architecture extends preservation beyond Tier 2's reach.

The answer is C-0029. Closing the gap requires an architecture that operates below and across domain-specific governance: a protocol-level, domain-agnostic substrate on which the same resilience properties apply to genomic sequences, sociology datasets, climate observations, and educational interventions, because the resilience lives in the protocol rather than in the community that happens to maintain a particular instance of it.

The economic constraint that produces the current coverage gap is not technical. Tier 2 participation is priced for well-funded disciplinary consortia — thousands to tens of thousands of dollars per year, with dedicated staffing and infrastructure expectations. Tier 3 participation scales down to existing institutional infrastructure at effectively zero marginal cost (C-0006). The economics make universal coverage architecturally possible at Tier 3 in a way Tier 2 has never been able to deliver.

This is the central architectural argument for moving Tier 3 from "aspirational" to "operating standard." It is the only architecture that can extend the resilience properties of the best-coordinated existing systems to the long tail of research output that produces most of the literature and most of the data.