Abyssal Convergence Architecture (ACA): Passive Autonomous Deep-Sea Data Acquisition via Depth-Gated Buoyancy Reconfiguration and Physical Data Engraving

A passive deep-sea architecture where hydrostatic pressure triggers autonomous recovery and simultaneously engraves environmental exposure into witness materials. ACA couples depth-gated buoyancy reconfiguration with Physical Data Engraving (PDE), shifting the trust anchor from fragile runtime electronics to post-retrieval physical evidence. Post-retrieval metrology (e.g., XRD and nanoindentation) reconstructs datasets from microstructural signatures. The manuscript provides a category-based related-work positioning, a minimal inverse-problem formalization, a failure-mode taxonomy, and a reproducible validation plan (bench → pressure chamber → field trial → abyssal readiness).