OMP Domain Profile: AI Governance and Accountability Evidence for US Housing Finance Under FHFA Bulletin 2025-16 and GSE AI/ML Model Risk Governance

This document defines a domain profile of the Operating Model Protocol (OMP) for AI and machine learning (ML) systems deployed in US housing finance contexts subject to the Federal Housing Finance Agency (FHFA) Bulletin 2025-16 (effective March 3, 2026), which establishes a comprehensive AI governance framework for Fannie Mae, Freddie Mac, and the Federal Home Loan Banks (the GSEs), requiring transparency, accountability, and ethical stewardship for AI/ML systems used in housing finance decisions. The profile -- designated HomeMark -- specifies how OMP's deterministic routing invariant, Watchtower enforcement framework, and three-layer cryptographic integrity architecture satisfy the AI governance evidence requirements of FHFA Bulletin 2025-16, including per-decision accountability, named individual responsibility, model risk governance documentation, fair lending evidence, and representation and warranty compliance for mortgage origination, credit decisioning, property valuation, and loan servicing. The OMP core specification is defined in the Operating Model Protocol Internet-Draft (draft-veridom-omp).