Add an integrated correctness analysis to the step-down section, combining the existing transaction/cursor and write-conflict models with subsequent schema and role-transition changes. Cover snapshots, cutoff publication/clearing, straddler checks, mirrored and ingest-only writes, checkpoint/schema publication, reader rebinding, and handle/eviction lifecycles. Include happens-before diagrams and a compact case audit. Assess whether internal synchronization permits weakening external requirements, with Staff+ concurrency-expert review before publishing the model or changing the documented contract.