Status: OUT
MVCC's three-layer visibility model (append-only versions, own-writes visibility, symmetric deletion) with active sets frozen at transaction begin would provide correct snapshot isolation across process restarts if all state were persisted, since the visibility rules themselves are sound and compose correctly.
The visibility model is correct in all observable respects within a session; only the total absence of persistence prevents the isolation guarantees from surviving a restart.
Depends on (SL): mvcc-three-layer-visibility-model, mvcc-active-set-frozen-at-begin
Unless: mvcc-no-persistence