Status: IN
Derived systems (secondary indexes, materialized views, projections) can maintain consistency with their source through position-tracked CDC replay: every derived system tracks how far through the CDC log it has processed, and any derived system can be rebuilt from scratch via full event replay producing identical state to incremental processing.
Rebuild-from-replay equivalence plus position tracking enables consistent derived state, gated on the CDC consumer position being volatile (in-memory only, lost on restart)
Depends on (SL): derived-systems-rebuildable-from-cdc, derived-systems-are-position-tracked