In reading order.
KC Star V9 fuses V8's intelligent recalculation with V6's permission-aware calculations - and folds the employee and their permissions into the very hash that decides what to recompute. Kicking off the series where two engines meet in one version, and complexity meets its reckoning.
Fusing per-employee permissions with per-change recalculation multiplies work by headcount. KC Star V9 ships both the naive per-employee implementation and an optimised per-permission-group one that collapses a thousand employees into seven groups. The most important design call in the version.
KC Star V9 checks permissions on every calculation, and checking is expensive. So it caches the yes/no answers in a PermissionCache table with a one-hour TTL and an upsert on every miss. Here is how it works, the claimed 95 percent hit rate, and the real cost of caching authorization.
When KC Star V9 denies a measure, it returns NULL, not zero - and the difference matters enormously once those values flow into aggregates. Here is the semantics of denial, the PermissionContext that records it, and why a redacted zero would quietly corrupt every total downstream.
