Phantom churn after identity resets
Merged accounts without a bridge table invent attrition that never reached the service desk.
Entity IDs that reset on migration create week-over-week cliffs that look like mass departure. The floor never lost those accounts—the warehouse simply forgot the bridge.
Reporting Cohort Rebuild treats late arrivals and soft deletes as rules, not exceptions. One lane at a time keeps the validation checklist honest.
If your weekly pack cannot survive a systems rename without rewriting history, start with identity before you start with colour palettes.