Feature-Flag Rollout Bucketing Simulator (2D)

Every mobile app that ships a "rolled out to 25% of users" remote-config flag is running the same small algorithm: hash each device's stable user ID together with the flag's salt into a bucket from 0–99, then flip the flag on if that bucket falls under the target percentage. This simulator renders a population of users as a live 2D grid you can pan and zoom, and lets you drag the rollout percentage while toggling between that real sticky, consistent-hash bucketing and a naive per-user coin flip re-rolled on every change. With sticky bucketing on, raising the percentage only ever turns more users on — the "consistency violations" counter proves it stays at zero. Switch it off and watch users flicker in and out even as the percentage rises, the exact bug class a hash-based rollout is built to avoid.