How does the percentage rollout decide who gets a feature? Can't tell why a user is ON/OFF

### Is your feature request related to a problem? I set a flag's rollout to 25% but I have no idea **which users** that includes or **how** it's decided. When I test different user IDs in the demo, the same user always seems to get the same answer — which is neat, but I don't understand *why*, and there's nothing in the UI that explains it. ### What I expected Some visual way to understand how a percentage rollout maps to actual users, and a way to check **why a specific user is ON or OFF** for a flag. ### Suggestion - A visual (e.g. a grid of users) where I drag the percentage and see exactly who flips on/off — and that it's *stable* for each user. - A "why is this user ON/OFF?" explainer that shows the steps (is it enabled? are they targeted? are they in the rollout bucket?). That would make the whole "deterministic rollout" idea click for a beginner.