The group's derived current-window usage per (window, pool) enforcement bucket vs its caps: the self-service dashboard read (spend derives from the token ledger x the CURRENT rate card at read time)

GET /groups/{name}/usage: one group's DERIVED current-window usage, one row per enforcement bucket (each (window, pool?) its limits materialise), against that bucket's caps. The dashboard read: spend/tokens/requests per tier vs the budgets, straight off the ledger x the CURRENT rate card (reprice-on-read, nothing stored). The customer's self-service tool consumes this per group (user:<sub> leaf = one person's view) and re-scopes it.