Meta Regions

Region codes accepted by the regions= query param, which books in each one are actually writing prices, and the exact book set regions= narrows /odds to.

active_books is the coverage answer: a book is active in a region only if the region declares it, it is neither suppressed nor retired, it is in the registry /v1/bookmakers publishes, and it has written rows in the last 24 hours. books / odds_filter_books remain the /odds filter, which is a different and larger set.

Public, no auth, no credits. Pair with /v1/meta/markets (canonical market keys), /v1/meta/parser-coverage (live per-book per-sport coverage matrix), and /v1/meta/per-book-sla (freshness thresholds).