List Markets

List supported markets filter values across the API. Public, no auth, no credits. iter_062 #474.

The market_key vocabulary is large (60+ values) and grows over the season as books add new prop markets. This endpoint returns the current canonical set used by /odds, /props, /ev, /consensus, and /parlay/price.

sleep_iter_22 #521: emits ETag + supports If-None-Match.