Prospect pool stages are the smaller buckets inside a prospect pool that recruiters use to track where each passive prospect sits in their nurture process — for example Not Reviewed, In Discussion, or Keep Warm - Senior. Each stage belongs to a single prospect pool; a prospect's current_prospect_pool_stage_id points at the row they currently occupy. Stage names and counts are fully customer-defined per pool (there is no Greenhouse-managed default set), so the same name can appear in multiple pools but is unique within a pool. Scope the list with parent=prospect_pool plus ids to pull the stages for one or more specific pools.