- getReadyChaptersForSlug(slug, preferredVoice) in pocketbase.ts: per-slug done jobs map, cached 60s, prefers user's voice
- GET /api/audio/chapters?slug=&voice= endpoint
- Chapter list (/books/[slug]/chapters): amber headphones icon on ready rows, play button for instant listen, banner showing ready count
- Chapter reader: audioReady + availableVoice from server load; 'Audio ready — Listen now' banner shown when audio exists and player is not yet active; sets voice preference before expanding player
