Cross-cutting authored writing. Consumed by both sides: the client ships fallback text and quest/story data; the api reads NPC knowledge lists to build prompts. That shared ownership is why it sits at the repo root, not inside either folder.

/quests    Story skeletons and quest definitions (authored, not AI-generated — §17)
/npcs      Per-NPC knowledge lists — the entire content an NPC can draw on (§6)
/fallback  Authored degraded-DM text for every AI surface (§13)

Authoring notes

NPC knowledge lists are the whole design (§6). They are the only thing stopping the blacksmith from revealing the twist. Real authoring work — budget for it.
Fallback text is content, not error handling (§13). Written in the DM's voice, lives beside the rest of the writing. Every AI-dependent surface needs one before it ships.
Story skeletons are authored for now. AI-generated skeletons are v2, out of POC scope (§17).