Public read of the LLM-picked highlight reel for an article. No auth — the clip URL is meant for social-share embeds (Twitter audio cards, Reddit native players, etc.) where adding listener auth would defeat the share funnel.

Returns 404 when the article hasn't been clipped yet (worker hasn't run, listen_seconds too short, daily Haiku cap exhausted, etc.). Clients should treat the 404 as "no highlight available" not as a broken article.