HN thread reports some Claude Fable 5 requests answered by Opus 5

Sources: HN thread
Summary: An HN thread reports that some requests sent to Claude Fable 5 are answered by Claude Opus 5 instead, and describes the routing as a safeguards measure. This run resolved no Anthropic page stating that routing, and Anthropic's system prompt release notes carry a model index with collapsed dated entries and neither that statement nor the word safeguards. The claim rests on the thread alone and is uncorroborated.
Why it matters: If a request can be served by a model other than the one named, benchmarking, cost accounting, and output comparison rest on an assumption the caller cannot check.
Follow-up: Track whether Anthropic documents the routing in a citable page location.