Anthropic Changed What Fable 5 Answers Without Changing Its Version Number
On August 7, 2026, Anthropic retrained the classifier sitting in front of Claude Fable 5 and biology-topic fallbacks to Opus 5 dropped about 85%, but only about 7% on the API. No version bump, no pricing change, no config change on your side. Here is why your cost dashboard will not catch it and how to log which model actually answered.
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