Anthropic's Fable 5.1 shipped September 1 with the same $10/$50 sticker as GPT-6 Astra but a 75% cache-read cut and flat pricing across the full 1M window. That changes which agent loops become viable: persistent brand-context documents can stay open across hundreds of turns. Four jobs to give it, two to keep on Opus 5, and three API breaking changes marketers need to patch this week.
GPT-6 "Astra" landed September 3 at $10/$50 per 1M tokens with 1.05M context and 0% out-of-scope safety hits. The headline is Computer Use — a model that clicks through HubSpot, builds spreadsheets, and pulls competitor PDFs into structured tables. Five jobs worth routing to it, three to keep on Sol or Opus 5, and the routing principle that fits both.
