Willison built two throwaway tools in one afternoon with two different frontier models, and named which built what
Simon Willison's Weblog·medium signal
He had GPT-6 Astra (medium) in ChatGPT Work write an animated D3 transition between Mercator and Equal Earth projections, then had Claude Fable 5.1 in Claude Code for web build a browser video compressor on the WebAssembly build of FFMPEG to publish a demo of the first one. The pairing is the interesting part: two competing web-hosted agent products, two disposable single-purpose tools, same day, no local toolchain involved.