Simon Willison built a GeoJSON map viewer with PNG export using GPT-5.6-Sol, Claude Code for web, and Fable 5.1.
Simon Willison describes building a GeoJSON map viewer that displays boundary files and exports maps as PNGs. GPT-5.6-Sol proactively offered to create the tool, and iterations used Claude Code for web and Fable 5.1. He also notes ChatGPT Work will assemble boundary polygons from government data sources when asked.
Simon Willison used ChatGPT Work with GPT-6 Astra to generate 5K/10K running loops from OpenStreetMap data, noting the agent's executed code was not visible.
Simon Willison prompted ChatGPT Work running GPT-6 Astra (Max) to design looping 5K and 10K running routes from his address using OpenStreetMap data. The agent ran for 27 minutes and delivered an embedded visualization plus downloadable GPX and GeoJSON files, stating it used Nominatim for geocoding and Overpass to fetch local OSM roads and trails. He notes frustration that the actual executed code and exact actions were not visible in the ChatGPT UI, highlighting a transparency gap in agentic AI products.