A single prompt requesting a 3D Berlin built with pure WebGL2 without libraries was given to Fable 5.1, and it was published as a live service 4 hours later

Fable 5.1 autonomously generated and deployed a WebGL2-based 3D map of Berlin in 4 hours and 8 minutes under strict constraints such as a ban on external libraries.

Autonomous Coding and Verification Capabilities

The model wrote 7,895 lines of code and shaders, and implemented a physics engine, audio synthesis, an OpenStreetMap XML parser, and triangulation on its own. Notably, without browser MCP, it utilized Node.js WebSocket to directly write a headless Chromium harness, and analyzed 30 screenshots to autonomously discover and fix Z-fighting bugs and lighting issues.

Resource Usage and Cost

A total of 137 API calls and 34.6 million tokens were used, of which 33.8 million tokens were cache reads. The main session cost was $27.49. Two sub-agents were utilized in parallel for the data pipeline and audio generation, and a pipeline agent that was interrupted midway due to limits resumed from the point of interruption and completed the task.