Anthropic's Unreleased Claude Fable 5.5 Spotted Generating 66-Second Animation Through Code

Early tests of Anthropic's unreleased Claude Fable 5.5 model show it can autonomously write code for nearly three hours to produce a complete 66-second animated short film with visuals and audio entirely from scratch. This demonstrates a major shift toward long-horizon autonomous code generation and complex multimedia asset creation, moving beyond traditional diffusion models to algorithmic rendering. The model operated for roughly 2 hours and 40 minutes without external image, video, or audio libraries, ultimately packaging the animation and procedural sound effects into a single HTML file.