Building a multiplayer game world with autonomous Fable-class models

This piece by Jacob Sansbury describes Spawn, a massively multiplayer gaming environment where players prompt an in-game agent, Savi, to modify the game world, and which is now developed autonomously by a swarm of Fable-powered agents costing over $3 million in tokens per month. Agents change live code directly and ship to production hourly, with about 60% of work starting from production errors, Savi bug reports, log anomalies or feature requests, and an hour without a ship treated as a SEV-0 incident. Sansbury says Fable 5 (and then 5.1) made this level of autonomy possible, while a GPT-6 Astra attempt to apply security-review fixes disabled every feature instead.