Code World Model: Building World Models for Computation – Jacob Kahn, FAIR Meta
Dec 17, 2025 · 16:41
Jacob Kahn, a research scientist at FAIR Meta, presents the Code World Model (CWM), a 32 billion parameter dense transformer that models program execution rather than just syntax. CWM predicts execution traces line by line, enabling neural debugging and approximation of the halting problem. Trained on GitHub data and refined with synchronous RL and long-context mid-training, CWM uses bash-oriented tool use and achieves strong throughput through asynchronous model updates. The model is open-source on Hugging Face, with code and a technical report available, and aims to build foundations for reasoning and planning in AI-driven software systems.
