Alleged Mythos Class Anthropic Checkpoint Leak

An alleged leak of an Anthropic Mythos-class checkpoint, internally codenamed numbat, has surfaced. This checkpoint, from a training run referenced in the Claude Code source leak (Mar 2026), is described as a ~14T parameter, 114-layer model utilizing hybrid GDN/MLA and MoE with 1,224 experts. The leak includes configuration files like configuration_numbat.py, a reference implementation modeling_numbat.py, a tokenizer.json, and 772 model.safetensors shards, along with checkpoint metadata and training logs.