China's GLM-5.1 Works Autonomously for 8 Hours

Chinese AI startup Z.ai has released GLM-5.1, a 754-billion parameter open source model under a permissive MIT License, available on Hugging Face for commercial use. The model outperforms Claude Opus 4.6 and GPT-5.4 on SWE-Bench Pro benchmarks. Unlike competitors focused on reasoning tokens, GLM-5.1 is engineered for extended autonomous operation, capable of working up to eight hours on a single task across thousands of tool calls. The release signals a strategic shift toward agentic AI engineering.