Tencent Hy4 Preview: 770B Open Weights Aimed Straight at Agents
Tencent just open-sourced Hy4 Preview, and the headline numbers are hard to ignore: 770B total parameters, 49B active, a context window past 1M tokens, Apache 2.0 license. It scored 85.4 on Terminal Bench 2.1, above DeepSeek V4 Pro, and jumped from 28.0 to 64.3 on DeepSWE. Weights are on Hugging Face day one, FP8 variant included, with vLLM and SGLang recipes ready.
The most interesting claim isn't a benchmark. Tencent says Hy4 coordinated several Codex sessions in parallel, evaluated their results, and merged the work. That's not a chatbot pitch, that's an orchestrator pitch. Chinese labs have stopped selling open models on MMLU and started selling them on whether they can run a fleet of coding agents, which tells you where everyone thinks the actual market is.
Zoom out and this is the third major Chinese open-weights drop in three days: Qwen3.8-Flash-Next on the 27th, GLM-5.3 weights on the 28th, now Hy4. The API is priced at $0.834 per million input tokens and $2.501 output, and it's free for two weeks inside WorkBuddy and CodeBuddy. The frontier labs charge more every quarter while the open tier gets a new flagship every 24 hours. That gap is the story of this month.
Weights: https://huggingface.co/tencent/Hy4-preview
Repo: https://github.com/Tencent-Hunyuan/Hy4-preview
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The most interesting claim isn't a benchmark. Tencent says Hy4 coordinated several Codex sessions in parallel, evaluated their results, and merged the work. That's not a chatbot pitch, that's an orchestrator pitch. Chinese labs have stopped selling open models on MMLU and started selling them on whether they can run a fleet of coding agents, which tells you where everyone thinks the actual market is.
Zoom out and this is the third major Chinese open-weights drop in three days: Qwen3.8-Flash-Next on the 27th, GLM-5.3 weights on the 28th, now Hy4. The API is priced at $0.834 per million input tokens and $2.501 output, and it's free for two weeks inside WorkBuddy and CodeBuddy. The frontier labs charge more every quarter while the open tier gets a new flagship every 24 hours. That gap is the story of this month.
Weights: https://huggingface.co/tencent/Hy4-preview
Repo: https://github.com/Tencent-Hunyuan/Hy4-preview
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