Hy4 Preview is a flagship mixture-of-experts language model designed for advanced reasoning and agentic workloads, drawing on the broader Hy family lineage from Tencent. Its architecture pairs a 78-layer backbone with 256 routed experts and a shared expert per MoE layer, activating roughly 49B parameters per token through Top-8 routing, while a dedicated multi-token prediction layer supports speculative decoding for faster inference. The model is offered with open weights, making it accessible for self-hosted deployments and research customization rather than locking users into a closed API ecosystem.
In benchmark evaluations, Hy4 Preview demonstrates elite-tier performance across professional knowledge work, scientific reasoning, and agentic coding. It posts a near-perfect score on GPQA Diamond and a strong Elo rating on GDPval-AA, reflecting mastery of graduate-level questions and economically valuable agent tasks. On Terminal-Bench 2.1 it also performs competitively, underscoring practical competence for autonomous tool use and real-world software workflows. With a very large context window and the ability to handle long conversations gracefully, Hy4 Preview is well suited for enterprise assistants, research agents, and developers seeking an open-weight alternative to closed frontier models.