Tencent open-sources Hy4 preview: 770B / 49B-active MoE with Gated DSA + iHC, 1M context, Apache 2.0

Tencent's Hy team open-sourced Hy4 preview and an FP8 variant on Hugging Face, ModelScope, GitCode and CNB on Aug 27-28, 2026. It is a 770B-total / 49B-active MoE (78 layers, 1 dense + 77 MoE with 256 routed + 1 shared expert, top-8 routed), with a native MTP layer (10B/0.7B-active) for speculative decoding, Gated DeepSeek Sparse Attention with IndexCache cross-layer sparse index reuse, and identity Hyper-Connections (iHC) on the residual pathway. Native context is 1M tokens, vocabulary 120,832, and weights are released under Apache 2.0. Tencent's internal blind eval (163 experts, 203 engineering tasks) puts Hy4 preview slightly ahead of GLM-5.3 (2.99 vs 2.92; 46.8% wins / 12.8% ties / 40.4% losses) and Kimi K3 (2.99 vs 2.94; 51.2% wins / 7.9% ties / 40.9% losses).