Tencent Hy4 preview: 770B Parameters, 49B Active, 1M-Token Context — The Complete Guide (2026)
Tencent's Hunyuan Hy4 preview is the open-source flagship the summer was building toward: 770B total / 49B active, native 1M-token context, Apache 2.0 weights in BF16 and FP8, Gated DSA + IndexCache attention, built-in MTP speculative decoding, day-zero vLLM/SGLang support, and $0.834-per-million-token pricing — with every benchmark still vendor-reported.