Hy4 preview

Tencent Hunyuan's fourth-generation flagship, released and open-sourced under Apache-2.0 on Aug 28 2026 (weights and an FP8 variant on Hugging Face as tencent/Hy4-preview). A Mixture-of-Experts model with 770B total parameters and ~49B activated per token: a 78-layer backbone with 256 routed experts plus a shared expert in most layers (8 routed experts selected per token) and a native multi-token-prediction layer for speculative decoding. Carries a 1M-token (1,048,576) context and is aimed at long-horizon software engineering (planning, debugging, verification across extended tasks with tool calling), office and financial analysis, cross-document work, game-development prototyping, and scientific workloads. Available via Tencent Cloud TokenHub and OpenRouter (model id tencent/hy4-preview, tool calling + structured outputs) or self-hosted on vLLM/SGLang; OpenRouter listed launch pricing of $0.834 input / $2.501 output / $0.042 cache-read per 1M tokens (Aug 28 snapshot). In Tencent's internal blind test (163 experts over 203 engineering tasks) Hy4 averaged 2.99 vs 2.92 for GLM-5.3 and 2.94 for Kimi K3 — narrow margins, and Tencent flags preview-stage tendencies to over-reason and over-verify. All figures vendor-reported and unverified by independent labs at launch.