Descriptions:
Tencent’s Hunyuan AI team has released Hy4 Preview, a 770-billion-parameter mixture-of-experts model with 49 billion active parameters per token, a context window exceeding one million tokens, and a specific design focus on coding agents and long multi-step productivity tasks. On benchmarks including TerminalBench 2.1, DeepSweep, and Sweep-at-Less-Refactoring, Hy4 claims top open-source positions ahead of GLM 5.3, Kimi K3, and DeepSeek V4 Pro—and trades leads with Claude Opus 5 depending on task type.
Fahd Mirza tests the model against a fully Dockerized real-world application: Atlas of Enough, a global retirement calculator built on Flask, PostgreSQL, and a rich frontend running across 20 countries, where the calculation output was off by a factor of 100. Without any hint about the nature of the bug, Hy4—accessed through a Hermes agent setup—autonomously identifies and fixes the root cause. The demo is slowed by heavy API throttling (the model is free for its first two weeks, causing widespread demand spikes), but the core agentic loop functions correctly.
The video also covers two architectural innovations distinguishing Hy4 from standard transformer designs: Identity Hyper Connections (IHC), which maintains multiple parallel memory lanes so early-layer information reaches late layers without stepwise dilution, and Gated DSA, which enables selective attention over million-token contexts by learning which portions of the text are relevant to the current pass—making long-context reasoning dramatically more efficient than naive full-attention approaches.
📺 Source: Fahd Mirza · Published August 28, 2026
🏷️ Format: Hands On Build
