OpenCode Zen
DeepSeek-V4.1-Flash was released on September 10, 2026, and the Coursiv blog lays out the architectural changes versus V4 Flash: backbone parameters grew from 284B to 552B, active parameters per token fell from 13B to 8B for reading input and 16B for generating output, the architecture shifted from a Mixture-of-Experts The post also reports Terminal-Bench 2.1 rising from 82.7 to 90.6, Terminal-Bench 4.0 from 7.0 to 31.2, and DeepSWE v1.1 from 54.4 to 74.2 versus V4 Flash. From 12:00 Beijing time on September 14, 2026 (04:00 UTC), every request to `deepseek-v4-pro` is routed to V4.1 Flash and billed at Flash rates, a cut of roughly 77
