The model is already up on Opencode, but they require a consent to use Chinese datacenters.

Apparently `deepseek-v4-flash` automatically routes to the new model, if you are using the official provider:

   The official release of the DeepSeek-V4-Flash API is now in public beta. The API calling method remains unchanged — simply set the model name to deepseek-v4-flash to use the latest version.