I've been using DeepSeek V4 a lot in the last week and I am very happy with it. If you have a really gnarly bug, you might need a SOTA model like Opus. For most things it is very very good, and costs significantly less (even without the discount).

I've been using it as part of a complex DOS game decompilation project[0]. I'm working on refactoring the software rendering pipeline so that we can add GPU rendering. The hardest part of this so far is converting the 90's polygon rendering from screen to world space.

It spun its wheels a few times doing a large mostly mechanical change. After resetting and improving my prompts it was able to get through it. I'm using Matt Pocock's skills[1] for this work, which has been quite nice.

[0]: https://github.com/FatalDecomp/ROLLER

[1]: https://github.com/mattpocock/skills

What agentic harness do you use deepseek with?