Most likely they built this as a post-train of an open model that is already strong on coding like Qwen 2.5.
for coding you use anthropic or google models, I haven't found anyone who swears by openAI models for coding... Their reasoning models are either too expensive or hallucinate massively to the point of being useless... I would assume the gpt 4.1 family will be popular for SWE's
Having a smaller scope model (agentic coding only) allows for much cheaper inference and windsurf building its own moat (so far agentic IDE's haven't had a moat)
This suggests OpenAI models do have tasks they're better at than the "less rounded" competition, who have taks they're weaker in. Could you name a single sucg task (except for image generation, which is an entirely different usecase), that OpenAI models are better at than Gemini 2.5 and Claude 3.7 without costing at least 5x as much?
It is very puzzling why "wrapper" companies don't (and religiously say they won't ever) do something on this front. The only barrier is talents.
That being said I am sure a lot of the so called wrapper companies are paying insanely well too, but competing with FAANGMULA might be trickier for them.
OAI is trying frantically to build a moat without doing any digging.