I rebuilt my open-source AI coding agent that routes each pipeline stage to a different LLM

The pattern in AI coding tools has been bugging me for a while. You sign up for one of them. You agree to a per-seat subscription. You get exactly one model: the one the vendor picked for you. Underneath, the whole thing is glued to that vendor’s SDK, so even if you wanted to swap models, you couldn’t without forking. Then the next month, a better model ships from a different vendor, and you’re stuck. That way of building locks users out of one of the most valuable properties of LLMs: They are s