I highly recommend pi.dev for doing anything creative with agents and harnesses. It separates the harness from the model, so you need to BYOM keys and subscriptions.

You can build your own harness quite easily or use a harness something like pi.dev which offers a lot of flexibility in customization in terms of tools, models ised, resume sessions at a prior point in time, etc.

I have used pi.dev to easily start from a known context and goal and use it to compare the cost effectiveness, token isage, etc. of different models to reach the goal state.

I am sure there are many ways to do this successfully.