I'm leaning in this direction. Recently slopforked pi to python and created a version that's basically a loop, an LLM call to openrouter and a hook system using pluggy. I have been able to one-shot pretty much any feature a coding agent has. Still toy project but this thread seems to be leading me towards mantaining my own harness. I have a feeling it will be just documenting features in other systems and maintaining evals/tests.