I built a harness that externalizes state into files so you can swap providers. I regularly move between claude and gpt, but it works with all providers including pi and local models.

I log everything - user messages, tasks, project memory, even bash commands for forensics. As a consequence you can do reflection where you analyze past work and extract refinements for the harness and realign the project when it diverged from user intentions. I don't have to do this manually, it reduces steering work.

https://github.com/horiacristescu/playbook-harness