I'm working on fyai, a rather opinionated agent harness, built to work as a unix tool and the idea that eventually AI is going to be a commodity, where having control of your own data is what's important.
It is still quite alpha, but at a usable state.
The biggest technical difference between fyai and other harnesses is that in fyai the state is durable and stored in a disk deduplicated arena, which means that git like branching is free and storage requirements are very modest compared to JSONL/SQLite storage.
Latest additions has been full markdown/mermaid rendering support and (very alpha) Claude code and Codex session import.