github.com/charmracelet/crush
The company that had that acrimonious split from OpenCode. Still, fully written in Go and compared to node-based harnesses, uses 1/5th the RAM. (At least for me.)
Works with any provider (including OpenRouter free ones).
No conflict of interest here, just a happy "customer" of this excellent resource.
it's a 404
https://github.com/charmbracelet/crush (Haven't used it, but also hit the 404 and wanted to see it)