I would probably go that route if I could use other harnesses with claude models, but I don't want to be locked in to claude code, and their API pricing (which you need to use it with other harnesses) is so much higher than subscription.
The active project seems to use Claude code's agent API https://github.com/anthropics/claude-agent-sdk-typescript so yes you can issue commands to Claude code from opencode, but the harness in that case is still ultimately Claude code, with all the big fat system prompts that come with it.
Did you use some kind of plugin? I'd like to use opencode with my Claude subscription.