You can't control it to the level of individual LLM requests and orchestration of those. And that is very valuable, practically required, to build a tool like this. Otherwise, you just have a wrapper over another big program and can barely do anything interesting/useful to make it actually work better.

This is what ACP and https://github.com/zed-industries/claude-code-acp enables. ACP controls agents - there is native support in Copilot CLI and Gemini and adapters for claude code and codex.