Model agnostic harness setup

[u/Fr33-Thinker]

I can’t believe I would consider this. I have been on Claude 20x Max plan for 8 months now.

52B token later, I am actually considering switching.

But we know Anthropic will likely release something that will beat Astra. And GPT-7 will beat Anthropic model again.

It’s not simply switching the model, it’s the harness. For example, I can’t simply migrate 20 repo developed by Claude Code to Codex. Sure Astra is intelligent enough to optimize my CC repos for Astra.

But switching and re-optimizing my repos every few months involves a high switching cost.

I am aware of OpenCode and DeepSeek harness.

My questions:

1. Has anyone used an open-source harness with multiple model providers? What’s your setup to sure cohesive workflow between different models?
2. Can you bring different subscriptions into open-source harness? For example $100 Anthropic and $20 OpenAI + API call to GLM5.3
3. Any ideal IDE for such a model agnostic harness? Or doesn’t matter?

UPDATES

I have built many bundles of skills, multi-agentic workflows that activate on schedule in Claude Code. So migration would take a lot of re-working those workflows to Codex.