How to implement automation of the feature implemented by openspec?

[guru1306]

Hi All

I implemented a feature using OpenSpec and the flow worked well. Now I need
end-to-end automation for it, and I'm not sure where it belongs. Automation code needs to be independent flow, which requires it to bring all the required environment and test the flows required for the feature.

I'm considering a custom schema for it, but before I build one:

1. What have others done here — a custom schema, an extra artifact, ?
2. Is the intent that test strategy lives in design.md, or that teams add their own
   artifact? The default spec-driven schema says only "specs should be testable."

Thanks