I think what's throwing me off is that the examples aren't just transparent things like debug/tracing. They mention credentials and user ids, which the app cod

I think what's throwing me off is that the examples aren't just transparent things like debug/tracing. They mention credentials and user ids, which the app code can observe and rely on. The combination of out-of-band/out-of-schema data with APIs to set and get from app code seems like a bad match. I'd prefer if it was completely invisible to app code and existed only in interceptors.