Thanks Jeremy, first star appreciated! On your question: my line so far has been that anything a client can't distinguish in a test suite belongs in the mock (state machines, pagination, signature schemes), but the semantics stay provider-native.

A Stripe refund and an Adyen reversal aren't the same object, and abstracting them is how payment integrations get burned IMHO. The one place I'd promote to a shared contract is cross-cutting shape: cursor pagination, idempotency keys, webhook signature verification, retry-after semantics. Vyral's evidence-qualified adapters sound like the other half of that — offline simulation vs live qualification if I am getting it right. If I were you I'd add a demo or something to Vyral's README, make it shorter, like progressive disclosure with all the nice details on the website (link it so agents can find it). Show the money shot, if that makes sense.

I am going to look into Vyral in more depth because I am intrigued. I'll reach out if anything comes to my mind. If you have any ideas about how a collaboration could look like, feel free to hit me up! I mean, we are already collaborating in a way :)

Thanks again for this, I appreciate it.