I agree with you

don't think the "agent" abstraction is stable enough to standardize the behavior/runtime layer yet.

thing I'm trying to test is smaller: is that possible to standardize the outer contract around agents?

what inputs does it accept? what outputs does it promise? what model does it use? what prompt/template does it depend on? what tools can it call? what target should it be built or applied to?

so here it is intentionally not trying to describe the full control loop or become a runtime. it's more like a source-of-truth layer for the parts that are already showing up everywhere, even if the runtime patterns keep changing underneath.

I might be wrong, but my bet is that the runtime layer will keep changing, while the need for reviewable/diffable agent contracts will not.