have you considered implementing the addition of a leading canary sentinel that fires at the earliest/cheapest possible point instead of only on lag of some actual load-bearing constraint violation?

Do you mean catching errors as tokens stream back versus waiting for the full message? If so, then no I hadn't looked into that. This was mostly geared towards local models so token cost isn't really a big deal, though latency might be.

And if you didn't mean that then please elaborate :)