Dry-run a routing decision

Answer "what would this operation route to right now" without spending a model call. The question runs through the same resolver that serves live traffic, so the answer is evidence rather than a forecast: the ordered candidate chain that would serve the operation, and every candidate the policy discarded with the constraint that discarded it.

When the policy permits no route, the response is still 201 with routable: false and a plain-language explanation. A policy that permits no route is a valid configuration whose consequence is that the live call fails closed rather than reaching a provider the policy forbids.

model pins a specific logical model instead of letting the operation's class choose; class pins a specific model class. Both are optional.