Recipe: use diagnostics to spot semantic loss

Treat diagnostics as part of the result, not as an afterthought. They explain where a route preserved structure, widened a value, or skipped a construct.

A three-pass review

First check errors: an error means the output needs repair before use. Then scan warnings for intentional loss, such as unsupported annotations or a target format with fewer constraints. Finally, read informational notes for assumptions worth carrying into a code review.

Compare with the IR

When the output looks surprising, compare it with Shape IR. This separates a parsing problem from a generator limitation and gives you a concrete place to improve the route.