get_diagnostics could report an Error for a NodeType whose own compilation status was Ok, and keep reporting it: on one portal the same 403,625-byte payload came back byte-identical nine minutes apart.

The workspace cache treated a NodeType's source versions as the whole identity of its compilation. But the reference set moves independently of the sources — a module arriving or changing alters what the code compiles against without touching a single source file. When that happened, the cached workspace stayed pinned to the old references and answered from them indefinitely, because nothing else could evict it.

The cache now keys on everything a workspace is built from: the reference set and its order, the skeleton, the global usings and the assembly name, alongside the source versions it already tracked. Unchanged inputs still reuse the workspace, so editing stays as fast as before.

The direction that mattered most is the quiet one: the same staleness could answer clean for a type that had since broken, and this tool is the one the pre-deploy sweep relies on.