The window decided whether a record type could be added
(GetConstructor(Type.EmptyTypes)), made it with Activator.CreateInstance,
and matched records to a type with IsAssignableFrom twice, duplicating
RecordCandidates.
Add and Create now ask the model's CreateElement, and its notice is the
refusal. The record list and the per-type counts come from
RecordCandidates. The window only renders.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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