Extract the profession↔diploma table out of DiplomaRules into a dedicated Stamdata.Professions module (business-editable data, separated from the rules that consume it) and add StamdataValidationTests as the build-time gate: every seeded diploma program must resolve to a real profession, no blank entries. A bad edit now fails the build instead of silently rendering "Onbekend". Rules and behaviour unchanged. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>