diff --git a/CLAUDE.md b/CLAUDE.md
index 5c501df..512eac1 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -26,7 +26,7 @@ Technology stack not yet documented. Will populate after codebase mapping or fir
 <!-- GSD:conventions-start source:CONVENTIONS.md -->
 ## Conventions
 
-Conventions not yet established. Will populate as patterns emerge during development.
+- Immer deutsche Umlaute (ä, ö, ü, Ä, Ö, Ü, ß) in UI-Texten verwenden, niemals ae/oe/ue Transliterierung.
 <!-- GSD:conventions-end -->
 
 <!-- GSD:architecture-start source:ARCHITECTURE.md -->