diff --git a/backend/src/test/java/org/raddatz/familienarchiv/shared/ArchitectureTest.java b/backend/src/test/java/org/raddatz/familienarchiv/shared/ArchitectureTest.java
index 61804b01..9ec21149 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/shared/ArchitectureTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/shared/ArchitectureTest.java
@@ -118,11 +118,15 @@ class ArchitectureTest {
     // Tracked in: http://heim-nas:3005/marcel/familienarchiv/issues/427
 
     private static DescribedPredicate<JavaClass> foreignJpaRepositoryFor(String ownDomain) {
+        // Exact-segment match: prevents a domain name that is a substring of another
+        // (e.g. "tag" inside "tagging") from silently escaping the predicate.
+        // The pattern matches the domain as a complete path segment, with an optional sub-package.
+        String ownPackagePattern = ".*\\.familienarchiv\\." + ownDomain + "(\\..+)?$";
         return new DescribedPredicate<JavaClass>("be a JPA repository from a domain other than " + ownDomain) {
             @Override
             public boolean test(JavaClass clazz) {
                 return clazz.isAssignableTo(JpaRepository.class)
-                       && !clazz.getPackageName().contains("." + ownDomain);
+                       && !clazz.getPackageName().matches(ownPackagePattern);
             }
         };
     }