diff --git a/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/model/Device.kt b/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/model/Device.kt
index b10250c9..292e21ab 100644
--- a/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/model/Device.kt
+++ b/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/model/Device.kt
@@ -1,7 +1,7 @@
 package at.mocode.identity.domain.model
 
-import kotlinx.datetime.Instant
 import java.util.*
+import kotlin.time.Instant
 
 /**
  * Repräsentiert eine registrierte Desktop-Instanz ("Gerät").
@@ -13,7 +13,8 @@ data class Device(
   val securityKeyHash: String, // Gehasht für Sicherheit
   val role: DeviceRole = DeviceRole.CLIENT,
   val lastSyncAt: Instant? = null,
-  val createdAt: Instant
+  val createdAt: Instant,
+  val updatedAt: Instant = createdAt
 )
 
 enum class DeviceRole {
diff --git a/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/repository/DeviceRepository.kt b/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/repository/DeviceRepository.kt
index 024999cd..58964615 100644
--- a/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/repository/DeviceRepository.kt
+++ b/backend/services/identity/identity-domain/src/main/kotlin/at/mocode/identity/domain/repository/DeviceRepository.kt
@@ -1,8 +1,8 @@
 package at.mocode.identity.domain.repository
 
 import at.mocode.identity.domain.model.Device
-import kotlinx.datetime.Instant
 import java.util.*
+import kotlin.time.Instant
 
 interface DeviceRepository {
   suspend fun findById(id: UUID): Device?
diff --git a/backend/services/identity/identity-infrastructure/src/main/kotlin/at/mocode/identity/infrastructure/persistence/ExposedDeviceRepository.kt b/backend/services/identity/identity-infrastructure/src/main/kotlin/at/mocode/identity/infrastructure/persistence/ExposedDeviceRepository.kt
index d3692d33..57ef8bde 100644
--- a/backend/services/identity/identity-infrastructure/src/main/kotlin/at/mocode/identity/infrastructure/persistence/ExposedDeviceRepository.kt
+++ b/backend/services/identity/identity-infrastructure/src/main/kotlin/at/mocode/identity/infrastructure/persistence/ExposedDeviceRepository.kt
@@ -11,7 +11,6 @@ import org.jetbrains.exposed.v1.jdbc.update
 import java.util.*
 import kotlin.time.Clock
 import kotlin.time.Instant
-import kotlin.time.toJavaInstant
 
 class ExposedDeviceRepository : DeviceRepository {
 
@@ -36,8 +35,8 @@ class ExposedDeviceRepository : DeviceRepository {
         it[name] = device.name
         it[securityKeyHash] = device.securityKeyHash
         it[role] = device.role
-        it[lastSyncAt] = device.lastSyncAt?.toJavaInstant()
-        it[updatedAt] = now.toJavaInstant()
+        it[lastSyncAt] = device.lastSyncAt
+        it[updatedAt] = now
       }
     } else {
       DeviceTable.insert {
@@ -45,19 +44,18 @@ class ExposedDeviceRepository : DeviceRepository {
         it[name] = device.name
         it[securityKeyHash] = device.securityKeyHash
         it[role] = device.role
-        it[lastSyncAt] = device.lastSyncAt?.toJavaInstant()
-        it[createdAt] = now.toJavaInstant()
-        it[updatedAt] = now.toJavaInstant()
+        it[lastSyncAt] = device.lastSyncAt
+        it[createdAt] = device.createdAt
+        it[updatedAt] = now
       }
     }
-    device
+    device.copy(updatedAt = now)
   }
 
   override suspend fun updateLastSyncAt(id: UUID, at: Instant): Boolean = transaction {
-    val javaInstant = at.toJavaInstant()
     DeviceTable.update({ DeviceTable.id eq id }) {
-      it[lastSyncAt] = javaInstant
-      it[updatedAt] = javaInstant
+      it[lastSyncAt] = at
+      it[updatedAt] = at
     } > 0
   }
 
@@ -66,7 +64,8 @@ class ExposedDeviceRepository : DeviceRepository {
     name = row[DeviceTable.name],
     securityKeyHash = row[DeviceTable.securityKeyHash],
     role = row[DeviceTable.role],
-    lastSyncAt = row[DeviceTable.lastSyncAt]?.let { Instant.fromEpochMilliseconds(it.toEpochMilli()) },
-    createdAt = Instant.fromEpochMilliseconds(row[DeviceTable.createdAt].toEpochMilli())
+    lastSyncAt = row[DeviceTable.lastSyncAt],
+    createdAt = row[DeviceTable.createdAt],
+    updatedAt = row[DeviceTable.updatedAt]
   )
 }
diff --git a/frontend/features/turnier-feature/src/jvmMain/kotlin/at/mocode/turnier/feature/presentation/TurnierStammdatenTab.kt b/frontend/features/turnier-feature/src/jvmMain/kotlin/at/mocode/turnier/feature/presentation/TurnierStammdatenTab.kt
index b8421ef9..fe119c43 100644
--- a/frontend/features/turnier-feature/src/jvmMain/kotlin/at/mocode/turnier/feature/presentation/TurnierStammdatenTab.kt
+++ b/frontend/features/turnier-feature/src/jvmMain/kotlin/at/mocode/turnier/feature/presentation/TurnierStammdatenTab.kt
@@ -100,7 +100,10 @@ fun StammdatenTabContent(
           val katField = tClass.getDeclaredField("kategorie")
           katField.isAccessible = true
           val kats = katField.get(turnier) as? List<String>
-          kats?.let { kat.addAll(it) }
+          kats?.let {
+            kat.clear()
+            kat.addAll(it)
+          }
 
           val typField = tClass.getDeclaredField("typ")
           typField.isAccessible = true