diff --git a/Sources/Core/Auth/AppConfig.swift b/Sources/Core/Auth/AppConfig.swift
index d07e8ab..dca6f6f 100644
--- a/Sources/Core/Auth/AppConfig.swift
+++ b/Sources/Core/Auth/AppConfig.swift
@@ -8,7 +8,9 @@ enum AppConfig {
     static let manaAppConfig: ManaAppConfig = DefaultManaAppConfig(
         authBaseURL: URL(string: "https://auth.mana.how")!,
         keychainService: "ev.mana.cardecky",
-        keychainAccessGroup: nil
+        // Explizit auf TeamID.BundleID, statt nil. Vermeidet Logout
+        // bei TestFlight-Cert-Drift (siehe mana-swift-core v1.5.1).
+        keychainAccessGroup: "QP3GLU8PH3.ev.mana.cardecky"
     )
 
     static let apiBaseURL = URL(string: "https://cardecky-api.mana.how")!