refactor(security): extract requireUserId to SecurityUtils

Both DocumentController and TranscriptionBlockController contained
identical private requireUserId helpers. Extracted to a shared static
utility in the security package ahead of DashboardController which
also needs actor resolution.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/controller/DocumentController.java

@@ -28,6 +28,7 @@ import org.raddatz.familienarchiv.model.DocumentVersion;
 import org.raddatz.familienarchiv.model.AppUser;
 import org.raddatz.familienarchiv.security.Permission;
 import org.raddatz.familienarchiv.security.RequirePermission;
+import org.raddatz.familienarchiv.security.SecurityUtils;
 import org.raddatz.familienarchiv.service.DocumentService;
 import org.raddatz.familienarchiv.service.DocumentVersionService;
 import org.raddatz.familienarchiv.service.FileService;
@@ -286,13 +287,6 @@ public class DocumentController {
     }
 
     private UUID requireUserId(Authentication authentication) {
-        if (authentication == null || !authentication.isAuthenticated()) {
-            throw DomainException.unauthorized("Authentication required");
-        }
-        AppUser user = userService.findByEmail(authentication.getName());
-        if (user == null) {
-            throw DomainException.unauthorized("User not found");
-        }
-        return user.getId();
+        return SecurityUtils.requireUserId(authentication, userService);
     }
 }

backend/src/main/java/org/raddatz/familienarchiv/controller/TranscriptionBlockController.java

@@ -5,12 +5,11 @@ import lombok.extern.slf4j.Slf4j;
 import org.raddatz.familienarchiv.dto.CreateTranscriptionBlockDTO;
 import org.raddatz.familienarchiv.dto.ReorderTranscriptionBlocksDTO;
 import org.raddatz.familienarchiv.dto.UpdateTranscriptionBlockDTO;
-import org.raddatz.familienarchiv.exception.DomainException;
-import org.raddatz.familienarchiv.model.AppUser;
 import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.raddatz.familienarchiv.model.TranscriptionBlockVersion;
 import org.raddatz.familienarchiv.security.Permission;
 import org.raddatz.familienarchiv.security.RequirePermission;
+import org.raddatz.familienarchiv.security.SecurityUtils;
 import org.raddatz.familienarchiv.service.TranscriptionService;
 import org.raddatz.familienarchiv.service.UserService;
 import org.springframework.http.HttpStatus;
@@ -100,13 +99,6 @@ public class TranscriptionBlockController {
     }
 
     private UUID requireUserId(Authentication authentication) {
-        if (authentication == null || !authentication.isAuthenticated()) {
-            throw DomainException.unauthorized("Authentication required");
-        }
-        AppUser user = userService.findByEmail(authentication.getName());
-        if (user == null) {
-            throw DomainException.unauthorized("User not found");
-        }
-        return user.getId();
+        return SecurityUtils.requireUserId(authentication, userService);
     }
 }

backend/src/main/java/org/raddatz/familienarchiv/security/SecurityUtils.java

@@ -0,0 +1,24 @@
+package org.raddatz.familienarchiv.security;
+
+import org.raddatz.familienarchiv.exception.DomainException;
+import org.raddatz.familienarchiv.model.AppUser;
+import org.raddatz.familienarchiv.service.UserService;
+import org.springframework.security.core.Authentication;
+
+import java.util.UUID;
+
+public final class SecurityUtils {
+
+    private SecurityUtils() {}
+
+    public static UUID requireUserId(Authentication authentication, UserService userService) {
+        if (authentication == null || !authentication.isAuthenticated()) {
+            throw DomainException.unauthorized("Authentication required");
+        }
+        AppUser user = userService.findByEmail(authentication.getName());
+        if (user == null) {
+            throw DomainException.unauthorized("User not found");
+        }
+        return user.getId();
+    }
+}

backend/src/test/java/org/raddatz/familienarchiv/security/SecurityUtilsTest.java

@@ -0,0 +1,58 @@
+package org.raddatz.familienarchiv.security;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.raddatz.familienarchiv.exception.DomainException;
+import org.raddatz.familienarchiv.model.AppUser;
+import org.raddatz.familienarchiv.service.UserService;
+import org.springframework.security.core.Authentication;
+
+import java.util.UUID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class SecurityUtilsTest {
+
+    @Mock Authentication authentication;
+    @Mock UserService userService;
+
+    @Test
+    void requireUserId_throwsUnauthorized_whenAuthenticationIsNull() {
+        assertThatThrownBy(() -> SecurityUtils.requireUserId(null, userService))
+                .isInstanceOf(DomainException.class);
+    }
+
+    @Test
+    void requireUserId_throwsUnauthorized_whenNotAuthenticated() {
+        when(authentication.isAuthenticated()).thenReturn(false);
+        assertThatThrownBy(() -> SecurityUtils.requireUserId(authentication, userService))
+                .isInstanceOf(DomainException.class);
+    }
+
+    @Test
+    void requireUserId_throwsUnauthorized_whenUserNotFound() {
+        when(authentication.isAuthenticated()).thenReturn(true);
+        when(authentication.getName()).thenReturn("ghost@example.com");
+        when(userService.findByEmail("ghost@example.com")).thenReturn(null);
+        assertThatThrownBy(() -> SecurityUtils.requireUserId(authentication, userService))
+                .isInstanceOf(DomainException.class);
+    }
+
+    @Test
+    void requireUserId_returnsUserId_whenAuthenticated() {
+        UUID userId = UUID.randomUUID();
+        AppUser user = AppUser.builder().id(userId).email("user@example.com").password("pw").build();
+        when(authentication.isAuthenticated()).thenReturn(true);
+        when(authentication.getName()).thenReturn("user@example.com");
+        when(userService.findByEmail("user@example.com")).thenReturn(user);
+
+        UUID result = SecurityUtils.requireUserId(authentication, userService);
+
+        assertThat(result).isEqualTo(userId);
+    }
+}