feat: add admin backfill-versions endpoint for documents without history

Adds POST /api/admin/backfill-versions which creates an initial snapshot
(editorName="Datenimport", changedFields=[]) for every document that has
no version entry yet, using the document's createdAt as the version timestamp.

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

backend/src/test/java/org/raddatz/familienarchiv/controller/AdminControllerTest.java

@@ -0,0 +1,61 @@
+package org.raddatz.familienarchiv.controller;
+
+import org.junit.jupiter.api.Test;
+import org.raddatz.familienarchiv.config.SecurityConfig;
+import org.raddatz.familienarchiv.model.Document;
+import org.raddatz.familienarchiv.security.PermissionAspect;
+import org.raddatz.familienarchiv.service.CustomUserDetailsService;
+import org.raddatz.familienarchiv.service.DocumentService;
+import org.raddatz.familienarchiv.service.DocumentVersionService;
+import org.raddatz.familienarchiv.service.MassImportService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.aop.AopAutoConfiguration;
+import org.springframework.boot.webmvc.test.autoconfigure.WebMvcTest;
+import org.springframework.context.annotation.Import;
+import org.springframework.security.test.context.support.WithMockUser;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.test.web.servlet.MockMvc;
+
+import java.util.List;
+
+import static org.mockito.ArgumentMatchers.anyList;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@WebMvcTest(AdminController.class)
+@Import({SecurityConfig.class, PermissionAspect.class, AopAutoConfiguration.class})
+class AdminControllerTest {
+
+    @Autowired MockMvc mockMvc;
+
+    @MockitoBean MassImportService massImportService;
+    @MockitoBean DocumentService documentService;
+    @MockitoBean DocumentVersionService documentVersionService;
+    @MockitoBean CustomUserDetailsService customUserDetailsService;
+
+    @Test
+    void backfillVersions_returns401_whenUnauthenticated() throws Exception {
+        mockMvc.perform(post("/api/admin/backfill-versions"))
+                .andExpect(status().isUnauthorized());
+    }
+
+    @Test
+    @WithMockUser(roles = "USER")
+    void backfillVersions_returns403_whenNotAdmin() throws Exception {
+        mockMvc.perform(post("/api/admin/backfill-versions"))
+                .andExpect(status().isForbidden());
+    }
+
+    @Test
+    @WithMockUser(authorities = "ADMIN")
+    void backfillVersions_returns200_withCount_whenAdmin() throws Exception {
+        when(documentService.getDocumentsWithoutVersions()).thenReturn(List.of(Document.builder().build()));
+        when(documentVersionService.backfillMissingVersions(anyList())).thenReturn(1);
+
+        mockMvc.perform(post("/api/admin/backfill-versions"))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.count").value(1));
+    }
+}

backend/src/test/java/org/raddatz/familienarchiv/service/DocumentVersionServiceTest.java

@@ -304,6 +304,76 @@ class DocumentVersionServiceTest {
                 .isInstanceOf(DomainException.class);
     }
 
+    // ─── backfillMissingVersions ──────────────────────────────────────────────
+
+    @Test
+    void backfill_createsVersion_withEditorNameDatenimport() {
+        Document doc = minimalDocument();
+        when(versionRepository.findByDocumentIdOrderBySavedAtAsc(doc.getId())).thenReturn(List.of());
+        when(versionRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        versionService.backfillMissingVersions(List.of(doc));
+
+        ArgumentCaptor<DocumentVersion> captor = ArgumentCaptor.forClass(DocumentVersion.class);
+        verify(versionRepository).save(captor.capture());
+        assertThat(captor.getValue().getEditorName()).isEqualTo("Datenimport");
+    }
+
+    @Test
+    void backfill_usesDocumentCreatedAt_asSavedAt() {
+        LocalDateTime createdAt = LocalDateTime.of(2020, 3, 15, 10, 0);
+        Document doc = Document.builder()
+                .id(UUID.randomUUID()).title("T").createdAt(createdAt).build();
+        when(versionRepository.findByDocumentIdOrderBySavedAtAsc(doc.getId())).thenReturn(List.of());
+        when(versionRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        versionService.backfillMissingVersions(List.of(doc));
+
+        ArgumentCaptor<DocumentVersion> captor = ArgumentCaptor.forClass(DocumentVersion.class);
+        verify(versionRepository).save(captor.capture());
+        assertThat(captor.getValue().getSavedAt()).isEqualTo(createdAt);
+    }
+
+    @Test
+    void backfill_setsChangedFieldsEmpty() {
+        Document doc = minimalDocument();
+        when(versionRepository.findByDocumentIdOrderBySavedAtAsc(doc.getId())).thenReturn(List.of());
+        when(versionRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        versionService.backfillMissingVersions(List.of(doc));
+
+        ArgumentCaptor<DocumentVersion> captor = ArgumentCaptor.forClass(DocumentVersion.class);
+        verify(versionRepository).save(captor.capture());
+        assertThat(captor.getValue().getChangedFields()).isEqualTo("[]");
+    }
+
+    @Test
+    void backfill_skipsDocuments_thatAlreadyHaveVersions() {
+        Document doc = minimalDocument();
+        DocumentVersion existing = DocumentVersion.builder()
+                .id(UUID.randomUUID()).documentId(doc.getId()).snapshot("{}")
+                .changedFields("[]").editorName("user").savedAt(LocalDateTime.now()).build();
+        when(versionRepository.findByDocumentIdOrderBySavedAtAsc(doc.getId())).thenReturn(List.of(existing));
+
+        int count = versionService.backfillMissingVersions(List.of(doc));
+
+        verify(versionRepository, never()).save(any());
+        assertThat(count).isZero();
+    }
+
+    @Test
+    void backfill_returnsCountOfCreatedVersions() {
+        Document d1 = minimalDocument();
+        Document d2 = minimalDocument();
+        when(versionRepository.findByDocumentIdOrderBySavedAtAsc(d1.getId())).thenReturn(List.of());
+        when(versionRepository.findByDocumentIdOrderBySavedAtAsc(d2.getId())).thenReturn(List.of());
+        when(versionRepository.save(any())).thenAnswer(inv -> inv.getArgument(0));
+
+        int count = versionService.backfillMissingVersions(List.of(d1, d2));
+
+        assertThat(count).isEqualTo(2);
+    }
+
     // ─── helpers ──────────────────────────────────────────────────────────────
 
     private void authenticateAs(String username) {