fix(comment): populate annotationId on block comments from the block

postBlockComment now looks up the block via TranscriptionService and
sets comment.annotationId from block.getAnnotationId(). This closes
the upstream root cause of issue #276, where notifications for block
comments were stored with annotationId=null, breaking the notification
deep-link flow on the document detail page.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/service/CommentService.java

@@ -8,6 +8,7 @@ import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.exception.ErrorCode;
 import org.raddatz.familienarchiv.model.AppUser;
 import org.raddatz.familienarchiv.model.DocumentComment;
+import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.raddatz.familienarchiv.repository.CommentRepository;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
@@ -26,6 +27,7 @@ public class CommentService {
     private final UserService userService;
     private final NotificationService notificationService;
     private final AuditService auditService;
+    private final TranscriptionService transcriptionService;
 
     public List<DocumentComment> getCommentsForDocument(UUID documentId) {
         List<DocumentComment> roots =
@@ -46,9 +48,11 @@ public class CommentService {
     @Transactional
     public DocumentComment postBlockComment(UUID documentId, UUID blockId, String content,
                                             List<UUID> mentionedUserIds, AppUser author) {
+        TranscriptionBlock block = transcriptionService.getBlock(documentId, blockId);
         DocumentComment comment = DocumentComment.builder()
                 .documentId(documentId)
                 .blockId(blockId)
+                .annotationId(block.getAnnotationId())
                 .content(content)
                 .authorId(author.getId())
                 .authorName(resolveAuthorName(author))

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

@@ -10,6 +10,7 @@ import org.raddatz.familienarchiv.audit.AuditService;
 import org.raddatz.familienarchiv.exception.DomainException;
 import org.raddatz.familienarchiv.model.AppUser;
 import org.raddatz.familienarchiv.model.DocumentComment;
+import org.raddatz.familienarchiv.model.TranscriptionBlock;
 import org.raddatz.familienarchiv.model.UserGroup;
 import org.raddatz.familienarchiv.repository.CommentRepository;
 
@@ -39,6 +40,7 @@ class CommentServiceTest {
     @Mock UserService userService;
     @Mock NotificationService notificationService;
     @Mock AuditService auditService;
+    @Mock TranscriptionService transcriptionService;
     @InjectMocks CommentService commentService;
 
     // ─── postComment ──────────────────────────────────────────────────────────
@@ -611,6 +613,8 @@ class CommentServiceTest {
         AppUser author = AppUser.builder().id(UUID.randomUUID()).email("felix@example.com").firstName("Felix").lastName("B").build();
         DocumentComment saved = DocumentComment.builder()
                 .id(savedId).documentId(docId).blockId(blockId).authorName("Felix B").content("Nice").build();
+        when(transcriptionService.getBlock(docId, blockId))
+                .thenReturn(TranscriptionBlock.builder().id(blockId).documentId(docId).annotationId(UUID.randomUUID()).sortOrder(0).build());
         when(commentRepository.save(any())).thenReturn(saved);
 
         commentService.postBlockComment(docId, blockId, "Nice", List.of(), author);
@@ -643,7 +647,10 @@ class CommentServiceTest {
     void postBlockComment_setsBlockIdOnComment() {
         UUID documentId = UUID.randomUUID();
         UUID blockId = UUID.randomUUID();
+        UUID annotationId = UUID.randomUUID();
         AppUser author = AppUser.builder().id(UUID.randomUUID()).email("felix@example.com").firstName("Felix").lastName("Brandt").build();
+        when(transcriptionService.getBlock(documentId, blockId))
+                .thenReturn(TranscriptionBlock.builder().id(blockId).documentId(documentId).annotationId(annotationId).sortOrder(0).build());
         when(commentRepository.save(any())).thenAnswer(inv -> {
             DocumentComment c = inv.getArgument(0);
             c.setId(UUID.randomUUID());
@@ -657,4 +664,39 @@ class CommentServiceTest {
         assertThat(result.getDocumentId()).isEqualTo(documentId);
         assertThat(result.getContent()).isEqualTo("Looks like Breslau");
     }
+
+    @Test
+    void postBlockComment_setsAnnotationIdFromBlock() {
+        UUID documentId = UUID.randomUUID();
+        UUID blockId = UUID.randomUUID();
+        UUID annotationId = UUID.randomUUID();
+        AppUser author = AppUser.builder().id(UUID.randomUUID()).email("felix@example.com").firstName("Felix").lastName("Brandt").build();
+        when(transcriptionService.getBlock(documentId, blockId))
+                .thenReturn(TranscriptionBlock.builder().id(blockId).documentId(documentId).annotationId(annotationId).sortOrder(0).build());
+        when(commentRepository.save(any())).thenAnswer(inv -> {
+            DocumentComment c = inv.getArgument(0);
+            c.setId(UUID.randomUUID());
+            return c;
+        });
+
+        DocumentComment result = commentService.postBlockComment(
+                documentId, blockId, "Nice work", List.of(), author);
+
+        assertThat(result.getAnnotationId()).isEqualTo(annotationId);
+    }
+
+    @Test
+    void postBlockComment_propagatesNotFound_whenBlockDoesNotExist() {
+        UUID documentId = UUID.randomUUID();
+        UUID blockId = UUID.randomUUID();
+        AppUser author = AppUser.builder().id(UUID.randomUUID()).email("felix@example.com").firstName("Felix").lastName("Brandt").build();
+        when(transcriptionService.getBlock(documentId, blockId))
+                .thenThrow(DomainException.notFound(
+                        org.raddatz.familienarchiv.exception.ErrorCode.TRANSCRIPTION_BLOCK_NOT_FOUND,
+                        "Transcription block not found: " + blockId));
+
+        assertThatThrownBy(() -> commentService.postBlockComment(documentId, blockId, "Hi", List.of(), author))
+                .isInstanceOf(DomainException.class)
+                .hasMessageContaining("Transcription block not found");
+    }
 }