feat(dashboard): add commentPreview to ActivityFeedItemDTO; wire via findDataByIds()

ActivityFeedItemDTO gains a nullable commentPreview field (plain-text, 120 chars max).
DashboardService.getActivity() now calls findDataByIds() once instead of
findAnnotationIdsByIds(), halving DB round-trips for the Chronik page load.
Empty-string previews are normalised to null so the frontend can use ?? cleanly.

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

backend/src/main/java/org/raddatz/familienarchiv/dashboard/ActivityFeedItemDTO.java

@@ -29,5 +29,11 @@ public record ActivityFeedItemDTO(
                 requiredMode = Schema.RequiredMode.NOT_REQUIRED,
                 description = "Annotation associated with the comment; populated only for COMMENT_ADDED and MENTION_CREATED kinds."
         )
-        UUID annotationId
+        UUID annotationId,
+        @Nullable
+        @Schema(
+                requiredMode = Schema.RequiredMode.NOT_REQUIRED,
+                description = "Plain-text preview of the comment body (HTML stripped server-side, truncated to 120 chars); null for non-comment feed items or deleted comments."
+        )
+        String commentPreview
 ) {}

backend/src/main/java/org/raddatz/familienarchiv/dashboard/DashboardService.java

@@ -12,6 +12,7 @@ import org.raddatz.familienarchiv.document.Document;
 import org.raddatz.familienarchiv.person.Person;
 import org.raddatz.familienarchiv.document.transcription.TranscriptionBlock;
 import org.raddatz.familienarchiv.document.comment.CommentService;
+import org.raddatz.familienarchiv.document.comment.CommentService.CommentData;
 import org.raddatz.familienarchiv.document.DocumentService;
 import org.raddatz.familienarchiv.document.transcription.TranscriptionService;
 import org.raddatz.familienarchiv.user.UserService;
@@ -133,9 +134,9 @@ public class DashboardService {
                 .filter(Objects::nonNull)
                 .distinct()
                 .toList();
-        Map<UUID, UUID> annotationByComment = commentIds.isEmpty()
+        Map<UUID, CommentData> commentDataByComment = commentIds.isEmpty()
                 ? Map.of()
-                : commentService.findAnnotationIdsByIds(commentIds);
+                : commentService.findDataByIds(commentIds);
 
         return rows.stream().map(row -> {
             ActivityActorDTO actor = row.getActorId() != null
@@ -146,7 +147,10 @@ public class DashboardService {
                     ? row.getHappenedAtUntil().atOffset(ZoneOffset.UTC)
                     : null;
             UUID commentId = row.getCommentId();
-            UUID annotationId = commentId != null ? annotationByComment.get(commentId) : null;
+            CommentData commentData = commentId != null ? commentDataByComment.get(commentId) : null;
+            UUID annotationId = commentData != null ? commentData.annotationId() : null;
+            String commentPreview = commentData != null && !commentData.preview().isEmpty()
+                    ? commentData.preview() : null;
             return new ActivityFeedItemDTO(
                     org.raddatz.familienarchiv.audit.AuditKind.valueOf(row.getKind()),
                     actor,
@@ -158,7 +162,8 @@ public class DashboardService {
                     row.getCount(),
                     happenedAtUntil,
                     commentId,
-                    annotationId
+                    annotationId,
+                    commentPreview
             );
         }).toList();
     }

backend/src/test/java/org/raddatz/familienarchiv/dashboard/DashboardServiceTest.java

@@ -13,6 +13,7 @@ import org.raddatz.familienarchiv.user.AppUser;
 import org.raddatz.familienarchiv.document.Document;
 import org.raddatz.familienarchiv.document.transcription.TranscriptionBlock;
 import org.raddatz.familienarchiv.document.comment.CommentService;
+import org.raddatz.familienarchiv.document.comment.CommentService.CommentData;
 import org.raddatz.familienarchiv.document.DocumentService;
 import org.raddatz.familienarchiv.document.transcription.TranscriptionService;
 import org.raddatz.familienarchiv.user.UserService;
@@ -142,7 +143,8 @@ class DashboardServiceTest {
         when(documentService.getDocumentsByIds(List.of(docId))).thenReturn(List.of(
                 Document.builder().id(docId).title("B").originalFilename("b.pdf").receivers(new HashSet<>()).build()
         ));
-        when(commentService.findAnnotationIdsByIds(List.of(commentId))).thenReturn(Map.of());
+        when(commentService.findDataByIds(List.of(commentId)))
+                .thenReturn(Map.of(commentId, new CommentData(null, "preview text")));
 
         List<ActivityFeedItemDTO> items = dashboardService.getActivity(userId, 5, AuditKind.ROLLUP_ELIGIBLE);
 
@@ -162,8 +164,8 @@ class DashboardServiceTest {
         when(documentService.getDocumentsByIds(List.of(docId))).thenReturn(List.of(
                 Document.builder().id(docId).title("B").originalFilename("b.pdf").receivers(new HashSet<>()).build()
         ));
-        when(commentService.findAnnotationIdsByIds(List.of(commentId)))
+        when(commentService.findDataByIds(List.of(commentId)))
-                .thenReturn(Map.of(commentId, annotationId));
+                .thenReturn(Map.of(commentId, new CommentData(annotationId, "preview text")));
 
         List<ActivityFeedItemDTO> items = dashboardService.getActivity(userId, 5, AuditKind.ROLLUP_ELIGIBLE);
 
@@ -187,7 +189,62 @@ class DashboardServiceTest {
         assertThat(items).hasSize(1);
         assertThat(items.get(0).commentId()).isNull();
         assertThat(items.get(0).annotationId()).isNull();
-        verify(commentService, never()).findAnnotationIdsByIds(anyList());
+        verify(commentService, never()).findDataByIds(anyList());
+    }
+
+    // ─── getActivity commentPreview ───────────────────────────────────────────
+
+    @Test
+    void getActivity_populates_commentPreview_for_COMMENT_ADDED_rows() {
+        UUID userId = UUID.randomUUID();
+        UUID docId = UUID.randomUUID();
+        UUID commentId = UUID.randomUUID();
+
+        ActivityFeedRow row = mockFeedRow(docId, "COMMENT_ADDED", commentId);
+        when(auditLogQueryService.findActivityFeed(userId, 5, AuditKind.ROLLUP_ELIGIBLE)).thenReturn(List.of(row));
+        when(documentService.getDocumentsByIds(List.of(docId))).thenReturn(List.of(
+                Document.builder().id(docId).title("B").originalFilename("b.pdf").receivers(new HashSet<>()).build()
+        ));
+        when(commentService.findDataByIds(List.of(commentId)))
+                .thenReturn(Map.of(commentId, new CommentData(null, "Hello family!")));
+
+        List<ActivityFeedItemDTO> items = dashboardService.getActivity(userId, 5, AuditKind.ROLLUP_ELIGIBLE);
+
+        assertThat(items.get(0).commentPreview()).isEqualTo("Hello family!");
+    }
+
+    @Test
+    void getActivity_leaves_commentPreview_null_for_TEXT_SAVED_rows() {
+        UUID userId = UUID.randomUUID();
+        UUID docId = UUID.randomUUID();
+
+        ActivityFeedRow row = mockFeedRow(docId, "TEXT_SAVED", null);
+        when(auditLogQueryService.findActivityFeed(userId, 5, AuditKind.ROLLUP_ELIGIBLE)).thenReturn(List.of(row));
+        when(documentService.getDocumentsByIds(List.of(docId))).thenReturn(List.of(
+                Document.builder().id(docId).title("B").originalFilename("b.pdf").receivers(new HashSet<>()).build()
+        ));
+
+        List<ActivityFeedItemDTO> items = dashboardService.getActivity(userId, 5, AuditKind.ROLLUP_ELIGIBLE);
+
+        assertThat(items.get(0).commentPreview()).isNull();
+    }
+
+    @Test
+    void getActivity_leaves_commentPreview_null_when_comment_is_deleted() {
+        UUID userId = UUID.randomUUID();
+        UUID docId = UUID.randomUUID();
+        UUID deletedCommentId = UUID.randomUUID();
+
+        ActivityFeedRow row = mockFeedRow(docId, "COMMENT_ADDED", deletedCommentId);
+        when(auditLogQueryService.findActivityFeed(userId, 5, AuditKind.ROLLUP_ELIGIBLE)).thenReturn(List.of(row));
+        when(documentService.getDocumentsByIds(List.of(docId))).thenReturn(List.of(
+                Document.builder().id(docId).title("B").originalFilename("b.pdf").receivers(new HashSet<>()).build()
+        ));
+        when(commentService.findDataByIds(List.of(deletedCommentId))).thenReturn(Map.of());
+
+        List<ActivityFeedItemDTO> items = dashboardService.getActivity(userId, 5, AuditKind.ROLLUP_ELIGIBLE);
+
+        assertThat(items.get(0).commentPreview()).isNull();
     }
 
     // ─── getPulse — always uses full ROLLUP_ELIGIBLE set ─────────────────────