diff --git a/backend/src/main/java/org/raddatz/familienarchiv/audit/ActivityFeedRow.java b/backend/src/main/java/org/raddatz/familienarchiv/audit/ActivityFeedRow.java
index 59cf64c9..d6b1f899 100644
--- a/backend/src/main/java/org/raddatz/familienarchiv/audit/ActivityFeedRow.java
+++ b/backend/src/main/java/org/raddatz/familienarchiv/audit/ActivityFeedRow.java
@@ -12,6 +12,7 @@ public interface ActivityFeedRow {
     UUID getDocumentId();
     Instant getHappenedAt();
     boolean isYouMentioned();
+    boolean isYouParticipated();
     int getCount();
     Instant getHappenedAtUntil();
 }
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/dashboard/AuditLogQueryRepositoryRolledUpTest.java b/backend/src/test/java/org/raddatz/familienarchiv/dashboard/AuditLogQueryRepositoryRolledUpTest.java
index 1f38a8a0..d7197b4c 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/dashboard/AuditLogQueryRepositoryRolledUpTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/dashboard/AuditLogQueryRepositoryRolledUpTest.java
@@ -17,6 +17,7 @@ import org.springframework.transaction.annotation.Transactional;
 import java.time.Instant;
 import java.time.OffsetDateTime;
 import java.util.List;
+import java.util.Map;
 import java.util.UUID;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -28,6 +29,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 class AuditLogQueryRepositoryRolledUpTest {
 
     static final UUID USER_ID = UUID.fromString("dddddddd-dddd-dddd-dddd-dddddddddddd");
+    static final UUID OTHER_USER_ID = UUID.fromString("cccccccc-cccc-cccc-cccc-cccccccccccc");
     static final UUID DOC_ID = UUID.fromString("eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee");
     static final UUID OTHER_DOC_ID = UUID.fromString("ffffffff-ffff-ffff-ffff-ffffffffffff");
 
@@ -42,6 +44,9 @@ class AuditLogQueryRepositoryRolledUpTest {
         jdbcTemplate.update(
                 "INSERT INTO users (id, enabled, email, password) VALUES (?, true, ?, 'pw')",
                 USER_ID, "rollup-" + USER_ID + "@test.com");
+        jdbcTemplate.update(
+                "INSERT INTO users (id, enabled, email, password) VALUES (?, true, ?, 'pw')",
+                OTHER_USER_ID, "rollup-" + OTHER_USER_ID + "@test.com");
         jdbcTemplate.update(
                 "INSERT INTO documents (id, title, original_filename, status) VALUES (?, 'Brief A', 'a.pdf', 'PLACEHOLDER')",
                 DOC_ID);
@@ -51,17 +56,32 @@ class AuditLogQueryRepositoryRolledUpTest {
     }
 
     private void insertAuditEvent(UUID actorId, UUID docId, String kind, Instant happenedAt) {
+        insertAuditEvent(actorId, docId, kind, happenedAt, Map.of());
+    }
+
+    private void insertAuditEvent(UUID actorId, UUID docId, String kind, Instant happenedAt, Map<String, String> payload) {
+        String payloadJson = payload.isEmpty() ? null
+                : payload.entrySet().stream()
+                    .map(e -> "\"" + e.getKey() + "\": \"" + e.getValue() + "\"")
+                    .collect(java.util.stream.Collectors.joining(", ", "{", "}"));
         MapSqlParameterSource params = new MapSqlParameterSource()
                 .addValue("kind", kind)
                 .addValue("actor", actorId)
                 .addValue("doc", docId)
-                .addValue("t", OffsetDateTime.ofInstant(happenedAt, java.time.ZoneOffset.UTC));
+                .addValue("t", OffsetDateTime.ofInstant(happenedAt, java.time.ZoneOffset.UTC))
+                .addValue("payload", payloadJson, java.sql.Types.OTHER);
         named().update(
-                "INSERT INTO audit_log (kind, actor_id, document_id, happened_at) "
-                        + "VALUES (:kind, :actor, :doc, :t)",
+                "INSERT INTO audit_log (kind, actor_id, document_id, happened_at, payload) "
+                        + "VALUES (:kind, :actor, :doc, :t, :payload::jsonb)",
                 params);
     }
 
+    private void insertReplyNotification(UUID recipientId, UUID docId, UUID commentId) {
+        jdbcTemplate.update(
+                "INSERT INTO notifications (recipient_id, type, document_id, reference_id) VALUES (?, 'REPLY', ?, ?)",
+                recipientId, docId, commentId);
+    }
+
     @Test
     void rolledUpFeed_combines_same_actor_same_doc_within_2h() {
         insertUserAndDocs();
@@ -173,4 +193,59 @@ class AuditLogQueryRepositoryRolledUpTest {
             assertThat(r.getHappenedAtUntil()).isNull();
         });
     }
+
+    @Test
+    void youParticipated_is_true_when_user_has_reply_notification_for_comment() {
+        insertUserAndDocs();
+        UUID commentId = UUID.randomUUID();
+        insertAuditEvent(OTHER_USER_ID, DOC_ID, "COMMENT_ADDED",
+                Instant.parse("2026-04-20T10:00:00Z"), Map.of("commentId", commentId.toString()));
+        insertReplyNotification(USER_ID, DOC_ID, commentId);
+
+        List<ActivityFeedRow> rows = auditLogQueryRepository.findRolledUpActivityFeed(USER_ID.toString(), 40);
+
+        assertThat(rows).anySatisfy(r ->
+                assertThat(r.isYouParticipated()).isTrue()
+        );
+    }
+
+    @Test
+    void youParticipated_is_false_for_comment_with_no_reply_notification() {
+        insertUserAndDocs();
+        UUID commentId = UUID.randomUUID();
+        insertAuditEvent(OTHER_USER_ID, DOC_ID, "COMMENT_ADDED",
+                Instant.parse("2026-04-20T10:00:00Z"), Map.of("commentId", commentId.toString()));
+
+        List<ActivityFeedRow> rows = auditLogQueryRepository.findRolledUpActivityFeed(USER_ID.toString(), 40);
+
+        assertThat(rows).allSatisfy(r ->
+                assertThat(r.isYouParticipated()).isFalse()
+        );
+    }
+
+    @Test
+    void youMentioned_is_true_when_mention_created_payload_matches_current_user() {
+        insertUserAndDocs();
+        insertAuditEvent(OTHER_USER_ID, DOC_ID, "MENTION_CREATED",
+                Instant.parse("2026-04-20T10:00:00Z"), Map.of("mentionedUserId", USER_ID.toString()));
+
+        List<ActivityFeedRow> rows = auditLogQueryRepository.findRolledUpActivityFeed(USER_ID.toString(), 40);
+
+        assertThat(rows).anySatisfy(r ->
+                assertThat(r.isYouMentioned()).isTrue()
+        );
+    }
+
+    @Test
+    void youMentioned_is_false_when_mention_created_payload_targets_different_user() {
+        insertUserAndDocs();
+        insertAuditEvent(USER_ID, DOC_ID, "MENTION_CREATED",
+                Instant.parse("2026-04-20T10:00:00Z"), Map.of("mentionedUserId", OTHER_USER_ID.toString()));
+
+        List<ActivityFeedRow> rows = auditLogQueryRepository.findRolledUpActivityFeed(USER_ID.toString(), 40);
+
+        assertThat(rows).allSatisfy(r ->
+                assertThat(r.isYouMentioned()).isFalse()
+        );
+    }
 }
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/dashboard/DashboardServiceTest.java b/backend/src/test/java/org/raddatz/familienarchiv/dashboard/DashboardServiceTest.java
index 19692ad4..30a163d1 100644
--- a/backend/src/test/java/org/raddatz/familienarchiv/dashboard/DashboardServiceTest.java
+++ b/backend/src/test/java/org/raddatz/familienarchiv/dashboard/DashboardServiceTest.java
@@ -104,6 +104,7 @@ class DashboardServiceTest {
             public UUID getDocumentId() { return docId; }
             public Instant getHappenedAt() { return Instant.now(); }
             public boolean isYouMentioned() { return false; }
+            public boolean isYouParticipated() { return false; }
             public int getCount() { return 1; }
             public Instant getHappenedAtUntil() { return null; }
         };