fix: avoid hidden N+1 in workflow comment participants

api/models/comment.py

@@ -101,23 +101,31 @@ class WorkflowComment(Base):
     @property
     def participants(self):
         """Get all participants (creator + repliers + mentioned users)."""
-        participant_ids = set()
+        participant_ids: set[str] = set()
+        participants: list[Account] = []
 
-        # Add comment creator
-        participant_ids.add(self.created_by)
+        # Use account properties to reuse preloaded caches and avoid hidden N+1.
+        if self.created_by not in participant_ids:
+            participant_ids.add(self.created_by)
+            created_by_account = self.created_by_account
+            if created_by_account:
+                participants.append(created_by_account)
 
-        # Add reply creators
-        participant_ids.update(reply.created_by for reply in self.replies)
+        for reply in self.replies:
+            if reply.created_by in participant_ids:
+                continue
+            participant_ids.add(reply.created_by)
+            reply_account = reply.created_by_account
+            if reply_account:
+                participants.append(reply_account)
 
-        # Add mentioned users
-        participant_ids.update(mention.mentioned_user_id for mention in self.mentions)
-
-        # Get account objects
-        participants = []
-        for user_id in participant_ids:
-            account = db.session.get(Account, user_id)
-            if account:
-                participants.append(account)
+        for mention in self.mentions:
+            if mention.mentioned_user_id in participant_ids:
+                continue
+            participant_ids.add(mention.mentioned_user_id)
+            mentioned_account = mention.mentioned_user_account
+            if mentioned_account:
+                participants.append(mentioned_account)
 
         return participants
 

api/tests/unit_tests/models/test_comment_models.py

@@ -60,6 +60,27 @@ def test_workflow_comment_counts_and_participants() -> None:
     assert get_mock.call_count == 4
 
 
+def test_workflow_comment_participants_use_cached_accounts() -> None:
+    reply = WorkflowCommentReply(comment_id="comment-1", content="reply-1", created_by="user-2")
+    mention = WorkflowCommentMention(comment_id="comment-1", mentioned_user_id="user-3")
+    comment = WorkflowComment(created_by="user-1", resolved_by=None, content="hello", position_x=1, position_y=2)
+    comment.replies = [reply]
+    comment.mentions = [mention]
+
+    account_1 = Mock(id="user-1")
+    account_2 = Mock(id="user-2")
+    account_3 = Mock(id="user-3")
+    comment.cache_created_by_account(account_1)
+    reply.cache_created_by_account(account_2)
+    mention.cache_mentioned_user_account(account_3)
+
+    with patch("models.comment.db.session.get") as get_mock:
+        participants = comment.participants
+
+    assert set(participants) == {account_1, account_2, account_3}
+    get_mock.assert_not_called()
+
+
 def test_reply_and_mention_account_properties_and_cache() -> None:
     reply = WorkflowCommentReply(comment_id="comment-1", content="reply", created_by="user-1")
     mention = WorkflowCommentMention(comment_id="comment-1", mentioned_user_id="user-2")