fix(server): send comment mention to comment author by default (#13018)

close AF-2708



#### PR Dependency Tree


* **PR #13018** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **New Features**
* Added notifications for users when their comment receives a reply,
marking them with a mention.
* **Tests**
* Introduced an end-to-end test to verify that replying to a comment
sends a mention notification to the original comment author.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/e2e/comment/resolver.spec.ts

@@ -687,6 +687,63 @@ e2e(
   }
 );
 
+e2e(
+  'should create reply and send comment mention notification to comment author',
+  async t => {
+    const docId = randomUUID();
+    await app.create(Mockers.DocUser, {
+      workspaceId: teamWorkspace.id,
+      docId,
+      userId: owner.id,
+      type: DocRole.Owner,
+    });
+
+    await app.login(member);
+    const createResult = await app.gql({
+      query: createCommentMutation,
+      variables: {
+        input: {
+          workspaceId: teamWorkspace.id,
+          docId,
+          docMode: DocMode.page,
+          docTitle: 'test',
+          content: {
+            type: 'paragraph',
+            content: [{ type: 'text', text: 'test' }],
+          },
+        },
+      },
+    });
+
+    // owner login to create reply and send notification to comment author: member
+    await app.login(owner);
+    const count = app.queue.count('notification.sendComment');
+    const result = await app.gql({
+      query: createReplyMutation,
+      variables: {
+        input: {
+          commentId: createResult.createComment.id,
+          docMode: DocMode.page,
+          docTitle: 'test',
+          content: {
+            type: 'paragraph',
+            content: [{ type: 'text', text: 'test' }],
+          },
+        },
+      },
+    });
+
+    t.truthy(result.createReply.id);
+    t.is(result.createReply.commentId, createResult.createComment.id);
+    t.is(app.queue.count('notification.sendComment'), count + 1);
+    const notification = app.queue.last('notification.sendComment');
+    t.is(notification.name, 'notification.sendComment');
+    t.is(notification.payload.userId, member.id);
+    t.is(notification.payload.body.replyId, result.createReply.id);
+    t.is(notification.payload.isMention, true);
+  }
+);
+
 e2e('should create reply work when user is Commenter', async t => {
   const docId = randomUUID();
   await app.create(Mockers.DocUser, {

packages/backend/server/src/core/comment/resolver.ts

@@ -396,11 +396,34 @@ export class CommentResolver {
       });
     }
 
+    // send comment mention notification to comment author on reply
+    if (reply && comment.userId !== sender.id) {
+      await this.queue.add('notification.sendComment', {
+        isMention: true,
+        userId: comment.userId,
+        body: {
+          workspaceId: comment.workspaceId,
+          createdByUserId: sender.id,
+          commentId: comment.id,
+          replyId: reply.id,
+          doc: {
+            id: comment.docId,
+            title: docTitle,
+            mode: docMode,
+          },
+        },
+      });
+    }
+
     // send comment mention notification to mentioned users
     if (mentions) {
       for (const mentionUserId of mentions) {
-        // skip if the mention user is the doc owner
-        if (mentionUserId === owner?.userId || mentionUserId === sender.id) {
+        // skip if the mention user is the doc owner or the comment author
+        if (
+          mentionUserId === owner?.userId ||
+          mentionUserId === sender.id ||
+          mentionUserId === comment.userId
+        ) {
           continue;
         }