feat: add inline mentions in comments

internal/service/notification_service.go

@@ -37,6 +37,7 @@ const (
 	NotifPostMention    = "post_mention"
 	NotifPostComment    = "post_comment"
 	NotifCommentReply   = "comment_reply"
+	NotifCommentMention = "comment_mention"
 
 	// Reminder kinds are delivered live (email + push + a websocket toast)
 	// but NOT persisted — they're ephemeral nudges, not history.
@@ -394,8 +395,11 @@ func (s *NotificationService) notifyComment(ctx context.Context, kind, postID, r
 		url = s.frontendURL + "/u/" + h + "/posts#post-" + postID
 	}
 	title, body := "New comment", who+" commented on your post"
-	if kind == NotifCommentReply {
+	switch kind {
+	case NotifCommentReply:
 		title, body = "New reply", who+" replied to your comment"
+	case NotifCommentMention:
+		title, body = "You were mentioned", who+" mentioned you in a comment"
 	}
 	s.push.SendToUser(ctx, recipientID, PushPayload{
 		Title: title,
@@ -406,6 +410,31 @@ func (s *NotificationService) notifyComment(ctx context.Context, kind, postID, r
 	})
 }
 
+// NotifyCommentMentions tells each user named by `handles` that `actorID`
+// mentioned them in a comment on `postID`. Handles are resolved to users,
+// deduped, and the actor plus any `skip` ids (e.g. the post/parent author who
+// already got a comment/reply notification) are excluded so nobody is
+// double-pinged. Reuses the comment notification path (row + realtime + push).
+func (s *NotificationService) NotifyCommentMentions(ctx context.Context, postID, actorID string, handles []string, skip ...string) {
+	if actorID == "" || len(handles) == 0 {
+		return
+	}
+	skipSet := map[string]bool{actorID: true}
+	for _, id := range skip {
+		if id != "" {
+			skipSet[id] = true
+		}
+	}
+	for _, h := range handles {
+		u, err := s.users.FindByHandle(ctx, h)
+		if err != nil || u == nil || skipSet[u.ID] {
+			continue
+		}
+		skipSet[u.ID] = true // dedupe repeats of the same mention
+		s.notifyComment(ctx, NotifCommentMention, postID, u.ID, actorID)
+	}
+}
+
 // likeMessage renders the aggregated like text: "X liked your post" or
 // "X and N others liked your post".
 func likeMessage(who string, count int) string {