Add X-GitLab-NotificationReason header to note emails

The 'assigned' reason doesn't apply to notes, but the other two
can ('mentioned' and 'own_activity'), so we can still use this for note
emails.

app/mailers/emails/notes.rb

@@ -2,44 +2,44 @@
 module Emails
   module Notes
-    def note_commit_email(recipient_id, note_id)
+    def note_commit_email(recipient_id, note_id, reason = nil)
       setup_note_mail(note_id, recipient_id)
       @commit = @note.noteable
       @target_url = project_commit_url(*note_target_url_options)
-      mail_answer_note_thread(@commit, @note, note_thread_options(recipient_id))
+      mail_answer_note_thread(@commit, @note, note_thread_options(recipient_id, reason))
     end
-    def note_issue_email(recipient_id, note_id)
+    def note_issue_email(recipient_id, note_id, reason = nil)
       setup_note_mail(note_id, recipient_id)
       @issue = @note.noteable
       @target_url = project_issue_url(*note_target_url_options)
-      mail_answer_note_thread(@issue, @note, note_thread_options(recipient_id))
+      mail_answer_note_thread(@issue, @note, note_thread_options(recipient_id, reason))
     end
-    def note_merge_request_email(recipient_id, note_id)
+    def note_merge_request_email(recipient_id, note_id, reason = nil)
       setup_note_mail(note_id, recipient_id)
       @merge_request = @note.noteable
       @target_url = project_merge_request_url(*note_target_url_options)
-      mail_answer_note_thread(@merge_request, @note, note_thread_options(recipient_id))
+      mail_answer_note_thread(@merge_request, @note, note_thread_options(recipient_id, reason))
     end
-    def note_project_snippet_email(recipient_id, note_id)
+    def note_project_snippet_email(recipient_id, note_id, reason = nil)
       setup_note_mail(note_id, recipient_id)
       @snippet = @note.noteable
       @target_url = project_snippet_url(*note_target_url_options)
-      mail_answer_note_thread(@snippet, @note, note_thread_options(recipient_id))
+      mail_answer_note_thread(@snippet, @note, note_thread_options(recipient_id, reason))
     end
-    def note_personal_snippet_email(recipient_id, note_id)
+    def note_personal_snippet_email(recipient_id, note_id, reason = nil)
       setup_note_mail(note_id, recipient_id)
       @snippet = @note.noteable
       @target_url = snippet_url(@note.noteable)
-      mail_answer_note_thread(@snippet, @note, note_thread_options(recipient_id))
+      mail_answer_note_thread(@snippet, @note, note_thread_options(recipient_id, reason))
     end
     private
@@ -48,11 +48,12 @@ module Emails
       [@project || @group, @note.noteable, anchor: "note_#{@note.id}"]
     end
-    def note_thread_options(recipient_id)
+    def note_thread_options(recipient_id, reason)
       {
         from: sender(@note.author_id),
         to: recipient(recipient_id, @project&.group || @group),
-        subject: subject("#{@note.noteable.title} (#{@note.noteable.reference_link_text})")
+        subject: subject("#{@note.noteable.title} (#{@note.noteable.reference_link_text})"),
+        'X-GitLab-NotificationReason' => reason
       }
     end

app/services/notification_service.rb

@@ -285,7 +285,7 @@ class NotificationService
     recipients = NotificationRecipientService.build_new_note_recipients(note)
     recipients.each do |recipient|
-      mailer.send(notify_method, recipient.user.id, note.id).deliver_later
+      mailer.send(notify_method, recipient.user.id, note.id, recipient.reason).deliver_later
     end
   end

changelogs/unreleased/add-notification-reason-to-note-emails.yml

+---
+title: Add X-GitLab-NotificationReason header to note emails
+merge_request: 32422
+author:
+type: fixed

spec/services/notification_service_spec.rb

@@ -278,6 +278,7 @@ describe NotificationService, :mailer do
             notification.new_note(note)
             should_email(note.author)
+            expect(find_email_for(note.author)).to have_header('X-GitLab-NotificationReason', 'own_activity')
           end
           it_behaves_like 'project emails are disabled' do
@@ -335,6 +336,9 @@ describe NotificationService, :mailer do
             should_not_email(@u_participating)
             should_not_email(@u_disabled)
             should_not_email(@u_lazy_participant)
+
+            expect(find_email_for(@u_mentioned)).to have_header('X-GitLab-NotificationReason', 'mentioned')
+            expect(find_email_for(@u_custom_global)).to have_header('X-GitLab-NotificationReason', '')
           end
         end