#399

backend/app/services/post_create_preflight.rb

@@ -31,6 +31,7 @@ class PostCreatePreflight
           video_ms: preview[:attributes]['video_ms'],
           field_warnings: final_field_warnings(preview[:field_warnings] || { }),
           base_warnings: preview[:base_warnings],
+          existing_post_id: preview[:existing_post_id],
           existing_post: existing_post_compact(preview[:existing_post_id]) }
     end
 
@@ -70,6 +71,7 @@ class PostCreatePreflight
         normalised_parent_post_ids: plan[:normalised_parent_post_ids],
         field_warnings: final_field_warnings(preview[:field_warnings] || { }),
         base_warnings: preview[:base_warnings],
+        existing_post_id: preview[:existing_post_id],
         existing_post: existing_post_compact(preview[:existing_post_id]) }
   end