#399

backend/app/services/post_create_plan.rb

@@ -87,7 +87,7 @@ class PostCreatePlan
     end
     raise Tag::SectionLiteralParseError.new(raw_name, raw_name) if name.include?('[') || name.include?(']')
 
-    [TagName.canonicalise(name).first, category&.to_sym, sections]
+    [resolved_tag_name(name), category&.to_sym, sections]
   end
 
   def build_default_tag_specs direct_tag_specs
@@ -254,4 +254,11 @@ class PostCreatePlan
       end
     end
   end
+
+  def resolved_tag_name name
+    tag_name = TagName.includes(:canonical).find_by(name:)
+    return name if tag_name.nil?
+
+    (tag_name.canonical || tag_name).name
+  end
 end