From f0745de7f661a27b4d20d2ba317d1b31bf9a6c4b Mon Sep 17 00:00:00 2001
From: erdgeist <erdgeist@erdgeist.org>
Date: Thu, 23 Jul 2026 19:58:31 +0200
Subject: Force tags to be lowercase. A script unifies existing tags in both
 cases

---
 app/views/nodes/edit.html.erb              |  2 +-
 config/initializers/acts_as_taggable_on.rb |  1 +
 lib/tasks/tags.rake                        | 37 ++++++++++++++++++++++++++++++
 public/stylesheets/admin.css               |  4 ++++
 4 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 config/initializers/acts_as_taggable_on.rb
 create mode 100644 lib/tasks/tags.rake

diff --git a/app/views/nodes/edit.html.erb b/app/views/nodes/edit.html.erb
index fc1d18fa..55397d42 100644
--- a/app/views/nodes/edit.html.erb
+++ b/app/views/nodes/edit.html.erb
@@ -117,7 +117,7 @@
         <div class="node_description">Tags</div>
         <div class="node_content">
           <%= text_field_tag :tag_list, @page.tag_list.join(', ') %>
-          <span class="field_hint">Comma separated.</span>
+          <span class="field_hint">Comma separated, lowercase.</span>
         </div>
 
         <div class="node_description">Publish at</div>
diff --git a/config/initializers/acts_as_taggable_on.rb b/config/initializers/acts_as_taggable_on.rb
new file mode 100644
index 00000000..08d8aa67
--- /dev/null
+++ b/config/initializers/acts_as_taggable_on.rb
@@ -0,0 +1 @@
+ActsAsTaggableOn.force_lowercase = true
diff --git a/lib/tasks/tags.rake b/lib/tasks/tags.rake
new file mode 100644
index 00000000..7521c2f9
--- /dev/null
+++ b/lib/tasks/tags.rake
@@ -0,0 +1,37 @@
+namespace :tags do
+  desc "Merge tags differing only in case into one lowercase tag and " \
+       "lowercase every remaining name. Idempotent; safe to re-run."
+  task :merge_case_duplicates => :environment do
+    merged = renamed = 0
+
+    ActiveRecord::Base.transaction do
+      ActsAsTaggableOn::Tag.pluck(Arel.sql("DISTINCT LOWER(name)")).each do |lower|
+        group  = ActsAsTaggableOn::Tag.where("LOWER(name) = ?", lower).order(:id).to_a
+        keeper = group.find { |t| t.name == lower } || group.first
+
+        (group - [keeper]).each do |dup|
+          dup.taggings.find_each do |tagging|
+            duplicate = ActsAsTaggableOn::Tagging.where(
+              :tag_id => keeper.id,
+              :taggable_type => tagging.taggable_type,
+              :taggable_id   => tagging.taggable_id,
+              :context       => tagging.context,
+              :tagger_type   => tagging.tagger_type,
+              :tagger_id     => tagging.tagger_id).exists?
+            duplicate ? tagging.destroy : tagging.update!(:tag_id => keeper.id)
+          end
+          dup.reload.destroy!
+          merged += 1
+        end
+
+        if keeper.name != lower
+          keeper.update!(:name => lower)
+          renamed += 1
+        end
+        ActsAsTaggableOn::Tag.reset_counters(keeper.id, :taggings)
+      end
+    end
+
+    puts "Merged #{merged} duplicate tags, lowercased #{renamed} names"
+  end
+end
diff --git a/public/stylesheets/admin.css b/public/stylesheets/admin.css
index 69f0fcf2..fe702b09 100644
--- a/public/stylesheets/admin.css
+++ b/public/stylesheets/admin.css
@@ -966,6 +966,10 @@ div#page_editor {
   padding: 5px;
 }
 
+input#tag_list {
+  text-transform: lowercase;
+}
+
 @media(min-width:1016px) {
   input#menu_search_term,
   input#menu_item_node_id,
-- 
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