diff --git a/Gemfile b/Gemfile
index d283ff8f1..d1d92b9d3 100644
--- a/Gemfile
+++ b/Gemfile
@@ -78,7 +78,7 @@ gem "carrierwave-base64"
 gem "mini_magick"
 
 # Mail
-gem "mjml-rails"
+gem "mjml-rails", "~> 4.0"
 gem "letter_opener_web"
 gem "sendgrid-actionmailer"
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 55276ebaa..b84e20400 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -10,10 +10,10 @@ GIT
 
 GIT
   remote: https://github.com/activeadmin-plugins/active_admin_sidebar.git
-  revision: 18b38b0586192cc0acab70b914b3536ca5be04de
+  revision: 463f5e33f8fb12001748ab4a2f4b13ede0a09607
   specs:
-    active_admin_sidebar (2.0.0)
-      activeadmin
+    active_admin_sidebar (3.0.0)
+      activeadmin (>= 3.0, < 4.0)
 
 GIT
   remote: https://github.com/tsubik/activeadmin-globalize.git
@@ -135,8 +135,8 @@ GEM
       timeout (>= 0.4.0)
     activerecord-import (2.2.0)
       activerecord (>= 4.2)
-    activerecord-postgis-adapter (10.0.2)
-      activerecord (~> 7.2.0)
+    activerecord-postgis-adapter (10.0.3)
+      activerecord (~> 7.2)
       rgeo-activerecord (~> 8.0.0)
     activestorage (7.2.3.1)
       actionpack (= 7.2.3.1)
@@ -159,7 +159,7 @@ GEM
     acts_as_list (1.2.6)
       activerecord (>= 6.1)
       activesupport (>= 6.1)
-    addressable (2.8.9)
+    addressable (2.9.0)
       public_suffix (>= 2.0.2, < 8.0)
     airbrussh (1.6.1)
       sshkit (>= 1.6.1, != 1.7.0)
@@ -174,14 +174,14 @@ GEM
     base64 (0.3.0)
     bcrypt (3.1.22)
     benchmark (0.5.0)
-    bigdecimal (4.1.0)
+    bigdecimal (4.1.2)
     bindex (0.8.1)
-    bootsnap (1.23.0)
+    bootsnap (1.24.3)
       msgpack (~> 1.2)
     brakeman (8.0.4)
       racc
     builder (3.3.0)
-    bullet (8.1.0)
+    bullet (8.1.1)
       activesupport (>= 3.0.0)
       uniform_notifier (~> 1.11)
     bundler-audit (0.9.3)
@@ -274,15 +274,15 @@ GEM
       dotenv (= 2.8.1)
       railties (>= 3.2)
     drb (2.2.3)
-    erb (6.0.2)
+    erb (6.0.4)
     erubi (1.13.1)
-    execjs (2.10.0)
-    factory_bot (6.5.6)
+    execjs (2.10.1)
+    factory_bot (6.6.0)
       activesupport (>= 6.1.0)
     factory_bot_rails (6.5.1)
       factory_bot (~> 6.5)
       railties (>= 6.1.0)
-    faker (3.6.1)
+    faker (3.8.0)
       i18n (>= 1.8.11, < 2)
     faraday (2.14.1)
       faraday-net_http (>= 2.0, < 3.5)
@@ -300,7 +300,7 @@ GEM
       websocket-driver (~> 0.7)
     ffi (1.17.4)
     ffi (1.17.4-x86_64-linux-gnu)
-    ffi-compiler (1.3.2)
+    ffi-compiler (1.4.2)
       ffi (>= 1.15.5)
       rake
     formtastic (6.0.0)
@@ -334,7 +334,7 @@ GEM
     google-cloud-location (1.3.0)
       gapic-common (~> 1.2)
       google-cloud-errors (~> 1.0)
-    google-cloud-translate (3.7.4)
+    google-cloud-translate (3.8.0)
       google-cloud-core (~> 1.6)
       google-cloud-translate-v2 (>= 0.0, < 2.a)
       google-cloud-translate-v3 (>= 0.11, < 2.a)
@@ -344,7 +344,7 @@ GEM
       googleapis-common-protos (>= 1.3.10, < 2.a)
       googleapis-common-protos-types (>= 1.0.5, < 2.a)
       googleauth (>= 0.16.2, < 2.a)
-    google-cloud-translate-v3 (1.7.1)
+    google-cloud-translate-v3 (1.9.0)
       gapic-common (~> 1.2)
       google-cloud-errors (~> 1.0)
       google-cloud-location (~> 1.0)
@@ -374,8 +374,8 @@ GEM
       multi_json (~> 1.11)
       os (>= 0.9, < 2.0)
       signet (>= 0.16, < 2.a)
-    groupdate (6.7.0)
-      activesupport (>= 7.1)
+    groupdate (6.8.0)
+      activesupport (>= 7.2)
     grpc (1.80.0)
       google-protobuf (>= 3.25, < 5.0)
       googleapis-common-protos-types (~> 1.0)
@@ -395,7 +395,7 @@ GEM
       http-cookie (~> 1.0)
       http-form_data (~> 2.2)
       llhttp-ffi (~> 0.5.0)
-    http-cookie (1.1.0)
+    http-cookie (1.1.6)
       domain_name (~> 0.5)
     http-form_data (2.3.0)
     i18n (1.14.8)
@@ -412,7 +412,7 @@ GEM
       railties (>= 6.0)
       responders (>= 2)
     io-console (0.8.2)
-    irb (1.17.0)
+    irb (1.18.0)
       pp (>= 0.6.0)
       prism (>= 1.3.0)
       rdoc (>= 4.0.0)
@@ -421,7 +421,7 @@ GEM
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
-    json (2.19.3)
+    json (2.19.5)
     jwt (3.1.2)
       base64
     kaminari (1.2.2)
@@ -472,7 +472,7 @@ GEM
     mime-types (3.7.0)
       logger
       mime-types-data (~> 3.2025, >= 3.2025.0507)
-    mime-types-data (3.2026.0317)
+    mime-types-data (3.2026.0414)
     mini_magick (5.3.1)
       logger
     mini_mime (1.1.5)
@@ -480,11 +480,11 @@ GEM
     minitest (5.27.0)
     mjml-rails (4.16.0)
     msgpack (1.8.0)
-    multi_json (1.19.1)
+    multi_json (1.21.1)
     mustache (1.1.2)
     net-http (0.9.1)
       uri (>= 0.11.1)
-    net-imap (0.6.3)
+    net-imap (0.6.4)
       date
       net-protocol
     net-pop (0.1.2)
@@ -499,12 +499,12 @@ GEM
       net-protocol
     net-ssh (7.3.2)
     nio4r (2.7.5)
-    nokogiri (1.19.2)
+    nokogiri (1.19.3)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
-    nokogiri (1.19.2-x86_64-linux-gnu)
+    nokogiri (1.19.3-x86_64-linux-gnu)
       racc (~> 1.4)
-    oj (3.16.16)
+    oj (3.17.0)
       bigdecimal (>= 3.0)
       ostruct (>= 0.2)
     oj_mimic_json (1.0.1)
@@ -515,8 +515,8 @@ GEM
     paper_trail (17.0.0)
       activerecord (>= 7.1)
       request_store (~> 1.4)
-    parallel (1.27.0)
-    parallel_tests (5.6.0)
+    parallel (1.28.0)
+    parallel_tests (5.7.0)
       parallel
     paranoia (3.1.0)
       activerecord (>= 7, < 8.2)
@@ -538,13 +538,13 @@ GEM
     puma (6.6.1)
       nio4r (~> 2.0)
     racc (1.8.1)
-    rack (3.2.5)
+    rack (3.2.6)
     rack-cors (3.0.0)
       logger
       rack (>= 3.0.14)
     rack-mini-profiler (2.3.4)
       rack (>= 1.2.0)
-    rack-session (2.1.1)
+    rack-session (2.1.2)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
     rack-test (2.2.0)
@@ -583,7 +583,7 @@ GEM
       tsort (>= 0.2)
       zeitwerk (~> 2.6)
     rainbow (3.1.1)
-    rake (13.3.1)
+    rake (13.4.2)
     ransack (4.4.1)
       activerecord (>= 7.2)
       activesupport (>= 7.2)
@@ -613,7 +613,7 @@ GEM
       redis-store (>= 1.2, < 2)
     redis-store (1.11.0)
       redis (>= 4, < 6)
-    regexp_parser (2.11.3)
+    regexp_parser (2.12.0)
     reline (0.6.3)
       io-console (~> 0.5)
     request_store (1.7.0)
@@ -715,7 +715,7 @@ GEM
       logger
     shoulda-matchers (4.0.1)
       activesupport (>= 4.2.0)
-    sidekiq (8.1.2)
+    sidekiq (8.1.3)
       connection_pool (>= 3.0.0)
       json (>= 2.16.0)
       logger (>= 1.7.0)
@@ -732,7 +732,7 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.13.2)
     simplecov_json_formatter (0.1.4)
-    spring (4.4.2)
+    spring (4.5.0)
     spring-commands-rspec (1.0.4)
       spring (>= 0.9.1)
     sprockets (4.2.2)
@@ -750,7 +750,7 @@ GEM
       net-sftp (>= 2.1.2)
       net-ssh (>= 2.8.0)
       ostruct
-    ssrf_filter (1.3.0)
+    ssrf_filter (1.5.0)
     standard (1.54.0)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.0)
@@ -764,17 +764,17 @@ GEM
       lint_roller (~> 1.1)
       rubocop-performance (~> 1.26.0)
     stringio (3.2.0)
-    super_diff (0.18.0)
-      attr_extras (>= 6.2.4)
-      diff-lcs
-      patience_diff
+    super_diff (0.19.0)
+      attr_extras (>= 6.2.4, < 8)
+      diff-lcs (~> 1.5)
+      patience_diff (~> 1.2)
     thor (1.5.0)
     tilt (2.7.0)
     timeout (0.6.1)
     tsort (0.2.0)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
-    tzinfo-data (1.2026.1)
+    tzinfo-data (1.2026.2)
       tzinfo (>= 1.0.0)
     uglifier (4.2.1)
       execjs (>= 0.3.0, < 3)
@@ -865,7 +865,7 @@ DEPENDENCIES
   letter_opener_web
   maxmind-geoip2
   mini_magick
-  mjml-rails
+  mjml-rails (~> 4.0)
   nokogiri
   oj
   oj_mimic_json
diff --git a/config/initializers/active_admin.rb b/config/initializers/active_admin.rb
index 90fa6eb4f..68b449da2 100644
--- a/config/initializers/active_admin.rb
+++ b/config/initializers/active_admin.rb
@@ -143,7 +143,7 @@
   # Active Admin resources and pages from here.
   #
   config.before_action do
-    left_sidebar!(collapsed: true) if respond_to?(:left_sidebar!)
+    left_sidebar!(collapsible: true, start_collapsed: false) if respond_to?(:left_sidebar!)
   end
 
   # Set default locale for active admin
diff --git a/config/initializers/paper_trail.rb b/config/initializers/paper_trail.rb
index 0579225d5..924708e95 100644
--- a/config/initializers/paper_trail.rb
+++ b/config/initializers/paper_trail.rb
@@ -6,3 +6,4 @@
   on: %i[create update destroy]
 }
 PaperTrail.config.version_limit = nil
+PaperTrail.serializer = PaperTrail::Serializers::JSON
diff --git a/db/migrate/20260416100821_paper_trail_to_json.rb b/db/migrate/20260416100821_paper_trail_to_json.rb
new file mode 100644
index 000000000..f27412f9b
--- /dev/null
+++ b/db/migrate/20260416100821_paper_trail_to_json.rb
@@ -0,0 +1,11 @@
+class PaperTrailToJson < ActiveRecord::Migration[7.2]
+  def change
+    rename_column :versions, :object, :old_object
+    rename_column :versions, :object_changes, :old_object_changes
+
+    change_table :versions, bulk: true do |t|
+      t.jsonb :object
+      t.jsonb :object_changes
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 9cf752bbe..e5412cbcf 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2026_03_18_192753) do
+ActiveRecord::Schema[7.2].define(version: 2026_04_16_100821) do
   create_schema "tiger"
   create_schema "tiger_data"
   create_schema "topology"
@@ -1133,10 +1133,12 @@
     t.bigint "item_id", null: false
     t.string "event", null: false
     t.string "whodunnit"
-    t.text "object"
+    t.text "old_object"
     t.string "locale"
     t.datetime "created_at", precision: nil
-    t.text "object_changes"
+    t.text "old_object_changes"
+    t.jsonb "object"
+    t.jsonb "object_changes"
     t.index ["item_type", "item_id", "locale"], name: "index_versions_on_item_type_and_item_id_and_locale"
     t.index ["item_type", "item_id"], name: "index_versions_on_item_type_and_item_id"
   end
diff --git a/lib/tasks/data_migrations.rake b/lib/tasks/data_migrations.rake
index 49f74ef61..59637b7d8 100644
--- a/lib/tasks/data_migrations.rake
+++ b/lib/tasks/data_migrations.rake
@@ -50,4 +50,37 @@ namespace :data_migrations do
     end
     puts "Wrote tmp/data_migrations_report_mission_type_report.csv"
   end
+
+  desc "Move PaperTrail versions from YAML to JSON columns."
+  task paper_trail_to_json: :environment do
+    for_real = ENV["FOR_REAL"] == "true"
+    batch_size = (ENV["BATCH_SIZE"] || 2000).to_i
+    puts "DRY RUN" unless for_real
+
+    scope = PaperTrail::Version.all
+    total = scope.count
+    processed = 0
+    errors = 0
+    puts "Migrating #{total} PaperTrail versions to JSON (batch_size=#{batch_size})..."
+
+    scope.find_in_batches(batch_size: batch_size) do |batch|
+      ActiveRecord::Base.transaction do
+        batch.each do |version|
+          attrs = {}
+          attrs[:object] = PaperTrail::Serializers::YAML.load(version.old_object) if version.old_object.present?
+          attrs[:object_changes] = PaperTrail::Serializers::YAML.load(version.old_object_changes) if version.old_object_changes.present?
+          version.update_columns(attrs) if for_real
+        rescue => e
+          errors += 1
+          warn "\n  Error parsing version #{version.id}: #{e.message}"
+        end
+      end
+
+      processed += batch.size
+      print "\r  #{processed}/#{total} (#{"%.1f" % (processed.to_f / total * 100)}%)"
+    end
+
+    warn "\n  #{errors} version(s) failed to parse and were skipped." if errors > 0
+    puts "\nFinished migrating PaperTrail versions to JSON columns. You can now remove the old YAML columns with a separate migration."
+  end
 end