Persist timezones in the server

Add a beacon to persist timezones when these change (or the first time)

app/controllers/concerns/current_timezone.rb

@@ -3,6 +3,8 @@ module CurrentTimezone
 
   included do
     around_action :set_current_timezone
+
+    helper_method :timezone_from_cookie
   end
 
   private
@@ -12,6 +14,6 @@ module CurrentTimezone
 
     def timezone_from_cookie
       timezone = cookies[:timezone]
-      timezone if timezone.present? && ActiveSupport::TimeZone[timezone]
+      ActiveSupport::TimeZone[timezone] if timezone.present?
     end
 end

app/controllers/my/timezones_controller.rb

@@ -0,0 +1,10 @@
+class My::TimezonesController < ApplicationController
+  def update
+    Current.user.settings.update!(timezone_name: timezone_param)
+  end
+
+  private
+    def timezone_param
+      params[:timezone_name]
+    end
+end

app/models/user/configurable.rb

@@ -6,5 +6,7 @@ module User::Configurable
     has_many :push_subscriptions, class_name: "Push::Subscription", dependent: :delete_all
 
     after_create :create_settings, unless: :system?
+
+    delegate :timezone, to: :settings, allow_nil: true
   end
 end

app/models/user/settings.rb

@@ -23,6 +23,10 @@ class User::Settings < ApplicationRecord
     !bundle_email_never?
   end
 
+  def timezone
+    ActiveSupport::TimeZone[timezone_name] if timezone_name.present?
+  end
+
   private
     def review_pending_bundles
       if bundling_emails?

app/views/layouts/application.html.erb

@@ -9,6 +9,7 @@
     </header>
 
     <%= render "layouts/shared/flash" %>
+    <%= render "layouts/shared/time_zone" %>
 
     <main id="main">
       <%= yield %>

app/views/layouts/shared/_time_zone.html.erb

@@ -0,0 +1,5 @@
+<% if timezone_from_cookie.present? && timezone_from_cookie != Current.user.timezone %>
+  <%= auto_submit_form_with url: my_timezone_path, method: :put do %>
+    <%= hidden_field_tag :timezone_name, timezone_from_cookie.name %>
+  <% end %>
+<% end %>

config/routes.rb

@@ -119,6 +119,7 @@ Rails.application.routes.draw do
 
   namespace :my do
     resources :pins
+    resource :timezone
   end
 
   namespace :prompts do

db/migrate/20250905093718_add_timezone_name_to_user_settings.rb

@@ -0,0 +1,5 @@
+class AddTimezoneNameToUserSettings < ActiveRecord::Migration[8.1]
+  def change
+    add_column :user_settings, :timezone_name, :string
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.1].define(version: 2025_09_02_093943) do
+ActiveRecord::Schema[8.1].define(version: 2025_09_05_093718) do
   create_table "accesses", force: :cascade do |t|
     t.datetime "accessed_at"
     t.integer "collection_id", null: false
@@ -426,6 +426,7 @@ ActiveRecord::Schema[8.1].define(version: 2025_09_02_093943) do
   create_table "user_settings", force: :cascade do |t|
     t.integer "bundle_email_frequency", default: 0, null: false
     t.datetime "created_at", null: false
+    t.string "timezone_name"
     t.datetime "updated_at", null: false
     t.integer "user_id", null: false
     t.index ["user_id", "bundle_email_frequency"], name: "index_user_settings_on_user_id_and_bundle_email_frequency"

db/schema_cache.yml

@@ -1246,6 +1246,16 @@ columns:
     comment:
   - *5
   - *6
+  - !ruby/object:ActiveRecord::ConnectionAdapters::SQLite3::Column
+    auto_increment:
+    name: timezone_name
+    cast_type: *7
+    sql_type_metadata: *8
+    'null': true
+    default:
+    default_function:
+    collation:
+    comment:
   - *9
   - *18
   users:
@@ -2996,4 +3006,4 @@ indexes:
     comment:
     valid: true
   workflows: []
-version: 20250902093943
+version: 20250905093718

test/controllers/my/timezones_controller_test.rb

@@ -0,0 +1,15 @@
+require "test_helper"
+
+class My::TimezonesControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in_as :kevin
+  end
+
+  test "update" do
+    time_zone = ActiveSupport::TimeZone["America/New_York"]
+
+    assert_not_equal time_zone, users(:kevin).timezone
+    patch my_timezone_path, params: { timezone_name: "America/New_York" }
+    assert_equal time_zone, users(:kevin).reload.timezone
+  end
+end