A lot :)

config/environments/development.rb

@@ -1,4 +1,4 @@
-require 'active_support/core_ext/integer/time'
+require "active_support/core_ext/integer/time"
 
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
@@ -14,19 +14,17 @@ Rails.application.configure do
   # Show full error reports.
   config.consider_all_requests_local = true
 
-  # Enable server timing
+  # Enable server timing.
   config.server_timing = true
 
   # Enable/disable caching. By default caching is disabled.
   # Run rails dev:cache to toggle caching.
-  if Rails.root.join('tmp/caching-dev.txt').exist?
+  if Rails.root.join("tmp/caching-dev.txt").exist?
     config.action_controller.perform_caching = true
     config.action_controller.enable_fragment_cache_logging = true
 
     config.cache_store = :memory_store
-    config.public_file_server.headers = {
-      'Cache-Control' => "public, max-age=#{2.days.to_i}"
-    }
+    config.public_file_server.headers = { "Cache-Control" => "public, max-age=#{2.days.to_i}" }
   else
     config.action_controller.perform_caching = false
 
@@ -39,8 +37,12 @@ Rails.application.configure do
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false
 
+  # Disable caching for Action Mailer templates even if Action Controller
+  # caching is enabled.
   config.action_mailer.perform_caching = false
 
+  config.action_mailer.default_url_options = { host: "a11yist.localhost" }
+
   # Print deprecation notices to the Rails logger.
   config.active_support.deprecation = :log
 
@@ -66,13 +68,16 @@ Rails.application.configure do
   # config.i18n.raise_on_missing_translations = true
 
   # Annotate rendered view with file names.
-  # config.action_view.annotate_rendered_view_with_filenames = true
+  config.action_view.annotate_rendered_view_with_filenames = true
 
   # Uncomment if you wish to allow Action Cable access from any origin.
   # config.action_cable.disable_request_forgery_protection = true
 
-  # Raise error when a before_action's only/except options reference missing actions
+  # Raise error when a before_action's only/except options reference missing actions.
   config.action_controller.raise_on_missing_callback_actions = true
 
-  config.web_console.permissions = ['192.168.0.0/16', '10.10.0.0/16']
+  # Apply autocorrection by RuboCop to files generated by `bin/rails generate`.
+  # config.generators.apply_rubocop_autocorrect_after_generate!
+  # 
+  config.web_console.allowed_ips = ["10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "127.0.0.0/8"]
 end