Configure letter opener

Gemfile

@@ -60,6 +60,7 @@ group :development, :test do
   gem "bundler-audit", require: false
   gem "brakeman", require: false
   gem "rubocop-rails-omakase", require: false
+  gem "letter_opener"
 end
 
 group :test do

Gemfile.lock

@@ -276,6 +276,8 @@ GEM
       rack-test (>= 0.6.3)
       regexp_parser (>= 1.5, < 3.0)
       xpath (~> 3.2)
+    childprocess (5.1.0)
+      logger (~> 1.5)
     chunky_png (1.4.0)
     concurrent-ruby (1.3.5)
     connection_pool (2.5.3)
@@ -342,6 +344,12 @@ GEM
     jwt (3.1.2)
       base64
     language_server-protocol (3.17.0.5)
+    launchy (3.1.1)
+      addressable (~> 2.8)
+      childprocess (~> 5.0)
+      logger (~> 1.6)
+    letter_opener (1.10.0)
+      launchy (>= 2.2, < 4)
     lint_roller (1.1.0)
     logger (1.7.0)
     loofah (2.24.1)
@@ -611,6 +619,7 @@ DEPENDENCIES
   importmap-rails
   jbuilder
   kamal!
+  letter_opener
   lexxy!
   mission_control-jobs
   mocha

README.md

@@ -63,6 +63,19 @@ A typical scenario is making modifications LLM prompts. You need to:
 Notice that if you pass changing data to the prompt, this mechanism won't work. E.g: if you pass data timestamps.
 You need to make sure those timestamps are always the same across executions.
 
+### Outbound Emails
+
+#### Development
+
+You can view email previews at http://know-it-all.localhost:3005/rails/mailers.
+
+You can enable or disable [`letter_opener`](https://github.com/ryanb/letter_opener) to
+open sent emails automatically with:
+
+    bin/rails dev:email
+
+Under the hood, this will create or remove `tmp/email-dev.txt`.
+
 ## Environments
 
 Fizzy is deployed with Kamal. You'll need to have the 1Password CLI set up in order to access the secrets that are used when deploying. Provided you have that, it should be as simple as `bin/kamal deploy` to the correct environment.

config/environments/development.rb

@@ -72,8 +72,12 @@ Rails.application.configure do
   # Raise error when a before_action's only/except options reference missing actions
   config.action_controller.raise_on_missing_callback_actions = true
 
-  # Allow all hosts in development
-  config.hosts = nil
+  if Rails.root.join("tmp/email-dev.txt").exist?
+    config.action_mailer.delivery_method = :letter_opener
+    config.action_mailer.perform_deliveries = true
+  else
+    config.action_mailer.raise_delivery_errors = false
+  end
 
   config.hosts = %w[ fizzy.localhost localhost 127.0.0.1 ]
 

lib/tasks/dev.rake

@@ -0,0 +1,16 @@
+namespace :dev do
+  desc "Toggle using Letter Opener to preview emails"
+  task :email do
+    file_path = Rails.root.join("tmp", "email-dev.txt")
+
+    if File.exist?(file_path)
+      File.delete(file_path)
+      puts "Letter Opener turned off"
+    else
+      FileUtils.touch(file_path)
+      puts "Letter Opener turned on"
+    end
+
+    %x(bin/rails restart)
+  end
+end