DSL entity struct for resource-level locale configuration.

Defines which locales should have templates generated and serves as the default locale list for all events in the resource.

Usage in Resource DSL

dispatch do
  locales ["sv", "en", "no"],
    default_locale: "sv",
    locale_from: :visitor_locale

  event :created, trigger_on: :create do
    channels [
      [transport: :email, audience: :customer],
      [transport: :email, audience: :admin, locale: "sv"]
    ]
  end
end

Fields

• locales - List of locale codes (e.g., ["sv", "en"]). Templates will be generated for each locale when running mix ash.codegen.

• default_locale - Fallback locale when none can be determined from the record. Falls back to AshDispatch.Config.default_locale() if not set.

• locale_from - Atom field name on the resource to read runtime locale from. At dispatch time, this field is read from the record to determine which locale-specific template to render.

Locale Resolution Priority

1. Channel-level locale (static override)
2. Channel-level locale_from (dynamic from record)
3. Event-level locale_from
4. Resource-level locale_from (this config)
5. Auto-detected common fields: :visitor_locale, :locale
6. Config default (AshDispatch.Config.default_locale())

Template Fallback Chain

When resolving templates, AshDispatch tries these in order:

1. email.admin.sv.html.heex (variant + locale)
2. email.admin.html.heex (variant only)
3. email.sv.html.heex (locale only)
4. email.html.heex (base template)
5. default.sv.html.heex (default + locale)
6. default.html.heex (ultimate fallback)