copy-pasta rails migration template here verbatim

well, with only one rename of `table_name` to
`domain_prefixed_relation_name`. otherwise, no changes.

lib/generators/categoria/model_generator.rb

@@ -21,6 +21,9 @@ module Generators
     #     security-by-obscurity.
     #   - models are not in `app/models` but instead internal to domain.
     class ModelGenerator < ::Rails::Generators::NamedBase
+      desc <<~DOC.squish
+      DOC
+
       include ::Rails::Generators::ModelHelpers
       include ::Rails::Generators::Migration
       include ::ActiveRecord::Generators::Migration
@@ -37,7 +40,7 @@ class ModelGenerator < ::Rails::Generators::NamedBase
       def create_migration_file
         migration_template(
           "model_migration.rb.erb",
-          File.join(db_migrate_path, "create_#{relation_name}_table.rb"),
+          File.join(db_migrate_path, "create_#{domain_prefixed_relation_name}_table.rb"),
           migration_version:
         )
       end
@@ -77,7 +80,10 @@ def internal_model_name
       end
 
       sig { returns(String) }
-      def relation_name = %(#{domain_name}_#{internal_model_name.pluralize})
+      def domain_prefixed_relation_name = %(#{domain_name}_#{internal_model_name.pluralize})
+
+      sig { returns(T::Array[String]) }
+      def attributes_with_index = attributes.select { !_1.reference? && _1.has_index? }
 
       sig { params(dirname: String).returns(String) }
       def self.next_migration_number(dirname)

lib/generators/categoria/templates/model_migration.rb.erb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class <%= migration_class_name %> < ActiveRecord::Migration[<%= ActiveRecord::Migration.current_version %>]
+  def change
+    create_table :<%= domain_prefixed_relation_name %><%= primary_key_type %> do |t|
+<% attributes.each do |attribute| -%>
+<% if attribute.password_digest? -%>
+      t.string :password_digest<%= attribute.inject_options %>
+<% elsif attribute.token? -%>
+      t.string :<%= attribute.name %><%= attribute.inject_options %>
+<% elsif attribute.reference? -%>
+      t.<%= attribute.type %> :<%= attribute.name %><%= attribute.inject_options %><%= foreign_key_type %>
+<% elsif !attribute.virtual? -%>
+      t.<%= attribute.type %> :<%= attribute.name %><%= attribute.inject_options %>
+<% end -%>
+<% end -%>
+<% if options[:timestamps] %>
+      t.timestamps
+<% end -%>
+    end
+<% attributes.select(&:token?).each do |attribute| -%>
+    add_index :<%= table_name %>, :<%= attribute.index_name %><%= attribute.inject_index_options %>, unique: true
+<% end -%>
+<% attributes_with_index.each do |attribute| -%>
+    add_index :<%= table_name %>, :<%= attribute.index_name %><%= attribute.inject_index_options %>
+<% end -%>
+  end
+end