How to disable stimulus:manifest:update when generating a stimulus controller

On Rails 7, when I run rails generate stimulus controller_name, rails stimulus:manifest:update is automatically triggered. Is there any way to disable this hook ?

This is not optional (unless you have importmap.rb):
https://github.com/hotwired/stimulus-rails/blob/v1.2.1/lib/generators/stimulus/stimulus_generator.rb#L9

Two solutions:

Make a generator

You could make your own generator and use it instead of bin/rails g stimulus:

$ rails g generator stimulus/controller

# lib/generators/stimulus/controller_generator.rb

require "generators/stimulus/stimulus_generator"

class Stimulus::ControllerGenerator < StimulusGenerator
  # +++
  source_root superclass.source_root

  # -m to update manifest, otherwise no update
  class_option :manifest, type: :boolean, default: false, aliases: "-m"
  # -M to skip manifest, otherwise update
  # class_option :skip_manifest, type: :boolean, default: false, aliases: "-M"
  # ###

  def copy_view_files
    @attribute = stimulus_attribute_value(controller_name)
    template "controller.js", "app/javascript/controllers/#{controller_name}_controller.js"

    # +++
    return if !options[:manifest]         # no update by default
    # return if options[:skip_manifest]   # update by default
    # ###

    rails_command "stimulus:manifest:update" unless Rails.root.join("config/importmap.rb").exist?
  end
end

$ bin/rails g stimulus:controller test
      create  app/javascript/controllers/test_controller.js

$ bin/rails g stimulus:controller test -m
   identical  app/javascript/controllers/test_controller.js
       rails  stimulus:manifest:update

Skip "stimulus:manifest:update" task

This is a simpler option to make the default bin/rails g stimulus skip the update:

# lib/tasks/skip_stimulus_manifest.rake

Rake::Task["stimulus:manifest:update"].clear

namespace :stimulus do
  namespace :manifest do
    task :update do
      puts "Skipping manifest update"
    end
  end
end

$ bin/rails g stimulus test
   identical  app/javascript/controllers/test_controller.js
       rails  stimulus:manifest:update
Skipping manifest update