diff --git a/test/builder_test.rb b/test/builder_test.rb
index ec2ad1d1..86120747 100644
--- a/test/builder_test.rb
+++ b/test/builder_test.rb
@@ -84,7 +84,7 @@ def test_external_env_variables
   end
 
   def test_missing_executable
-    refresh_config('VITE_RUBY_VITE_BIN_PATH' => 'none/vite')
+    refresh_config(vite_bin_path: 'none/vite')
 
     # It fails because we stub the File.exist? check, so the binary is missing.
     error = assert_raises(ViteRuby::MissingExecutableError) {
diff --git a/test/dev_server_test.rb b/test/dev_server_test.rb
index 41448957..7a6b19bd 100644
--- a/test/dev_server_test.rb
+++ b/test/dev_server_test.rb
@@ -6,12 +6,12 @@ class DevServerTest < ViteRuby::Test
   def test_not_running
     refute ViteRuby.instance.dev_server_running?
 
-    refresh_config('VITE_RUBY_MODE' => 'development')
+    refresh_config(mode: 'development')
     refute ViteRuby.instance.dev_server_running?
   end
 
   def test_running
-    refresh_config('VITE_RUBY_MODE' => 'development')
+    refresh_config(mode: 'development')
     ViteRuby.instance.instance_variable_set('@running_at', Time.now)
     assert ViteRuby.instance.dev_server_running?
   ensure
diff --git a/test/engine_rake_tasks_test.rb b/test/engine_rake_tasks_test.rb
index 3c37df7c..69bef1bc 100644
--- a/test/engine_rake_tasks_test.rb
+++ b/test/engine_rake_tasks_test.rb
@@ -58,7 +58,10 @@ def test_cli
   def test_cli_commands
     within_mounted_app_root {
       ViteRuby.commands.verify_install
-      refresh_config('VITE_RUBY_ROOT' => Dir.pwd)
+
+      ENV['VITE_RUBY_ROOT'] = Dir.pwd
+      refresh_config
+
       ViteRuby::CLI::Install.new.call
       ViteRuby.commands.verify_install
       ViteRuby::CLI::Version.new.call
@@ -70,6 +73,9 @@ def test_cli_commands
       }
       ViteRuby::CLI::Clobber.new.call(mode: ViteRuby.mode)
     }
+  ensure
+    ENV.delete('VITE_RUBY_ROOT')
+    refresh_config
   end
 
 private
@@ -88,7 +94,7 @@ def stub_runner(*args, **opts, &block)
     mock.expect(:call, [:stdout, :stderr, status]) do |*argv, **options|
       assert_equal [args, opts].flatten.reject(&:blank?), (argv + [options]).flatten.reject(&:blank?)
     end
-    ViteRuby.stub(:run, mock, &block)
+    ViteRuby.stub_any_instance(:run, ->(*stub_args, **stub_opts) { mock.call(*stub_args, **stub_opts) }, &block)
     mock.verify
   end
 
diff --git a/test/test_helper.rb b/test/test_helper.rb
index a47bc4bd..abe91c47 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -29,9 +29,8 @@ def teardown
     refresh_config
   end
 
-  def refresh_config(env_variables = ViteRuby.load_env_variables)
-    ViteRuby.env.tap(&:clear)
-    ViteRuby.reload_with(env_variables)
+  def refresh_config(**options)
+    ViteRuby.reload_with(**options).config
   end
 
   def with_rails_env(env)
diff --git a/vite_ruby/lib/vite_ruby.rb b/vite_ruby/lib/vite_ruby.rb
index c9fe2f16..d2158914 100644
--- a/vite_ruby/lib/vite_ruby.rb
+++ b/vite_ruby/lib/vite_ruby.rb
@@ -35,19 +35,11 @@ class ViteRuby
   class << self
     extend Forwardable
 
-    def_delegators :instance, :config, :commands, :run_proxy?
+    def_delegators :instance, :config, :commands, :env, :run, :run_proxy?
     def_delegators :config, :mode
 
     def instance
-      @instance ||= ViteRuby.new
-    end
-
-    # Public: Additional environment variables to pass to Vite.
-    #
-    # Example:
-    #   ViteRuby.env['VITE_RUBY_CONFIG_PATH'] = 'config/alternate_vite.json'
-    def env
-      @env ||= load_env_variables
+      @instance ||= new
     end
 
     # Internal: Refreshes the manifest.
@@ -60,21 +52,9 @@ def install_tasks
       load File.expand_path('tasks/vite.rake', __dir__)
     end
 
-    # Internal: Executes the vite binary.
-    def run(argv, **options)
-      ViteRuby::Runner.new(instance).run(argv, **options)
-    end
-
-    # Internal: Refreshes the config after setting the env vars.
-    def reload_with(env_vars)
-      env.update(env_vars)
-      @instance = nil
-      config
-    end
-
-    # Internal: Allows to obtain any env variables for configuration options.
-    def load_env_variables
-      ENV.select { |key, _| key.start_with?(ENV_PREFIX) }
+    # Internal: Creates a new instance with the specified options.
+    def reload_with(**config_options)
+      @instance = new(**config_options)
     end
 
     # Internal: Detects if the application has installed a framework-specific
@@ -90,6 +70,10 @@ def framework_libraries
 
   attr_writer :logger
 
+  def initialize(**config_options)
+    @config_options = config_options
+  end
+
   def logger
     @logger ||= Logger.new($stdout)
   end
@@ -107,6 +91,14 @@ def dev_server_running?
     @running_at = false
   end
 
+  # Public: Additional environment variables to pass to Vite.
+  #
+  # Example:
+  #   ViteRuby.env['VITE_RUBY_CONFIG_PATH'] = 'config/alternate_vite.json'
+  def env
+    @env ||= ENV.select { |key, _| key.start_with?(ENV_PREFIX) }
+  end
+
   # Public: The proxy for assets should only run in development mode.
   def run_proxy?
     config.mode == 'development'
@@ -115,6 +107,11 @@ def run_proxy?
     false
   end
 
+  # Internal: Executes the vite binary.
+  def run(argv, **options)
+    (@runner ||= ViteRuby::Runner.new(self)).run(argv, **options)
+  end
+
   # Public: Keeps track of watched files and triggers builds as needed.
   def builder
     @builder ||= ViteRuby::Builder.new(self)
@@ -127,7 +124,7 @@ def commands
 
   # Public: Current instance configuration for Vite.
   def config
-    @config ||= ViteRuby::Config.resolve_config
+    @config ||= ViteRuby::Config.resolve_config(**@config_options)
   end
 
   # Public: Enables looking up assets managed by Vite using name and type.
diff --git a/vite_ruby/lib/vite_ruby/builder.rb b/vite_ruby/lib/vite_ruby/builder.rb
index 0a7cc375..f4824b78 100644
--- a/vite_ruby/lib/vite_ruby/builder.rb
+++ b/vite_ruby/lib/vite_ruby/builder.rb
@@ -33,7 +33,7 @@ def last_build_metadata
 
   extend Forwardable
 
-  def_delegators :@vite_ruby, :config, :logger
+  def_delegators :@vite_ruby, :config, :logger, :run
 
   # Internal: Reads metadata recorded on the last build, if it exists.
   def last_build_attrs
@@ -69,7 +69,7 @@ def watched_files_digest
   def build_with_vite(*args)
     logger.info 'Building with Vite ⚡️'
 
-    stdout, stderr, status = ViteRuby.run(['build', *args])
+    stdout, stderr, status = run(['build', *args])
     log_build_result(stdout, stderr.to_s, status)
 
     status.success?
diff --git a/vite_ruby/lib/vite_ruby/cli/install.rb b/vite_ruby/lib/vite_ruby/cli/install.rb
index 13303807..549f98d2 100644
--- a/vite_ruby/lib/vite_ruby/cli/install.rb
+++ b/vite_ruby/lib/vite_ruby/cli/install.rb
@@ -72,7 +72,7 @@ def copy_template(path, to:)
   def create_configuration_files
     copy_template 'config/vite.config.ts', to: root.join('vite.config.ts')
     setup_app_files
-    ViteRuby.reload_with('VITE_RUBY_CONFIG_PATH' => config.config_path)
+    ViteRuby.reload_with(config_path: config.config_path)
   end
 
   # Internal: Installs vite and vite-plugin-ruby at the project level.