Fix test failures: restore PackerUtils logic and update bin/dev tests

- Restore proper PackerUtils.using_packer? logic from master branch
- Fix precompile? method to handle missing shakapacker properly
- Update bin/dev tests to match new simplified template structure
- Update server_manager_spec to expect Open3.capture3 instead of system

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

lib/react_on_rails/packer_utils.rb

@@ -3,11 +3,20 @@
 module ReactOnRails
   module PackerUtils
     def self.using_packer?
-      true
+      using_shakapacker_const?
+    end
+
+    def self.using_shakapacker_const?
+      return @using_shakapacker_const if defined?(@using_shakapacker_const)
+
+      @using_shakapacker_const = ReactOnRails::Utils.gem_available?("shakapacker") &&
+                                 shakapacker_version_requirement_met?("8.2.0")
     end
 
     def self.packer_type
-      "shakapacker"
+      return "shakapacker" if using_shakapacker_const?
+
+      nil
     end
 
     def self.packer
@@ -84,7 +93,9 @@ def self.asset_uri_from_packer(asset_name)
     end
 
     def self.precompile?
-      ::Shakapacker.config.shakapacker_precompile?
+      return ::Shakapacker.config.shakapacker_precompile? if using_shakapacker_const?
+
+      false
     end
 
     def self.packer_source_path

spec/react_on_rails/binstubs/dev_spec.rb

@@ -3,7 +3,7 @@
 require "react_on_rails/dev"
 
 RSpec.describe "bin/dev script" do
-  let(:script_path) { "lib/generators/react_on_rails/bin/dev" }
+  let(:script_path) { "lib/generators/react_on_rails/templates/base/base/bin/dev" }
 
   # To suppress stdout during tests
   original_stderr = $stderr
@@ -40,36 +40,20 @@ def setup_script_execution_for_tool_tests
     expect(script_content).to include("require \"react_on_rails/dev\"")
   end
 
-  it "supports static development mode" do
+  it "delegates to ServerManager command line interface" do
     script_content = File.read(script_path)
-    expect(script_content).to include("ReactOnRails::Dev::ServerManager.start(:static")
-  end
-
-  it "supports production-like mode" do
-    script_content = File.read(script_path)
-    expect(script_content).to include("ReactOnRails::Dev::ServerManager.start(:production_like")
-  end
-
-  it "supports help command" do
-    script_content = File.read(script_path)
-    expect(script_content).to include('when "help", "--help", "-h"')
-    expect(script_content).to include("ReactOnRails::Dev::ServerManager.show_help")
-  end
-
-  it "supports kill command" do
-    script_content = File.read(script_path)
-    expect(script_content).to include("ReactOnRails::Dev::ServerManager.kill_processes")
+    expect(script_content).to include("ReactOnRails::Dev::ServerManager.run_from_command_line")
   end
 
   it "with ReactOnRails::Dev loaded, delegates to ServerManager" do
     setup_script_execution_for_tool_tests
-    allow(ReactOnRails::Dev::ServerManager).to receive(:start)
+    allow(ReactOnRails::Dev::ServerManager).to receive(:run_from_command_line)
 
     # Mock the require to succeed
     allow_any_instance_of(Kernel).to receive(:require).with("bundler/setup").and_return(true)
     allow_any_instance_of(Kernel).to receive(:require).with("react_on_rails/dev").and_return(true)
 
-    expect(ReactOnRails::Dev::ServerManager).to receive(:start).with(:development, "Procfile.dev")
+    expect(ReactOnRails::Dev::ServerManager).to receive(:run_from_command_line).with(ARGV)
 
     load script_path
   end

spec/react_on_rails/dev/server_manager_spec.rb

@@ -54,8 +54,8 @@ def mock_system_calls
     end
 
     it "starts production-like mode" do
-      command = "RAILS_ENV=production NODE_ENV=production bundle exec rails assets:precompile"
-      expect_any_instance_of(Kernel).to receive(:system).with(command).and_return(true)
+      command = "NODE_ENV=production bundle exec rails assets:precompile"
+      expect(Open3).to receive(:capture3).with(command).and_return(["output", "", double(success?: true)])
       expect(ReactOnRails::Dev::ProcessManager).to receive(:ensure_procfile).with("Procfile.dev-prod-assets")
       expect(ReactOnRails::Dev::ProcessManager).to receive(:run_with_process_manager).with("Procfile.dev-prod-assets")