Fix: Universal process manager bundler context fallback

lib/react_on_rails/dev/process_manager.rb

@@ -1,14 +1,18 @@
 # frozen_string_literal: true
 
+require "timeout"
+
 module ReactOnRails
   module Dev
     class ProcessManager
+      # Timeout for version check operations to prevent hanging
+      VERSION_CHECK_TIMEOUT = 5
+
       class << self
+        # Check if a process is available and usable in the current execution context
+        # This accounts for bundler context where system commands might be intercepted
         def installed?(process)
-          IO.popen([process, "-v"], &:close)
-          true
-        rescue Errno::ENOENT
-          false
+          installed_in_current_context?(process)
         end
 
         def ensure_procfile(procfile)
@@ -31,20 +35,124 @@ def run_with_process_manager(procfile)
           # Clean up stale files before starting
           FileManager.cleanup_stale_files
 
-          if installed?("overmind")
-            system("overmind", "start", "-f", procfile)
-          elsif installed?("foreman")
-            system("foreman", "start", "-f", procfile)
+          # Try process managers in order of preference
+          return if run_process_if_available("overmind", ["start", "-f", procfile])
+          return if run_process_if_available("foreman", ["start", "-f", procfile])
+
+          show_process_manager_installation_help
+          exit 1
+        end
+
+        private
+
+        # Check if a process is actually usable in the current execution context
+        # This is important for commands that might be intercepted by bundler
+        def installed_in_current_context?(process)
+          # Try to execute the process with version flags to see if it works
+          # Use system() because that's how we'll actually call it later
+          version_flags_for(process).any? do |flag|
+            # Add timeout to prevent hanging on version checks
+            Timeout.timeout(VERSION_CHECK_TIMEOUT) do
+              system(process, flag, out: File::NULL, err: File::NULL)
+            end
+          end
+        rescue Errno::ENOENT, Timeout::Error
+          false
+        end
+
+        # Get appropriate version flags for different processes
+        def version_flags_for(process)
+          case process
+          when "overmind"
+            ["--version"]
+          when "foreman"
+            ["--version", "-v"]
           else
-            warn <<~MSG
-              NOTICE:
-              For this script to run, you need either 'overmind' or 'foreman' installed on your machine. Please try this script after installing one of them.
-            MSG
-            exit 1
+            ["--version", "-v", "-V"]
           end
         end
 
-        private
+        # Try to run a process if it's available, with intelligent fallback strategy
+        # Returns true if process was found and executed, false if not available
+        def run_process_if_available(process, args)
+          # First attempt: try in current context (works for bundled processes)
+          return system(process, *args) if installed?(process)
+
+          # Second attempt: try in system context (works for system-installed processes)
+          return run_process_outside_bundle(process, args) if process_available_in_system?(process)
+
+          # Process not available in either context
+          false
+        end
+
+        # Run a process outside of bundler context
+        # This allows using system-installed processes even when they're not in the Gemfile
+        def run_process_outside_bundle(process, args)
+          if defined?(Bundler)
+            with_unbundled_context do
+              system(process, *args)
+            end
+          else
+            # Fallback if Bundler is not available
+            system(process, *args)
+          end
+        end
+
+        # Check if a process is available system-wide (outside bundle context)
+        def process_available_in_system?(process)
+          return false unless defined?(Bundler)
+
+          with_unbundled_context do
+            # Try version flags to check if process exists outside bundler context
+            version_flags_for(process).any? do |flag|
+              # Add timeout to prevent hanging on version checks
+              Timeout.timeout(VERSION_CHECK_TIMEOUT) do
+                system(process, flag, out: File::NULL, err: File::NULL)
+              end
+            end
+          end
+        rescue Errno::ENOENT, Timeout::Error
+          false
+        end
+
+        # DRY helper method for Bundler context switching with API compatibility
+        # Supports both new (with_unbundled_env) and legacy (with_clean_env) Bundler APIs
+        def with_unbundled_context(&block)
+          if Bundler.respond_to?(:with_unbundled_env)
+            Bundler.with_unbundled_env(&block)
+          elsif Bundler.respond_to?(:with_clean_env)
+            Bundler.with_clean_env(&block)
+          else
+            # Fallback if neither method is available (very old Bundler versions)
+            yield
+          end
+        end
+
+        # Improved error message with helpful guidance
+        def show_process_manager_installation_help
+          warn <<~MSG
+            ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+            ERROR: Process Manager Not Found
+            ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+            To run the React on Rails development server, you need either 'overmind' or
+            'foreman' installed on your system.
+
+            RECOMMENDED INSTALLATION:
+
+              macOS:    brew install overmind
+              Linux:    gem install foreman
+
+            IMPORTANT:
+            DO NOT add foreman to your Gemfile. Install it globally on your system.
+
+            For more information about why foreman should not be in your Gemfile, see:
+            https://github.com/shakacode/react_on_rails/blob/master/docs/javascript/foreman-issues.md
+
+            After installation, try running this script again.
+            ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+          MSG
+        end
 
         def valid_procfile_path?(procfile)
           # Reject paths with shell metacharacters