Move Rails environment require before precompile tasks

Load the Rails environment at script startup rather than lazily inside
the locale generation step. This ensures ReactOnRails configuration is
available before any precompile tasks run.

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

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: justin808

bin/dev

@@ -7,6 +7,12 @@
 # server management. The core logic is implemented in ReactOnRails::Dev
 # classes for better maintainability and testing.
 #
+# Before starting the Procfile processes, this script runs precompile tasks:
+# 1. rescript:build - Compiles .res files to .res.js
+# 2. react_on_rails:locale - Generates i18n JavaScript files
+#
+# This ensures all generated files exist before webpack starts watching.
+#
 # Each command uses a specific Procfile for process management:
 # - bin/dev (default/hmr): Uses Procfile.dev
 # - bin/dev static: Uses Procfile.dev-static-assets
@@ -20,6 +26,41 @@
 
 require "bundler/setup"
 require "react_on_rails/dev"
+require_relative "../config/environment"
+
+# Run precompile tasks before starting development server
+# This ensures rescript and locale files are generated before webpack starts
+def run_precompile_tasks
+  puts "📦 Running precompile tasks..."
+
+  # Build ReScript files first
+  print "   ReScript build... "
+  if system("yarn res:build > /dev/null 2>&1")
+    puts "✅"
+  else
+    puts "❌"
+    puts "   Failed to build ReScript files. Run 'yarn res:build' to see errors."
+    exit 1
+  end
+
+  # Generate locale files using ReactOnRails directly (avoids shell Ruby version issues)
+  print "   Locale generation... "
+  begin
+    ReactOnRails::Locales.compile
+    puts "✅"
+  rescue StandardError => e
+    puts "❌"
+    puts "   Failed to generate locales: #{e.message}"
+    exit 1
+  end
+
+  puts ""
+end
+
+# Run precompile before starting the server (unless running kill or help commands)
+unless ARGV.include?("kill") || ARGV.include?("-h") || ARGV.include?("--help")
+  run_precompile_tasks
+end
 
 # Main execution
 ReactOnRails::Dev::ServerManager.run_from_command_line(ARGV)