CLAUDE.md for PHP: 13 Rules That Make AI Write Modern, Secure, Idiomatic PHP

If you're using Claude or another AI assistant for PHP development without a CLAUDE.md , you've seen this pattern: the AI generates working code, but it's PHP 5-era style — no type hints, mysql_* functions, procedural globals, or die() error handling. PHP has evolved dramatically. PHP 8.x has union types, enums, fibers, named arguments, match expressions, and readonly properties. Modern PHP is a different language from what most AI training data contains. Without explicit rules, AI defaults to t