app/Http/Controllers).declare(strict_types=1);.ValidationRule interface for custom rules.Str, to_route, etc.).Handler using reportUsing() and renderUsing() for cleaner error reporting.public, protected, private) for all class constants.#[\Override] attribute for all overridden methods to ensure override correctness.json_validate() to safely check JSON strings before decoding.public const string STATUS = 'active';) for stricter contracts.$class::{$constant}).array_map([ClassName::class, 'method'], $items)).readonly properties to be mutable only within constructors when using readonly classes.[ClassName::method]($arg) syntax for first-class callables once supported.__getProperty(), __setProperty()) if implemented; prefer explicit accessors.readonly classes for immutable DTOs and service response models.