Craft CMS 5 PHP Guidelines

Complete PHP coding standards and conventions for Craft CMS 5 plugin and module development. These extend Craft's official coding guidelines with project-specific conventions.

Core principles: PHPDocs on everything — classes, methods, and properties — regardless of type hints. No declare(strict_types=1) in plugin source files (matching Craft core convention).

Companion Skills — Always Load Together

• craftcms — Architecture patterns, element lifecycle, controllers, events, migrations. Required for any Craft plugin or module development.
• ddev — All commands run through DDEV. Required for running ECS, PHPStan, scaffolding, and tests.

Documentation

• Official coding guidelines: https://craftcms.com/docs/5.x/extend/coding-guidelines.html
• Class reference: https://docs.craftcms.com/api/v5/
• Generator reference: https://craftcms.com/docs/5.x/extend/generator.html

When unsure about a convention, WebFetch the coding guidelines page for the authoritative answer.