How do I extend the reviewer with my own org-specific rules?

Edit .claude/agents/code-reviewer.md. Add a ## Org-specific rules section with concrete prohibitions: "No new dependencies in composer.json without architecture-team approval. All new admin controllers must extend Vendor\Common\Controller\Adminhtml\Base. All new emails must use the Vendor_Email template loader, not Magento_Email." The agent treats these the same as the built-in EQP rules. For pattern-based rules (regex matches) that the model would miss, add a PostToolUse hook that runs a literal grep and feeds findings back. Treat the code-reviewer.md file as living documentation — it is the source of truth for what "shippable" means in your org.