Worked on the Shopify/rails repository to stabilize bundled templates during the transition to Herb 0.10+. Focused on resolving HTML-aware ERB compiler errors, enabling all templates to compile cleanly and comply with stricter validation requirements. Addressed issues in routing error templates, mailer previews, and the layout switcher, which improved HTML correctness and reduced stray artifacts in rendered output. Utilized Ruby, ERB, and Ruby on Rails to ensure template reliability and prepare the codebase for future Herb upgrades. This work enhanced the maintainability of the template system and strengthened the safety of the upgrade path for the Herb gem.