Storefront, performance, and errors

Storefront

• Support viewports for mobile, tablet, and desktop.
• No inline CSS in storefront templates. Use your own classes and compile CSS with the plugin. See Add SCSS variables.
• Avoid !important unless it is unavoidable.
• Design for accessibility; the extension must not break the overall look of the store and must be responsive.

Performance

• The extension must not measurably impair store or server performance.
• Stability under load matters for review: avoid severe performance regressions.
• Run a Google Lighthouse audit before and after activating the extension. Significant regressions in performance, accessibility, best practices, or SEO can fail review.

Errors and HTTP behavior

• No JavaScript or console errors in the storefront or checkout. Test the full Storefront with the browser developer tools.
• No HTTP 500 errors.
• No 404s introduced by the extension.
• No 400/500 responses except when tied to a documented API call.
• Error messages must clearly state what went wrong or what the user should do.
• Extensions must work without uncaught 500 errors in normal operation.

Tools

• Google Lighthouse — performance and quality audits.
• Google Rich Results Test — use together with SEO and structured data when you change product or listing markup.

After uninstalling the extension, Shopping Experiences must keep working in the storefront. See Uninstallation and data cleanup for data and CMS cleanup rules.