A quick debugging checklist for those “works for me/breaks for customers” add-to-cart issues:
- Console errors on the affected device
- Network failures (401/403/429/CORS) around cart calls
- CSP changes blocking scripts
- Mobile-only theme JS differences (cart drawer etc.)
- Test with a clean theme or disable the last app/change
If it’s flaky, capturing a Playwright trace has been the only way I’ve found to make the repro repeatable.
What else do you all check first?