Most regressions are boring: a missing meta title on a new template, a banner that shifts layout, a script added “temporarily.” A short pre-deploy gate beats heroic firefighting.
Before you merge
- Hit the changed URLs on preview: title, H1, canonical, and no accidental noindex.
- Keyboard through any new modal, menu, or form once.
- Confirm images have dimensions; no lazy-load on above-the-fold LCP media.
- Check response headers on the preview host if you changed CSP or cookies.
Right after deploy
- Smoke the homepage, sign-in, and one revenue path.
- Watch error rate and p95 latency for 15–30 minutes.
- Run or schedule an audit on the touched templates.
- Verify redirects if URLs moved — old links should land cleanly.
When to block the release
Block on broken auth/checkout, security header removals you didn’t intend, or LCP/CLS collapses on primary landing pages. Don’t block on every low-severity lint — park those in the backlog with an owner.
Keep the checklist short
If the gate takes half an hour, people skip it. Aim for five to ten minutes of human checks plus automated scans. Expand only when a class of incident keeps repeating.
Health Mesh fits here as the automated half: scan after deploy, compare to the previous run, and catch regressions while rollback is still cheap.