Data access
Database rules, who can read whose records, admin keys leaking to the browser.
Login and roles
Server-side checks on every route, password reset, invitations, account takeover.
Payments
Webhook verification, retries, refunds, access granted from real payment state.
AI cost and safety
Spend caps per user, prompt injection, unsafe rendering of model output.
Secrets
Keys in code, git history, public env vars and preview deploys.
Rebuildability
Can the database and app be rebuilt from the repo alone if something goes wrong?
Deploys
Staging that touches production, missing CI, outdated dependencies.
Email delivery
SPF, DKIM, DMARC, so signup and password emails don't land in spam.
Monitoring
Error tracking, logs without passwords or tokens, uptime alerts.
Performance
Page weight and load time on a normal phone, slow queries.
Privacy
What you collect versus what your policy says. Health or finance data flagged.
Handover
Could a new developer, or an AI agent, safely change it next month?