A real Next.js modernization produced a playbook — and instead of letting it rot in a wiki, I turned it into a tested AI agent skill. The arc: capture the bruises, convert ordering into gates, pitfalls into tripwires, checks into code, and prove it with baselined evals (14/14 vs 7/14).
I moved my portfolio's Postgres from Neon to Supabase in one evening — and the real reason it was easy is timing. The cheap-migration-window thesis, plus the adapter swap, pooler modes, restore ordering, and the username gotcha.
A $19.95/month plan whose only job was delivering my own contact form — until a paywall forced the audit. The one-evening SendGrid-to-Resend migration, and a four-signal framework for spotting vendor inertia.
The production-proven stack from my portfolio rebuild — Next.js 16, Payload, Tailwind v4, Clerk, the AI SDK, and a real testing spine — plus the upgrade discipline that matters more than any single tool choice.
A field report from replacing a five-system Notion content pipeline with Payload embedded in Next.js: what the workspace-tool era got right, where it broke down, and the architecture decisions worth stealing.
