LegacyCore + Vercel Integration

The problem

An insurance fulfillment platform has two completely different runtime profiles in a single codebase. The marketing surface needs to be globally fast and SEO-perfect because LLM search engines and Google both rank on first-byte latency. The application surface needs to handle webhook bursts, long-running cron jobs, authenticated agent traffic, and webhook signatures verified per request — without paying for idle capacity. Stitching that together on raw cloud infrastructure is possible but expensive in engineering hours we would rather spend on the AI agent stack.

How the integration works

LegacyCore runs as a Next.js 14 application on Vercel in standalone build mode. The marketing pages — home, partners, integrations, FAQ, pricing — render as cached static HTML at the Edge Network with sub-100ms time-to-first-byte from anywhere in North America. The authenticated portal and API surface run as serverless functions, which means cold starts only on the first request after a quiet period and zero cost when traffic is idle.

Vercel Cron drives the background jobs that keep the platform alive: the conservation outreach scheduler, the webhook retry queue, the carrier-sync poller, and the daily report aggregator. Every cron entry has matching crons and functions blocks in vercel.json — a pattern we hard-learned when an early cron job silently failed to fire because only one of the two was registered. Fire-and-forget post-response work uses waitUntil() from @vercel/functions, not bare promises, which we hard-learned when a Hermes CS fanout was getting killed mid-flight by lambda termination.

We pin the next dependency to exact 14.2.35 — no caret — because npm audit fix has been observed silently upgrading it to 16.x and breaking the build. Node version is pinned to 20.x in package.json engines because Vercel defaults to 24.x without it and our native dependencies do not all support 24 cleanly. NODE_ENV is never set as a project env var because Vercel sets it automatically and a manual override poisons the runtime, including undici’s TLS validation on internal self-calls.

Why Vercel specifically

Vercel is the only hosting provider where Next.js gets first-party treatment, and Next.js is the right framework for a hybrid marketing-plus-application surface like ours. The Edge Network performance, the deploy preview model, the cron primitive, and the env-var pipeline together remove an entire category of infrastructure work we would otherwise have to staff for. Cost scales with traffic, not with idle capacity, which matters when traffic is bursty by design.

Read the docs

Full Vercel documentation lives at vercel.com/docs. The Edge Network, serverless function model, and Cron primitive we depend on are all documented there.