06.01 — Vercel Edge stack#

`package.json`#

{
  "name": "tests-workers",
  "version": "1.0.0",
  "scripts": {
    "vercel-build": "echo 'Build skipped'"
  },
  "packageManager": "pnpm@11.2.2",
  "dependencies": {
    "@upstash/redis": "^1.36.2",
    "otplib": "^13.2.1"
  },
  "devDependencies": {
    "@types/node": "^25.2.0",
    "next": "^16.1.6",
    "@vercel/node": "^5.5.28",
    "typescript": "^5.9.3"
  },
  "license": "ISC"
}

Lib	Role
`@upstash/redis` (runtime)	REST Redis client (no TCP). Edge-compatible.
`otplib` (runtime)	RFC 6238 TOTP generation.
`next` (dev only)	Types only (`NextRequest`). No Next.js app.
`@vercel/node` (dev only)	Vercel types.
`@types/node` (dev only)	Node 22+ types.

No runtime dependency beyond @upstash/redis + otplib. Bundle is microscopic → cold start < 100ms.

`vercel.json`#

{
  "version": 2,
  "buildCommand": "echo 'No build required'",
  "outputDirectory": ".",
  "framework": null
}

Field	Value	Effect
`version: 2`	Vercel v2	—
`buildCommand: "echo 'No build required'"`	No build	TypeScript is transpiled on the fly by the Vercel runtime
`outputDirectory: "."`	Repo root	No `dist/` to produce
`framework: null`	No framework detected	Vercel doesn’t auto-config

The Edge runtime#

Each endpoint declares:

export const config = { runtime: "edge" };

Aspect	Edge Functions	Node Serverless
Cold start	< 50ms	200–500ms
Memory	~128 MB	up to 3 GB
Node API	Limited (no `fs`, `child_process`)	Full Node
Geo	Co-located with the user	Single region
`fetch`, `crypto.getRandomValues`, `URL`	Native	Native
Pricing	Cheaper	More expensive

For 3 endpoints that do only HTTP + Redis, Edge is the right pick.

Why `next` is in `devDependencies`#

import type { NextRequest } from "next/server";

tests-workers uses Next.js for one thing: the NextRequest type. No Next.js app. Vercel publishes those types because they’re compatible with Edge Functions.

At runtime the object is a standard Request, but typed as NextRequest for autocomplete on searchParams helpers and friends.

Why Upstash rather than a classic Redis#

Classic Redis (TCP)	Upstash (REST)
Persistent connection	HTTP per request
Not Edge-compatible	Edge-compatible
Faster on multi-ops	Simpler on single-op
Self-hosted or managed	Managed (Cloudflare-style)

Edge has no TCP socket. Upstash exposes Redis over HTTP+REST.

`API_SECRET`#

const API_SECRET = process.env.API_SECRET;

Read at cold start. Stays in memory for the lifetime of the worker instance (which can serve N requests).

`UPSTASH_REDIS_REST_*`#

// lib/redis.ts
const redis = new Redis({
  url: process.env.UPSTASH_REDIS_REST_URL,
  token: process.env.UPSTASH_REDIS_REST_TOKEN,
});

UPSTASH_REDIS_REST_URL: the HTTPS URL of the Upstash Redis.
UPSTASH_REDIS_REST_TOKEN: the Bearer token to authenticate.

vercel env add ... (see README).

Why only 3 endpoints#

Endpoint	Why
`/api/otp?_user=<u>`	Generates an OTP for the MFA login test
`/api/otp-history`	Gives Ocarina the OTP Igoristan just generated
`/api/corsicadex?id=N`	Provides data for the “Corsican Pokédex” page

No webhook, no polling, no DB other than Redis. The bare minimum.

06.01 — Vercel Edge stack#

package.json#

vercel.json#