Vercel

Serverless — routes must be pre-compiled

Vercel functions have no persistent filesystem. Lacis cannot scan your routes/ directory at request time. You must run lacis build first to generate a routes manifest.

How it differs from Node/Bun

	Node / Bun	Vercel / Netlify
Config	routesDir string	ServerlessConfig object
Route discovery	loadRoutes() at startup	Pre-built manifest
Build step	Optional	Required (lacis build)

Project structure

my-app/
├── api/
│   └── [...slug].ts     ← Vercel catch-all handler
├── routes/
│   ├── users/
│   │   └── index.ts
│   └── posts/
│       └── [id]/
│           └── index.ts
└── vercel.json

API handler

// api/[...slug].ts
import { vercelAdapter } from 'lacis/adapters'
import { routes, middlewares } from '../routes/_manifest.js'

const handler = vercelAdapter.createHandler({ routes, middlewares })

export default handler

Note

createHandler initializes routes, CORS, middleware, and hooks once on first invocation and caches the result for subsequent requests in the same function instance.

vercel.json

{
  "rewrites": [
    { "source": "/(.*)", "destination": "/api/slug" }
  ]
}

Deploy flow

1. Add lacis build to your build command in package.json:

   {
     "scripts": {
       "build": "lacis build"
     }
   }

2. Commit your handler:

   git add api/ vercel.json
   git commit -m "add lacis vercel handler"

3. Deploy:

   vercel deploy --prod

   Vercel runs lacis build automatically on each deploy, regenerating the routes manifest.

Optional config

const handler = vercelAdapter.createHandler({
  routes,
  middlewares,
  cors: { origin: 'https://myapp.com', credentials: true },
  hooks: {
    onNotFound: async (req, res) => {
      res.status(404).json({ error: 'Not found', path: req.url })
    },
  },
})