vega.app()

Creates an app. One project deploys one app; export it from the file named in vega.json.

api/index.ts

import { vega } from '@vega/sdk';

export const api = vega.app({ region: 'global' });

Options

Option	Type	Default	Description
region	'global' | string[]	'global'	Deploy everywhere, or pin to specific region codes
cache	{ ttl?: number; stale?: number }	{ ttl: 60, stale: 600 }	Default freshness for cache.swr() calls
onError	(error, ctx) => Response	JSON 500	Called for uncaught handler errors; the error is already recorded on the trace

export const api = vega.app({
  region: ['fra', 'lhr', 'ams'],
  cache: { ttl: 300, stale: 3600 },
  onError: (error, ctx) =>
    Response.json({ error: 'internal_error', trace: ctx.trace.id }, { status: 500 }),
});

Route methods

app.get, app.post, app.put, app.patch, app.delete, and app.all register a handler for a path pattern:

api.get('/users/:id', async ({ params }) => {
  const user = await db.users.find(params.id);
  if (!user) return Response.json({ error: 'not_found' }, { status: 404 });
  return Response.json(user);
});

Handlers receive a single Context and return a Response (or a promise of one). app.all matches every method and is checked after method-specific routes.

app.use()

Registers middleware, run in registration order before the matched handler:

api.use(async (ctx, next) => {
  const start = performance.now();
  const res = await next();
  res.headers.set('server-timing', `app;dur=${(performance.now() - start).toFixed(1)}`);
  return res;
});

Return early without calling next() to short-circuit — the usual shape for auth:

api.use(async (ctx, next) => {
  if (!ctx.request.headers.get('authorization')) {
    return Response.json({ error: 'unauthorized' }, { status: 401 });
  }
  return next();
});

app.mount()

Mounts a router under a prefix:

import { users } from './routes/users';

api.mount('/v1/users', users);

app.fetch()

The app is a standard fetch handler, which makes tests dependency-free:

api/index.test.ts

import { api } from './index';

const res = await api.fetch(new Request('http://test/health'));
expect(res.status).toBe(200);

No server, no port — handlers, middleware, and routing all run exactly as deployed.