@seamstack/fastify

Fastify backend adapter for SeamStack — mounts a Seam frontend as a Fastify plugin and serves built assets.

pnpm add @seamstack/fastify fastify

Usage

Wire the adapter in seam.config.ts:

import { defineWeave } from '@seamstack/cli'
import vite from '@seamstack/vite/adapter'
import fastify from '@seamstack/fastify/adapter'

export default defineWeave({
  fabric: [vite({ root: './client' }), fastify({ entry: './server/index.ts' })],
  port: 4567,
})

In your Fastify server, destructure { inlay, host, port } from seam() and register inlay after your routes:

import Fastify from 'fastify'
import { seam } from '@seamstack/fastify'

const app = Fastify()
app.get('/api/hello', async () => ({ msg: 'hi from fastify' }))

const { inlay, host, port } = seam()
await app.register(inlay)

await app.listen({ host, port })
console.log(`[fastify] listening on http://${host}:${port}`)

inlay is inert in dev (Vite/Astro/Angular handle the frontend then). In prod it serves the built SPA via @fastify/static from the manifest written by seam build.

More

See the SeamStack README for the bigger picture, the mix-and-match support table, and CLI docs.