sveltekit-adapter-bare

sveltekit-adapter-bare

⚠️ Highly experimental. This adapter is a proof of concept for running a SvelteKit app inside the bare runtime so it can be packaged with bare-build and rendered in a native window via bare-native. Expect rough edges, missing features, and breaking changes.

A SvelteKit adapter that produces a server bundle runnable by bare instead of Node.js. The output is a plain build/ directory you can hand to bare-build to produce a single-file, native-windowed app.

Demo: https://github.com/Drache93/bare-svelte-demo

Install

npm install --save-dev sveltekit-adapter-bare

All bare runtime deps (bare-http1, bare-fs, bare-native, bare-fetch, bare-form-data, paparam, etc.) are pulled in transitively — you don't need to declare them in your own package.json.

Configure

In svelte.config.js, swap out your adapter:

import adapter from 'sveltekit-adapter-bare'

/** @type {import('@sveltejs/kit').Config} */
const config = {
  compilerOptions: {
    // Force runes mode for the project, except for libraries. Can be removed in svelte 6.
    runes: ({ filename }) => (filename.split(/[/\\]/).includes('node_modules') ? undefined : true)
  },
  kit: {
    adapter: adapter({
      window: { width: 1200, height: 800, inspectable: false }
    }),
    csrf: { checkOrigin: false }
  }
}

export default config

Options:

option	default	description
out	'build'	Directory to emit the server bundle.
window.width	800	Native window width in pixels.
window.height	600	Native window height in pixels.
window.inspectable	false	Enable the WebView's remote DevTools inspector.

Vite plugin

Add vitePlugin() to vite.config.ts to automatically externalize all bare-* packages from Vite's SSR bundler. Without this, Vite tries to bundle native Bare modules and fails.

import { vitePlugin as bareExternals } from 'sveltekit-adapter-bare'
import { sveltekit } from '@sveltejs/kit/vite'
import { defineConfig } from 'vite'

export default defineConfig({
  plugins: [sveltekit(), bareExternals()],
  ssr: {
    // vitePlugin handles bare-* automatically; add non-bare holepunch packages manually:
    external: ['distributed-drive', 'hyperdb', 'corestore', 'hyperswarm', 'hyperdrive', ...]
  }
})

Graceful shutdown and sveltekit:close

The adapter fires sveltekit:close on process exit (Ctrl-C, SIGTERM, and native window close). Use it to tear down long-lived resources:

// src/hooks.server.ts
process.on('sveltekit:close', async () => {
  await app?.close()
})

macOS window close caveat: AppKitWindow emits will-close but the NativeWindow wrapper does not forward it. The adapter hooks win._native?.on?.('will-close', shutdown) directly, so Ctrl-X on the window triggers the same clean shutdown as Ctrl-C.

Build

Three steps — SvelteKit produces the bare-compatible server, bare-build links it for a target platform against the bare-native runtime, and bare-build wraps the result into a native app:

# 1. Vite build — the adapter emits ./build
npm run build

# 2. Build the native app for the target host/arch using the bare-native runtime
npx bare-build \
  --out build/darwin-arm64 \
  --host darwin-arm64 \
  --runtime bare-native/runtime \
  build/index.js

Swap --host / --out to target a different platform (linux-x64, android-arm64, etc.).

The emitted entry (build/index.js) is a small paparam CLI that spins up bare-http1, opens a bare-native window, and loads http://localhost:<port>:

./build/<platform>/<name>.app --width 800 --height 600 --inspectable

Flags:

• --host (default 0.0.0.0) — interface to listen on.
• --port (default 0) — TCP port. 0 asks the OS for a free port; the chosen port is logged at startup and handed to the WebView automatically.
• --width, --height — native window size (override window option from svelte.config.js).
• --inspectable — enable the WebView's remote inspector (connect from desktop Chrome via chrome://inspect).

What the adapter does

• Bundles SvelteKit's server with esbuild, aliasing node:* builtins to their bare-* equivalents.
• Patches out SvelteKit's lazy obfuscated_import("node:crypto") fallback — globalThis.crypto is assigned at startup from bare-crypto.
• Stubs node:async_hooks (bare doesn't ship an equivalent; SvelteKit's AsyncLocalStorage usage works against a minimal shim).
• Emits an assets.js module with one static import.meta.asset() call per file in client/ and prerendered/, so bare-module-traverse preserves every static asset when bare-build bundles the app.
• Correctly forwards multiple Set-Cookie headers using getSetCookie() instead of flattening them.

Known limitations

• multipart/form-data file uploads are not implemented (text fields only).
• No HTTPS, no clustering, no compression, no range requests.

License

Apache-2.0