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:

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