comark-arrow

A Comark plugin for ArrowJS sandboxed widgets.

Turn a ```arrow fence (or ::arrow) into a live, interactive widget — with no upfront component registration. Agent-authored source runs inside @arrow-js/sandbox (QuickJS/WASM), not in the host page realm.

Install

pnpm add comark-arrow @arrow-js/sandbox

comark is a peer dependency. @arrow-js/sandbox is required for the Vue renderer (optional if you only parse).

For the Vue renderer:

pnpm add vue @comark/vue

Usage

Plugin only (parse)

import { parseMarkdown } from 'comark'
import arrow from 'comark-arrow'

const tree = await parseMarkdown(content, {
  plugins: [arrow()],
})

Vue (interactive)

import arrow, { ArrowSandbox, provideArrowHostBridge } from 'comark-arrow/vue'
// <Markdown :plugins="[arrow()]" :components="{ ArrowSandbox }" />

Fenced block

```arrow {height="120px"}
const state = reactive({ count: 0 })

export default html`
  <button @click="${() => state.count++}">
    Clicked ${() => state.count}
  </button>
`
```

```arrow-css
button { font: inherit; padding: 0.5rem 1rem; }
```

Optional adjacent ```arrow-css supplies main.css.

Bound directive

::arrow{:source="widgets.reorderCalculator"}
::

Both forms emit the same ['ArrowSandbox', attrs] AST node.

Streaming

Comark does not close unterminated code fences. While the host is streaming, pass a getter so the last open fence stays non-executable:

arrow({ streaming: () => isStreaming.value })

Pair with <Markdown :streaming="isStreaming">. Incomplete frames get status: 'pending'; <ArrowSandbox> shows a placeholder and never boots the VM.

hostBridge

Expose allowlisted host functions to sandboxed code. Never put bridge functions on the AST — supply them from the app:

provideArrowHostBridge({
  'host-bridge:erp': {
    getStockLevel: (sku) => inventory.read(String(sku)),
  },
})

// inside the sandboxed block
import { getStockLevel } from 'host-bridge:erp'

Prefer read-only bridge names. Mutating functions are an explicit host opt-in (route writes through a confirmation step in the host app).

Security

• Agent-authored source runs only inside QuickJS/WASM (R9.1).
• Isolation is not correctness — review generated widgets like generated numbers (R9.6).
• Upstream @arrow-js/sandbox still bridges a restricted fetch() (https, no credentials, 15s, 1 MB) and timers. Host cookies and DOM stay unreachable.
• If you use security({ allowedTags: [...] }), include ArrowSandbox in the allowlist.
• Pin @arrow-js/sandbox to 1.0.6 (Early Access). Re-check the API on upgrade.

Static fallbacks

Non-executing targets (HTML string, ANSI, PDF, email) must not boot the VM:

import arrow from 'comark-arrow'
import { ArrowSandbox } from 'comark-arrow/html'
// createHtmlRenderer({ plugins: [arrow()], components: { ArrowSandbox } })

Fence attr or plugin option fallback: source | placeholder | caption (default).

SSR / Nuxt: the Vue component mounts the sandbox only in onMounted.

Vite hosts: @arrow-js/sandbox does import ts from 'typescript'. Pre-bundle TypeScript so the default export works:

// vite.config / nuxt.config → vite.optimizeDeps
optimizeDeps: {
  include: ['typescript', '@arrow-js/sandbox', 'quickjs-emscripten'],
},

Development

pnpm install
pnpm play       # tsx playground against the plugin
pnpm play:nuxt  # Nuxt docs + playground site
pnpm test
pnpm build

License

MIT