Succinix
Succinix is a project terminal environment that runs in the browser. It gives a web app one configured workspace, terminal, command runner, and persistence layer instead of asking it to imitate a terminal in the UI.
What It Is
Succinix runs inside WebContainer. Node.js, Python, and common Unix commands see the same project files; the browser only renders the terminal and forwards input. It can also be embedded in another application as a Cordis plugin.
What It Is For
- Create, edit, and run projects in the browser without a local Node.js or Python installation.
- Use
node,npm,npx,python,pip, and common Unix commands on the same files. - Start development servers and open their browser preview URLs.
- Save workspace state, settings, and snapshots across refreshes.
- Give Cordis plugins file access, command confinement, terminal sessions, and session persistence.
The limits are deliberate: Chromium only; ports are browser previews, not public services; Python runs scripts but has no general REPL; native binaries, apt, and real permission isolation are unavailable.
How To Use It
Run the standalone app
npm install
npm run dev
Open http://localhost:7892, then enter help. A typical workflow is:
npm create vite@latest demo
cd demo
npm install
npm run dev
Use ports to find the preview URL, snapshot save to keep the workspace, and succinix doctor to check the environment.
Embed it in an application
Install the dependencies and publish the engine assets as static files. Installing the npm package alone does not make those files available to the browser.
npm install @succinix/engine@0.7.0 @deepseek-ai/cordis @webcontainer/api
mkdir -p public/engine
cp -R node_modules/@succinix/engine/assets/. public/engine/
Configure the plugin, attach the WebContainer created by the application, then create the default instance:
import { Context } from '@deepseek-ai/cordis'
import engine from '@succinix/engine'
import { WebContainer } from '@webcontainer/api'
const ctx = new Context()
const fiber = ctx.plugin(engine, {
hostJsUrl: '/engine/host.js',
lifoCoreUrl: '/engine/lifo-core.js',
pythonAssetsUrl: '/engine/pyodide/',
container: { mode: 'external' },
defaultInstance: {
instanceId: 'default',
persistence: { dbName: 'my-app', storeKey: 'default' },
},
})
await fiber
const host = ctx.get('succinix', false)!
await host.attach(await WebContainer.boot())
await host.ensureInstance('default', { executor: {} })
await host.executor.exec('npm run dev')
Application plugins explicitly inject fs, sandbox, terminals, and sessionPersistence as needed. Use ctx.get('succinix', false) only when managing the host lifecycle, instances, ports, or executor.
Documentation
- Features: decide whether Succinix fits the task.
- Runtimes: supported languages, packages, and limits.
- Integration: embed Succinix in a Cordis application.
- Third-party plugins: write a Cordis plugin that uses Succinix.
- Migration: upgrade older integrations.
- Protocol and contract: only for host, transport, or strict compatibility work.
Development Checks
npx tsc -p tsconfig.json --noEmit
node scripts/build-host.mjs
npm run build
npm run lint
npm run test
npm run check:docs
See AGENTS.md for the complete quality gates.