Worker Setup (Optional)

By default, Dendrite runs the LLM engine on the main thread. This works out of the box with zero setup.

For better performance — especially during model loading and long conversations — you can offload the engine to a Web Worker. This keeps the main thread responsive.

When to Use a Worker

Scenario	Worker?
Quick prototype / testing	No — default is fine
Production chat UI	Yes — smoother UX
Long conversations (10+ turns)	Yes — main thread stays responsive
Simple single-response use	No — overhead not worth it

Setup

1. Create a Worker File

Create worker.ts (or worker.js) in your project:

// worker.ts
import { WebWorkerMLCEngineHandler } from '@mlc-ai/web-llm'

const handler = new WebWorkerMLCEngineHandler()
self.onmessage = (msg: MessageEvent) => handler.onmessage(msg)

INFO

This is the only place in your code that touches @mlc-ai/web-llm directly. Dendrite handles everything else.

2. Pass to createNeuron

const neuron = createNeuron({
  modelId: 'gemma-2-2b-it-q4f16_1-MLC',
  worker: new Worker(
    new URL('./worker.ts', import.meta.url),
    { type: 'module' }
  ),
})

The new URL('./worker.ts', import.meta.url) pattern works with Vite, Webpack 5, and most modern bundlers.

Worker Factory

If you need to create fresh workers (e.g., after model switching), pass a factory function:

worker: () => new Worker(
  new URL('./worker.ts', import.meta.url),
  { type: 'module' }
)

Without a Worker

If you don't pass worker, Dendrite uses CreateMLCEngine (main thread mode). This is the default and requires no extra files:

// This just works — no worker needed
const neuron = createNeuron({
  modelId: 'gemma-2-2b-it-q4f16_1-MLC',
  systemPrompt: 'You are a pirate.',
})

Framework Notes

Vite (Vue, React, Svelte)

Works out of the box. Place worker.ts anywhere in src/.

Next.js

Place the worker in public/worker.js (compiled JS, not TS):

worker: new Worker('/worker.js', { type: 'module' })

Webpack

With webpack 5, the new URL() pattern works natively:

worker: new Worker(
  new URL('./worker.ts', import.meta.url),
  { type: 'module' }
)