Super Harness

Super Harness is an ecosystem plugin for building and operating multi-agent applications. It adds a supervisor/subagent runtime with durable session trees, human-in-the-loop approvals, and full-fidelity streaming over your existing super-line connection.

What it adds

Super Harness contributes the harness request and event surface plus four typed collections: harness.threads, harness.nodes, harness.tools, and harness.membership. It works alongside your own contract, handlers, authentication, and collections backend; it doesn't require a second service or client connection.

Add it to your server

Merge the contract fragment, mount the server plugin, and provide the same collections backend and authenticated principal that your application uses.

import { defineContract, defineSurface } from '@super-line/core'
import { createSuperLineServer } from '@super-line/server'
import { memoryCollections } from '@super-line/collections-memory'
import { createHarness } from '@super-harness/core'
import { harness } from '@super-harness/server'
import { harnessContract } from '@super-harness/shared'

const app = defineContract({
  plugins: [harnessContract()],
  shared: defineSurface({}),
  roles: { user: {} },
})

const engine = createHarness({ supervisor, subagents: [{ agent: researcher }] })

const server = createSuperLineServer(app, {
  transports,
  collections: memoryCollections(),
  authenticate,
  identify: (connection) => connection.ctx.userId,
  plugins: [harness(engine)],
})

identify is required for the harness's membership-based row-level security. Without it, clients can connect but can't read their session tree. The harness owns its harness.* handlers, so they are removed from your implement() obligation.

Harness or plugin-chat?

If the application you're building is chat-shaped — channels, streaming agent messages, shared channel resources a human and an agent co-edit — @super-line/plugin-chat now covers that ground natively. The chat-supervisor example rebuilds the Super Harness supervisor/worker flow on super-line alone — no bespoke harness, no bespoke canvas store; see Run an AI chat bot for the agent side.

Super Harness remains the fuller agent runtime: reach for it when you need durable session trees, human-in-the-loop approvals, or full-fidelity streaming at every depth of a subagent tree.

Learn more

For package installation, prerequisites, standalone hosting, React bindings, and complete examples, read the Super Harness documentation or browse the Super Harness repository.

To understand how this integration composes with the host application, read the plugin model and Build a plugin.