@ai-sdk/harness-deepagents

A HarnessV1 adapter that runs Deep Agents (LangChain's LangGraph-based agent harness) as a coding-agent runtime inside an AI SDK sandbox.

This is a bridge-backed harness: the Deep Agents runtime runs inside the sandbox via a Node bridge (node bridge.mjs) built on the shared @ai-sdk/harness/bridge runtime, while the host adapter drives turns over a WebSocket.

Status: happy-path validated. The host adapter (doStart + session: doPromptTurn/doStop/doDestroy) and the Node bridge (driving the deepagents npm package via createDeepAgent + streamEvents) are validated end-to-end against a live Vercel Sandbox: text generation, streaming, multi-turn memory, and host-executed tools all work. Turn continuation, suspend/detach, cross-process resume, and built-in tool approvals throw HarnessCapabilityUnsupportedError and are follow-ups.

Setup

pnpm add @ai-sdk/harness-deepagents @ai-sdk/harness

The harness installs the bridge's Node dependencies (the deepagents package and LangChain) into its bootstrap directory via pnpm at startup.

Usage

import { HarnessAgent } from '@ai-sdk/harness/agent';
import { deepAgents } from '@ai-sdk/harness-deepagents';

const agent = new HarnessAgent({
  harness: deepAgents,
  // ...sandbox provider configuration
});

Configure the model and auth via createDeepAgents({ model, auth }).

Auth

Auth is optional and provider-aware: the provider is resolved from the model id (anthropic/… or openai/…, defaulting to Anthropic). With none configured the adapter falls back to ambient AI Gateway credentials (AI_GATEWAY_API_KEY, then VERCEL_OIDC_TOKEN), then ambient provider creds (ANTHROPIC_* / OPENAI_*). Pin explicitly with auth.anthropic, auth.openai, or auth.gateway:

createDeepAgents({
  model: 'openai/gpt-5',
  auth: { openai: { apiKey: process.env.OPENAI_API_KEY } },
});

Built-in tools

| Common name | Native (LangGraph) tool | | ----------- | ----------------------- | | read | read_file | | write | write_file | | bash | shell | | grep | search |

See the harness docs for broader concepts.