Harnesses with Terminal UI

@ai-sdk/tui can render harness streams, tool calls, reasoning sections, and approval prompts in a terminal. Because HarnessAgent requires a session on every call, wrap it with a small AgentTUIAgent adapter that injects one session for the lifetime of the terminal UI.

Installation 

pnpm add @ai-sdk/tui @ai-sdk/harness @ai-sdk/harness-codex @ai-sdk/sandbox-vercel

Example

tui.ts
import { HarnessAgent, type HarnessAgentSession } from '@ai-sdk/harness/agent';
import { codex } from '@ai-sdk/harness-codex';
import { createVercelSandbox } from '@ai-sdk/sandbox-vercel';
import { runAgentTUI, type AgentTUIAgent } from '@ai-sdk/tui';


const agent = new HarnessAgent({
  harness: codex,
  sandbox: createVercelSandbox({
    runtime: 'node24',
    ports: [4000],
  }),
});


function createTUIAgent({
  agent,
  session,
}: {
  agent: HarnessAgent<any, any, any>;
  session: HarnessAgentSession;
}): AgentTUIAgent {
  return {
    version: 'agent-v1',
    id: agent.id,
    tools: agent.tools,
    generate(request) {
      return agent.generate({
        ...request,
        session,
      } as Parameters<typeof agent.generate>[0]);
    },
    stream(request) {
      return agent.stream({
        ...request,
        session,
      } as Parameters<typeof agent.stream>[0]);
    },
  } as AgentTUIAgent;
}


const session = await agent.createSession();


try {
  await runAgentTUI({
    title: 'Codex',
    agent: createTUIAgent({ agent, session }),
    tools: 'auto-collapsed',
    reasoning: 'collapsed',
  });
} finally {
  await session.destroy();
}

The terminal UI runs until the user exits with Esc or Ctrl+C.

Use one session per terminal run. For long-lived terminal tools, persist the state from session.detach() or session.stop() if you need to resume later.