Sub-agents

import { createAgent } from '@lousho/build-ai-agent';

const researcher = createAgent({
  provider,
  instructions: 'You research a question and report your sources.',
  description: 'Finds and summarizes sources',
});
const writer = createAgent({
  provider,
  instructions: 'You write clear, short articles.',
  description: 'Turns notes into a polished article',
});

const lead = createAgent({
  provider,
  instructions: 'You coordinate research and writing.',
  subagents: { researcher, writer },
});

const { text } = await lead.send('Write a short article about the history of the bicycle.');

The first bicycles appeared in the 1810s ...

[sub-agent 'researcher': 3 step(s), finish reason 'stop', taskId 'task_1']

import { createAgent } from '@lousho/build-ai-agent';
import { SqliteStore } from '@lousho/build-ai-agent/sqlite';

const store = new SqliteStore('./.lousho/agent.db');
const researcher = createAgent({ provider, instructions: 'You research.', description: 'Finds and summarizes sources' });
const lead = createAgent({ provider, instructions: 'You coordinate research.', store, subagents: { researcher } });

const chat = lead.session({ id: 'user-42' });
await chat.send('Research the history of the bicycle.'); // the lead calls task -> taskId 'task_1'
await chat.send('Ask the researcher which source it trusted most.'); // the lead calls task({ taskId: 'task_1', ... })

import { createAgent } from '@lousho/build-ai-agent';

const researcher = createAgent({ provider, instructions: 'You research.', description: 'Finds and summarizes sources' });

const lead = createAgent({
  provider,
  instructions: 'You coordinate research.',
  subagents: { researcher },
  subagentOptions: { maxConcurrent: 2, awaitBackgroundOnFinish: true },
});

import { createAgent } from '@lousho/build-ai-agent';

const researcher = createAgent({ provider, instructions: 'You research.', description: 'Finds and summarizes sources' });
const lead = createAgent({ provider, instructions: 'You coordinate research.', subagents: { researcher } });

const result = await lead.send('Research three topics in the background.');
for (const task of result.backgroundTasks ?? []) {
  console.log(task.taskId, task.agent, task.status); // e.g. task_1 researcher cancelled
}

import { createAgent, type SubagentCatalog } from '@lousho/build-ai-agent';

const experts = new Map([
  ['researcher', createAgent({ provider, instructions: 'You research.' })],
]);

const catalog: SubagentCatalog = {
  list: async () => [{ name: 'researcher', description: 'Finds and summarizes sources' }],
  resolve: async (name) => experts.get(name),
};

const lead = createAgent({ provider, instructions: 'You coordinate.', subagents: catalog });

import { createAgent, remoteAgent } from '@lousho/build-ai-agent';

const lead = createAgent({
  provider,
  instructions: 'You coordinate.',
  subagents: {
    researcher: remoteAgent({
      url: 'https://researcher.example.workers.dev',
      auth: process.env.RESEARCHER_TOKEN, // the deployment's LOUSHO_API_TOKEN; or () => string | Promise<string>
      description: 'Finds and summarizes sources',
    }),
  },
});

import type { SimpleAgent } from '@lousho/build-ai-agent';
declare const lead: SimpleAgent; // the lead agent above

const paused = await lead.send('Deploy the docs site');
if (paused.finishReason === 'awaiting-approval') {
  const [pending] = await lead.approvals.list(); // e.g. { toolName: 'deploy', args: {...}, subagentPath: ['researcher'] }
  const result = await lead.approvals.resolve({ id: pending.id, approved: true });
  console.log(result.text);
}

import { HookRegistry } from '@lousho/build-ai-agent';

const hooks = new HookRegistry();
hooks.register({
  name: 'audit',
  preToolCall(ctx) {
    if (ctx.subagent) return; // top-level tool calls only
    console.log('tool call', ctx.toolName, ctx.args);
  },
});

import { AgentExecutor, resumeAfterApproval, ToolRegistry, createAgent } from '@lousho/build-ai-agent';

const subagents = { researcher: createAgent({ provider, instructions: 'You research.', description: 'Researches' }) };

const paused = await AgentExecutor.execute({ agent, input: 'Go', provider, subagents, approvalStore });
if (paused.finishReason === 'awaiting-approval' && paused.approvalId) {
  const result = await resumeAfterApproval(
    { id: paused.approvalId, approved: true },
    approvalStore,
    new ToolRegistry(),
    provider,
    { subagents }
  );
  console.log(result.text);
}

import { AgentExecutor, createDelegateTool, ToolRegistry } from '@lousho/build-ai-agent';

const billingAgent = {
  name: 'Billing Agent',
  prompt: 'You answer billing questions and look up invoices.',
};

const registry = new ToolRegistry();
registry.register(
  'delegate_billing_agent',
  createDelegateTool({
    agent: billingAgent,
    provider,
    contextMode: 'none', // 'full-history' shares the parent's context array too
    maxSteps: 10,
    maxDepth: 3, // bounds a delegation chain (e.g. A -> B -> A) before it throws
  })
);

const supportAgent = {
  name: 'Support Agent',
  prompt: 'You help customers. Delegate billing questions to the billing agent.',
  tools: { delegate_billing_agent: { tool: 'delegate_billing_agent' } },
};

const result = await AgentExecutor.execute({
  agent: supportAgent,
  input: 'Why was I charged twice this month?',
  provider,
  toolRegistry: registry,
});