Build an AI Agent in Typescript / lesson 3 of 8

Subagents

Unlock scalable AI automation by teaching your local coding agent to deploy sub-agents

Unlock scalable AI automation by teaching your local coding agent to deploy sub-agents, solving context window blowup and enabling true delegation. Build multi-agent systems on Apple Silicon Macs that handle complex software development tasks without performance bottlenecks.

First we’ll move some stuff around to make it more modular

import { createOpenAI } from "@ai-sdk/openai";
import { generateText, isLoopFinished } from "ai";
import type { ModelMessage } from "ai";
import * as readline from "readline";
import { TOOLS } from './tools'
import { api, MODEL, WORKDIR } from './config'

/** CONSTANTS */
const WORKDIR = process.cwd();
const MODEL = "qwen3.5:35b-a3b-coding-nvfp4";

/** API */
const ollama = createOpenAI({
  baseURL: "http://localhost:11434/v1",
  apiKey: "ollama",
});

...

/** AGENT LOOP */

const agentLoop = async (messages: ModelMessage[]): Promise<string> => {
  const { text } = await generateText({
    model: ollama.chat(MODEL),
    model: api.chat(MODEL),
    system: `You are a coding agent at ${WORKDIR}. Use tools to solve tasks.  Act, dont explain.`,
    messages,
    tools: TOOLS,
    stopWhen: isLoopFinished(),
  });
  return text;
};

prompt();

And we’ll create a new module called config.ts

import { createOpenAI, generateText } from "@ai-sdk/openai";

/** CONSTANTS */
export const WORKDIR = process.cwd();
export const MODEL = "qwen3.5:35b-a3b-coding-nvfp4";

/** API */
export const api = createOpenAI({ // renamed from ollama -> api
  baseURL: "http://localhost:11434/v1",
  apiKey: "ollama",
});

Now we’ll create our new tool in tools.ts

import { tool, zodSchema } from "ai";
import { tool, zodSchema, generateText, isLoopFinished } from "ai";
import {z} from "zod":
import { spawnSync } from "node: child_process";
import { api, MODEL, WORKDIR } from './config'

/** CONSTANTS */
const WORKDIR = process.cwd();
const BLOCKED_COMMANDS = ["rm -rf /", "sudo", "shutdown", "reboot", "> /dev/"];

const safePath = (p: string) => {
  const resolved = path.resolve(WORKDIR, p);
  if (!resolved.startsWith(WORKDIR)) {
    throw new Error(`Path is not in ${WORKDIR}`);
  }
  return resolved;
};

/** TOOLS */
const runBash = (command: string): string => {/* ... */};

const runRead = (filePath: string, limit?: number) => {/* ... */};

const runWrite = (filePath: string, content: string) => {/* ... */};

const runEdit = (filePath: string, oldText: string, newText: string) => {/* ... */};

export const TOOLS = {
  /* ... */
};

const runSubagent = async (prompt: string): Promise<string> => {
  const { text } = await generateText({
    model: api.chat(MODEL),
    system: `You are a coding subagent at ${WORKDIR}. Complete your given task, then summarize your findings.`,
    messages: [
      {
        role: "user",
        content: prompt,
      },
    ],
    tools: TOOLS,
    stopWhen: isLoopFinished(),
  });
  return text;
};

export const PARENT_TOOLS = {
  ...TOOLS,
  task: tool({
    description:
      "Spawn a subagent with fresh context, it shares the file system, but not the conversation history",
    inputSchema: zodSchema(
      z.object({
        task: z.string(),
      }),
    ),
    execute: async ({ task }) => await runSubagent(task),
  }),
};

Finally we’ll add our new PARENT_TOOLS to the index.ts

import { createOpenAI } from "@ai-sdk/openai";
import { generateText, isLoopFinished } from "ai";
import type { ModelMessage } from "ai";
import * as readline from "readline";
import { TOOLS } from './tools'
import { PARENT_TOOLS } from './tools'
import { api, MODEL, WORKDIR } from './config'

...

/** AGENT LOOP */

const agentLoop = async (messages: ModelMessage[]): Promise<string> => {
  const { text } = await generateText({
    model: api.chat(MODEL),
    system: `You are a coding agent at ${WORKDIR}. Use tools to solve tasks.  Act, dont explain.`,
    messages,
    tools: TOOLS,
    tools: PARENT_TOOLS,
    stopWhen: isLoopFinished(),
  });
  return text;
};

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