Vibe first.
Then FastAgent.

// anywhere in your codebase — a job, a queue consumer, a test
import { collect } from "@fastagent-sh/fastagent";

const { text } = await collect(
  agent.invoke({ session: "job-42" }, { text: "summarize today's failures" })
);

// app/api/invoke/route.ts
import { createInvokeHandler, createPiAgentFromDefinition } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "openai-codex/gpt-5.5",
});

export const POST = createInvokeHandler(agent);
export const runtime = "nodejs";

// app.ts
import { Hono } from "hono";
import { createInvokeHandler, createPiAgentFromDefinition } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "anthropic/claude-sonnet-4",
});

const app = new Hono();
app.post("/invoke", createInvokeHandler(agent));

export default app;

// app.ts
import express from "express";
import { createInvokeHandler, createPiAgentFromDefinition, nodeListener } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "anthropic/claude-sonnet-4",
});

const app = express();
app.post("/invoke", nodeListener(createInvokeHandler(agent))); // no body parser on this route
app.listen(8787);

// src/pages/api/invoke.ts
import { createInvokeHandler, createPiAgentFromDefinition } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "openai-codex/gpt-5.5",
});

export const POST = createInvokeHandler(agent);

// server/api/invoke.post.ts
import { createInvokeHandler, createPiAgentFromDefinition } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "openai-codex/gpt-5.5",
});
const handler = createInvokeHandler(agent);

export default defineEventHandler((event) => handler(toWebRequest(event)));

// src/routes/invoke/+server.ts
import { createInvokeHandler, createPiAgentFromDefinition } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "anthropic/claude-sonnet-4",
});
const handler = createInvokeHandler(agent);

export const POST = ({ request }) => handler(request);

// server.ts — keep the body stream unread, hijack the reply
import { createInvokeHandler, createPiAgentFromDefinition, nodeListener } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "openai-codex/gpt-5.5",
});
const listener = nodeListener(createInvokeHandler(agent));

app.register(async (scope) => {
  scope.removeAllContentTypeParsers();
  scope.addContentTypeParser("*", (_req, payload, done) => done(null, payload));
  scope.post("/invoke", (req, reply) => { reply.hijack(); listener(req.raw, reply.raw); });
});

// server.ts
import { createInvokeHandler, createPiAgentFromDefinition } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "openai-codex/gpt-5.5",
});

const invoke = createInvokeHandler(agent);

Bun.serve({
  port: 8787,
  fetch(req) {
    const url = new URL(req.url);
    return url.pathname === "/invoke" ? invoke(req) : new Response("ok");
  },
});

// server.ts
import { createInvokeHandler, createPiAgentFromDefinition, router, serveNode } from "@fastagent-sh/fastagent";

const { agent } = await createPiAgentFromDefinition("./agent", {
  model: "openai-codex/gpt-5.5",
});

serveNode(router({ "POST /invoke": createInvokeHandler(agent) }), { port: 8787 });