Flue agents on Render

A Render template for hosting Flue agents as webhook endpoints. Each TypeScript file in .flue/agents/ becomes a POST /agents// route on a single Node.js web service, with built-in streaming, structured outputs, and session continuity. This template ships two webhook-triggered agents, a single render.yaml Blueprint, and the Node.js build target so the entire stack deploys as one Render web service.

What's included

Component	Description
Translate agent	Translates text between languages and returns a typed result (translation + confidence) using a valibot schema.
Assistant agent	A general-purpose conversational agent. Continues the same conversation when you reuse the agent ID in the request URL.
Bundled HTTP server	flue build --target node produces a single self-contained dist/server.mjs that exposes every webhook agent as POST /agents/<name>/<id>.
One-click deploy	A render.yaml Blueprint that provisions the web service with the right build, start, and health check settings.

Project structure

.
├── .flue/
│   └── agents/
│       ├── translate.ts      # Webhook agent — structured translation
│       └── assistant.ts      # Webhook agent — conversational replies
├── AGENTS.md                 # Default system prompt for every agent
├── .env.example              # Provider keys for local development
├── package.json
├── render.yaml               # Render Blueprint (web service)
└── tsconfig.json

Flue discovers agents from .flue/agents/. Each file exports a default async handler and a triggers object — { webhook: true } exposes the agent over HTTP. See the Flue README for the full agent API.

Deploy to Render

1. Click the Deploy to Render button above (or use this link).
2. Set the ANTHROPIC_API_KEY environment variable to your Anthropic API key.
3. Click Apply to create the web service.

Render runs npm ci --include=dev && npm run build (which calls flue build --target node), then starts the bundled server with node dist/server.mjs. The --include=dev flag is needed because @flue/cli is a build-time dependency and NODE_ENV=production would otherwise skip it. Render injects PORT and Flue's Hono server binds to it automatically. The /health endpoint backs the health check.

Note: This Blueprint uses Render's free plan, which spins down after 15 minutes of inactivity. For production traffic, change plan: free to plan: starter (or higher) in render.yaml before deploying.

Important: Webhook agents in this template are unauthenticated. Anyone who finds your service URL can invoke the agents and incur LLM provider costs on your account. Flue does not ship built-in auth, and its handler context does not expose request headers. Before you point real traffic at this service, do at least one of the following:

• Add an in-payload shared-secret check inside each agent (read a token from payload and compare against an env var set with generateValue: true).
• Front the service with an authenticated reverse proxy or API gateway.
• Move the Flue service to a Render private service and gate access with another web service that handles auth.

A follow-up template that pairs Flue with a pserv and a small auth front door is on the roadmap.

Run locally

Prerequisites

• Node.js 22 or later
• An Anthropic API key

Install and configure

git clone https://github.com/render-examples/flue.git
cd flue
npm install
cp .env.example .env

Edit .env and set your ANTHROPIC_API_KEY:

ANTHROPIC_API_KEY=sk-ant-...

Start the dev server

npm run dev

Flue's dev server starts at http://localhost:3583 and rebuilds on file changes. Edit an agent under .flue/agents/, save, and the next request picks up your change.

API usage

Every webhook agent is exposed at POST /agents/<agent-name>/<id>. The <id> is the session ID — reuse it to continue a conversation, or generate a new one to start fresh.

Translate agent

curl -X POST http://localhost:3583/agents/translate/demo \
  -H "Content-Type: application/json" \
  -d '{"text": "Hello world", "language": "French"}'

The response includes the typed result that matches the agent's valibot schema:

{
  "result": {
    "translation": "Bonjour le monde",
    "confidence": "high"
  }
}

Assistant agent

curl -X POST http://localhost:3583/agents/assistant/session-abc \
  -H "Content-Type: application/json" \
  -d '{"message": "What is the capital of Japan?"}'

Send another request to the same session-abc ID to continue the same thread:

curl -X POST http://localhost:3583/agents/assistant/session-abc \
  -H "Content-Type: application/json" \
  -d '{"message": "And how many people live there?"}'

Use a different ID (session-xyz, user-42, a UUID — whatever makes sense for your app) to start a separate conversation.

Streaming responses

Pass Accept: text/event-stream to receive Server-Sent Events with progress updates as the agent runs:

curl -N -X POST http://localhost:3583/agents/assistant/demo \
  -H "Content-Type: application/json" \
  -H "Accept: text/event-stream" \
  -d '{"message": "Plan a 3-day trip to Tokyo."}'

Fire-and-forget mode

Pass X-Webhook: true to receive an immediate 202 Accepted response. The agent runs in the background:

curl -X POST http://localhost:3583/agents/assistant/job-1 \
  -H "Content-Type: application/json" \
  -H "X-Webhook: true" \
  -d '{"message": "Summarize this week's GitHub issues."}'

Configuration

Switch the model

Both agents read the default model from the MODEL_ID environment variable (provider/model-id format). Override it on your Render service or in your local .env:

Provider	Example MODEL_ID	Required key
Anthropic (default)	anthropic/claude-sonnet-4-6	ANTHROPIC_API_KEY
OpenAI	openai/gpt-5.5	OPENAI_API_KEY
OpenRouter	openrouter/moonshotai/kimi-k2.6	OPENROUTER_API_KEY

Each agent calls init({ model: env.MODEL_ID ?? 'anthropic/claude-sonnet-4-6' }), so the env var wins and the hardcoded default keeps the agent runnable if the var is unset. To override the model for a single call (without changing the agent default), pass { model: '...' } directly to session.prompt() or session.skill().

Add an agent

Drop a new file into .flue/agents/ with a default export and a triggers definition:

// .flue/agents/summarize.ts
import type { FlueContext } from '@flue/sdk/client';
import * as v from 'valibot';

export const triggers = { webhook: true };

export default async function ({ init, payload }: FlueContext) {
  const agent = await init({ model: 'anthropic/claude-sonnet-4-6' });
  const session = await agent.session();
  return await session.prompt(`Summarize in one sentence:\n\n${payload.text}`);
}

Redeploy and the agent is reachable at POST /agents/summarize/<id>.

Customize the system prompt

AGENTS.md at the repo root is the default system prompt for every agent. Edit it to set tone, response style, or guardrails that apply across the project. For per-agent overrides, define a role under .flue/roles/<role>.md and pass { role: '<role>' } to session.prompt().

Add tools, skills, or sandboxes

Flue supports custom tool definitions, markdown-defined skills under .agents/skills/, MCP servers via connectMcpServer(), and full container sandboxes through connectors like Daytona. See the Flue README for examples.

How the deploy works

Step	What happens
Build	npm ci --include=dev && npm run build installs dependencies (including @flue/cli from devDependencies) and runs flue build --target node, which discovers agents in .flue/agents/ and emits a single bundled dist/server.mjs plus a dist/manifest.json.
Start	node dist/server.mjs starts a Hono HTTP server. It registers /health, /agents (manifest), and /agents/:name/:id for every webhook agent.
Port	The server reads process.env.PORT (Render injects this) and binds to all interfaces.
Shutdown	The server handles SIGTERM and SIGINT for clean rollouts during Render deploys.

Limits

• No authentication. Webhook endpoints are publicly invokable. See the Deploy to Render section for mitigation options.
• Flue's Node.js target stores session message history in memory. Sessions reset on every restart or deploy. For durable sessions, use the Cloudflare target (Durable Objects) or supply a custom session store.
• dist/ is rebuilt on every deploy; nothing in dist/ should be committed to git.
• The free plan in render.yaml is fine for trying the template but not for production traffic. Upgrade the plan or set up autoscaling for sustained workloads.

Learn more

• Flue framework
• Flue on GitHub
• Render web services
• Render Blueprints
• valibot schema validation