flue README

The project's README from github.com/withastro/flue. As one markdown file: README.md.

Flue — The Agent Harness Framework

Not another SDK. Build autonomous agents with Flue's programmable TypeScript harness.

// agents/triage.ts
'use agent';
import { useModel, useSandbox, useSkill, useTool } from '@flue/runtime';
import { local } from '@flue/runtime/node';
import triage from '../skills/triage/SKILL.md';
import verify from '../skills/verify/SKILL.md';
import { openIssue, searchCode } from '../tools/github.ts';

// The agent IS the function. Compose the complete harness it needs to do
// real work, complete with virtual, local, or remote container sandbox.
export function Triage() {
  useModel('anthropic/claude-sonnet-4-6');
  useSandbox(local());
  useSkill(triage);
  useSkill(verify);
  useTool(openIssue);
  useTool(searchCode);

  // Give agents the context and autonomy to solve complex tasks:
  return `
Triage a bug report end-to-end: reproduce the bug,
diagnose the root cause, verify whether the behavior is
intentional, and attempt a fix.

...`;
}

The framework for building the next generation of agents.

The first agents were built with raw LLM API calls. This worked for simple chatbots and scripted tasks, but not much else.

Agents like Claude Code and Codex broke the mold. These were real agents. Autonomous. You give them a task — not a pre-defined series of steps — and trust them to complete it using the context and tools that you provide.

Flue unlocks this new architecture for agents. Its built-in TypeScript harness gives any model the context and environment it needs for truly autonomous work: sessions, tools, skills, instructions, filesystem access, and a secure sandbox to run in. Run your agents locally via CLI or deploy them to your hosted runtime of choice.

Features

Build agents that can safely take action, maintain continuity, and connect to the systems where work already happens.

Deploy Anywhere

Packages

Package Description
@flue/runtime Runtime: harness, sessions, tools, sandbox
@flue/vite Vite plugin: vite dev / vite build for Node and Cloudflare
@flue/cli CLI (flue binary): local runs, blueprints, offline docs
@flue/sdk Client SDK for consuming deployed agent conversations
@flue/opentelemetry OpenTelemetry tracing adapter
@flue/postgres Postgres persistence adapter

flue (withastro/flue)

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Flue
What is this?Flue is a TypeScript framework for building autonomous AI agents that get a secure sandbox, sessions, tools, skills, and filesystem access instead of just raw LLM API calls.
Is this a framework or an SDK?Flue describes itself as an agent harness framework, not an SDK — it ships the runtime, tools, sandbox, and session management itself rather than just wrapping LLM calls.
How do I start building an agent with Flue?You pull in the @flue/cli package to get the 'flue' binary for local runs, blueprints, and offline docs, and @flue/vite for 'vite dev'/'vite build' support on Node or Cloudflare.
What do I need installed to work with the Flue monorepo?Node.js 22+ and pnpm 11.x are required; the core runtime itself depends on 'just-bash' and 'valibot'.
Does an agent need extra setup to survive restarts?To keep progress through failures and restarts, you need the durability feature backed by a persistence adapter like @flue/postgres — without it, recovery isn't automatic.
Where can I actually deploy a Flue agent?Agents can run locally via the CLI or be deployed to Node.js, Cloudflare Workers, GitHub Actions, GitLab CI/CD, Daytona, or Render.
What are Skills in Flue?Skills are reusable packages of expertise and workflows that an agent can load whenever a task needs specialized guidance, similar to how Claude Code skills work.
What's the difference between tools and subagents?Tools are typed actions for calling APIs or making controlled changes, while subagents are specialized roles your main agent can delegate entire tasks to.
Can I connect agents to Slack or GitHub?Yes — Flue's Channels feature lets agents receive verified events from Slack, Microsoft Teams, Discord, GitHub, and more.
How do I monitor what my agents are doing in production?Flue exports OpenTelemetry traces and has built-in integrations for Braintrust and Sentry, or you can plug in your own observer.
What are similar projects?ruflo, open-multi-agent, trueforge, turnstone, Observal, cayu, tardigrade, go-micro
Which topics is it in?sentry, turborepo, durable-execution, tracing, telemetry, subagents, pnpm, cloudflare-workers, ci-cd, agent-framework, harness, github-actions
Creator
withastro
Size
18.6 MB
Stars
8.5K
Updated
CommitOct 12Release@flue/[email protected]Sep 28
Age
8mo
Commits · 90 Days