Flue is a sandbox agent framework that enables developers to build autonomous agents in TypeScript with built-in harness capabilities for context management, tool integration, and secure execution environments.
The framework addresses the challenge of building truly autonomous agents that can maintain context across conversations, take real actions safely, and work toward goals without pre-defined step sequences. Rather than wrapping raw LLM API calls, Flue provides a programmable TypeScript harness that gives agents the infrastructure they need: persistent sessions, typed tools for controlled actions, skills for reusable expertise, filesystem access within sandboxes, and durable recovery mechanisms that preserve progress through failures. Agents can delegate specialized work to subagents, connect to external services through Model Context Protocol servers, and receive verified events from communication platforms like Slack, Teams, Discord, and GitHub.
Flue suits teams building production agents that need to perform real work autonomously while maintaining safety and observability. The framework is designed for developers comfortable with TypeScript who want to move beyond simple chatbot patterns toward agents that can manage complex, multi-step tasks with continuity. The tool supports flexible deployment across Node.js, Cloudflare Workers, GitHub Actions, GitLab CI/CD, and other platforms, making it adaptable to different infrastructure choices. Observability is built in, with support for exporting telemetry through OpenTelemetry, Braintrust, Sentry, or custom observers.
The project shows active development with regular updates to core functionality and ecosystem integrations. The codebase maintains focus on the agent harness architecture rather than expanding into unrelated domains. Documentation is comprehensive and organized around key concepts like agents, sandboxes, durability, and tool integration, suggesting sustained investment in developer experience.
