TL;DR
Flue is a TypeScript harness framework for building autonomous agents, providing a secure environment for agents to use tools, modify files, and complete complex tasks autonomously.
Key features
Agents: Maintain context across conversations and events while working autonomously toward a goal
Workflows: Run structured automations where code guides agent reasoning
Sandboxes: Secure environment for agents to use tools and modify files
Durable Execution: Preserve progress through failures and restarts
Subagents: Define specialized roles and delegate tasks
Tools: Type-safe actions for calling APIs, querying data, etc.
Skills: Package reusable expertise and workflows
MCP Servers: Connect to the Model Context Protocol ecosystem
Observability: Integrate with OpenTelemetry, Sentry, etc.
Channels: Receive verified events from Slack, Teams, Discord, GitHub
When to use it
When building AI agents that autonomously perform complex tasks
When agents need to use tools and files in a secure sandbox environment
When multi-agent collaboration or structured workflows are required