Eko is a TypeScript framework for building production-ready AI agents that can automate workflows across browser, Node.js, and web extension environments. The core orchestration engine (Eko class) takes a natural language task, uses an LLM to generate a multi-agent workflow plan encoded as XML, then executes it with parallel/serial agent execution, replanning, and human-in-the-loop support. The system provides a clean abstraction over LLM providers (OpenAI, Anthropic, etc.) with retry and fallback, a ReAct tool-calling loop, and built-in browser automation agents that operate via screenshots or DOM labels. It also includes MCP client implementations (SSE, HTTP, stdio) for integrating external tools, and a chat agent for conversational interactions with tool delegation. The architecture is modular with separate npm packages: @eko-ai/eko-core (core engine), @eko-ai/eko-nodejs (Playwright-based browser agent), @eko-ai/eko-extension (Chrome extension agent), and @eko-ai/eko-web (web environment agent). The repository includes working examples (Chrome extension with side panel, Node.js automation using Playwright, and a React web app). The framework is designed for developers who want to automate complex, multi-step tasks using language models, with a focus on reliability, human oversight, and extensibility via custom agents and tools.