airb is an open-source CLI programming agent that helps developers build software using modern LLMs (OpenAI, Anthropic, Gemini). Built on a clean, composable architecture inspired by Stafford Beer's Viable System Model, it features streaming responses, structured tool calling, built-in file operations, and optional web-based observability. Designed for hackability with small objects, clear seams, and UNIXy ergonomics.