Agent Flow is a real-time visualization tool for monitoring AI agent orchestration, specifically designed for Claude Code and Codex sessions. It captures agent events via hook scripts and file tailing, processes them through a simulation layer, and renders an interactive node graph showing agent relationships, tool calls, discoveries, and performance metrics. The system comprises three main components: a VS Code extension for editor integration, a standalone Node.js server for direct use, and a Next.js-based web application serving as the core visualization frontend. Events are transmitted via Server-Sent Events (SSE) from a relay server to the frontend, which uses React with Tailwind CSS and d3-force for physics-based layout. Key features include live monitoring, timeline scrubbing, session replay, file attention tracking, token usage visualization, and stress testing scenarios. The architecture emphasizes performance through ref-based state management, memoized computations, and virtualized lists for handling large event logs.